1 Muscles
and fasciae of thorax and abdomen. Topography and fasciae.
Diaphragm. Inguinal canal
2 Muscles
of head (classification, origin, insertion, action). Fasciae of the head
3 Muscles,
topography and fasciae of the neck
LESSON ¹ 8
Theme 1. Thoracic
region. THE MUSCLES OF THE Thorax. Diaphragm
Muscles of the thorax
subdivide into superficial and proper (deep) groups.
Pectoral
Musculature
1. Pectoralis
major
· Origin:
1. medial 1/3
of clavicle
2. anterior
aspect of manubrium & length of body of sternum
3. cartilaginous
attachments of upper 6 ribs
4. external
oblique's aponeurosis
· Insertion:
1. lateral lip
of bicipital groove to the crest of the greater
tubercle
2. clavicular
fibers insert more distally; sternal fibers more proximally
· Action:
1. adducts humerus
2. medially
rotates humerus
3. flexion of
the arm from extension (clavicular portion)
· Blood:
1. pectoralis
branch of thoracoacromial artery (runs with lateral pec. nerve)
2. lateral
thoracic artery (lesser supply, and runs with medial pectoral nerve)
· Nerve:
1. lateral
pectoral nerve, C5,6,7 to clavicular portion
2. medial
pectoral nerve, C8,T1 to sternal portion
2. Pectoralis
minor
· Origin: outer surface of ribs 2-5 or 3-5 or
6
· Insertion: medial aspect of coracoid process
of the scapula
· Action:
1. depresses
& downwardly rotates the scapula
2. assists in
scapular protraction from a retracted position
3. stabilizes
the scapula
· Blood: lateral thoracic artery
· Nerve: medial pectoral nerve, C8,T1
3. Subclavius
· Origin:
first rib about the junction of bone and cartilage
· Insertion: lower surface of clavicle
· Action: assists in stabilizing the clavicle
· Blood: clavicular
branch of thoracoacromial artery
· Nerve: nerve to the subclavius,
C5,6
4. Serratus
anterior
· Origin: fleshy slips from the outer surface
of upper 8 or 9 ribs
· Insertion: costal aspect of medial margin of
the scapula
· Action:
1. protract
scapula
2. stabilize
scapula
3. assists in
upward rotation
· Blood:
1. lateral
thoracic artery supplies the upper part
2. thoracodorsal
artery supplies the lower part
· Nerve:
long thoracic nerve, C5,6,7
Follow muscles belong to Proper
(deep) group of the thorax:
1.
External intercostal muscles elevate
the ribs
2.
Internal intercostal muscles lower
ribs
3.
Subcostal muscles lower the ribs
4.
Transversus thoracis muscles lower the ribs
5.
Levators costarum (short and long). They originatefrom
cervical and thoracic vertebrae, inserte to ribs.
Action: elevates ribs.
Diaphragm - muscular
and tendon organ that separates thoracic and abdominal cavities.
It has muscular portion and the tendon. Muscular part is divided into three
parts: sternal part, costal and lumbar parts. There are weak places where
diaphragmatic hernia can be happen – lubocostal and sternocostal tringles. The
diaphragm is the dome-shaped sheet of muscle that separates the chest from the
abdomen. It is attached to the spine, ribs and sternum and plays a very
important role in the breathing process. The lungs are enclosed in a kind of
cage in which the ribs form the sides and the diaphragm, an upwardly arching
sheet of muscle, forms the floor. When we breathe, the diaphragm is drawn downward
until it is flat. At the same time, the muscles around the ribs pull them up
like a hoop skirt. The chest cavity becomes deeper and larger, making more air
space. The muscle fibers of the diaphragm converge on
the central tendon, which is a
thick, flat plate of dense fibers. There are openings
in the diaphragm for the esophagus (esophageal
hiatus), the phrenic nerve (which controls the movements of the diaphragm
to produce breathing), and the aorta (aortic
hiatus) and vena cava blood vessels (foramen
venae cavae inferioris),
which lead to and from the heart. When air is drawn into the
lungs, the muscles in the diaphragm contract, pulling the central tendon down.
This enlarges the chest, and air then passes into the lungs to fill the larger
space. The diaphragm sometimes contracts involuntarily because the controlling
nerves are irritated by eating too fast (or for some other reason). At this time, if air is inhaled, the space between the vocal cords
at the back of the throat close suddenly, producing the clicking noise we call
"hiccups."
Breathing
The diaphragm contracts and moves downward elongating the thoracic
cavity while the external intercostal
muscles contract widening the thoracic cavity causing air to fill the lungs
through suction (inspiration). The diaphragm and external intercostal then relax, decreasing the
thorax size and reducing lung capacity forcing air out of the lungs (expiration).
The muscles of the abdomen may be divided into two groups: (1) the anterolateral
muscles; (2) the posterior muscles.
1. the Antero-lateral Muscles of the Abdomen—The muscles of this group are:
Obliquus externus.
Transversus.
Obliquus internus.
Rectus.
Pyramidalis.
The
Obliquus externus abdominis.
The Obliquus externus abdominis (External
or descending oblique muscle) situated on the lateral and anterior
parts of the abdomen, is the largest and the most superficial of the three flat
muscles in this region. It is broad, thin, and irregularly quadrilateral, its
muscular portion occupying the side, its aponeurosis
the anterior wall of the abdomen. It arises, by eight fleshy
digitations, from the external surfaces and inferior borders of the lower eight
ribs; these digitations are arranged in an oblique line which runs downward and
backward, the upper ones being attached close to the cartilages of the corresponding
ribs, the lowest to the apex of the cartilage of the last rib, the intermediate
ones to the ribs at some distance from their cartilages. The five superior
serrations increase in size from above downward, and are received between
corresponding processes of the Serratus anterior; the
three lower ones diminish in size from above downward and receive between them
corresponding processes from the Latissimus dorsi. From these attachments the fleshy fibers proceed in various directions. Those from the lowest
ribs pass nearly vertically downward, and are inserted into the anterior half
of the outer lip of the iliac crest; the middle and upper fibers,
directed downward and forward, end in an aponeurosis,
opposite a line drawn from the prominence of the ninth costal cartilage to the
anterior superior iliac spine.
