1. Structure of the larynx and trachea. Development,
topography, age peculiarities
2. Structure, topography and funct³on of lungs and
pleura. Mediastinum, its contents. Radiograph anatomy of digestive and respiratory organs
3. Urinary organs. External and
internal structure of kidney. Nephron morphological
and functional unit of kidney. Blood suplying.
Capsules and topography of kidney
Lesson No 15
Theme 1.
Structure of the larynx and trachea. Development,
topography, age peculiarities
The word “respiration” describes two processes.
Internal or cellular respiration is the process by which glucose or other small
molecules are oxidised to produce energy: this
requires oxygen and generates carbon dioxide. External respiration (breathing)
involves simply the stage of taking oxygen from the air and returning carbon
dioxide to it.
The respiratory tract, where external respiration
occurs, starts at the nose and mouth. (Description of respiratory tract from
nose to trachea here from overheads) (There is a brief complication where the
airstream crosses the path taken by food and drink in the pharynx: air flows on
down the trachea where food normally passes down the oesophagus
to the stomach. )
The trachea (windpipe) extends from the neck into
the thorax, where it divides into right and left main bronchi, which enter the
right and left lungs, breaking up as they do so into smaller bronchi and
bronchioles and ending in small air sacs or alveoli, where gaseous exchange
occurs.
The lungs are divided first into right and left,
the left being smaller to accommodate the heart, then into lobes (three on the
right, two on the left) supplied by lobar bronchi.
Bronchi, pulmonary arteries and veins (which
supply deoxygenated blood and remove oxygenated blood), bronchial arteries and
veins (which supply oxygenated blood to the substance of the lung itself) and lymphatics all enter and leave the lung by its root (or
hilum). Lymph nodes blackened by soot particles can often be seen here and the
substance of the lung itself may be blackened by soot in city dwellers or heavy
smokers.
Each lobe of the lung is further divided into a
pyramidal bronchopulmonary segments. Bronchopulmonary segments have the apex of the pyramid in
the hilum whence they receive a tertiary bronchus, and appropriate blood
vessels. The 10 segments of the right lung and eight of the left are virtually self contained units not in communication with other parts
of the lung. This is of obvious use in surgery when appropriate knowledge will
allow a practically bloodless excision of a diseased segment. Gaseous exchange
relies on simple diffusion. In order to provide sufficient oxygen and to get
rid of sufficient carbon dioxide there must be:
·
a large surface area for gaseous
exchange
·
a very short diffusion path between
alveolar air and blood
·
concentration
gradients for oxygen and carbon dioxide between alveolar air and blood.
The surface available in an adult is
around
·
ventilation (breathing) which renews
alveolar air, maintaining oxygen concentration near that of atmospheric air and
preventing the accumulation of carbon dioxide
·
the flow of blood in alveolar
capillaries which continually brings blood with low oxygen concentration and
high carbon dioxide concentration
Haemoglobin
in blood continually removes dissolved oxygen from the blood and binds with it.
The presence of this tennis court, separated from the outside air by a very
narrow barrier imposes demands on the respiratory tract.
Outside air:
·
varies
in temperature. At the alveolar surface it must be at body temperature
·
varies
from very dry to very humid. At the alveolar surface it must be saturated with
water vapour
·
contains
dust and debris. These must not reach the alveolar wall
·
contains
micro-organisms, which must be filtered out of the inspired air and disposed of
before they reach the alveoli, enter the blood and cause possible problems.
It is easy to see that the temperature and
humidity of inspired air will increase as it passes down a long series of tubes
lined with a moist mucosa at body temperature. The mechanisms for filtering are
not so obvious.
Mucus.
The respiratory tract, from nasal cavities to the smallest bronchi, is lined by
a layer of sticky mucus, secreted by the epithelium assisted by small ducted
glands. Particles which hit the side wall of the tract are trapped in this
mucus. This is encouraged by: (a) the air stream changing direction, as it
repeatedly does in a continually dividing tube. (b) random
(Brownian) movement of small particles suspended in the airstream.
The first of these works particularly well on
more massive particles, the second on smaller bits.
Length.
The length of the respiratory tract helps in both bringing the air to the right
temperature and humidity but hinders the actual ventilation, as a long tract
has a greater volume of air trapped within it, and demands a large breath to
clear out residual air.
Protection.
The entry of food and drink into the larynx is prevented by the structure of
the larynx and by the complicated act of swallowing. The larynx is protected by
three pairs of folds which close off the airway. In man these have a secondary function, they vibrate in the airstream to produce sounds,
the basis of speech and singing. Below the larynx the trachea is usually patent
i.e. open, and kept so by rings of cartilage in its walls. However it may be
necessary to ensure that this condition is maintained by passing a tube
(endotracheal intubation) to maintain the airway, especially post operatively
if the patient has been given a muscle relaxant. Another common surgical
procedure, tracheotomy, involves a small transverse cut in the neck. If this is
done with anatomical knowledge no major structure is disturbed and the opening
may be used for a suction tube, a ventilator, or in cases of tracheal
obstruction as a permanent airway.
Ventilation and perfusion .
The gills of fish and the lungs of birds allow water and air receptively to
flow continually over the exchanging surface. In common with all mammals humans
ventilate their lungs by breathing in and out. This reciprocal movement of air
is less efficient and is achieved by alternately increasing and decreasing the
volume of the chest in breathing. The body's requirements for oxygen vary
widely with muscular activity. In violent exercise the rate and depth of
ventilation increase greatly: this will only work in conjunction with increase
in blood flow, controlled mainly by the rich innervation of the lungs.. Gas exchange can be improved by breathing enriched air,
which produces significantly reduced times for track events. Inadequate gas
exchange is common in many diseases, producing respiratory distress.
Breathing works by making the cage bigger: the
pleural layers slide over each other and the pressure in the lung is decreased,
so air is sucked in. Breathing out does the reverse, the cage collapses and air
is expelled. The main component acting here is the diaphragm. This is a layer
of muscle which is convex above, domed, and squashed in the centre
by the heart. When it contracts it flattens and increases the space above it.
When it relaxes the abdominal contents push it up again. The proportion of
breathing which is diaphragmatic varies from person to person. For instance
breathing in children and pregnant women is largely diaphragmatic, and there is
said to be more diaphragmatic respiration in women than in men.
The process is helped by the ribs which move up
and out also increasing the space available. The complexity of breathing
increases as does the need for efficiency. In quiet respiration, say whilst
lying on ones back, almost all movement is diaphragmatic and the chest wall is
still. This will increase thoracic volume by 500-700ml. The expansion of the
lung deforms the flexible walls of the alveoli and bronchi and stretches the
elastic fibres in the lung. When the diaphragm
relaxes elastic recoil and abdominal musculature reposition the diaphragm
again.
Deeper respiration brings in the muscles of the
chest wall, so that the ribs move too.
We must therefore understand the skeleton and muscular system of the
thoracic wall. The 12 pairs of ribs pass around the thoracic wall, articulating
via synovial joints with the vertebral column - in fact two per rib. The ribs
then curve outwards then forwards and downwards and attach to the sternum via
the flexible costal cartilages. The first seven pairs of ribs (true ribs)
attach directly, the next five hitch a lift on each
other and the last two float i.e. are unattached. Costal cartilages are
flexible. The first rib is rather different, short, flattened above and below
and suspended beneath a set of fairly hefty muscles passing up into the neck,
the scalene muscles. Between the ribs run two sets of intercostal muscles, the
external intercostals running forward and downwards,
the internal intercostals running up and back. These
two muscle sheets thus run between ribs with fibres
roughly at right angles. When they contract each rib moves closer to its neighbours. Because the lowest ribs float, and the first
rib is suspended from the scalene muscles contraction of the intercostal
muscles tends to lift rib two towards rib 1, and so on. The ribs are all,
therefore pulled up towards the horizontal, increasing anteroom-posterior and
lateral thoracic diameters.
These movements are sometimes divided intopump handle movements, the rib abducting on its
vertebral joints and bucket handle movements, the rib rotating on its axis
around anterior and posterior attachments: these are not necessarily helpful.
With more and more effort put into deeper and deeper breathing the scalene
muscles of the neck contract, raising the first rib and hence the rest of the
cage, then other neck muscles and even those of the upper limb become involved.
A patient with difficulty in breathing often grips a table edge in order to stabilise the limbs so that their muscles can be used to
help in moving the thoracic wall.
Apparatus
Respiratorius; Respiratory System
The respiratory apparatus consists of
the larynx, trachea, bronchi, lungs, and pleuræ.
Development.—The rudiment of the respiratory
organs appears as a median longitudinal groove in the ventral wall of the
pharynx. The groove deepens and its lips fuse to form a septum which grows from
below upward and converts the groove into a tube, the laryngo-tracheal
tube, the cephalic end of which opens into the pharynx by a slit-like aperture
formed by the persistent anterior part of the groove. The tube is lined by entoderm from which the epithelial lining of the
respiratory tract is developed. The cephalic part of the tube becomes the
larynx, and its next succeeding part the trachea, while from its caudal end two
lateral outgrowths, the right and left lung buds, arise, and from them the
bronchi and lungs are developed. The first rudiment of the larynx consists of
two arytenoid swellings, which appear, one on either side of the cephalic end
of the laryngo-tracheal groove, and are continuous in
front of the groove with a transverse ridge (furcula
of His) which lies between the ventral ends of the third branchial
arches and from which the epiglottis is subsequently developed. After the
separation of the trachea from the esophagus the arytenoid swellings come into
contact with one another and with the back of the epiglottis, and the entrance
to the larynx assumes the form of a T-shaped cleft, the margins of the cleft
adhere to one another and the laryngeal entrance is for a time occluded. The
mesodermal wall of the tube becomes condensed to form the cartilages of the
larynx and trachea. The arytenoid swellings are differentiated into the
arytenoid and corniculate cartilages, and the folds
joining them to the epiglottis form the aryepiglottic
folds in which the cuneiform cartilages are developed as derivatives of the
epiglottis. The thyroid cartilage appears as two lateral plates, each chondrified from two centers and united in the mid-ventral
line by membrane in which an additional center of chondrification
develops. The cricoid cartilage arises from two cartilaginous centers, which
soon unite ventrally and gradually extend and ultimately fuse on the dorsal
aspect of the tube.
