22

Lesson 4

 

Muscles of neck and head

GENERAL ANATOMIC AND PHYSIOLOGICAL DATA ABOUT MUSCLES. AGE PECULIARITIES OF THE STRUCTURE OF THE MUSCULAR SYSTEM

 

THE MUSCLES are connected with the bones, cartilages, ligaments, and skin, either directly, or through the intervention of fibrous structures called tendons or aponeuroses. Where a muscle is attached to bone or cartilage, the fibers end in blunt extremities upon the periosteum or perichondrium, and do not come into direct relation with the osseous or cartilaginous tissue. Where muscles are connected with its skin, they lie as a flattened layer beneath it, and are connected with its areolar tissue by larger or smaller bundles of fibers, as in the muscles of the face.

  The muscles vary extremely in their form. In the limbs, they are of considerable length, especially the more superficial ones; they surround the bones, and constitute an important protection to the various joints. In the trunk, they are broad, flattened, and expanded, and assist in forming the walls of the trunk cavities. Hence the reason of the terms, long, broad, short, etc., used in the description of a muscle.

  There is considerable variation in the arrangement of the fibers of certain muscles with reference to the tendons to which they are attached. In some muscles the fibers are parallel and run directly from their origin to their insertion; these are quadrilateral muscles, such as the Thyreohyoideus. A modification of these is found in the fusiform muscles, in which the fibers are not quite parallel, but slightly curved, so that the muscle tapers at either end; in their actions, however, they resemble the quadrilateral muscles.

 

 

ќписание: ќписание: image361

 

VIDEO

 

The Direction of the Muscle Pull.ЧIn those muscles where the fibers always run in a straight line from origin to insertion in all positions of the joint, a straight line joining the middle of the surface of origin with the middle of the insertion surface will give the direction of the pull. If, however, the muscle or its tendon is bent out of a straight line by a bony process or ligament so that it runs over a pulley-like arrangement, the direction of the muscle pull is naturally bent out of line. The direction of the pull in such cases is from the middle point of insertion to the middle point of the pulley where the muscle or tendon is bent. Muscles or tendons of muscles which pass over more than one joint and pass through more than one pulley may be resolved, so far as the direction of the pull is concerned, into two or more units or single-joint muscles . The tendons of the Flexor profundus digitorum, for example, pass through several pulleys formed by fibrous sheaths. The direction of the pull is different for each joint and varies for each joint according to the position of the bones. The direction is determined in each case, however, by a straight line between the centers of the pulleys on either side of the joint (Fig. 363). The direction of the pull in any of the segments would not be altered by any change in the position or origin of the muscle belly above the proximal pulley.

ќписание: ќписание: image363

 

The Action of the Muscle Pull on the Tendon.ЧWhere the muscle fibers are parallel or nearly parallel to the direction of the tendon the entire strength of the muscle contraction acts in the direction of the tendon.

 

ќписание: ќписание: image365

 

A, fusiform; B, unipinnate; C, bipinnate; P.C.S., physiological cross-section

 

The Scalp 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.

 

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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.ЧBoth 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.ЧThe Frontalis is supplied by the temporal branches of the facial nerve, and the Occipitalis by the posterior auricular branch of the same nerve.

 Actions.ЧThe 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

Х Origin:

Х Superficial: 1.zygomatic process of the maxilla 2.inferior border of zygomatic arch

Х Intermediate: inner surface of zygomatic arch Х Deep: posterior aspect of inferior border of zygomatic arch

Х Insertion:

Х Superficial: 1.angle of mandible 2.lateral surface of mandibular ramus

Х Intermediate: ramus of mandible Х Deep: 1.superior ramus of mandible 2.coronoid process of mandible

Х Action: 1.closes the lower jaw (clenches the teeth) 2.may deviate mandible to opposite side of contraction

Х Blood: masseteric arteryХ Nerve: masseteric nerve

 

Medial pterygoid

Х Origin:

1.medial surface of lateral pterygoid plate of the sphenoid 2.palatine bone 3.pterygoid fossa

Х Insertion:

1.inner surface of mandibular ramus 2.angle of the mandible

Х Action:

1.closes the lower jaw (clenches the teeth) 2.can protrude the mandible in combination with the lateral pterygoid

Х Blood: medial pterygoid artery Х Nerve: medial pterygoid nerve

 

Lateral pterygoid

Х Origin:

1.Superior head: lateral surface of the greater wing of the sphenoid 2.Inferior head: lateral surface of the lateral pterygoid plate

Х Insert together:

1.neck of the mandibular condyle 2.articular disk of the TMJ

Х 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)

Х Blood: lateral pterygoid artery Х Nerve: lateral pterygoid nerve

 

Temporalis

Х Origin:

Х Temporal fossa

Х Insertion: coronoid process of the mandible

Х Action:

1.closes the lower jaw (clenches the teeth) 2.retraction, pulles back

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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 Ц elastic skin

 

Muscles of Facial Expression (mimetic)

 

Orbicularis oculi

Х Origin:

1.orbital portion: nasal process of frontal bone 2.palpebral portion: palpebral ligament 3.lacrimal portion: lacrimal crest of lacrimal bone

Х Insertion: circumferentially around orbit meeting in palpebral raphe

Х Action: powerfully closes the eye Х Blood: ophthalmic artery Х Nerve: zygomatic branch of facial nerve

 

Corrugator supercilii

Х Origin: frontal bone just above the nose Х Insertion: skin of the medial portion of the eyebrows Х Action: draws the eyebrows downward and medially Х Blood: ophthalmic artery Х Nerve: zygomatic branch of facial nerve

 


Orbicularis oris

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Scheme showing arrangement of fibers of Orbicularis oris.

 

Х Origin:

1.alveolar border of maxilla 2.lateral to midline of mandible

Х Insertion:

1.circumferentially around mouth 2.blends with other muscles

Х Action:

1.closes the lips 2.protrudes the lips

Х Blood: facial artery Х Nerve: buccal branch of facial nerve

 

Levator labii superioris

Х Action: 1.elevates the upper lip 2.flares the nostrils

 

Zygomaticus minor

Х Action: elevates the upper lip

 

Zygomaticus major

Х Action: lifts and draws back the angle(s) of the mouth (as in smiling)

 

Risorius (may be absent)

Х Action: draws the mouth laterally (as in smiling)

 

Levator anguli oris

Х Action: lifts the angle(s) of the mouth (as in smiling)

 

Buccinator

Х Action: compresses the cheek(s)

 

Depressor anguli oris

Х Action: lowers the angle(s) of the mouth (as in frowning)

 

Depressor labii inferioris

Х Action: draws the lower lip downward and laterally

 


Epicranial Musculature

 

Occipitalis (2 bellies)

Х Origin:

1.lateral 2/3 of superior nuchal line 2.external occipital protuberance

Х Insertion: galea aponeurosis, over the occipital bone Х Action: draws back the scalp to raise the eyebrows and wrinkle the brow Х Blood: occipital artery Х Nerve: posterior auricular branch of facial nerve

 

Frontalis (2 bellies)

Х Origin: galea aponeurosis, anterior to the vertex Х Insertion: skin above the nose and eyes Х Action: draws back the scalp to raise the eyebrows and wrinkle the brow Х Blood: ophthalmic artery Х Nerve: temporal branch of facial nerve

 

Anterior, posterior and superior auricularis muscles

Х 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

Х Origin: subcutaneous skin over delto-pectoral region Х Insertion: invests in the skin widely over the mandible Х Action: 1.depress mandible and lower lip 2.tenses the skin over the lower neck

Х Blood: superficial vessels of the neck Х Nerve: cervical branch of facial nerve (VII cranial)

 

Sternocleidomastoid

Х Origin: (two heads)

1.manubrium of sternum 2.medial portion of clavicle

Х Insertion: mastoid process of temporal bone Х Action:

1.rotates to side opposite of contraction 2.laterally flexes to the contracted side 3.bilaterally flexes the neck

Х Blood:

1.occipital artery 2.superior thyroid artery

Х Nerve:

1.motor: spinal accessory (XI cranial) 2.sensory: ventral rami of C2,(C3)

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Suprahyoid group

1. Stylohyoid

Х Origin: styloid process of temporal bone Х Insertion: lateral margin of hyoid (near greater horn) Х Action:

1.pulls the hyoid superiorly & posteriorly during swallowing 2.fixes the hyoid bone for infrahyoid action

Х Blood: facial & occipital artery Х Nerve: facial nerve (VII cranial)

 

2. Digastric

Х Attachments:

1.post belly: mastoid process of temporal bone 2.anterior belly: digastric fossa of internal mandible