The aponeurosis of the Obliquus externus abdominis is a thin but strong membranous structure,
the fibers of which are directed downward and medialward. It is joined with that of the opposite muscle
along the middle line, and covers the whole of the front of the abdomen; above,
it is covered by and gives origin to the lower fibers
of the Pectoralis major; below, its fibers are closely aggregated together, and extend
obliquely across from the anterior superior iliac spine to the public tubercle
and the pectineal line. In the middle line, it
interlaces with the aponeurosis of the opposite
muscle, forming the linea alba, which extends from the xiphoid process to the symphysis pubis.
That portion of the aponeurosis
which extends between the anterior superior iliac spine and the pubic tubercle
is a thick band, folded inward, and continuous below with the fascia lata; it is called the inguinal ligament. The
portion which is reflected from the inguinal ligament at the pubic tubercle is
attached to the pectineal line and is called the lacunar
ligament. From the point of attachment of the latter to the pectineal line, a few fibers pass
upward and medialward, behind the medial crus of the
subcutaneous inguinal ring, to the linea alba; they
diverge as they ascend, and form a thin triangular fibrous band which is called
the reflected inguinal ligament.
In the aponeurosis of the Obliquus externus, immediately
above the crest of the pubis, is a triangular opening, the subcutaneous
inguinal ring, formed by a separation of the fibers
of the aponeurosis in this situation.
The following structures require further description, viz.,
the subcutaneous inguinal ring, the intercrural
fibers and fascia, and the inguinal, lacunar,
and reflected inguinal ligaments.
Variations.—The Obliquus externus may show
decrease or doubling of its attachments to the ribs; addition slips from lumbar
aponeurosis; doubling between lower ribs and ilium or
inguinal ligament. Rarely tendinous inscriptions
occur.
The Obliquus internus abdominis (Internal
or ascending oblique muscle) thinner and smaller than the Obliquus externus, beneath which
it lies, is of an irregularly quadrilateral form, and situated at the lateral
and anterior parts of the abdomen. It arises, by fleshy fibers, from the lateral half of the grooved upper surface
of the inguinal ligament, from the anterior two-thirds of the middle lip of the
iliac crest, and from the posterior lamella of the lumbodorsal
fascia. From this origin the fibers diverge; those
from the inguinal ligament, few in number and paler in color
than the rest, arch downward and medialward across
the spermatic cord in the male and the round ligament of the uterus in the
female, and, becoming tendinous, are inserted,
conjointly with those of the Transversus, into the
crest of the pubis and medial part of the pectineal
line behind the lacunar ligament, forming what is known as the inguinal aponeurotic falx. Those from
the anterior third of the iliac origin are horizontal in their direction, and,
becoming tendinous along the lower fourth of the linea semilunaris, pass in front
of the Rectus abdominis to be inserted into the linea alba. Those arising from the middle third of the
iliac origin run obliquely upward and medialward, and
end in an aponeurosis; this divides at the lateral
border of the Rectus into two lamellæ, which
are continued forward, one in front of and the other behind this muscle, to the
linea alba: the posterior lamella has an attachment
to the cartilages of the seventh, eighth, and ninth ribs. The most posterior fibers pass almost vertically upward, to be inserted into
the inferior borders of the cartilages of the three lower ribs, being
continuous with the Intercostales interni.
The
Obliquus internus abdominis.
Variations.—Occasionally, tendinous inscriptions occur from the tips of the tenth or
eleventh cartilages or even from the ninth; an additional slip to the ninth
cartilage is sometimes found; separation between iliac and inguinal parts may
occur.
The Cremaster is a thin muscular layer, composed of a number of fasciculi which arise
from the middle of the inguinal ligament where its fibers
are continuous with those of the Obliquus internus and also occasionally with the Transversus.
It passes along the lateral side of the spermatic cord, descends with it
through the subcutaneous inguinal ring upon the front and sides of the cord,
and forms a series of loops which differ in thickness and length in different
subjects. At the upper part of the cord the loops are short, but they become in
succession longer and longer, the longest reaching down as low as the testis, where
a few are inserted into the tunica vaginalis. These
loops are united together by areolar tissue, and form a thin covering over the
cord and testis, the cremasteric fascia.
The fibers ascend along the medial side of the cord,
and are inserted by a small pointed tendon into the tubercle and crest of the
pubis and into the front of the sheath of the Rectus abdominis.
The
Cremaster.
The Transversus abdominis (Transversalis
muscle) so called from the direction of its fibers,
is the most internal of the flat muscles of the abdomen, being placed
immediately beneath the Obliquus internus.
It arises, by fleshy fibers, from the lateral
third of the inguinal ligament, from the anterior three-fourths of the inner
lip of the iliac crest, from the inner surfaces of the cartilages of the lower
six ribs, interdigitating with the diaphragm, and
from the lumbodorsal fascia. The muscle ends in front
in a broad aponeurosis, the lower fibers
of which curve downward and medialward, and are inserted,
together with those of the Obliquus internus, into the crest of the pubis and pectineal line, forming the inguinal aponeurotic
falx. Throughout the rest of its extent the aponeurosis passes horizontally to the middle line, and is
inserted into the linea alba; its upper three-fourths
lie behind the Rectus and blend with the posterior lamella of the aponeurosis of the Obliquus internus; its lower fourth is in front of the Rectus.
Variations.—It
may be more or less fused with the Obliquus internus or absent. The spermatic cord may pierce its lower
border. Slender muscle slips from the ileopectineal
line to transversalis fascia, the aponeurosis
of the Transversus abdominis
or the outer end of the linea semicircularis
and other slender slips are occasionally found.
The inguinal aponeurotic falx (falx aponeurotica inguinalis;
conjoined tendon of Internal oblique and Transversalis
muscle) of the Obliquus internus
and Transversus is mainly formed by the lower part of
the tendon of the Transversus, and is inserted into
the crest of the pubis and pectineal line immediately
behind the subcutaneous inguinal ring, serving to protect what would otherwise
be aweak point in the abdominal wall. Lateral to the falx is a ligamentous band connected with the lower margin
of the Transversus and extending down in front of the
inferior epigastric artery to the superior ramus of
the pubis; it is termed the interfoveolar
ligament of Hesselbach and sometimes contains a
few muscular fibers.