The opening of the pulmonary diverticulum lies
between the two fifth arch masses and behind a “central mass” in the middle
line—the proximal end of the diverticulum is compressed between the fifth arch
masses. The fifth arch is joined by the fourth to form a “lateral mass” on each
side of the opening, and these “lateral masses” grow forward and overlap the
central mass and so form a secondary transverse cavity, which is really a part
of the cavity of the pharynx. The two parts of the cavity of the larynx are
separated in the adult by a line drawn back along the vocal fold and then
upward along the border of the arytenoid eminence to the interarytenoid
notch. The arytenoid and cricoid are developed in the fifth arch mass. The
thyroid is primarily a fourth arch derivative, and if it has a fifth arch
element this is a later addition. The epiglottis is derived from the “central
mass,” and has a third arch element in its oral and upper aspect; the arch
value of the “central mass” is doubtful.
The right and left lung buds grow out behind the
ducts of Cuvier, and are at first symmetrical, but their ends soon become
lobulated, three lobules appearing on the right, and two on the left; these
subdivisions are the early indications of the corresponding lobes of the lungs.
The buds undergo further subdivision and ramification, and ultimately end in
minute expanded extremities—the infundibula of the lung. After the sixth month
the air-sacs begin to make their appearance on the infundibula in the form of
minute pouches. The pulmonary arteries are derived from the sixth aortic
arches. During the course of their development the lungs migrate in a caudal
direction, so that by the time of birth the bifurcation of the trachea is opposite
the fourth thoracic vertebra. As the lungs grow they project into that part of
the celom which will ultimately form the pleural
cavities, and the superficial layer of the mesoderm enveloping the lung
rudiment expands on the growing lung and is converted into the pulmonary
pleura.
The Larynx
The larynx or organ of voice is placed at the
upper part of the air passage. It is situated between the trachea and the root
of the tongue, at the upper and forepart of the neck, where it presents a
considerable projection in the middle line. It forms the lower part of the
anterior wall of the pharynx, and is covered behind by the mucous lining of
that cavity; on either side of it lie the great vessels of the neck. Its
vertical extent corresponds to the fourth, fifth, and sixth cervical vertebræ, but it is placed somewhat higher in the
female and also during childhood. Symington found that in infants between six
and twelve months of age the tip of the epiglottis was a little above the level
of the fibrocartilage between the odontoid process and body of the axis, and
that between infancy and adult life the larynx descends for a distance equal to
two vertebral bodies and two intervertebral fibrocartilages. According to Sappey the average measurements of the adult larynx are as
follows:
In males. In
females.
Length
Transverse diameter
Antero-posterior diameter
Circumference
Until
puberty the larynx of the male differs little in size from that of the female.
In the female its increase after puberty is only slight; in the male it
undergoes considerable increase; all the cartilages are enlarged and the
thyroid cartilage becomes prominent in the middle line of the neck, while the
length of the rima glottidis
is nearly doubled.
The
Cartilages of the Larynx (cartilagines laryngis) are nine in number, three single and three
paired, as follows: Thyroid. Two Corniculate. Cricoid. Two Cuneiform. Two Arytenoid. Epiglottis.
Ossification of cartilages commences about the
twenty-fifth year in the thyroid cartilage, and somewhat later in the cricoid
and arytenoids; by the sixty-fifth year these cartilages may be completely
converted into bone.
Ligaments.—The ligaments
of the larynx are extrinsic, i. e., those connecting
the thyroid cartilage and epiglottis with the hyoid bone, and the cricoid
cartilage with the trachea; and intrinsic, those which connect the several
cartilages of the larynx to each other.
Extrinsic Ligaments.—The
ligaments connecting the thyroid cartilage with the hyoid bone are the hyothyroid membrane, and a middle and two lateral hyothyroid ligaments.
Intrinsic Ligaments.—Beneath
the mucous membrane of the larynx is a broad sheet of fibrous tissue containing
many elastic fibers, and termed the elastic membrane of the larynx. It is
subdivided on either side by the interval between the ventricular and vocal
ligaments, the upper portion extends between the arytenoid cartilage and the
epiglottis and is often poorly defined; the lower part is a well-marked
membrane forming, with its fellow of the opposite side, the conus
elasticus which connects the thyroid, cricoid, and
arytenoid cartilages to one another. In addition the joints between the
individual cartilages are provided with ligaments.
The Conus Elasticus (cricothyroid membrane) is composed mainly of yellow elastic
tissue. It consists of an anterior and two lateral portions. The anterior part
or middle cricothyroid ligament (ligamentum
cricothyreoideum medium; central part of cricothyroid membrane) is thick and strong, narrow above
and broad below. It connects together the front parts of the contiguous margins
of the thyroid and cricoid cartilages. It is overlapped on either side by the An articular capsule, strengthened posteriorly by a
well-marked fibrous band, encloses the articulation of the inferior cornu of the thyroid with the cricoid cartilage on either
side.
Each
arytenoid cartilage is connected to the cricoid by a capsule and a posterior cricoarytenoid ligament. The capsule (capsula
articularis cricoarytenoidea)
is thin and loose, and is attached to the margins of the articular surfaces.
The posterior cricoarytenoid ligament (ligamentum cricoarytenoideum posterius) extends from the cricoid to the medial and back
part of the base of the arytenoid.
The thyroepiglottic ligament (ligamentum
thyreoepiglotticum) is a long, slender, elastic cord
which connects the stem of the epiglottis with the angle of the thyroid
cartilage, immediately beneath the superior thyroid notch, above the attachment
of the ventricular ligaments.
Movements.—The
articulation between the inferior cornu of the
thyroid cartilage and the cricoid cartilage on either side is a diarthrodial one, and permits of rotatory and gliding
movements. The rotatory movement is one in which the cricoid cartilage rotates
upon the inferior cornua of the thyroid cartilage
around an axis passing transversely through both joints. The gliding movement
consists in a limited shifting of the cricoid on the thyroid in different
directions.
The
articulation between the arytenoid cartilages and the cricoid is also a diarthrodial one, and permits of two varieties of movement:
one is a rotation of the arytenoid on a vertical axis, whereby the vocal
process is moved lateralward or medialward,
and the rima glottidis
increased or diminished; the other is a gliding movement, and allows the
arytenoid cartilages to approach or recede from each other; from the direction
and slope of the articular surfaces lateral gliding is accompanied by a forward
and downward movement. The two movements of gliding and rotation are
associated, the medial gliding being connected with medialward
rotation, and the lateral gliding with lateralward
rotation. The posterior cricoarytenoid ligaments
limit the forward movement of the arytenoid cartilages on the cricoid.
Interior of the Larynx.—The
cavity of the larynx (cavum laryngis)
extends from the laryngeal entrance to the lower border of the cricoid
cartilage where it is continuous with that of the trachea. It is divided into
two parts by the projection of the vocal folds, between which is a narrow
triangular fissure or chink, the rima glottidis. The portion of the cavity of the larynx above the
vocal folds is called the vestibule; it is wide and triangular in shape, its
base or anterior wall presenting, however, about its center the backward
projection of the tubercle of the epiglottis. It contains the ventricular
folds, and between these and the vocal folds are the ventricles of the larynx.
The portion below the vocal folds is at first of an elliptical form, but lower
down it widens out, assumes a circular form, and is continuous with the tube of
the trachea.
The
entrance of the larynx is a triangular opening, wide in front, narrow behind,
and sloping obliquely downward and backward. It is bounded, in front, by the
epiglottis; behind, by the apices of the arytenoid cartilages, the corniculate cartilages, and the interarytenoid
notch; and on either side, by a fold of mucous membrane, enclosing ligamentous
and muscular fibers, stretched between the side of the epiglottis and the apex
of the arytenoid cartilage; this is the aryepiglottic
fold, on the posterior part of the margin of which the cuneiform cartilage
forms a more or less distinct whitish prominence, the cuneiform tubercle.
The Ventricular Folds (plicœ
ventriculares; superior or false vocal cords) are two
thick folds of mucous membrane, each enclosing a narrow band of fibrous tissue,
the ventricular ligament which is attached in front to the angle of the thyroid
cartilage immediately below the attachment of the epiglottis, and behind to the
antero-lateral surface of the arytenoid cartilage, a
short distance above the vocal process. The lower border of this ligament,
enclosed in mucous membrane, forms a free crescentic
margin, which constitutes the upper boundary of the ventricle of the larynx.
The Vocal
Folds (plicœ vocales;
inferior or true vocal cords) are concerned in the production of sound, and
enclose two strong bands, named the vocal ligaments (ligamenta
vocales; inferior thyroarytenoid).
Each ligament consists of a band of yellow elastic tissue, attached in front to
the angle of the thyroid cartilage, and behind to the vocal process of the
arytenoid. Its lower border is continuous with the thin lateral part of the conus elasticus. Its upper border
forms the lower boundary of the ventricle of the larynx. Laterally, the Vocalis muscle lies parallel with it. It is covered
medially by mucous membrane, which is extremely thin and closely adherent to
its surface.
The Ventricle of the Larynx (ventriculus
laryngis [Morgagnii];
laryngeal sinus) is a fusiform fossa, situated between the ventricular and
vocal folds on either side, and extending nearly their entire length. The fossa
is bounded, above, by the free crescentic edge of the
ventricular fold; below, by the straight margin of the vocal fold; laterally,
by the mucous membrane covering the corresponding Thyreoarytænoideus.
The anterior part of the ventricle leads up by a narrow opening into a cecal pouch of mucous membrane of variable size called the
appendix.
The
appendix of the laryngeal ventricle (appendix ventriculi
laryngis; laryngeal saccule)
is a membranous sac, placed between the ventricular fold and the inner surface
of the thyroid cartilage, occasionally extending as far as its upper border or
even higher; it is conical in form, and curved
slightly backward. On the surface of its mucous membrane are the openings of
sixty or seventy mucous glands, which are lodged in the submucous
areolar tissue. This sac is enclosed in a fibrous capsule, continuous below
with the ventricular ligament. Its medial surface is covered by a few delicate
muscular fasciculi, which arise from the apex of the arytenoid cartilage and
become lost in the aryepiglottic fold of mucous
membrane; laterally it is separated from the thyroid cartilage by the Thyreoepiglotticus. These muscles compress the sac, and
express the secretion it contains upon the vocal folds to lubricate their
surfaces.