Х both bellies meet and attach at the lateral aspect of body of hyoid by a pulley tendon Х Action:

1.open mouth by depressing mandible 2.fixes hyoid bone for infrahyoid action

Х Blood: branches of the external carotid Х Nerve:

1.posterior belly: facial nerve (VII cranial) 2.anterior belly: mylohyoid nerve

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3. Mylohyoid

Х Origin: inner surface of mandible off the mylohyoid line Х Insertion:

1.body of hyoid 2.along midline at mylohyoid raphe

Х Action:

1.elevates the hyoid bone 2.raises floor of mouth (for swallowing) 3.depresses mandible when hyoid is fixed

Х Blood: lingual artery Х Nerve: mylohyoid nerve (branch of mandibular division, V3 cranial)

 

4. Geniohyoid

Х Origin: inner surface of the mandible

Х Insertion: body of hyoid (paired muscles)

Х Action:

1.pulles the tongue 2.depress the mandible 3.works with mylohyoid

Х Blood: lingual artery Х Nerve:

 

Infrahyoid group

1. Sternohyoid

Х Origin:

1.posterior aspect of manubrium 2.sternal end of clavicle

Х Insertion: body of hyoid Х Action:

1.depresses hyoid & larynx 2.acts eccentrically with the suprahyoid muscles to provide them a stable base

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х Nerve:

1.upper portions: superior root of ansa cervicalis, C2 2.lower portions: inferior root of ansa cervicalis, C2,3

 

2. Omohyoid

Х Attachments:

1.superior belly: hyoid bone (lateral to sternohyoid) 2.inferior belly: superior scapular border (medial to suprascapular notch)

Х both bellies meet at the clavicle & are held to the clavicle by a pulley tendon Х Action:

1.depresses hyoid & larynx 2.acts eccentrically with the suprahyoid muscles to provide them a stable base

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х Nerve:

1.upper portions: superior root of ansa cervicalis, C2 2.lower portions: inferior root of ansa cervicalis, C2,3

 

3. Sternothyroid

Х Origin: posterior aspect of manubrium Х Insertion: oblique line of thyroid cartilage Х Action:

1.depresses hyoid & larynx 2.acts eccentrically with the suprahyoid muscles to provide them a stable base

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х Nerve:

1.upper portions: superior root of ansa cervicalis, C2 2.lower portions: inferior root of ansa cervicalis, C2,3

 

4. Thyrohyoid

Х Origin: oblique line of thyroid cartilage Х Insertion: body of hyoid Х Action:

1.depresses hyoid 2.may assist in larynx elevation

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х 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

Х Attachment A: anterior tubercles of transverse processes of C3-C6 Х Attachment B: 1st rib Х 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

Х Blood: inferior thyroid artery (branch of the thyrocervical trunk) Х Nerve: ventral rami C3-C6

 

Middle scalene

Х Attachment A: transverse processes of all cervical vertebrae Х Attachment B: 1st rib (behind anterior scalene) Х 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

Х Blood: ascending cervical artery Х Nerve: ventral rami C3-C8

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Posterior scalene

Х Attachment A: posterior tubercles of transverse processes of C5 & C6 Х Attachment B: 2nd and/or 3rd rib Х 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

Х Blood: ascending cervical artery Х Nerve: ventral rami C5-C7

 

Neck prevertebral deep Musculature

Longus colli

ХOrigin: lower anterior vertebral bodies and transverse processes Х Insertion: anterior vertebral bodies and transverse processes several segments above Х Action: flexes the head and neck Х Blood: muscular branches of the aorta Х Nerve: ventral rami C2-C6

 

Longus capitis

Х Origin: upper anterior vertebral bodies and transverse processes Х Insertion: anterior vertebral bodies and transverse processes several segments above Х Action: flexes the head and neck Х Blood: muscular branches of the aorta Х Nerve: ventral rami C1-C3

 

Rectus capitis anterior

Х Origin: anterior base of the transverse process of the atlas Х Insertion: occipital bone anterior to foramen magnum Х Action: flexes the head Х Blood: muscular branches of the aorta Х Nerve: ventral rami C2,3

Rectus capitis lateralis

Х Origin: transverse process of the atlas Х Insertion: jugular process of the occipital bone Х Action: bends the head laterally Х Blood: muscular branches of the aorta Х Nerve: ventral rami C2,3

 

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 Ц 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 glandЧthe 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.