The
Transversus abdominis,
Rectus abdominis, and Pyramidalis.
The Rectus abdominis is a
long flat muscle, which extends along the whole length of the front of the
abdomen, and is separated from its fellow of the opposite side by the linea alba. It is much broader,
but thinner, above than below, and arises by two tendons; the lateral or
larger is attached to the crest of the pubis, the
medial interlaces with its fellow of the opposite side, and is connected with
the ligaments covering the front of the symphysis
pubis. The muscle is inserted by three portions of unequal size into the
cartilages of the fifth, sixth, and seventh ribs. The upper portion, attached
principally to the cartilage of the fifth rib, usually has some fibers of insertion into the anterior extremity of the rib
itself. Some fibers are occasionally connected with
the costoxiphoid ligaments, and the side of the
xiphoid process.
The Rectus is crossed by fibrous bands, three in number,
which are named the tendinous inscriptions;
one is usually situated opposite the umbilicus, one at the extremity of the
xiphoid process, and the third about midway between the xiphoid process and the
umbilicus. These inscriptions pass transversely or obliquely across the muscle
in a zigzag course; they rarely extend completely through its substance and may
pass only halfway across it; they are intimately adherent
in front to the sheath of the muscle. Sometimes one or two additional
inscriptions, generally incomplete, are present below the umbilicus.
The
interfoveolar ligament, seen from in front.
The Rectus is enclosed in a sheath formed by the aponeuroses of the Obliqui and Transversus, which are arranged in the following manner. At
the lateral margin of the Rectus, the aponeurosis of
the Obliquus internus
divides into two lamellæ, one of which passes
in front of the Rectus, blending with the aponeurosis
of the Obliquus externus,
the other, behind it, blending with the aponeurosis
of the Transversus, and these, joining again at the
medial border of the Rectus, are inserted into the linea
alba. This arrangement of the aponeurosis exists from
the costal margin to midway between the umbilicus and symphysis
pubis, where the posterior wall of the sheath ends in a thin curved margin, the
linea semicircularis,
the concavity of which is directed downward: below this level the aponeuroses of all three muscles pass in front of the
Rectus. The Rectus, in the situation where its sheath is deficient below, is
separated from the peritoneum by the transversalis
fascia. Since the tendons of the Obliquus internus and Transversus only
reach as high as the costal margin, it follows that above this level the sheath
of the Rectus is deficient behind, the muscle resting directly on the
cartilages of the ribs, and being covered merely by the tendon of the Obliquus externus.
The Pyramidalis is a small
triangular muscle, placed at the lower part of the abdomen, in front of the
Rectus, and contained in the sheath of that muscle. It arises by tendinous fibers from the front
of the pubis and the anterior pubic ligament; the fleshy portion of the muscle
passes upward, diminishing in size as it ascends, and ends by a pointed
extremity which is inserted into the linea alba,
midway between the umbilicus and pubis. This muscle may be wanting on one or
both sides; the lower end of the Rectus then becomes proportionately increased
in size. Occasionally it is double on one side, and the muscles of the two
sides are sometimes of unequal size. It may extend higher
than the level stated.
Diagram
of sheath of Rectus.
Besides the Rectus and Pyramidalis,
the sheath of the Rectus contains the superior and inferior epigastric
arteries, and the lower intercostal nerves.
Variations.—The
Rectus may insert as high as the fourth or third rib or may fail to reach the
fifth. Fibers may spring from the lower part of the linea alba.
Nerves.—The
abdominal muscles are supplied by the lower intercostal nerves. The Obliquus internus and Transversus also receive filaments from the anterior branch
of the iliohypogastric and sometimes from the ilioinguinal. The Cremaster is
supplied by the external spermatic branch of the genitofemoral
and the Pyramidalis usually by the twelfth thoracic.
The Linea Alba.—The
linea alba is a tendinous raphé in the middle line of the abdomen, stretching
between the xiphoid process and the symphysis pubis.
It is placed between the medial borders of the Recti, and is formed by the
blending of the aponeuroses of the Obliqui and Transversi. It is narrow
below, corresponding to the linear interval existing between the Recti; but
broader above, where these muscles diverge from one another. At its lower end
the linea alba has a double attachment—its
superficial fibers passing in front of the medial
heads of the Recti to the symphysis pubis, while its
deeper fibers form a triangular lamella, attached
behind the Recti to the posterior lip of the crest of the pubis, and named the adminiculum lineæ
albæ. It presents apertures for the passage
of vessels and nerves; the umbilicus, which in the fetus
exists as an aperture and transmits the umbilical vessels, is closed in the
adult.
Diagram
of a transverse section through the anterior abdomina
wall, below the linea semicircularis.
The Lineæ Semilunares.—The lineæ semilunares
are two curved tendinous lines placed one on either
side of the linea alba. Each corresponds with the
lateral border of the Rectus, extends from the cartilage of the ninth rib to
the pubic tubercle, and is formed by the aponeurosis
of the Obliquus internus at
its line of division to enclose the Rectus, reinforced in front by that of the Obliquus externus, and behind by
that of the Transversus.
Actions.—When the
pelvis and thorax are fixed, the abdominal muscles compress the abdominal
viscera by constricting the cavity of the abdomen, in which action they are
materially assisted by the descent of the diaphragm. By these means assistance
is given in expelling the feces from the rectum, the
urine from the bladder, the fetus from the uterus,
and the contents of the stomach in vomiting.
If the pelvis and vertebral column be fixed, these muscles
compress the lower part of the thorax, materially assisting expiration. If the
pelvis alone be fixed, the thorax is bent directly forward, when the muscles of
both sides act; when the muscles of only one side contract, the trunk is bent
toward that side and rotated toward the opposite side.
If the thorax be fixed, the muscles, acting together, draw
the pelvis upward, as in climbing; or, acting singly, they draw the pelvis
upward, and bend the vertebral column to one side or the other. The Recti, acting
from below, depress the thorax, and consequently flex the vertebral column;
when acting from above, they flex the pelvis upon the vertebral column. The Pyramidales are tensors of the linea
alba.