The Rima Glottidis is
the elongated fissure or chink between the vocal folds in front, and the bases
and vocal processes of the arytenoid cartilages behind. It is therefore
subdivided into a larger anterior intramembranous part (glottis vocalis), which measures about three-fifths of the length
of the entire aperture, and a posterior intercartilaginous
part (glottis respiratoria). Posteriorly it is
limited by the mucous membrane passing between the arytenoid cartilages. The rima glottidis is the narrowest
part of the cavity of the larynx, and its level corresponds with the bases of
the arytenoid cartilages. Its length, in the male, is about
Muscles.—The muscles of the larynx are extrinsic,
passing between the larynx and parts around—these have been described in the
section on Myology; and intrinsic, confined entirely to the larynx.
The intrinsic muscles are: Cricothyreoideus. Cricoarytænoideus lateralis. Cricoarytænoideus posterior. Arytænoideus. Thyroarytænoideus.
Actions.—In considering the actions of the
muscles of the larynx, they may be conveniently divided into two groups, vix.: 1.
Those which open and close the glottis. 2. Those which regulate the degree of
tension of the vocal folds.
The Cricoarytœnoidei posteriores
separate the vocal folds, and, consequently, open the glottis, by rotating the
arytenoid cartilages outward around a vertical axis passing through the cricoarytenoid joints; so that their vocal processes and
the vocal folds attached to them become widely separated.
The Cricoarytœnoidei laterales
close the glottis by rotating the arytenoid cartilages inward, so as to
approximate their vocal processes.
The Arytœnoideus approximates the arytenoid cartilages,
and thus closes the opening of the glottis, especially at its back part.
The Cricothyreoidei produce tension and elongation of the vocal
folds by drawing up the arch of the cricoid cartilage and tilting back the
upper border of its lamina; the distance between the vocal processes and the
angle of the thyroid is thus increased, and the folds are consequently
elongated.
The Thyreoarytœnoidei, consisting of two parts having
different attachments and different directions, are rather complicated as
regards their action. Their main use is to draw the arytenoid cartilages
forward toward the thyroid, and thus shorten and relax the vocal folds. But,
owing to the connection of the deeper portion with the vocal fold, this part,
if acting separately, is supposed to modify its elasticity and tension, while
the lateral portion rotates the arytenoid cartilage inward, and thus narrows
the rima glottidis by
bringing the two vocal folds together.
The Trachea and Bronchi
The trachea or windpipe is a cartilaginous and
membranous tube, extending from the lower part of the larynx, on a level with
the sixth cervical vertebra, to the upper border of the fifth thoracic
vertebra, where it divides into the two bronchi, one for each lung. The trachea
is nearly but not quite cylindrical, being flattened posteriorly; it measures
about
Relations.—The anterior surface of the trachea is
convex, and covered, in the neck, from above downward, by the isthmus of the
thyroid gland, the inferior thyroid veins, the arteria
thyroidea ima (when that
vessel exists), the Sternothyreoideus and Sternohyoideus muscles, the cervical fascia, and, more
superficially, by the anastomosing branches between the anterior jugular veins;
in the thorax, it is covered from before backward by the manubrium sterni, the remains of the thymus, the left innominate
vein, the aortic arch, the innominate and left common carotid arteries, and the
deep cardiac plexus. Posteriorly it is in contact with the esophagus.
Laterally, in the neck, it is in relation with the common carotid arteries, the
right and left lobes of the thyroid gland, the inferior thyroid arteries, and
the recurrent nerves; in the thorax, it lies in the superior mediastinum, and
is in relation on the right side with the pleura and right vagus,
and near the root of the neck with the innominate artery; on its left side are
the left recurrent nerve, the aortic arch, and the left common carotid and subclavian arteries
Structure.—The trachea and extrapulmonary
bronchi are composed of imperfect rings of hyaline cartilage, fibrous tissue,
muscular fibers, mucous membrane, and glands.
The Lungs (Pulmones)
The lungs are the essential organs of
respiration; they are two in number, placed one on either side within the
thorax, and separated from each other by the heart and other contents of the
mediastinum. The substance of the lung is of a light, porous, spongy texture;
it floats in water, and crepitates when handled, owing to the presence of air
in the alveoli; it is also highly elastic; hence the retracted state of these
organs when they are removed from the closed cavity of the thorax. The surface
is smooth, shining, and marked out into numerous polyhedral areas, indicating
the lobules of the organ: each of these areas is crossed by numerous lighter
lines.
At birth the lungs are pinkish white in color; in
adult life the color is a dark slaty gray, mottled in
patches; and as age advances, this mottling assumes a black color. The coloring
matter consists of granules of a carbonaceous substance deposited in the
areolar tissue near the surface of the organ. It increases in quantity as age
advances, and is more abundant in males than in females. As a rule, the
posterior border of the lung is darker than the anterior.
The right
lung usually weighs about
Each lung
is conical in shape, and presents for examination an apex, a base, three
borders, and two surfaces.
The apex
(apex pulmonis) is rounded, and extends into the root
of the neck, reaching from 2.5 to
The base
(basis pulmonis) is broad, concave, and rests upon
the convex surface of the diaphragm, which separates the right lung from the
right lobe of the liver, and the left lung from the left lobe of the liver, the
stomach, and the spleen. Since the diaphragm extends higher on the right than
on the left side, the concavity on the base of the right lung is deeper than
that on the left. Laterally and behind, the base is bounded by a thin, sharp
margin which projects for some distance into the phrenicocostal
sinus of the pleura, between the lower ribs and the costal attachment of the
diaphragm. The base of the lung descends during inspiration and ascends during
expiration.
Borders.—The inferior
border (margo inferior) is thin and sharp where it
separates the base from the costal surface and extends into the phrenicocostal sinus; medially where it divides the base
from the mediastinal surface it is blunt and
rounded.
The
posterior border (margo
posterior) is broad and rounded, and is received into the deep concavity on
either side of the vertebral column. It is much longer than the anterior border,
and projects, below, into the phrenicocostal sinus.
The
anterior border (margo
anterior) is thin and sharp, and overlaps the front of the pericardium. The
anterior border of the right lung is almost vertical, and projects into the costomediastinal sinus; that of the left presents, below,
an angular notch, the cardiac notch, in which the pericardium is exposed.
Opposite this notch the anterior margin of the left lung is situated some
little distance lateral to the line of reflection of
the corresponding part of the pleura.
The right lung is divided into three lobes,
superior, middle, and inferior, by two interlobular fissures. One of these
separates the inferior from the middle and superior lobes, and corresponds
closely with the fissure in the left lung. Its direction is, however, more
vertical, and it cuts the lower border about
The right
lung, although shorter by
The Root of the Lung (radix pulmonis).—A
little above the middle of the mediastinal surface of
each lung, and nearer its posterior than its anterior border, is its root, by
which the lung is connected to the heart and the trachea. The root is formed by
the bronchus, the pulmonary artery, the pulmonary veins, the bronchial arteries
and veins, the pulmonary plexuses of nerves, lymphatic vessels, bronchial lymph
glands, and areolar tissue, all of which are enclosed by a reflection of the
pleura. The root of the right lung lies behind the superior vena cava and part
of the right atrium, and below the azygos vein. That
of the left lung passes beneath the aortic arch and in front of the descending
aorta; the phrenic nerve, the pericardiacophrenic
artery and vein, and the anterior pulmonary plexus, lie in front of each, and
the vagus and posterior pulmonary plexus behind each;
below each is the pulmonary ligament.
The chief
structures composing the root of each lung are arranged in a similar manner
from before backward on both sides, viz., the upper of the two pulmonary veins
in front; the pulmonary artery in the middle; and the bronchus, together with
the bronchial vessels, behind. From above downward, on the two sides, their
arrangement differs, thus:
On the
right side their position is—eparterial bronchus,
pulmonary artery, hyparterial bronchus, pulmonary
veins, but on the left side their position is—pulmonary artery, bronchus, pulmonary veins. The lower of the two pulmonary veins, is
situated below the bronchus, at the apex or lowest part of the hilus.
Divisions of the Bronchi.—Just as the lungs
differ from each other in the number of their lobes, so the bronchi differ in
their mode of subdivision.
The right
bronchus gives off, about
The left
bronchus passes below the level of the pulmonary artery before it divides, and
hence all its branches are hyparterial; it may
therefore be looked upon as equivalent to that portion of the right bronchus
which lies on the distal side of its eparterial
branch. The first branch of the left bronchus arises about
Structure.—The lungs are
composed of an external serous coat, a subserous
areolar tissue and the pulmonary substance or parenchyma.
The
serous coat is the pulmonary pleura; it is thin, transparent, and invests the
entire organ as far as the root.
The subserous areolar tissue contains a large proportion of
elastic fibers; it invests the entire surface of the lung, and extends inward
between the lobules.
The
parenchyma is composed of secondary lobules which, although closely connected
together by an interlobular areolar tissue, are quite distinct from one
another, and may be teased asunder without much difficulty in the fetus. The
secondary lobules vary in size; those on the surface are large, of pyramidal
form, the base turned toward the surface; those in the interior smaller, and of
various forms. Each secondary lobule is composed of several primary lobules,
the anatomical units of the lung. The primary lobule consists of an alveolar
duct, the air spaces connected with it and their bloodvessels,
lymphatics and nerves.
The
intrapulmonary bronchi divide and subdivide throughout the entire organ, the
smallest subdivisions constituting the lobular bronchioles. The larger
divisions consist of: (1) an outer coat of fibrous tissue in which are found at
intervals irregular plates of hyaline cartilage, most developed at the points of
division; (2) internal to the fibrous coat, a layer of circularly disposed
smooth muscle fibers, the bronchial muscle; and (3) most internally, the mucous
membrane, lined by columnar ciliated epithelium resting on a basement membrane.
