THE NECK PART I BONES AND JOINTS OF THE NECK MUSCLES OF THE NECK SCM CAROTID TRIANGLE ENDOCRINE LAYER OF THE CERVICAL VISCERA

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1 THE NECK PART I BONES AND JOINTS OF THE NECK MUSCLES OF THE NECK SCM CAROTID TRIANGLE ENDOCRINE LAYER OF THE CERVICAL VISCERA

2 THE NECK THE NECK The neck has four major compartments, which are enclosed by an outer musculofascial collar: The vertebral compartment contains the cervical vertebrae and associated postural muscles. The visceral compartment contains important glands (thyroid, parathyroid, and thymus), and parts of the respiratory and digesrve tracts that pass between the head and thorax. The two vascular compartments, one on each side, contain the major blood vessels and the vagus nerve.

3 THE NECK THE NECK The anterior porron of the neck contains the major visceral structures between the head and the thorax: pharynx larynx trachea esophagus thyroid and parathyroid glands

4 THE NECK THE CERVICAL VERTEBRAE THE NECK The skeleton of the neck is formed by: the cervical vertebrae, hyoid bone, manubrium of the sternum, clavicles

5 THE NECK THE CERVICAL VERTEBRAE THE CERVICAL VERTEBRAE The seven cervical vertebrae have transverse foramina (for the vertebral arteries to pass through) within their transverse processes VERTEBRAL ARTERIES These vessels enter the foramen transversarium of the 6th cervical vertebra, emerging above the 1st cervical vertebra to enter the suboccipital triangle The most disrncrve feature of each cervical vertebra is the oval foramen transversarium (transverse foramen) in the transverse process.

6 THE NECK THE CERVICAL VERTEBRAE THE CERVICAL VERTEBRAE There are 7 cervical vertebrae: the 4 typical cervical vertebrae C3 C6 the 3 atypical cervical vertebrae (C1, C2, and C7) The four typical cervical vertebrae C3 C6 have the following characterisrcs: The vertebral body is small and longer from side to side than anteroposteriorly; the superior surface is concave, and the inferior surface is convex. The vertebral foramen is large and triangular. The transverse processes of all cervical vertebrae (typical or atypical) include foramina transversaria for the vertebral vessels (the vertebral veins and, except for vertebra C7, the vertebral arteries). Their spinous processes are short and bifid.

7 THE NECK THE CERVICAL VERTEBRAE THE CERVICAL VERTEBRAE The vertebral arteries and their accompanying veins pass through the transverse foramina, except those in C7, which transmit only small accessory veins. The first (C1, atlas), second (C2, axis) and seventh (C7, vertebra prominens) cervical vertebrae are atypical. Vertebrae C3 C6 are the typical cervical vertebrae.

8 THE NECK THE CERVICAL VERTEBRAE THE CERVICAL VERTEBRAE There are three atypical cervical vertebrae (C1, C2, and C7): The C1 vertebra or atlas: a ring-like, kidney-shaped bone lacking a spinous process or body and consisrng of two lateral masses connected by anterior and posterior arches. Its concave superior arrcular facets receive the occipital condyles. The C2 vertebra or axis: a peg-like dens (odontoid process) projects superiorly from its body. The vertebra prominens (C7 ): so-named because of its long spinous process, which is not bifid. Its transverse processes are large, but its foramina transversaria are small.

9 THE NECK THE HYOID BONE THE HYOID BONE The hyoid is unique among bones for its isolapon from the remainder of the skeleton. It is suspended from the styloid processes of the temporal bones by the stylohyoid ligaments and is firmly bound to the thyroid carplage. FuncRonally, the hyoid serves as an a_achment for anterior neck muscles and a prop to keep the airway open. The hyoid lies in the anterior part of the neck at the level of the C3 vertebra.

10 THE NECK THE HYOID BONE THE HYOID BONE C3 - level of body of hyoid The body of the hyoid Each end of its body is united to a greater horn that projects posterosuperiorly and laterally from the body. Each lesser horn is a small bony projecron. FRACTURE OF HYOID BONE It occurs in people who are manually strangled by compression of the throat. This results in depression of the body of the hyoid onto the thyroid carplage. Inability to elevate the hyoid and move it anteriorly beneath the tongue makes swallowing and maintenance of the separaron of the alimentary and respiratory tracts difficult and may result in aspirapon pneumonia.