The Transversalis Fascia.—The transversalis
fascia is a thin aponeurotic membrane which lies
between the inner surface of the Transversus and the extraperitoneal fat. It forms part of the general layer of
fascia lining the abdominal parietes, and is directly
continuous with the iliac and pelvic fasciæ. In
the inguinal region, the transversalis fascia is
thick and dense in structure and is joined by fibers
from the aponeurosis of the Transversus,
but it becomes thin as it ascends to the diaphragm, and blends with the fascia
covering the under surface of this muscle. Behind, it is lost in the fat
which covers the posterior surfaces of the kidneys. Below, it has the
following attachments: posteriorly, to the whole length of the iliac
crest, between the attachments of the Transversus and
Iliacus; between the anterior superior iliac spine
and the femoral vessels it is connected to the posterior margin of the inguinal
ligament, and is there continuous with the iliac fascia. Medial to the femoral
vessels it is thin and attached to the pubis and pectineal
line, behind the inguinal aponeurotic falx, with which it is united; it descends in front of the
femoral vessels to form the anterior wall of the femoral sheath. Beneath the
inguinal ligament it is strengthened by a band of fibrous tissue, which is only
loosely connected to the ligament, and is specialized as the deep crural arch. The spermatic cord in the male and the
round ligament of the uterus in the female pass through the transversalis
fascia at a spot called the abdominal inguinal ring. This opening is not
visible externally, since the transversalis fascia is
prolonged on these structures as the infundibuliform
fascia.
The Abdominal Inguinal Ring (annulus inguinalis
abdominis; internal or deep abdominal ring).—The abdominal inguinal ring is situated in the transversalis
fascia, midway between the anterior superior iliac spine and the symphysis pubis, and about
The
Extraperitoneal Connective Tissue.—Between the inner
surface of the general layer of the fascia which lines the interior of the
abdominal and pelvic cavities, and the peritoneum, there is a considerable
amount of connective tissue, termed the extraperitoneal
or subperitoneal connective tissue.
The parietal portion lines the cavity in varying
quantities in different situations. It is especially abundant on the posterior
wall of the abdomen, and particularly around the kidneys, where it contains
much fat. On the anterior wall of the abdomen, except in the public region, and
on the lateral wall above the iliac crest, it is scanty, and here the transversalis fascia is more closely connected with the
peritoneum. There is a considerable amount of extraperitoneal
connective tissue in the pelvis.
The visceral portion follows the course of the
branches of the abdominal aorta between the layers of the mesenterics
and other folds of peritoneum which connect the various viscera to the
abdominal wall. The two portions are
directly continuous with each other.
The abdominal inguinal
ring.
The Deep Crural Arch.—Curving over the external iliac vessels, at the spot where they become
femoral, on the abdominal side of the inguinal ligaments and loosely connected
with it, is a thickened band of fibers called the
deep crural arch. It is apparently a thickening of
the transversalis fascia joined laterally to the center of the lower margin of the inguinal ligament, and
arching across the front of the femoral sheath to be inserted by a broad
attachment into the pubic tubercle and pectineal
line, behind the inguinal aponeurotic falx. In some subjects this structure is not very
prominently marked, and not infrequently it is altogether wanting.
2. The Posterior Muscles of the Abdomen
Quadratus
lumborum.
The Psoas major, the Psoas minor, and the Iliacus, with the fasciæ
covering them, will be described with the muscles of the lower extremity (see
page 466).
The Fascia Covering the Quadratus Lumborum.—This is a thin layer
attached, medially, to the bases of the transverse processes of the
lumbar vertebræ; below, to the iliolumbar ligament; above, to the apex and lower
border of the last rib. The upper margin of this fascia, which extends from the
transverse process of the first lumbar vertebra to the apex and lower border of
the last rib, constitutes the lateral lumbocostal
arch (page 405). Laterally, it blends with the lumbodorsal
fascia, the anterior layer of which intervenes between the Quadratus
lumborum and the Sacrospinalis.
The Quadratus lumborum is irregularly quadrilateral in shape, and
broader below than above. It arises by aponeurotic
fibers from the iliolumbar
ligament and the adjacent portion of the iliac crest for about
Variations.—The number of
attachments to the vertebræ and the extent of
its attachment to the last rib vary.
Nerve Supply.—The twelfth thoracic
and first and second lumbar nerves supply this muscle.
Actions.—The Quadratus lumborum draws down the last rib, and acts as a muscle of
inspiration by helping to fix the origin of the diaphragm. If the thorax and
vertebral column are fixed, it may act upon the pelvis, raising it toward its
own side when only one muscle is put in action; and when both muscles act
together, either from below or above, they flex the trunk.
Theme 2. THE MUSCLES OF THE HEAD AND NECK
The Fasciæ and Muscles of the Head. a.
The Muscles of the Scalp
Epicranius
The Skin of the Scalp.—This is thicker than
in any other part of the body. It is intimately adherent to the superficial fascia,
which attaches it firmly to the underlying aponeurosis
and muscle. Movements of the muscle move the skin. The hair follicles are very
closely set together, and extend throughout the whole thickness of the skin. It also contains a number of sebaceous glands.
The superficial fascia in the cranial region is a firm, dense,
fibro-fatty layer, intimately adherent to the integument, and to the Epicranius and its tendinous aponeurosis; it is continuous, behind, with the superficial
fascia at the back of the neck; and, laterally, is continued over the temporal
fascia. It contains between its layers the superficial vessels and nerves and
much granular fat.
The Epicranius (Occipitofrontalis) is a broad, musculofibrous
layer, which covers the whole of one side of the vertex of the skull, from the
occipital bone to the eyebrow. It consists of two parts, the Occipitalis and the Frontalis,
connected by an intervening tendinous aponeurosis, the galea aponeurotica.
The Occipitalis,
thin and quadrilateral in form, arises by tendinous
fibers from the lateral two-thirds of the superior
nuchal line of the occipital bone, and from the mastoid part of the temporal.
It ends in the galea aponeurotica.
Muscles of the head,
face, and neck.
The Frontalis is thin, of a
quadrilateral form, and intimately adherent to the superficial fascia. It is
broader than the Occipitalis and its fibers are longer and paler in color.