The corium of the mucous membrane contains numerous elastic fibers running
longitudinally, and a certain amount of lymphoid tissue; it also contains the
ducts of mucous glands, the acini of which lie in the
fibrous coat. The lobular bronchioles differ from the larger tubes in
containing no cartilage and in the fact that the ciliated epithelial cells are
cubical in shape. The lobular bronchioles are about
Each
bronchiole divides into two or more respiratory bronchioles, with scattered
alveoli, and each of these again divides into several alveolar ducts, with a
greater number of alveoli connected with them. Each alveolar duct is connected
with a variable number of irregularly spherical spaces, which also possess
alveoli, the atria. With each atrium a variable number (2–5) of alveolar sacs
are connected which bear on all parts of their circumference alveoli or air
sacs.
The
alveoli are lined by a delicate layer of simple squamous epithelium, the cells
of which are united at their edges by cement substance. Between the squames are here and there smaller, polygonal, nucleated
cells. Outside the epithelial lining is a little delicate connective tissue
containing numerous elastic fibers and a close net-work of blood capillaries,
and forming a common wall to adjacent alveoli.
The fetal lung resembles a gland in that the
alveoli have a small lumen and are lined by cubical epithelium. After the first
respiration the alveoli become distended, and the epithelium takes on the
characters described above.
The Pleuræ
Each lung is invested by an exceedingly delicate
serous membrane, the pleura, which is arranged in the
form of a closed invaginated sac. A portion of the
serous membrane covers the surface of the lung and dips into the fissures
between its lobes; it is called the pulmonary pleura. The rest of the membrane
lines the inner surface of the chest wall, covers the diaphragm, and is
reflected over the structures occupying the middle of the thorax; this portion
is termed the parietal pleura. The two layers are continuous with one another
around and below the root of the lung; in health they are in actual contact
with one another, but the potential space between them is known as the pleural
cavity. When the lung collapses or when air or fluid collects between the two
layers the cavity becomes apparent. The right and left pleural sacs are
entirely separate from one another; between them are all the thoracic viscera
except the lungs, and they only touch each other for a short distance in front;
opposite the second and third pieces of the sternum the interval between the
two sacs is termed the mediastinum.
Reflections of the Pleura.—Commencing at the
sternum, the pleura passes lateralward, lines the
inner surfaces of the costal cartilages, ribs, and Intercostales,
and at the back part of the thorax passes over the sympathetic trunk and its
branches, and is reflected upon the sides of the bodies of the vertebræ, where it is separated by a narrow interval,
the posterior mediastinum, from the opposite pleura. From the vertebral column
the pleura passes to the side of the pericardium, which it covers to a slight
extent; it then covers the back part of the root of the lung, from the lower
border of which a triangular sheet descends vertically toward the diaphragm. Above,
its cupula projects through the superior opening of
the thorax into the neck, extending from 2.5 to
The free surface of the pleura is smooth,
polished, and moistened by a serous fluid; its attached surface is intimately adherent to the lung, and to the pulmonary vessels as they
emerge from the pericardium; it is also adherent to the upper surface of the
diaphragm: throughout the rest of its extent it is easily separable from the
adjacent parts.
The Mediastinum (Interpleural
Space)
The mediastinum lies between the right and left pleuræ in and near the median sagittal plane of the
chest. It extends from the sternum in front to the vertebral column behind, and
contains all the thoracic viscera excepting the lungs. It may be divided for
purposes of description into two parts: an upper portion, above the upper level
of the pericardium, which is named the superior mediastinum; and a lower
portion, below the upper level of the pericardium. This lower portion is again
subdivided into three parts, viz., that in front of the pericardium, the
anterior mediastinum; that containing the pericardium and its contents, the
middle mediastinum; and that behind the pericardium, the posterior
mediastinum.
The
Superior Mediastinum is that portion of the interpleural
space which lies between the manubrium sterni in
front, and the upper thoracic vertebræ behind.
It is bounded below by a slightly oblique plane passing backward from the
junction of the manubrium and body of the sternum to the lower part of the body
of the fourth thoracic vertebra, and laterally by the pleuræ.
It contains the origins of the Sternohyoidei and Sternothyreoidei and the lower ends of the Longi colli; the aortic arch; the
innominate artery and the thoracic portions of the left common carotid and the
left subclavian arteries; the innominate veins and
the upper half of the superior vena cava; the left highest intercostal vein;
the vagus, cardiac, phrenic, and left recurrent
nerves; the trachea, esophagus, and thoracic duct; the remains of the thymus,
and some lymph glands.
The Anterior Mediastinum exists only on the left
side where the left pleura diverges from the mid-sternal
line. It is bounded in front by the sternum, laterally by the pleuræ, and behind by the pericardium. It is narrow,
above, but widens out a little below. Its anterior wall is formed by the left Transversus thoracis and the
fifth, sixth, and seventh left costal cartilages. It contains a quantity of
loose areolar tissue, some lymphatic vessels which ascend from the convex
surface of the liver, two or three anterior mediastinal
lymph glands, and the small mediastinal branches of
the internal mammary artery.
The Middle Mediastinum is the broadest part of
the interpleural space. It contains the heart
enclosed in the pericardium, the ascending aorta, the lower half of the
superior vena cava with the azygos vein opening into
it, the bifurcation of the trachea and the two bronchi, the pulmonary artery
dividing into its two branches, the right and left pulmonary veins, the phrenic
nerves, and some bronchial lymph glands.
The
Posterior Mediastinum is an irregular triangular space running parallel with
the vertebral column; it is bounded in front by the pericardium above, and by
the posterior surface of the diaphragm below, behind by the vertebral column
from the lower border of the fourth to the twelfth thoracic vertebra, and on
either side by the mediastinal pleura. It contains
the thoracic part of the descending aorta, the azygos
and the two hemiazygos veins, the vagus
and splanchnic nerves, the esophagus, the thoracic duct, and some lymph
glands.
The Larynx is situated in anterior neck
area on level IV-VI cervical vertebrae. At the front infrahyoid
muscles of neck cover it. Vessels and nervous bundles and lobes of thyroid
gland lie from sides of larynx. Laryngeal part of pharynx adjoins behind it.
Larynx
skeleton consists of pair and odd cartilages.
Odd
cartilages:
• Thyroid
cartilage, which consists of right and left plates (lamina dextra et sinistra),
and also has superior horns and inferior horns; the plates converge forming laryngeal
prominence (Adam’s apple);
• Cricoid
cartilage which has anteriorly arch behind - plate of cricoid cartilage;
• Epiglottis
cartilage.
The cartilages of the larynx. Posterior view.
Paired
cartilages:
• Arytenoid
cartilage, which has a base and apex, muscular process and vocal process. These
cartilage lie on plate of cricoid cartilage;
• Corniculate cartilage lies in aryepiglottic
fold on top of arytenoid cartilages;
• Cuneiform
cartilage lies in aryepiglottic fold front of corniculate
cartilages.
In
larynx they distinguish such articulations:
• Cricoid-thyroid
joint is between inferior cornu of thyroid
cartilage and arch of cricoid cartilage; in this joint movement is possible
around transversal axis;
• Cricoid-arytenoid
joint is situated between base of arytenoid cartilages and plate of cricoid
cartilage. Arytenoid cartilage can rotate slide to meet one another.
Ligaments
of the larynx:
• Thyro-hyoid membrane, which hangs larynx to hyoid bone;
• Crico-thyroid ligament;
• Thyro-epiglottic ligament;
• Hyoepiglottic ligament;
•
Vestibular ligaments, which are situated over vocal ligaments.
The ligaments of the larynx. Antero-lateral view.
Fibroelastic membrane
the larynx:
·
Elastic cone contains in its superior margin vocal
ligament;
·
Quadrangular membrane,
which is situated over elastic cone and in its inferior margin contains
vestibular ligament.
Fibroelastic membranes
together with laryngeal cartilages form a laryngeal skeleton.
The
laryngeal Muscles subdivide on muscles that narrow/broaden the glottis, muscles
that change tension of vocal ligament.
Constrictors
of the glottis:
·
lateral cricoarytenoid
muscle;
·
thyroarytenoid
muscle;
·
transverse arytenoid muscle;
·
oblique
arytenoid muscles.
Muscles-dilators
of the glottis
• thyro-arytenoid
muscle has thyro-epiglottic part. Action: it
raises the epiglottis and broadens an entrance into larynx and vestibule.
• posterior cricoid-arytenoid muscle.
Muscles
changing tension of vocal ligament:
• crico-thyroid
muscle stretches a vocal ligament.
• vocal muscle is situated in thickness of vocal
fold and changes an tension degree of vocal cords.
Laryngeal
cavity has aditus laryngis [entrance], vestibule, interventricular
space, glottis and infraglottic
cavity.
Larynx
has true vocal folds and glottis. Larynx begins by entrance
into larynx, which is limited at the front, by epiglottis, behind – by
arytenoid cartilages, and laterally - by arytenoepiglottic
folds, where cuneiform and corniculate tubercles are
situated (places of the same name cartilages). Glottis is a most narrow
place in laryngeal cavity; it is situated between right and left vocal plicae. Laryngeal ventricle is fissure disposed
between vocal and vestibular plicae.
Infraglottic cavity
is inferior broadened part of larynx, which continues into trachea.
The larynx or organ of voice is placed at the upper part
of the air passage. It is situated between the trachea and the root of the
tongue, at the upper and forepart of the neck, where it presents a considerable
projection in the middle line. It forms the lower part of the anterior wall of
the pharynx, and is covered behind by the mucous lining of that cavity; on
either side of it lie the great vessels of the neck. Its vertical extent
corresponds to the fourth, fifth, and sixth cervical vertebræ,
but it is placed somewhat higher in the female and also during childhood.
Symington found that in infants between six and twelve months of age the tip of
the epiglottis was a little above the level of the fibrocartilage between the
odontoid process and body of the axis, and that between infancy and adult life
the larynx descends for a distance equal to two vertebral bodies and two
intervertebral fibrocartilages. According to Sappey
the average measurements of the adult larynx are as follows:
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In males. |
In females. |
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Length |
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Transverse diameter |
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Antero-posterior diameter |
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Circumference |
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Until puberty the larynx of the male differs little in size from that of
the female. In the female its increase after puberty is only slight; in the
male it undergoes considerable increase; all the cartilages are enlarged and
the thyroid cartilage becomes prominent in the middle line of the neck, while
the length of the rima glottidis
is nearly doubled.