11 THE NECK THE HYOID BONE THE HYOID BONE The hyoid bone is suspended from the styloid processes by the stylohyoid ligaments and gives a_achment to the suprahyoid muscles and the infrahyoid muscles. The suprahyoid muscles raise the hyoid bone toward a stabilized mandible during swallowing. The suprahyoid region contains 4 muscles: Mylohyoid (V3) Digastric (V3 + VII) Stylohyoid (VII) Geniohyoid (C1-C2)

12 THE NECK THE HYOID BONE THE HYOID BONE The infrahyoid muscles depress the hyoid bone and larynx during swallowing and vocalizaron. The infrahyoid region contains 4 muscles commonly called strap muscles: Omohyoid Sternohyoid Sternothyroid Thyrohyoid INNERVATION: cervical plexus (C1 C3) The infrahyoid muscles are organized so that: sternohyoid and omohyoid lie superficially and sternothyroid and thyrohyoid lie more deeply

13 THE NECK THE HYOID BONE THE SUPRAHYOID AND INFRAHYOID REGIONS The suprahyoid region contains 4 muscles: Mylohyoid (V3) Digastric (V3 + VII) Stylohyoid (VII) Geniohyoid (C1 via hypoglossal nerve (CN XII)) The infrahyoid region contains 4 muscles commonly called strap muscles: Omohyoid Sternohyoid Sternothyroid Thyrohyoid cervical plexus (C1 C3)

14 THE NECK THE HYOID BONE THE HYOID MUSCLES Digastric Anterior belly: mylohyoid nerve, V 3 Posterior belly: facial nerve, CN VII Mylohyoid Mylohyoid nerve, V 3 Stylohyoid Facial nerve, CN VII The cervical plexus, composed of the ventral rami of C1-C4, innervates most of the neck muscles and provides sensory innervaron to the anterior and lateral neck

15 THE NECK THE CERVICAL PLEXUS THE CERVICAL PLEXUS The cervical plexus, composed of the ventral rami of C1-C4, innervates most of the neck muscles and provides sensory innervaron to the anterior and lateral neck. The (spinal) accessory nerve (CN XI) exits the jugular foramen and crosses the posterior triangle, innervarng the SCM and trapezius muscles

16 THE NECK THE CERVICAL PLEXUS THE CERVICAL PLEXUS AddiRonal innervaron includes: The mylohyoid nerve (CN V 3 ) innervates the mylohyoid muscle and anterior belly of the digastric muscle beneath the chin. The facial nerve (CN VII) innervates the platysma muscle through its cervical branch and posterior belly of the digastric muscle. The glossopharyngeal nerve (CN IX) supplies the carord body and sinus (visceral sensory). The vagus nerve (CN X) supplies the larynx through its superior and recurrent (inferior) laryngeal nerves. The hypoglossal nerve (CN XII) loops through the neck to innervate the tongue.

17 THE NECK THE FACIA OF THE NECK THE FACIA OF THE NECK The fascia of the neck is mulrlayered and encloses the muscles, glands, and neurovascular structures. The relaronships between the different fascial layers determine how infecpon and cancer spread in the neck.

18 FACIA OF THE NECK THE CERVICAL SUBCUTANEOUS TISSUE THE PLATYSMA THE DEEP CERVICAL FASCIA THE INVESTING LAYER OF DEEP CERVICAL FASCIA THE PRETRACHEAL LAYER OF DEEP CERVICAL FASCIA THE PREVERTEBRAL LAYER OF DEEP CERVICAL FASCIA

19 THE NECK THE FACIA OF THE NECK THE CERVICAL SUBCUTANEOUS TISSUE The neck is surrounded by the cervical subcutaneous Pssue / the superficial cervical fascia that lies deep to the skin and invests the platysma muscle. The cervical subcutaneous Pssue / the superficial cervical fascia lies between the dermis of the skin and the invesrng layer of deep cervical fascia It contains cutaneous nerves, blood and lympharc vessels, superficial lymph nodes, and variable amounts of fat. Anterolaterally, it contains the platysma. The platysma covers the anterolateral aspect of the neck. It derived from mesenchyme in the 2nd pharyngeal arch of the embryo, is supplied by cervical branch of the facial nerve, CN VII

20 FACIA OF THE NECK THE CERVICAL SUBCUTANEOUS TISSUE THE PLATYSMA THE DEEP CERVICAL FASCIA THE INVESTING LAYER OF DEEP CERVICAL FASCIA THE PRETRACHEAL LAYER OF DEEP CERVICAL FASCIA THE PREVERTEBRAL LAYER OF DEEP CERVICAL FASCIA

21 THE NECK THE FACIA OF THE NECK THE DEEP CERVICAL FACIA The deep cervical fascia consists of three fascial layers (sheaths): invespng, which surrounds all structures in the neck pretracheal, which encloses the viscera of the neck prevertebral, which surrounds the vertebral column and the deep muscles associated with the back The deep cervical fascia subdivides the neck into vascular (caropd sheath) vertebral visceral compartments This arrangement allows movement between adjacent structures and compartments and facilitates the surgical approach to specific areas. They limit the spread of abscesses (collecrons of pus) resulrng from infecrons.