It has no bony attachments. Its medial fibers are
continuous with those of the Procerus; its immediate fibers blend with the Corrugator and Orbicularis oculi; and
its lateral fibers are also blended with the latter
muscle over the zygomatic process of the frontal
bone. From these attachments the fibers are directed
upward, and join the galea aponeurotica
below the coronal suture. The medial margins of the Frontales
are joined together for some distance above the root of the nose; but between
the Occipitales there is a considerable, though
variable, interval, occupied by the galea aponeurotica.
The galea aponeurotica (epicranial
aponeurosis) covers the upper part of the
cranium; behind, it is attached, in the interval between its union with the Occipitales, to the external occipital protuberance and
highest nuchal lines of the occipital bone; in front, it forms a short and
narrow prolongation between its union with the Frontales.
On either side it gives origin to the Auriculares
anterior and superior; in this situation it loses its aponeurotic
character, and is continued over the temporal fascia to the zygomatic
arch as a layer of laminated areolar tissue. It is closely connected to the
integument by the firm, dense, fibro-fatty layer which forms the superficial
fascia of the scalp: it is attached to the pericranium
by loose cellular tissue, which allows the aponeurosis,
carrying with it the integument to move through a considerable distance.
Variations.—Both Frontalis and Occipitalis vary
considerably in size and in extent of attachment; either may be absent; fusion
of Frontalis to skin has been noted.
Nerves.—The Frontalis
is supplied by the temporal branches of the facial nerve, and the Occipitalis by the posterior auricular branch of the same
nerve.
Actions.—The Frontales raise the
eyebrows and the skin over the root of the nose, and at the same time draw the
scalp forward, throwing the integument of the forehead into transverse
wrinkles. The Occipitales draw the scalp backward. By
bringing alternately into action the Frontales and Occipitales the entire scalp may be moved forward and
backward. In the ordinary action of the muscles, the eyebrows are elevated, and
at the same time the aponeurosis is fixed by the Occipitales, thus giving to the face the expression of
surprise; if the action be exaggerated, the eyebrows are still further raised,
and the skin of the forehead thrown into transverse wrinkles, as in the
expression of fright or horror.
A thin muscular slip, the Transversus
nuchæ, is present in a considerable
proportion (25 per cent.) of cases; it arises from the external
occipital protuberance or from the superior nuchal line, either superficial or
deep to the Trapezius; it is frequently inserted with the Auricularis posterior, but may join the posterior edge of
the Sternocleidomastoideus.
Muscles of the Head
subdivided into
Mastication and Facial Expression
(mimetic) groups
Muscles of Mastication
Masseter
•
Origin:
• Superficial:
1.zygomatic process of the maxilla 2.inferior border of zygomatic
arch
•
Intermediate: inner surface of zygomatic arch • Deep:
posterior aspect of inferior border of zygomatic arch
•
Insertion:
•
Superficial: 1.angle of mandible 2.lateral surface of mandibular ramus
•
Intermediate: ramus of mandible • Deep: 1.superior ramus of mandible 2.coronoid
process of mandible
•
Action: 1.closes the lower jaw (clenches the teeth) 2.may deviate mandible to
opposite side of contraction
•
Blood: masseteric artery • Nerve: masseteric
nerve
Medial
pterygoid
•
Origin:
1.medial
surface of lateral pterygoid plate of the sphenoid
2.palatine bone 3.pterygoid fossa
•
Insertion:
1.inner
surface of mandibular ramus 2.angle of the mandible
•
Action:
1.closes
the lower jaw (clenches the teeth) 2.can protrude the mandible in combination
with the lateral pterygoid
•
Blood: medial pterygoid artery • Nerve: medial pterygoid nerve
Lateral
pterygoid
•
Origin:
1.Superior
head: lateral surface of the greater wing of the sphenoid 2.Inferior head:
lateral surface of the lateral pterygoid plate
•
Insert together:
1.neck
of the mandibular condyle 2.articular disk of the TMJ
•
Action:
1.deviates
mandible to side opposite of contraction (during chewing) 2.opens mouth by
protruding mandible (inferior head) 3.closes the mandible (superior head)
•
Blood: lateral pterygoid artery • Nerve: lateral pterygoid nerve
Temporalis
•
Origin:
•
Temporal fossa
•
Insertion: coronoid process of the mandible
•
Action:
1.closes
the lower jaw (clenches the teeth) 2.retraction, pulles
back
Muscles of Facial Expression (mimetic
muscles) have such peculiarities:
1.
Originate in bones of face and insert
into skin
2.
Do not throw over joints
3.
Do not have proper fasciae (exception
is buccinator muscle)
4.
Placed round natural orifices of the
face (eyes, nostrils, ears and mouth)
5.
They have an antagonists – elastic
skin
Muscles of Facial Expression
(mimetic)
Orbicularis
oculi
•
Origin:
1.orbital
portion: nasal process of frontal bone 2.palpebral portion: palpebral ligament
3.lacrimal portion: lacrimal crest of lacrimal bone
•
Insertion: circumferentially around orbit meeting in palpebral raphe
•
Action: powerfully closes the eye • Blood: ophthalmic artery • Nerve: zygomatic branch of facial nerve
Corrugator
supercilii
• Origin:
frontal bone just above the nose • Insertion: skin of the medial portion of the
eyebrows • Action: draws the eyebrows downward and medially • Blood: ophthalmic
artery • Nerve: zygomatic branch of facial nerve
Orbicularis
oris
Scheme showing
arrangement of fibers of Orbicularis oris.
•
Origin:
1.alveolar
border of maxilla 2.lateral to midline of mandible
•
Insertion:
1.circumferentially
around mouth 2.blends with other muscles
•
Action:
1.closes
the lips 2.protrudes the lips
•
Blood: facial artery • Nerve: buccal branch of facial
nerve
Levator labii superioris
•
Action: 1.elevates the upper lip 2.flares the nostrils
Zygomaticus minor
•
Action: elevates the upper lip
Zygomaticus major
•
Action: lifts and draws back the angle(s) of the mouth (as in smiling)
Risorius (may be
absent)
•
Action: draws the mouth laterally (as in smiling)
Levator anguli oris
•
Action: lifts the angle(s) of the mouth (as in smiling)
Buccinator
• Action:
compresses the cheek(s)
Depressor
anguli oris
•
Action: lowers the angle(s) of the mouth (as in frowning)
Depressor
labii inferioris
•
Action: draws the lower lip downward and laterally
Epicranial Musculature
Occipitalis (2 bellies)
•
Origin:
1.lateral
2/3 of superior nuchal line 2.external occipital protuberance
•
Insertion: galea aponeurosis,
over the occipital bone • Action: draws back the scalp to raise the eyebrows
and wrinkle the brow • Blood: occipital artery • Nerve: posterior auricular
branch of facial nerve
Frontalis (2 bellies)
•
Origin: galea aponeurosis,
anterior to the vertex • Insertion: skin above the nose and eyes • Action:
draws back the scalp to raise the eyebrows and wrinkle the brow • Blood:
ophthalmic artery • Nerve: temporal branch of facial nerve
Anterior, posterior and superior auricularis muscles
•
Action: draws the auricle
There are parotid
fascia, masseteric fascia and boccopharyngeal fascia in head region.
