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 № 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.