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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.ЧThe 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 7.5 cm. in breadth. When the clavicular origin is broad, it is occasionally subdivided into several slips, separated by narrow intervals. More rarely, the adjoining margins of the Sternocleidomastoideus and Trapezius have been found in contact. The Supraclavicularis muscle arises from the manubrium behind the Sternocleidomastoideus and passes behind the Sternocleidomastoideus to the upper surface of the clavicle.

 

Triangles of the Neck.ЧThis 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.ЧThe Sternocleidomastoideus is supplied by the accessory nerve and branches from the anterior divisions of the second and third cervical nerves.

 

Actions.ЧWhen 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 Ц 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.

 

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.ЧBoth 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.ЧThe Frontalis is supplied by the temporal branches of the facial nerve, and the Occipitalis by the posterior auricular branch of the same nerve.

 Actions.ЧThe 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

Х Origin:

Х Superficial: 1.zygomatic process of the maxilla 2.inferior border of zygomatic arch

Х Intermediate: inner surface of zygomatic arch Х Deep: posterior aspect of inferior border of zygomatic arch

Х Insertion:

Х Superficial: 1.angle of mandible 2.lateral surface of mandibular ramus

Х Intermediate: ramus of mandible Х Deep: 1.superior ramus of mandible 2.coronoid process of mandible

Х Action: 1.closes the lower jaw (clenches the teeth) 2.may deviate mandible to opposite side of contraction

Х Blood: masseteric arteryХ Nerve: masseteric nerve

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Medial pterygoid

Х Origin:

1.medial surface of lateral pterygoid plate of the sphenoid 2.palatine bone 3.pterygoid fossa

Х Insertion:

1.inner surface of mandibular ramus 2.angle of the mandible

Х Action:

1.closes the lower jaw (clenches the teeth) 2.can protrude the mandible in combination with the lateral pterygoid

Х Blood: medial pterygoid artery Х Nerve: medial pterygoid nerve

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Lateral pterygoid

Х Origin:

1.Superior head: lateral surface of the greater wing of the sphenoid 2.Inferior head: lateral surface of the lateral pterygoid plate

Х Insert together:

1.neck of the mandibular condyle 2.articular disk of the TMJ

Х 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)

Х Blood: lateral pterygoid artery Х Nerve: lateral pterygoid nerve

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Temporalis

Х Origin:

Х Temporal fossa

Х Insertion: coronoid process of the mandible

Х Action:

1.closes the lower jaw (clenches the teeth) 2.retraction, pulles back

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Muscles of Facial Expression (mimetic muscles) have such peculiarities:

6.                Originate in bones of face and insert into skin

7.                Do not throw over joints

8.                Do not have proper fasciae (exception is buccinator muscle)

9.                Placed round natural orifices of the face (eyes, nostrils, ears and mouth)

10.           They have an antagonists Ц elastic skin

 

Muscles of Facial Expression (mimetic)

 

Orbicularis oculi

Х Origin:

1.orbital portion: nasal process of frontal bone 2.palpebral portion: palpebral ligament 3.lacrimal portion: lacrimal crest of lacrimal bone

Х Insertion: circumferentially around orbit meeting in palpebral raphe

Х Action: powerfully closes the eye Х Blood: ophthalmic artery Х Nerve: zygomatic branch of facial nerve

Corrugator supercilii

Х Origin: frontal bone just above the nose Х Insertion: skin of the medial portion of the eyebrows Х Action: draws the eyebrows downward and medially Х Blood: ophthalmic artery Х Nerve: zygomatic branch of facial nerve

Orbicularis oris

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Scheme showing arrangement of fibers of Orbicularis oris.

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Х Origin:

1.alveolar border of maxilla 2.lateral to midline of mandible

Х Insertion:

1.circumferentially around mouth 2.blends with other muscles

Х Action:

1.closes the lips 2.protrudes the lips

Х Blood: facial artery Х Nerve: buccal branch of facial nerve

 

Levator labii superioris

Х Action: 1.elevates the upper lip 2.flares the nostrils

 

Zygomaticus minor

Х Action: elevates the upper lip

 

Zygomaticus major

Х Action: lifts and draws back the angle(s) of the mouth (as in smiling)

 

Risorius (may be absent)

Х Action: draws the mouth laterally (as in smiling)

 

Levator anguli oris

Х Action: lifts the angle(s) of the mouth (as in smiling)

 