The larynx is broad above, where it presents the form of a triangular
box flattened behind and at the sides, and bounded in front by a prominent
vertical ridge. Below, it is narrow and cylindrical. It is composed of
cartilages, which are connected together by ligaments and moved by numerous
muscles. It is lined by mucous membrane continuous above with that of the
pharynx and below with that of the trachea.
The Cartilages of the Larynx (cartilagines
laryngis) are nine in number, three single and
three paired, as follows:
Thyroid.
Cricoid.
Two Arytenoid.
Two Corniculate.
Two Cuneiform. Epiglottis
The Thyroid Cartilage (cartilago
thyreoidea) is the largest cartilage of the
larynx. It consists of two laminæ the anterior
borders of which are fused with each other at an acute angle in the middle line
of the neck, and form a subcutaneous projection named the laryngeal
prominence (pomum Adami).
This prominence is most distinct at its upper part, and is larger in the male
than in the female. Immediately above it the laminæ
are separated by a V-shaped notch, the superior thyroid notch. The laminæ are irregularly quadrilateral in shape, and
their posterior angles are prolonged into processes termed the superior
and inferior cornua.
The outer surface of each lamina presents an oblique line
which runs downward and forward from the superior thyroid tubercle situated
near the root of the superior cornu, to the inferior
thyroid tubercle on the lower border. This line gives attachment to the Sternothyreoideus, Thyreohyoideus,
and Constrictor pharyngis inferior.
The inner surface is smooth; above and behind, it is slightly
concave and covered by mucous membrane. In front, in the angle formed by the
junction of the laminæ, are attached the stem
of the epiglottis, the ventricular and vocal ligaments, the Thyreoarytænoidei,
Thyreoepiglottici and Vocales
muscles, and the thyroepiglottic ligament.
The upper border is concave behind and convex in front; it gives
attachment to the corresponding half of the hyothyroid
membrane.
The lower border is concave behind, and
nearly straight in front, the two parts being separated by the inferior thyroid
tubercle. A small part of it in and near the middle line is connected to the
cricoid cartilage by the middle cricothyroid
ligament.
The posterior border, thick and rounded, receives the insertions
of the Stylopharyngeus and Pharyngopalatinus.
It ends above, in the superior cornu, and below, in
the inferior cornu. The superior cornu is long and narrow, directed upward, backward,
and medialward, and ends in a conical extremity,
which gives attachment to the lateral hyothyroid
ligament. The inferior cornu is short and
thick; it is directed downward, with a slight inclination forward and medialward, and presents, on the medial side of its tip, a
small oval articular facet for articulation with the side of the cricoid
cartilage.
During infancy the laminæ of the thyroid
cartilage are joined to each other by a narrow, lozenge-shaped strip, named the
intrathyroid cartilage. This strip
extends from the upper to the lower border of the cartilage in the middle line,
and is distinguished from the laminæ by being
more transparent and more flexible.
The Cricoid Cartilage (cartilago
cricoidea) is smaller, but thicker and stronger
than the thyroid, and forms the lower and posterior parts of the wall of the
larynx. It consists of two parts: a posterior quadrate lamina, and a
narrow anterior arch, one-fourth or one-fifth of the depth of the
lamina.
The lamina (lamina cartilaginis cricoideæ; posterior portion) is deep and broad,
and measures from above downward about 2 or
The arch (arcus cartilaginis cricoideæ;
anterior portion) is narrow and convex, and measures vertically from 5 to
On either side, at the junction of the lamina with the arch, is a small
round articular surface, for articulation with the inferior cornu
of the thyroid cartilage.
The lower border of the cricoid cartilage is horizontal, and
connected to the highest ring of the trachea by the cricotracheal
ligament.
The upper border runs obliquely upward and backward, owing to the
great depth of the lamina. It gives attachment, in front, to the middle cricothyroid ligament; at the side, to the conus elasticus and the Cricoarytænoidei laterales;
behind, it presents, in the middle, a shallow notch, and on either side of this
is a smooth, oval, convex surface, directed upward and lateralward,
for articulation with the base of an arytenoid cartilage.
The inner surface of the cricoid cartilage is smooth, and lined
by mucous membrane.
The Arytenoid Cartilages (cartilagines
arytænoideæ) are two in number, and
situated at the upper border of the lamina of the cricoid cartilage, at the
back of the larynx. Each is pyramidal in form, and has three surfaces, a base,
and an apex.
The posterior surface is a triangular, smooth, concave, and gives
attachment to the Arytænoidei obliquus and transversus.
The antero-lateral surface is
somewhat convex and rough. On it, near the apex of the cartilage, is a rounded
elevation (colliculus) from which a ridge (crista
arcuata) curves at first backward and then
downward and forward to the vocal process. The lower part of this crest
intervenes between two depressions or foveæ,
an upper, triangular, and a lower oblong in shape; the latter gives attachment
to the Vocalis muscle.
The medial surface is narrow, smooth, and flattened, covered by
mucous membrane, and forms the lateral boundary of the intercartilaginous
part of the rima glottidis.
The base of each cartilage is broad, and on it is a concave
smooth surface, for articulation with the cricoid cartilage. Its lateral angle
is short, rounded, and prominent; it projects backward and lateralward,
and is termed the muscular process; it gives insertion to the Cricoarytænoideus posterior behind, and to the Cricoarytænoideus lateralis
in front. Its anterior angle, also prominent, but more pointed, projects
horizontally forward; it gives attachment to the vocal ligament, and is called
the vocal process.
The apex of each cartilage is pointed, curved backward and medialward, and surmounted by a small conical,
cartilaginous nodule, the corniculate
cartilage.
The Corniculate Cartilages (cartilagines corniculatæ;
cartilages of Santorini) are two small conical
nodules consisting of yellow elastic cartilage, which articulate with the summits
of the arytenoid cartilages and serve to prolong them backward and medialward. They are situated in the posterior parts of the
aryepiglottic folds of mucous membrane, and are
sometimes fused with the arytenoid cartilages.
The Cuneiform Cartilages (cartilagines
cuneiformes; cartilages of Wrisberg)
are two small, elongated pieces of yellow elastic cartilage, placed one on
either side, in the aryepiglottic fold, where they
give rise to small whitish elevations on the surface of the mucous membrane,
just in front of the arytenoid cartilages.
The Epiglottis (cartilago epiglottica) is a thin lamella of fibrocartilage of a
yellowish color, shaped like a leaf, and projecting
obliquely upward behind the root of the tongue, in front of the entrance to the
larynx. The free extremity is broad and rounded; the attached part or stem is
long, narrow, and connected by the thyroepiglottic
ligament to the angle formed by the two laminæ
of the thyroid cartilage, a short distance below the superior thyroid notch.
The lower part of its anterior surface is connected to the upper border of the
body of the hyoid bone by an elastic ligamentous band, the hyoepiglottic
ligament.
The anterior or lingual surface is curved forward, and
covered on its upper, free part by mucous membrane which is reflected on to the
sides and root of the tongue, forming a median and two lateral glossoepiglottic folds; the lateral folds are
partly attached to the wall of the pharynx. The depressions between the
epiglottis and the root of the tongue, on either side of the median fold, are
named the valleculæ. The lower
part of the anterior surface lies behind the hyoid bone, the hyothyroid membrane, and upper part of the thyroid
cartilage, but is separated from these structures by a mass of fatty tissue.
The posterior or laryngeal surface is smooth, concave from
side to side, concavo-convex from above downward; its
lower part projects backward as an elevation, the tubercle or cushion.
When the mucous membrane is removed, the surface of the cartilage is seen to be
indented by a number of small pits, in which mucous glands are lodged. To its
sides the aryepiglottic folds are attached.
Structure.—The corniculate and cuneiform cartilages, the epiglottis, and
the apices of the arytenoids at first consist of hyaline cartilage, but later
elastic fibers are deposited in the matrix,
converting them into yellow fibrocartilage, which shows little tendency to
calcification. The thyroid, cricoid, and the greater part of the arytenoids
consist of hyaline cartilage, and become more or less ossified as age advances.
Ossification commences about the twenty-fifth year in the thyroid cartilage,
and somewhat later in the cricoid and arytenoids; by the sixty-fifth year these
cartilages may be completely converted into bone.
Ligaments.—The
ligaments of the larynxare extrinsic, i. e., those connecting the thyroid cartilage
and epiglottis with the hyoid bone, and the cricoid cartilage with the trachea;
and intrinsic, those which connect the several cartilages of the larynx
to each other.
Extrinsic Ligaments.—The
ligaments connecting the thyroid cartilage with the hyoid bone are the hyothyroid membrane, and a middle and two lateral hyothyroid ligaments.
The Hyothyroid Membrane (membrana hyothyreoidea;
thyrohyoid membrane) is a broad, fibro-elastic
layer, attached below to the upper border of the thyroid cartilage and to the
front of its superior cornu, and above to the upper
margin of the posterior surface of the body and greater cornua
of the hyoid bone, thus passing behind the posterior surface of the body of the
hyoid, and being separated from it by a mucous bursa, which facilitates the
upward movement of the larynx during deglutition. Its middle thicker part is
termed the middle hyothyroid ligament (ligamentum hyothyreoideum
medium; middle thyrohyoid ligament), its lateral thinner portions are pierced by the superior
laryngeal vessels and the internal branch of the superior laryngeal nerve. Its
anterior surface is in relation with the Thyreohyoideus,
Sternohyoideus, and Omohyoideus,
and with the body of the hyoid bone.
The Lateral Hyothyroid Ligament (ligamentum hyothyreoideum
laterale; lateral thyrohyoid
ligament) is a round elastic cord, which forms the posterior border of the hyothyroid membrane and passes between the tip of the superior
cornu of the thyroid cartilage and the extremity of
the greater cornu of the hyoid bone. A small
cartilaginous nodule (cartilago triticea), sometimes bony, is frequently found in it.
Ligaments of the larynx. Posterior view.
The Epiglottis is connected with the hyoid bone by an elastic
band, the hyoepiglottic ligament (ligamentum hyoepiglotticum),
which extends from the anterior surface of the epiglottis to the upper border
of the body of the hyoid bone. The glossoepiglottic
folds of mucous membrane (page 1075) may also be considered as extrinsic
ligaments of the epiglottis.