Regions of
head: frontal, parietal, occipital, temporal, auditory,
mastoid and facial regions. Facial area has orbital, infraorbital,
parotidomasseteric, zygomatic,
nasal, oral and mental regions.
Neck Musculature
Subdivides into superficial and deep groups
Superficial Neck Musculature
Platysma
•
Origin: subcutaneous skin over delto-pectoral region
• Insertion: invests in the skin widely over the mandible • Action: 1.depress
mandible and lower lip 2.tenses the skin over the lower neck
•
Blood: superficial vessels of the neck • Nerve: cervical branch of facial nerve
(VII cranial)
Sternocleidomastoid
•
Origin: (two heads)
1.manubrium
of sternum 2.medial portion of clavicle
•
Insertion: mastoid process of temporal bone • Action:
1.rotates
to side opposite of contraction 2.laterally flexes to the contracted side
3.bilaterally flexes the neck
•
Blood:
1.occipital
artery 2.superior thyroid artery
•
Nerve:
1.motor:
spinal accessory (XI cranial) 2.sensory: ventral rami of C2,(C3)
Suprahyoid group
1.
Stylohyoid
•
Origin: styloid process of temporal bone • Insertion:
lateral margin of hyoid (near greater horn) • Action:
1.pulls
the hyoid superiorly & posteriorly during swallowing 2.fixes the hyoid bone
for infrahyoid action
•
Blood: facial & occipital artery • Nerve: facial nerve (VII cranial)
2.
Digastric
•
Attachments:
1.post
belly: mastoid process of temporal bone 2.anterior belly: digastric fossa of
internal mandible
•
both bellies meet and attach at the lateral aspect of body of hyoid by a pulley
tendon • Action:
1.open
mouth by depressing mandible 2.fixes hyoid bone for infrahyoid
action
•
Blood: branches of the external carotid • Nerve:
1.posterior
belly: facial nerve (VII cranial) 2.anterior belly: mylohyoid
nerve
3.
Mylohyoid
•
Origin: inner surface of mandible off the mylohyoid
line • Insertion:
1.body
of hyoid 2.along midline at mylohyoid raphe
•
Action:
1.elevates
the hyoid bone 2.raises floor of mouth (for swallowing) 3.depresses mandible
when hyoid is fixed
•
Blood: lingual artery • Nerve: mylohyoid nerve
(branch of mandibular division, V3 cranial)
4.
Geniohyoid
•
Origin: inner surface of the mandible
•
Insertion: body of hyoid (paired muscles)
•
Action:
1.pulles
the tongue 2.depress the mandible 3.works with mylohyoid
•
Blood: lingual artery • Nerve:
Infrahyoid group
1.
Sternohyoid
•
Origin:
1.posterior
aspect of manubrium 2.sternal end of clavicle
• Insertion:
body of hyoid • Action:
1.depresses
hyoid & larynx 2.acts eccentrically with the suprahyoid
muscles to provide them a stable base
•
Blood:
1.inferior
thyroid artery (primary) 2.superior thyroid artery
•
Nerve:
1.upper
portions: superior root of ansa cervicalis,
C2 2.lower portions: inferior root of ansa cervicalis, C2,3
2.
Omohyoid
•
Attachments:
1.superior
belly: hyoid bone (lateral to sternohyoid) 2.inferior
belly: superior scapular border (medial to suprascapular
notch)
•
both bellies meet at the clavicle & are held to the clavicle by a pulley
tendon • Action:
1.depresses
hyoid & larynx 2.acts eccentrically with the suprahyoid
muscles to provide them a stable base
•
Blood:
1.inferior
thyroid artery (primary) 2.superior thyroid artery
• Nerve:
1.upper
portions: superior root of ansa cervicalis,
C2 2.lower portions: inferior root of ansa cervicalis, C2,3
3.
Sternothyroid
•
Origin: posterior aspect of manubrium • Insertion: oblique line of thyroid
cartilage • Action:
1.depresses
hyoid & larynx 2.acts eccentrically with the suprahyoid
muscles to provide them a stable base
•
Blood:
1.inferior
thyroid artery (primary) 2.superior thyroid artery
•
Nerve:
1.upper
portions: superior root of ansa cervicalis,
C2 2.lower portions: inferior root of ansa cervicalis, C2,3
4.