Buccinator

Х Action: compresses the cheek(s)

 

Depressor anguli oris

Х Action: lowers the angle(s) of the mouth (as in frowning)

 

Depressor labii inferioris

Х Action: draws the lower lip downward and laterally

 

Epicranial Musculature

 

Occipitalis (2 bellies)

Х Origin:

1.lateral 2/3 of superior nuchal line 2.external occipital protuberance

Х Insertion: galea aponeurosis, over the occipital bone Х Action: draws back the scalp to raise the eyebrows and wrinkle the brow Х Blood: occipital artery Х Nerve: posterior auricular branch of facial nerve

 

Frontalis (2 bellies)

Х Origin: galea aponeurosis, anterior to the vertex Х Insertion: skin above the nose and eyes Х Action: draws back the scalp to raise the eyebrows and wrinkle the brow Х Blood: ophthalmic artery Х Nerve: temporal branch of facial nerve

 

Anterior, posterior and superior auricularis muscles

Х 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.

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Neck Musculature

Subdivides into superficial and deep groups

 

Superficial Neck Musculature

Platysma

Х Origin: subcutaneous skin over delto-pectoral region Х Insertion: invests in the skin widely over the mandible Х Action: 1.depress mandible and lower lip 2.tenses the skin over the lower neck

Х Blood: superficial vessels of the neck Х Nerve: cervical branch of facial nerve (VII cranial)

 

Sternocleidomastoid

Х Origin: (two heads)

1.manubrium of sternum 2.medial portion of clavicle

Х Insertion: mastoid process of temporal bone Х Action:

1.rotates to side opposite of contraction 2.laterally flexes to the contracted side 3.bilaterally flexes the neck

Х Blood:

1.occipital artery 2.superior thyroid artery

Х Nerve:

1.motor: spinal accessory (XI cranial) 2.sensory: ventral rami of C2,(C3)

1. Stylohyoid

Х Origin: styloid process of temporal bone Х Insertion: lateral margin of hyoid (near greater horn) Х Action:

1.pulls the hyoid superiorly & posteriorly during swallowing 2.fixes the hyoid bone for infrahyoid action

Х Blood: facial & occipital artery Х Nerve: facial nerve (VII cranial)

2. Digastric

Х Attachments:

1.post belly: mastoid process of temporal bone 2.anterior belly: digastric fossa of internal mandible

Х both bellies meet and attach at the lateral aspect of body of hyoid by a pulley tendon Х Action:

 

ќписание: ќписание: ќписание: image385

 

 

Suprahyoid group

 

1.open mouth by depressing mandible 2.fixes hyoid bone for infrahyoid action

Х Blood: branches of the external carotid Х Nerve:

1.posterior belly: facial nerve (VII cranial) 2.anterior belly: mylohyoid nerve

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3. Mylohyoid

Х Origin: inner surface of mandible off the mylohyoid line Х Insertion:

1.body of hyoid 2.along midline at mylohyoid raphe

Х Action:

1.elevates the hyoid bone 2.raises floor of mouth (for swallowing) 3.depresses mandible when hyoid is fixed

Х Blood: lingual artery Х Nerve: mylohyoid nerve (branch of mandibular division, V3 cranial)

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4. Geniohyoid

Х Origin: inner surface of the mandible

Х Insertion: body of hyoid (paired muscles)

Х Action:

1.pulles the tongue 2.depress the mandible 3.works with mylohyoid

Х Blood: lingual artery Х Nerve:

 

Infrahyoid group

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1. Sternohyoid

Х Origin:

1.posterior aspect of manubrium 2.sternal end of clavicle

Х Insertion: body of hyoid Х Action:

1.depresses hyoid & larynx 2.acts eccentrically with the suprahyoid muscles to provide them a stable base

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х Nerve:

1.upper portions: superior root of ansa cervicalis, C2 2.lower portions: inferior root of ansa cervicalis, C2,3

 

2. Omohyoid

Х Attachments:

1.superior belly: hyoid bone (lateral to sternohyoid) 2.inferior belly: superior scapular border (medial to suprascapular notch)

Х both bellies meet at the clavicle & are held to the clavicle by a pulley tendon Х Action:

1.depresses hyoid & larynx 2.acts eccentrically with the suprahyoid muscles to provide them a stable base

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х Nerve:

1.upper portions: superior root of ansa cervicalis, C2 2.lower portions: inferior root of ansa cervicalis, C2,3