The Cricotracheal Ligament (ligamentum cricotracheale)
connects the cricoid cartilage with the first ring of the trachea. It resembles
the fibrous membrane which connects the cartilaginous rings of the trachea to
each other.
Intrinsic Ligaments.—Beneath
the mucous membrane of the larynx is a broad sheet of fibrous tissue containing
many elastic fibers, and termed the elastic
membrane of the larynx. It is subdivided on either side by the interval
between the ventricular and vocal ligaments, the upper portion extends between
the arytenoid cartilage and the epiglottis and is often poorly defined; the
lower part is a well-marked membrane forming, with its fellow of the opposite
side, the conus elasticus
which connects the thyroid, cricoid, and arytenoid cartilages to one another.
In addition the joints between the individual cartilages are provided with
ligaments.
The Conus Elasticus
(cricothyroid membrane) is composed
mainly of yellow elastic tissue. It consists of an anterior and two lateral
portions. The anterior part or middle cricothyroid
ligament (ligamentum cricothyreoideum medium; central part of cricothyroid membrane) is thick and strong, narrow
above and broad below. It connects together the front parts of the contiguous
margins of the thyroid and cricoid cartilages. It is overlapped on either side
by the Cricothyreoideus, but between these is
subcutaneous; it is crossed horizontally by a small anastomotic arterial arch,
formed by the junction of the two cricothyroid
arteries, branches of which pierce it. The lateral portions are thinner
and lie close under the mucous membrane of the larynx; they extend from the
superior border of the cricoid cartilage to the inferior margin of the vocal
ligaments, with which they are continuous. These ligaments may therefore be
regarded as the free borders of the lateral portions of the conus
elasticus, and extend from the vocal processes of the
arytenoid cartilages to the angle of the thyroid cartilage about midway between
its upper and lower borders.
An articular capsule, strengthened posteriorly by a well-marked
fibrous band, encloses the articulation of the inferior cornu
of the thyroid with the cricoid cartilage on either side.
Each arytenoid cartilage is connected to the cricoid by a capsule and a
posterior cricoarytenoid ligament. The capsule
(capsula articularis
cricoarytenoidea) is thin and loose, and is
attached to the margins of the articular surfaces. The posterior cricoarytenoid ligament (ligamentum
cricoarytenoideum posterius)
extends from the cricoid to the medial and back part of the base of the
arytenoid.
The thyroepiglottic ligament (ligamentum thyreoepiglotticum)
is a long, slender, elastic cord which connects the stem of the epiglottis with
the angle of the thyroid cartilage, immediately beneath the superior thyroid
notch, above the attachment of the ventricular ligaments.
Movements.—The
articulation between the inferior cornu of the
thyroid cartilage and the cricoid cartilage on either side is a diarthrodial one, and permits of rotatory and gliding
movements. The rotatory movement is one in which the cricoid cartilage rotates
upon the inferior cornua of the thyroid cartilage
around an axis passing transversely through both joints. The gliding movement
consists in a limited shifting of the cricoid on the thyroid in different
directions.
The articulation between the arytenoid cartilages and the cricoid is
also a diarthrodial one, and permits of two varieties
of movement: one is a rotation of the arytenoid on a vertical axis, whereby the
vocal process is moved lateralward or medialward, and the rima glottidis increased or diminished; the other is a gliding
movement, and allows the arytenoid cartilages to approach or recede from each
other; from the direction and slope of the articular surfaces lateral gliding
is accompanied by a forward and downward movement. The two movements of gliding
and rotation are associated, the medial gliding being connected with medialward rotation, and the lateral gliding with lateralward rotation. The posterior cricoarytenoid
ligaments limit the forward movement of the arytenoid cartilages on the
cricoid.
Interior of the Larynx—The
cavity of the larynx (cavum laryngis) extends from the laryngeal entrance to the
lower border of the cricoid cartilage where it is continuous with that of the
trachea. It is divided into two parts by the projection of the vocal folds,
between which is a narrow triangular fissure or chink, the rima
glottidis. The portion of the cavity of the
larynx above the vocal folds is called the vestibule; it is wide and
triangular in shape, its base or anterior wall presenting, however, about its center the backward projection of the tubercle of the
epiglottis. It contains the ventricular folds, and between these and the vocal
folds are the ventricles of the larynx. The portion below the vocal
folds is at first of an elliptical form, but lower down it widens out, assumes
a circular form, and is continuous with the tube of the trachea.
The entrance of the larynx is a triangular opening, wide in
front, narrow behind, and sloping obliquely downward and backward. It is
bounded, in front, by the epiglottis; behind, by the apices of the arytenoid
cartilages, the corniculate cartilages, and the interarytenoid notch; and on either side, by a fold of
mucous membrane, enclosing ligamentous and muscular fibers,
stretched between the side of the epiglottis and the apex of the arytenoid
cartilage; this is the aryepiglottic fold,
on the posterior part of the margin of which the cuneiform cartilage forms a
more or less distinct whitish prominence, the cuneiform tubercle.
Sagittal section of the larynx and upper part of the trachea
The Ventricular Folds (plicœ
ventriculares; superior or false vocal cords) are
two thick folds of mucous membrane, each enclosing a narrow band of fibrous
tissue, the ventricular ligament which is attached in front to the angle
of the thyroid cartilage immediately below the attachment of the epiglottis,
and behind to the antero-lateral surface of the
arytenoid cartilage, a short distance above the vocal process. The lower border
of this ligament, enclosed in mucous membrane, forms a free crescentic
margin, which constitutes the upper boundary of the ventricle of the larynx.
The Vocal Folds (plicœ vocales; inferior or true vocal cords) are concerned in
the production of sound, and enclose two strong bands, named the vocal
ligaments (ligamenta vocales; inferior thyroarytenoid).
Each ligament consists of a band of yellow elastic tissue, attached in front to
the angle of the thyroid cartilage, and behind to the vocal process of the
arytenoid. Its lower border is continuous with the thin lateral part of the conus elasticus. Its upper border
forms the lower boundary of the ventricle of the larynx. Laterally, the Vocalis muscle lies parallel with it. It is covered
medially by mucous membrane, which is extremely thin and closely adherent to
its surface.
Coronal section of larynx and upper part
of trachea.
The Ventricle of the Larynx (ventriculus
laryngis [Morgagnii];
laryngeal sinus) is a fusiform fossa, situated between the ventricular
and vocal folds on either side, and extending nearly their entire length. The
fossa is bounded, above, by the free crescentic
edge of the ventricular fold; below, by the straight margin of the vocal
fold; laterally, by the mucous membrane covering the corresponding Thyreoarytænoideus. The anterior part of the
ventricle leads up by a narrow opening into a cecal
pouch of mucous membrane of variable size called the appendix.
The appendix of the laryngeal ventricle (appendix ventriculi laryngis; laryngeal saccule) is a membranous sac, placed between the
ventricular fold and the inner surface of the thyroid cartilage, occasionally
extending as far as its upper border or even higher; it is conical in form, and curved slightly backward. On the surface of its
mucous membrane are the openings of sixty or seventy mucous glands, which are
lodged in the submucous areolar tissue. This sac is
enclosed in a fibrous capsule, continuous below with the ventricular ligament.
Its medial surface is covered by a few delicate muscular fasciculi, which arise
from the apex of the arytenoid cartilage and become lost in the aryepiglottic fold of mucous membrane; laterally it is
separated from the thyroid cartilage by the Thyreoepiglotticus.
These muscles compress the sac, and express the secretion it contains upon the
vocal folds to lubricate their surfaces.
The entrance to the larynx, viewed from behind.
The Rima Glottidis is the elongated
fissure or chink between the vocal folds in front, and the bases and vocal
processes of the arytenoid cartilages behind. It is therefore subdivided into a
larger anterior intramembranous part (glottis vocalis),
which measures about three-fifths of the length of the entire aperture, and a
posterior intercartilaginous part (glottis respiratoria). Posteriorly it is limited by the mucous
membrane passing between the arytenoid cartilages. The rima
glottidis is the narrowest part of the cavity of the
larynx, and its level corresponds with the bases of the arytenoid cartilages.
Its length, in the male, is about
Laryngoscopic view of interior of larynx.)
Muscles.—The muscles of the larynx are extrinsic,
passing between the larynx and parts around—these have been described in the
section on Myology; and intrinsic, confined entirely to the larynx.
The intrinsic muscles are:
Cricothyreoideus.
Cricoarytænoideus lateralis.
Cricoarytænoideus posterior.
Arytænoideus.
Thyroarytænoideus.
The Cricothyreoideus (Cricothyroid) Triangular in form, arises from
the front and lateral part of the cricoid cartilage; its fibers
diverge, and are arranged in two groups. The lower fibers
constitute a pars obliqua and slant backward
and lateralward to the anterior border of the
inferior cornu; the anterior fibers,
forming a pars recta, run upward,
backward, and lateralward to the posterior part of
the lower border of the lamina of the thyroid cartilage.
The medial borders of the two muscles are separated by a triangular
interval, occupied by the middle cricothyroid
ligament.
The Cricoarytænoideus
posterior (posterior cricoarytenoid) (Fig. 958)
arises from the broad
depression on the corresponding half of the posterior surface of the lamina of
the cricoid cartilage; its fibers run upward and lateralward, and converge to be inserted into the
back of the muscular process of the arytenoid cartilage. The uppermost fibers are nearly horizontal, the middle oblique, and the
lowest almost vertical.
The Cricoarytænoideus lateralis (lateral cricoarytenoid)
(Fig. 959) is smaller than the preceding, and of an oblong form. It arises
from the upper border of the arch of the cricoid cartilage, and, passing
obliquely upward and backward, is inserted into the front of the muscular
process of the arytenoid cartilage.
Side view of the larynx, showing
muscular attachments.
Muscles of larynx. Posterior view.
Muscles of larynx. Side view. Right lamina of thyroid cartilage
removed.
The Arytænoideus is a single
muscle, filling up the posterior concave surfaces of the arytenoid cartilages.