Thyrohyoid
•
Origin: oblique line of thyroid cartilage • Insertion: body of hyoid • Action:
1.depresses
hyoid 2.may assist in larynx elevation
•
Blood:
1.inferior
thyroid artery (primary) 2.superior thyroid artery
•
Nerve:
1.upper
portions: superior root of ansa cervicalis,
C2 2.lower portions: inferior root of ansa cervicalis, C2,3
Deep Neck Muscles
have lateral, medial groups
Deep Lateral Neck
Musculature
Anterior scalene
•
Attachment A: anterior tubercles of transverse processes of C3-C6 • Attachment
B: 1st rib • Action:
if
transverse process fixed: 1.elevates the ribs for respiration
if
ribs fixed: 2.rotates to side opposite of contraction 3.laterally flexes to the
contracted side 4.bilaterally flexes the neck
•
Blood: inferior thyroid artery (branch of the thyrocervical
trunk) • Nerve: ventral rami C3-C6
Middle scalene
•
Attachment A: transverse processes of all cervical vertebrae • Attachment B:
1st rib (behind anterior scalene) • Action:
if
transverse process fixed: 1.elevates the ribs for respiration
if
ribs fixed: 2.rotates to side opposite of contraction 3.laterally flexes to the
contracted side 4.bilaterally flexes the neck
•
Blood: ascending cervical artery • Nerve: ventral rami C3-C8
Posterior scalene
•
Attachment A: posterior tubercles of transverse processes of C5 & C6 •
Attachment B: 2nd and/or 3rd rib • Action:
if
transverse process fixed: 1.elevates the ribs for respiration
if
ribs fixed: 2.rotates to side opposite of contraction 3.laterally flexes to the
contracted side 4.bilaterally flexes the neck
•
Blood: ascending cervical artery • Nerve: ventral rami C5-C7
Neck prevertebral
deep Musculature
Longus colli
• Origin: lower anterior vertebral bodies and
transverse processes • Insertion: anterior vertebral bodies and transverse
processes several segments above • Action: flexes the head and neck • Blood:
muscular branches of the aorta • Nerve: ventral rami C2-C6
Longus capitis
•
Origin: upper anterior vertebral bodies and transverse processes • Insertion:
anterior vertebral bodies and transverse processes several segments above •
Action: flexes the head and neck • Blood: muscular branches of the aorta •
Nerve: ventral rami C1-C3
Rectus capitis
anterior
•
Origin: anterior base of the transverse process of the atlas • Insertion:
occipital bone anterior to foramen magnum • Action: flexes the head • Blood:
muscular branches of the aorta • Nerve: ventral rami C2,3
Rectus
capitis lateralis
•
Origin: transverse process of the atlas • Insertion: jugular process of the
occipital bone • Action: bends the head laterally • Blood: muscular branches of
the aorta • Nerve: ventral rami C2,3
Theme 3. THE TOPOGRAPHY AND FASCIAE OF THE HEAD AND NECK
Topography
of the neck
Neck
has follow regions:
Anterior
region is bordered overhead by lower margin of mandible,
from below by sternum, from one side – by the sternocleidomastoid muscle.
Median line of the neck divides anterior region into right and left anterior
triangles. There are some areas in each triangle:
1.
Submandibular trigone
bordered by lower margin of mandible and both bellies of digastric muscle
2.
There is lingual trigone
of Pyrohov in Submandibular triangle that
bordered by back margin of mylohyoid muscle, tendon
of posterior belly of digastric muscle and hypoglossal nerve. There is lingual
artery in this triangle.
3.
Carotid trigone
bordered by posterior belly of digastric muscle,
superior belly of omohyoid, anterior margin of the
sternocleidomastoid and linea alba of the neck.
4.
Muscular (omotracheal)
trigone bordered by superior belly of omohyoid, anterior margin of the sternocleidomastoid and linea alba of the neck.
5.
Mental trigone
bordered by anterior bellies of both digastric muscles, hyoid bone and
mandible.
The Fascia Colli (deep cervical fascia)
lies under cover of the Platysma, and invests the neck; it also forms sheaths for
the carotid vessels, and for the structures situated in front of the vertebral
column.
The investing portion of the fascia is attached behind to
the ligamentum nuchæ
and to the spinous process of the seventh cervical
vertebra. It forms a thin investment to the Trapezius, and at the anterior
border of this muscle is continued forward as a rather loose areolar layer,
covering the posterior triangle of the neck, to the posterior border of the Sternocleidomastoideus, where it begins to assume the
appearance of a fascial membrane. Along the hinder
edge of the Sternocleidomastoideus it divides to
enclose the muscle, and at the anterior margin again forms a single lamella,
which covers the anterior triangle of the neck, and reaches forward to the
middle line, where it is continuous with the corresponding part from the
opposite side of the neck. In the middle line of the neck it is attached to the
symphysis menti and the
body of the hyoid bone.
Above, the fascia is attached to the superior nuchal line
of the occipital, to the mastoid process of the temporal, and to the whole
length of the inferior border of the body of the mandible. Opposite the angle
of the mandible the fascia is very strong, and binds the anterior edge of the Sternocleidomastoideus firmly to that bone. Between the
mandible and the mastoid process it ensheathes the
parotid gland—the layer which covers the gland extends upward under the name of
the parotideomasseteric fascia and is
fixed to the zygomatic arch. From the part which passes
under the parotid gland a strong band extends upward to the styloid
process, forming the stylomandibular
ligament. Two other bands may be defined: the sphenomandibular
(page 297) and the pterygospinous
ligaments. The pterygospinous ligament
stretches from the upper part of the posterior border of the lateral pterygoid plate to the spinous
process of the sphenoid. It occasionally ossifies, and in such cases, between
its upper border and the base of the skull, a foramen is formed which transmits
the branches of the mandibular nerve to the muscles of mastication.
Below, the fascia is attached to the acromion, the
clavicle, and the manubrium sterni. Some little
distance above the last it splits into two layers, superficial and deep. The
former is attached to the anterior border of the manubrium, the latter to its
posterior border and to the interclavicular ligament.
Between these two layers is a slit-like interval, the suprasternal space
(space of Burns); it contains a small quantity of areolar tissue, the
lower portions of the anterior jugular veins and their transverse connecting
branch, the sternal heads of the Sternocleidomastoidei,
and sometimes a lymph gland.
Section of the neck at
about the level of the sixth cervical vertebra.
Showing the arrangement
of the fascia coli.
The fascia which lines the deep surface of the Sternocleidomastoideus gives off the following processes:
(1) A process envelops the tendon at the Omohyoideus,
and binds it down to the sternum and first costal cartilage. (2) A strong
sheath, the carotid sheath, encloses the carotid artery, internal
jugular vein, and vagus nerve. (3) The prevertebral fascia extends medialward behind the carotid vessels, where it assists in
forming their sheath, and passes in front of the prevertebral
muscles. It forms the posterior limit of a fibrous compartment, which contains
the larynx and trachea, the thyroid gland, and the pharynx and esophagus. The prevertebral
fascia is fixed above to the base of the skull, and below is continued into the
thorax in front of the Longus colli
muscles. Parallel to the carotid sheath and along its medial aspect the prevertebral fascia gives off a thin lamina, the buccopharyngeal fascia, which closely invests
the Constrictor muscles of the pharynx, and is continued forward from the
Constrictor pharyngis superior on to the Buccinator. It is attached to the prevertebral
layer by loose connective tissue only, and thus an easily distended space, the retropharyngeal
space, is found between them. This space is limited above by the base of
the skull, while below it extends behind the esophagus
into the posterior mediastinal cavity of the thorax.