 

3. Sternothyroid

Х Origin: posterior aspect of manubrium Х Insertion: oblique line of thyroid cartilage Х Action:

1.depresses hyoid & larynx 2.acts eccentrically with the suprahyoid muscles to provide them a stable base

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х Nerve:

1.upper portions: superior root of ansa cervicalis, C2 2.lower portions: inferior root of ansa cervicalis, C2,3

 

4. Thyrohyoid

Х Origin: oblique line of thyroid cartilage Х Insertion: body of hyoid Х Action:

1.depresses hyoid 2.may assist in larynx elevation

Х Blood:

1.inferior thyroid artery (primary) 2.superior thyroid artery

Х 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

Х Attachment A: anterior tubercles of transverse processes of C3-C6 Х Attachment B: 1st rib Х 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

Х Blood: inferior thyroid artery (branch of the thyrocervical trunk) Х Nerve: ventral rami C3-C6

 

Middle scalene

Х Attachment A: transverse processes of all cervical vertebrae Х Attachment B: 1st rib (behind anterior scalene) Х 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

Х Blood: ascending cervical artery Х Nerve: ventral rami C3-C8

Posterior scalene

Х Attachment A: posterior tubercles of transverse processes of C5 & C6 Х Attachment B: 2nd and/or 3rd rib Х 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

Х Blood: ascending cervical artery Х Nerve: ventral rami C5-C7

Longus colli

ХOrigin: lower anterior vertebral bodies and transverse processes Х Insertion: anterior vertebral bodies and transverse processes several segments above Х Action: flexes the head and neck Х Blood: muscular branches of the aorta Х Nerve: ventral rami C2-C6

Longus capitis

Х Origin: upper anterior vertebral bodies and transverse processes Х Insertion: anterior vertebral bodies and transverse processes several segments above Х Action: flexes the head and neck Х Blood: muscular branches of the aorta Х Nerve: ventral rami C1-C3

 

Rectus capitis anterior

Х Origin: anterior base of the transverse process of the atlas Х Insertion: occipital bone anterior to foramen magnum Х Action: flexes the head Х Blood: muscular branches of the aorta Х Nerve: ventral rami C2,3

Rectus capitis lateralis

Х Origin: transverse process of the atlas Х Insertion: jugular process of the occipital bone Х Action: bends the head laterally Х Blood: muscular branches of the aorta Х Nerve: ventral rami C2,3

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Neck prevertebral deep Musculature

 

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 Ц 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:

6.                Submandibular trigone bordered by lower margin of mandible and both bellies of digastric muscle

7.                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.

8.                Carotid trigone bordered by posterior belly of digastric muscle, superior belly of omohyoid, anterior margin of the sternocleidomastoid and linea alba of the neck.

9.                Muscular (omotracheal) trigone bordered by superior belly of omohyoid, anterior margin of the sternocleidomastoid and linea alba of the neck.

10.           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 glandЧthe 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.

  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.

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Section of the neck at about the level of the sixth cervical vertebra.

Showing the arrangement of the fascia coli.

 

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.ЧThe 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 7.5 cm. in breadth. When the clavicular origin is broad, it is occasionally subdivided into several slips, separated by narrow intervals. More rarely, the adjoining margins of the Sternocleidomastoideus and Trapezius have been found in contact. The Supraclavicularis muscle arises from the manubrium behind the Sternocleidomastoideus and passes behind the Sternocleidomastoideus to the upper surface of the clavicle.

 

Triangles of the Neck.ЧThis 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.ЧThe Sternocleidomastoideus is supplied by the accessory nerve and branches from the anterior divisions of the second and third cervical nerves.

 

Actions.ЧWhen 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:

3.                Omo-trapezial trigone is bordered by back margin of the sternocleidomastoid, lower belly of omohyoid and anterior margin of the trapezius muscles.

4.                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.

s.

 

According international nomenclature (PNA)

there are 3 laminae of cervical fasciae:

IV - internal cervical fascia subdivides into parietal and visceral sheets. Parietal lamina envelopes all organs of neck together and visceral Ц 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 sheet

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.

 

4.          Superficial lamina meets the superficial lamina of the proper cervical fasciae according V.M.Shevkunenko and contains the suprasternal space.

5.          Pretracheal lamina meets the deep lamina of the proper cervical fasciae according V.M.Shevkunenko and forms carotid sheath.

6.          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.