It arises from the posterior surface and lateral border of one arytenoid
cartilage, and is inserted into the corresponding parts of the opposite
cartilage. It consists of oblique and transverse parts. The Arytænoideus
obliquus, the more superficial, forms two
fasciculi, which pass from the base of one cartilage to the apex of the
opposite one, and therefore cross each other like the limbs of the letter X; a
few fibers are continued around the lateral margin of
the cartilage, and are prolonged into the aryepiglottic
fold; they are sometimes described as a separate muscle, the Aryepiglotticus. The Arytænoideus
transversus crosses transversely between the two
cartilages.
The Thyreoarytænoideus (Thyroarytenoid) is a broad, thin,
muscle which lies parallel with and lateral to the vocal fold, and
supports the wall of the ventricle and its appendix. It arises in front
from the lower half of the angle of the thyroid cartilage, and from the middle cricothyroid ligament. Its fibers
pass backward and lateralward, to be inserted
into the base and anterior surface of the arytenoid cartilage. The lower and
deeper fibers of the muscle can be differentiated as
a triangular band which is inserted into the vocal process of the arytenoid
cartilage, and into the adjacent portion of its anterior surface; it is termed
the Vocalis, and lies parallel with the
vocal ligament, to which it is adherent.
Muscles of the larynx, seen from above.
A considerable number of the fibers of the Thyreoarytænoideus are prolonged into the aryepiglottic fold, where some of them become lost, while
others are continued to the margin of the epiglottis. They have received a
distinctive name, Thyreoepiglotticus,
and are sometimes described as a separate muscle. A few fibers
extend along the wall of the ventricle from the lateral wall of the arytenoid
cartilage to the side of the epiglottis and constitute the Ventricularis
muscle.
Actions.—In considering the actions of the
muscles of the larynx, they may be conveniently divided into two groups, vix.: 1.
Those which open and close the glottis. 2. Those which regulate the degree of
tension of the vocal folds.
The Cricoarytœnoidei posteriores separate the vocal folds, and,
consequently, open the glottis, by rotating the arytenoid cartilages outward
around a vertical axis passing through the cricoarytenoid
joints; so that their vocal processes and the vocal folds attached to them
become widely separated.
The Cricoarytœnoidei laterales close the glottis by rotating the arytenoid
cartilages inward, so as to approximate their vocal processes.
The Arytœnoideus approximates the
arytenoid cartilages, and thus closes the opening of the glottis, especially at
its back part.
The Cricothyreoidei produce tension and
elongation of the vocal folds by drawing up the arch of the cricoid cartilage
and tilting back the upper border of its lamina; the distance between the vocal
processes and the angle of the thyroid is thus increased, and the folds are
consequently elongated.
The Thyreoarytœnoidei,
consisting of two parts having different attachments and different directions,
are rather complicated as regards their action. Their main use is to draw the
arytenoid cartilages forward toward the thyroid, and thus shorten and relax the
vocal folds. But, owing to the connection of the deeper portion with the vocal
fold, this part, if acting separately, is supposed to modify its elasticity and
tension, while the lateral portion rotates the arytenoid cartilage inward, and
thus narrows the rima glottidis
by bringing the two vocal folds together.
Mucous Membrane.—The
mucous membrane of the larynx is continuous above with that lining the mouth
and pharynx, and is prolonged through the trachea and bronchi into the lungs.
It lines the posterior surface and the upper part of the anterior surface of
the epiglottis, to which it is closely adherent, and
forms the aryepiglottic folds which bound the
entrance of the larynx. It lines the whole of the cavity of the larynx; forms,
by its reduplication, the chief part of the ventricular fold, and, from the
ventricle, is continued into the ventricular appendix. It is then reflected
over the vocal ligament, where it is thin, and very intimately adherent; covers
the inner surface of the conus elasticus
and cricoid cartilage; and is ultimately continuous with the lining membrane of
the trachea. The anterior surface and the upper half of the posterior surface
of the epiglottis, the upper part of the aryepiglottic
folds and the vocal folds are covered by stratified squamous epithelium; all
the rest of the laryngeal mucous membrane is covered by columnar ciliated
cells, but patches of stratified squamous epithelium are found in the mucous
membrane above the glottis.
Glands.—The mucous membrane of the larynx
is furnished with numerous mucous secreting glands, the orifices of which are
found in nearly every part; they are very plentiful upon the epiglottis, being
lodged in little pits in its substance; they are also found in large numbers
along the margin of the aryepiglottic fold, in front
of the arytenoid cartilages, where they are termed the arytenoid glands.
They exist also in large numbers in the ventricular appendages. None are found
on the free edges of the vocal folds.
Vessels and Nerves.—The
chief arteries of the larynx are the laryngeal branches derived from the
superior and inferior thyroid. The veins accompany the arteries; those
accompanying the superior laryngeal artery join the superior thyroid vein which
opens into the internal jugular vein; while those accompanying the inferior
laryngeal artery join the inferior thyroid vein which opens into the innominate
vein. The lymphatic vessels consist of two sets, superior and inferior.
The former accompany the superior laryngeal artery and pierce the hyothyroid membrane, to end in the glands situated near the
bifurcation of the common carotid artery. Of the latter, some pass through the
middle cricothyroid ligament and open into a gland
lying in front of that ligament or in front of the upper part of the trachea,
while others pass to the deep cervical glands and to the glands accompanying
the inferior thyroid artery. The nerves are derived from the internal
and external branches of the superior laryngeal nerve, from the recurrent
nerve, and from the sympathetic. The internal laryngeal branch is almost
entirely sensory, but some motor filaments are said to be carried by it to the Arytænoideus. It enters the larynx by piercing the
posterior part of the hyothyroid membrane above the
superior laryngeal vessels, and divides into a branch which is distributed to
both surfaces of the epiglottis, a second to the aryepiglottic
fold, and a third, the largest, which supplies the mucous membrane over the
back of the larynx and communicates with the recurrent nerve. The external
laryngeal branch supplies the Cricothyreoideus. The
recurrent nerve passes upward beneath the lower border of the Constrictor pharyngis inferior immediately behind the cricothyroid joint. It supplies all the muscles of the
larynx except the Cricothyreoideus, and perhaps a
part of the Arytænoideus. The sensory branches
of the laryngeal nerves form subepithelial plexuses,
from which fibers pass to end between the cells
covering the mucous membrane.
Over the posterior surface of the epiglottis, in the aryepiglottic
folds, and less regularly in some other parts, taste-buds, similar to those in
the tongue, are found.
The TRACHEA is a
tube, which consists of 16-20 semicircular
cartilages, joint each other by annular
ligaments. Last built by connective tissue with smooth
muscular fibres. Behind semi-rings communicate by each other by membranous
tracheal wall. Trachea (windpipe) extends from VI cervical to V thoracic
vertebra, where it ramifies on two principal bronchi. This place is tracheal
bifurcation. Trachea has cervical part and thoracic part. Cervical part
at the front covered by infrahyoid muscles and isthmus
of thyroid gland that accords to the second-third
tracheal ring. Esophagus (gullet) passes behind the
trachea. Thoracic part of trachea is situated in superior mediastinum.
Front view of cartilages of larynx, trachea
PRINCIPAL
BRONCHI are generated from the bifurcation of trachea and have similar
structure as trachea. Right principal bronchus is wider than left and it
is continuation of trachea by its direction. It consists of 6-8 cartilaginous semirings. Left principal bronchus is longer and
narrower and passes with angle from trachea than right. It consists of 9-12
cartilaginous semi-ring. The principal bronchi are the
bronchi of first order, the bronchial tree starts from
them. The extraneous things, especially in children, more frequently get into
right principal bronchus.
Transverse section of the trachea, just
above its bifurcation, with a bird’s-eye view of the interior.
Theme 2.
Structure, topography and funct³on of lungs and pleura.
Mediastinum, its contents. Radiograph anatomy of digestive and respiratory organs
The LUNGS are the
pair parenchymatic organs, which occupy larger part
of thoracic cavity. Each lung has a pulmonal base
and apex; costal surface, diaphragmatic surface, interlobar surface and medial surface.
Medial surface subdivides into posterior (vertebral) surface and anterior (mediastinal) surface. They distinguish anterior margin and
inferior margin on lungs. There is pulmonal
hilus on mediastinal
surface through which pulmonary artery, bronchi and nerves,
enter into the lung, lymphatic vessels and pulmonary veins leave the lungs. All
these elements, which enter and exite from lungs
gates, form a pulmonary root.
Arrangement of vessels and bronchus in left pulmonary root: from above
downwards: pulmonary artery, bronchus and vein (ÀÂV). Arrangement of vessels
and bronchus in right pulmonary root (from above downwards): bronchus,
pulmonary artery, and vein (BAV). On lateral surface of lungs oblique fissura passes, which subdivides each
lung into superior lobe and inferior lobe.
Mediastinal surface of right lung.
Right lungs, except oblique fissure, has a
horizontal fissure passes on level of the IV ribs, which separates middle
and inferior lobes of the right lung. Left lung is more narrow
and longer than right one and in area of anterior margin it has cardiac notch
of left lung, limited from below by uvula. The principal bronchi,
turning into lung gates, subdivide into bronchi of second order, which
ventilate lung lobes (lobar bronchi). There are 2 lobar bronchi in left
lung, and 3 - in right lung. The lobar bronchi subdivide into bronchi of third
order, which ventilate lung area, dissociated from neighboring
by stratum of connective tissue, which is called as lung segment. That's
why these bronchi are called as by segmental bronchi. According to San
Paulo nomenclature in superior lobe of right lung situated 3 segments,
in middle - 2, and in inferior 5 segments; in right lung they count 10
segments. In superior lobe of left lung count 4 (or 5)
segments, and in inferior lobe - 6 (or 5) segments. So,
in left lung counts also 10 segments.
Bronchi and bronchioles. The lungs have been widely separated and tissue cut away to expose the
air-tubes:
Segmental bronchi dichotomically (each on two)
divides by bronchi of following orders, while do not pass as far as bronchi,
which ventilate lung area, that has a volume 1ìì3. This area is
called by pulmonary lobule and bronchi, which ventilate it, are called lobular
bronchi. Lesser bronchi contain more connective tissue in their wall and
less cartilaginous tissue. From each lobular bronchus 16-18 terminal
bronchiole start, their wall does not contain cartilaginous tissue. Bronchial
tree includes branching of the bronchi starting from the principal bronchi
and finishing by terminal bronchioli. Next branching
of the bronchial tubes they call acynus – morpho-functional lung unit.