The prevertebral fascia is prolonged downward and lateralward behind the carotid vessels and in front of the Scaleni, and forms a sheath for the brachial nerves and subclavian vessels in the posterior triangle of the neck;
it is continued under the clavicle as the axillary sheath and is attached to
the deep surface of the coracoclavicular fascia.
Immediately above and behind the clavicle an areolar space exists between the
investing layer and the sheath of the subclavian
vessels, and in this space are found the lower part of the external jugular
vein, the descending clavicular nerves, the
transverse scapular and transverse cervical vessels, and the inferior belly of
the Omohyoideus muscle. This space is limited below
by the fusion of the coracoclavicular fascia with the
anterior wall of the axillary sheath. (4) The pretrachial
fascia extends medially in front of the carotid vessels, and assists in
forming the carotid sheath. It is continued behind the depressor muscles of the
hyoid bone, and, after enveloping the thyroid gland, is prolonged in front of
the trachea to meet the corresponding layer of the opposite side. Above, it is
fixed to the hyoid bone, while below it is carried downward in front of the
trachea and large vessels at the root of the neck, and ultimately blends with
the fibrous pericardium. This layer is fused on either side with the prevertebral fascia, and with it completes the compartment
containing the larynx and trachea, the thyroid gland, and the pharynx and esophagus.
Variations.—The Sternocleidomastoideus varies much in the extent of its
origin from the clavicle: in some cases the clavicular
head may be as narrow as the sternal; in others it may be as much as
Triangles of the Neck.—This muscle divides
the quadrilateral area of the side of the neck into two triangles, an anterior
and a posterior. The boundaries of the anterior triangle are, in front,
the median line of the neck; above, the lower border of the body of the
mandible, and an imaginary line drawn from the angle of the mandible to the Sternocleidomastoideus; behind, the anterior border
of the Sternocleidomastoideus. The apex of the triangle
is at the upper border of the sternum. The boundaries of the posterior
triangle are, in front, the posterior border of the Sternocleidomastoideus; below, the middle third of
the clavicle; behind, the anterior margin of the Trapezius. The apex
corresponds with the meeting of the Sternocleidomastoideus
and Trapezius on the occipital bone. The anatomy of these triangles will be
more fully described with that of the vessels of the neck (p. 562).
Nerves.—The Sternocleidomastoideus
is supplied by the accessory nerve and branches from the anterior divisions of
the second and third cervical nerves.
Actions.—When only one Sternocleidomastoideus
acts, it draws the head toward the shoulder of the same side, assisted by the
Splenius and the Obliquus capitis
inferior of the opposite side. At the same time it rotates the head so as to
carry the face toward the opposite side. Acting together from their sternoclavicular attachments the muscles will flex the
cervical part of the vertebral column. If the head be fixed, the two muscles
assist in elevating the thorax in forced inspiration.
Sternocleidomastoid region
answers the projection of the same name muscle.
Lateral
region of the neck is bordered by back margin of the sternocleido-mastoid, anterior margin of the trapezius
muscle and upper margin of clavicle. There are follow areas in this region:
1.
Omo-trapezial trigone is bordered by back margin of the
sternocleidomastoid, lower belly of omohyoid and
anterior margin of the trapezius muscles.
2.
Omo-clavicular
(greater supraclavicular) trigone of neck is bordered
by back margin of the sternocleidomastoid, lower belly of omohyoid
and upper margin of the clavicle.
Posterior
region answers the projection of the trapezius muscle.
Cervical fascia
According
V.M.Shevkunenko there are 5 cervical fasciae:
I
- superficial
cervical fascia envelops the platizma
Proper
cervical fascia has two sheets:
II
- superficial
lamina of the proper cervical fasciae starts from front surface of the
sternum and clavicle, lower margin of mandible and attaches the spinous processes of the cervical vertebrae. It forms the
sheath for sternocleidomastoid and trapezius muscles.
III
- deep
lamina of the proper cervical fasciae starts from back surface of the
sternum and clavicle and attaches to the hyoid bone from sides bordered by omohyoid muscles. This fascia forms linea
alba of neck and the sheath for infrahyoid muscles.
Suprasternal
interaponeurotic space
made up between superficial and deep lamina of the proper cervical fasciae. It
contains jugular venous arch and fat tissue. Suprasternal space connects with
lateral recesses located behind the lower part of sternocleidomastoid muscle.
IV
- internal
cervical fascia subdivides into parietal
and visceral sheets. Parietal lamina
envelopes all organs of neck together and visceral – each organ separately. Previsceral space positioned between parietal
and visceral laminae and contains adipose tissue,
lymphatic nodes, and nerves and communicates with anterior mediastinum. Pretracheal space located before trachea
between parietal and visceral sheets.
V
- prevertebral
fascia envelops all deep cervical muscles forming their sheathes.
Retropharyngeal space made up between V fascia and parietal lamina of IV
fasciae. Retrovisceral space positioned
between internal cervical and prevertebral fasciae
and contains adipose tissue and continues into posterior mediastinum.
According international nomenclature (PNA)
there are 3 laminae of
cervical fasciae:
1.
Superficial lamina
meets the superficial lamina of the proper cervical fasciae according V.M.Shevkunenko and contains the suprasternal space.
2.
Pretracheal
lamina meets the deep lamina of the proper cervical
fasciae according V.M.Shevkunenko and forms carotid sheath.
3.
Prevertebral
lamina meets the same fasciae according V.M.Shevkunenko.
Interscalenum space positioned between anterior and
middle scalene muscles where subclavian artery
passes. Anterscalenum space located in front of scalene
muscles where subclavian vein passes.
Deep lamina of the proper cervical
fasciae (V.M.Shevkunenko) associating infrahyoid muscles forms omoclavicular
aponeurosis or cervical
sail (Rishe). Cervical sail assists to drain
superficial veins of neck that spliced with it.
Prepared
by
Reminetskyy B.Y.