Acynus
contains 14-16 respiratory bronch³oli, which
are ramification of one terminal bronch³oli and they
have alveoli in the wall. Each respiratory bronch³
forms to 1500 alveolar ductuli, which
terminate in alveolar saccule. One pulmonary
lobule contains 16-18 acynuses. The acynus is covered by network of vessels. Gas-exchange
between external environment and blood takes place here.
Parenchyma of the lungs and walls of thoracic cavity covered by serous membrane
named pleura. Sheet of pleurae which covers the lung called visceral,
and one which covers inner walls of thoracic cavity named parietal.
Parietal pleura pass into visceral one in place of pulmonal
ligament which lies in frontal plane. Parietal pleura divided into some
portions: costal portion, diaphragmatic, mediastinal
portion and has a cupola of pleurae.
Front view of thorax, showing the relations of the pleuræ
and lungs to the chest wall. Pleura in blue; lungs in purple.
Narrow fissure pleural cavity contains some serous liquid
situated between parietal and visceral pleurae. In areas, where one part of
parietal pleurae continues into other, recesses form, into which lung
deepens during taking a deep breath. They distinguish a costodiaphragmatic
recess (largest), diaphragmaticîmediastinal recess, vertebrîmediastinal recess and costomediastinal
recess.
The MEDIASTINUM is complex
of organs, which is situated between two pleural sacs. Mediastinum is limited -
at front by sternum, behind by thoracic part of backbone, from sides - by right
and left mediastinal pleurae. Its superior boundary
is superior foramen of thoracic cavity, and inferior - diaphragm.
Conventionally horizontal plane, carrying out from joint of manubrium sterni and corpus sterni to
cartilage between IV-V thoracic vertebrae, divides mediastinum into superior
mediastinum and inferior mediastinum.
In superior mediastinum thymus gland, superior cava vein,
aortal arch, part of trachea, superior part of thoracic esophageal
portion, suitable parts of thoracic lymphatic duct, sympathetic trunks, vagus and phrenic nerves are situated.
Transverse section through the upper
margin of the second thoracic vertebra.
Inferior mediastinum into its
turn subdivides into anterior mediastinum, middle mediastinum and posterior
mediastinum. Anterior mediastinum is situated between body by sternum
and anterior wall of pericardium. Internal thoracic arteries and veins,
lymphatic nodes and vessels are situated here. On middle mediastinum
heart, covered by pericardium, phrenic nerves and inner pericardial portions of
big vessels are located. Posterior mediastinum is situated between
posterior pericardial wall and backbone. Thoracic part of aorta, azygos and hemiazygos veins,
sympathetic trunks, splanchnic nerves, vagus nerves, esophagus, thoracic duct, lymphatic nodes passes here.
A transverse section of the thorax,
showing the contents of the middle and the posterior mediastinum. The pleural and pericardial cavities are exaggerated since normally there
is no space between parietal and visceral pleura and between pericardium and
heart.
In surgery mediastinum is subdivided by frontal plane, carrying out
through trachea and lung root, into anterior mediastinum and posterior
mediastinum. In anterior mediastinum heart, ascending aorta,
aortal arch, superior vena cava, trachea, lung root elements, phrenic nerves
and thymus gland are placed. In posterior mediastinum esophagus, descending aorta, inferior vena cava, azygos and hemiazygos veins,
splanchnic nerves, sympathetic trunk, thoracic lymphatic duct and vagus nerves are situated.
Front view of heart and lungs.
Boundaries of LUNGs and PLEURAe. The
superior border of lung and pleura (pleura cupola) coincide and situated
on 2-
Lateral view of thorax, showing the relations of the pleuræ
and lungs to the chest wall. Pleura in blue; lungs in purple.
Anterior lung boundary path also coincides with by anterior
pleural border. It passes from top of the lung to sternîclavicular
joint, passes over middle the manubrium sterni,
sternal body from II to IV costal cartilage. Anterior boundary of left lung
deviates here to the left, passes on parasternal line till VI rib, where
continues into inferior border. Anterior boundary path of right lung passes
along the border of left lung, but gradually deviates to the right and on level
of the VI costal cartilage on right parasternal line continues into inferior
border. Inferior boundary path of right lung is situated 1-
§ on
medioclavicular line - at level of the VI ribs,
§ on
anterior axillar line - on level of the VII ribs,
§ on
middle axillar line - on level of the VIII ribs,
§ on
posterior axillar line - on level of the IX ribs,
§ on
scapular line - on level of the Õ ribs,
§ on paravertebral line - on level
of the XI heads of rib.
Inferior
border of right pleura lies 1
cm beneath from lung border. Note that a left lung and
pleura inferior boundary path is situated 1-2 cm beneath, than right.
Theme 3.
Urinary organs. External and
internal structure of kidney. Nephron morphological
and functional unit of kidney. Blood suplying.
Capsules and topography of kidney
URINARY SYSTEM includes pair organ - kidney (organ
producing urine) and organs, which store up and bring out urine (ureters,
urinary bladder and urethra).
Two Kidneys are pair
parenchymatic organs, which positioned in abdominal
cavity behind peritoneum (retroperitoneal position) in right and left lumbar
regions. Kidney is projected on front abdominal wall in epigastric,
lateral and umbilical regions. Right kidney extends from Th
12 vertebra till L 3 lumbar vertebra, left one - from Th
11 vertebra till L 2 lumbar vertebra.
Posterior abdominal wall, after removal
of the peritoneum, showing kidneys, suprarenal capsules, and great vessels.
Posterior surface of each kidney in superior part
adjoins to diaphragm, and in middle and inferior - to muscular bed, which is
formed by muscle: psoas major, quadratus lumborum and transverse abdominis.
To anterior surface of left kidney adrenal gland adjoins above,
to superolateral part - spleen, to middle portion -
stomach and pancreas, inferiorly - medially is loops of small intestine, and superolaterally - colon. To anterior surface of right
kidney suprarenal gland adjoins above, to middle part - liver, to medial
margin - duodenum, to inferiomedial - loops of small
intestine and to inferiolateral - large intestine.
Vertical section of kidney.
Each kidney has superior extremity and inferior extremity,
anterior surface and posterior surface, medial margin
(concave) and lateral margin (convex). On medial margin are situated the
renal hilus, where artery, nerves
enter, and vein, lymphatic and renal pelvis exit.
The renal hilus gets into kidneys, forming a renal
sinus, filled by adipose tissue, also major renal calices and
minor renal calices and initial part of renal pelvis are present there.
To parenchyma of the kidney a fibrous capsule adjoins. Outside from last a fatty capsule is situated, which
noticeable better near posterior surface of kidney. More outer from
adipose capsule renal fascia disposed, which consists of anterior
sheet and posterior sheet. They fused together by superior edges and
laterally. From renal fascia stratums of connective tissue draw to fibrous
capsule kidney, which fix a kidney. Peritoneum
adjoins to anterior sheet of renal fascia. Kidneys are fixed by abdominal
pressure, renal fascia, muscular bed, renal vessels and nerves, which form a
renal leg.
Sagittal section through posterior
abdominal wall, showing the relations of the capsule of the kidney.
Renal parenchyma consists of cortex (superficially) and medulla
(deep location). In medulla they distinguish 7-10 renal pyramids, each
from which has a base of renal pyramids and a top (apex). Last
terminates in renal papilla where cribriform area disposed. The
stratums of cortical matter, which form the renal columns, lie between
pyramids. Cortical matter consists of convoluted part, between
which the stratums of medulla are
contained. They have a name medullar rays (radiata
part). Each renal pyramid forms renal lobe, and one convoluted
part and one radita part form renal lobule in
cortex. From top of renal pyramid urine gets into minor renal calices (7-
BLOOD SUPPLYING of KIDNEYS.
Kidney supplied by renal artery, which ramifies in hilus
area into anterior branch and posterior branch. Last divide by segmental
arteries, and segmental branches - into interlobar
arteries, which ramify on border of cortex and medulla into arcuate arteries. Arcuate
arteries give off the radial cortical (interlobular) arteries in
cortical matter. They give beginning for numerous of afferent vasa,
which disintegrate into arterial capillaries
and form a renal glomerulus. From renal glomerulus moves away efferent
vasa, which disintegrates into secondary arterial capillaries, that enshrouds the tubules of nephron. Such
system of blood supplying, when arterial vessels have double disintegration
into cappillaries
called as renal miracle arterial rete. Venous
capillaries form in cortical matter stellate venullae,
which fall into arcuate veins. Arcuate veins continue into interlobar
veins, last form a renal vein, which empties in inferior vena
cava.
FORMINg and transportation of URINE within the KIDNEY.
Primary urine arises by filtration blood plasma in nephron capsule,
which envelops each renal glomerulus. Capsule of renal glomerulus together with
glomerulus form a renal corpuscle, which is situated in
convoluted part of cortex. Proximal canalicule
of nephron passes from renal corpuscle, which continues into nephron loop (ansa of Henle).
Last continues into distal part of nephron canalicule
which falling into collecting duct. All of above counted urinary
tubules braid by thick net of secondary arterial capillaries and by reabsorbtion secondary urine here is formed. The elements,
where urine is formed, compose function and structural kidney unit – nephron:
After nephron urine streams into straight colligens (collecting) tubules, which
terminate by pappillar foramens on top
of renal pyramid. Last open on cribriform
area into minor renal calices. From small renal calices urine
flows into major renal calices, which join together and form a renal
pelvis, last continues into ureter.
The URETERS are
pair organ length 25-Ç0 cm, which lies retroperitoneally.
Ureter has abdominal part, pelvic part and intramural part. Last lies
in the wall of urinary bladder and opens on its fundus by foramen. Ureters wall
consists of external membrane, muscular membrane and mucous membrane. Muscular
membrane has external circular and internal longitudinal layers.
Ureter has follow narrow places:
• at transition of renal pelvis into ureter;
• at transition of abdominal part into pelvic
part;
• at transition of ureters into urinary bladder.
structure of kidney. Nephron morphological and
Prepared
by
A.V. MIZ