22 FACIA OF THE NECK THE CERVICAL SUBCUTANEOUS TISSUE THE PLATYSMA THE DEEP CERVICAL FASCIA THE INVESTING LAYER OF DEEP CERVICAL FASCIA THE PRETRACHEAL LAYER OF DEEP CERVICAL FASCIA THE PREVERTEBRAL LAYER OF DEEP CERVICAL FASCIA

23 THE NECK THE FACIA OF THE NECK THE INVESTING LAYER OF THE DEEP CERVICAL FACIA The most superficial deep fascial layer. Completely surrounds the enrre neck deep to the skin and subcutaneous Rssue. The invespng layer of cervical fascia encircles all structures of the neck by invesrng the sternocleidomastoid and trapezius muscles, the fascial roofs of the anterior and posterior cervical triangles, and the parord and submandibular salivary glands.

24 THE NECK THE FACIA OF THE NECK THE INVESTING LAYER OF THE DEEP CERVICAL FACIA A_aching posteriorly to the ligamentum nuchae and the spinous process of the CVII vertebra, this fascial layer splits as it passes forward to enclose the trapezius muscle, reunites into a single layer as it forms the roof of the posterior triangle, splits again to surround the sternocleidomastoid muscle, and reunites again to join its twin from the other side.

25 THE NECK THE FACIA OF THE NECK THE INVESTING LAYER OF THE DEEP CERVICAL FACIA Superiorly, the invesrng (or superficial) layer of deep cervical fascia a_aches to the: Superior nuchal lines of the occipital bone Mastoid processes of the temporal bones ZygomaRc arches Inferior border of the mandible Hyoid bone Spinous processes of the cervical vertebrae Just inferior to its a_achment to the mandible, the fascia splits to enclose the submandibular gland; Posterior to the mandible, it splits to form the fibrous capsule of the parord gland. Inferiorly, the invesrng layer of deep cervical fascia a_aches to the manubrium, clavicles, and acromions and spines of the scapula.

26 FACIA OF THE NECK THE CERVICAL SUBCUTANEOUS TISSUE THE PLATYSMA THE DEEP CERVICAL FASCIA THE INVESTING LAYER OF DEEP CERVICAL FASCIA THE PRETRACHEAL LAYER OF DEEP CERVICAL FASCIA THE PREVERTEBRAL LAYER OF DEEP CERVICAL FASCIA

27 THE NECK THE FACIA OF THE NECK THE PRETRACHEAL LAYER OF DEEP CERVICAL FASCIA It is limited to the anterior part of the neck. It extends inferiorly from the hyoid into the thorax, where it blends with the fibrous pericardium covering the heart. The pretracheal layer of fascia includes a thin muscular part, which encloses the infrahyoid muscles, and a visceral part, which encloses the thyroid gland, trachea, and esophagus It is conrnuous posteriorly and superiorly with the buccopharyngeal fascia of the pharynx. The buccopharyngeal fascia extends from the base of the skull and envelops the buccinator muscle and pharyngeal constrictors

28 FACIA OF THE NECK THE CERVICAL SUBCUTANEOUS TISSUE THE PLATYSMA THE DEEP CERVICAL FASCIA THE INVESTING LAYER OF DEEP CERVICAL FASCIA THE PRETRACHEAL LAYER OF DEEP CERVICAL FASCIA THE PREVERTEBRAL LAYER OF DEEP CERVICAL FASCIA

29 THE NECK THE FACIA OF THE NECK THE PREVERTEBRAL LAYER OF DEEP CERVICAL FASCIA The prevertebral layer of deep cervical fascia forms a tubular sheath for the vertebral column and the muscles associated with it. The prevertebral layer of deep fascia is fixed to the cranial base superiorly. Inferiorly, it blends with the endothoracic fascia peripherally The prevertebral fascia in an anterolateral posiron extends from the anterior and middle scalene muscles to surround the brachial plexus and subclavian artery as these structures pass into the axilla. This fascial extension is the axillary sheath The caropd sheath is a column of fascia that surrounds the common carord artery, the internal carord artery, the internal jugular vein, and the vagus nerve as these structures pass through the neck

30 THE NECK THE FACIA OF THE NECK THE PREVERTEBRAL LAYER OF DEEP CERVICAL FASCIA The caropd sheath contains the: Common and internal carord arteries Internal jugular vein Vagus nerve (CN X) Some deep cervical lymph nodes CaroRd sinus nerve SympatheRc nerve fibers (carord periarterial plexuses) The retropharyngeal space is the largest and most important interfascial space in the neck. The retropharyngeal space is a potenpal space that consists of loose connecrve Rssue between the visceral part of the prevertebral layer of deep cervical fascia and the buccopharyngeal fascia surrounding the pharynx superficially.

31 SUPERFICIAL STRUCTURES OF THE NECK CERVICAL REGIONS/TRIANGLES AND CONTENTS CUTANEOUS AND SUPERFICIAL MUSCLES OF NECK ARTERIES IN CERVICAL REGION VEINS IN CERVICAL REGION NERVES IN CERVICAL REGION LYMPH NODES IN CERVICAL REGION

32 THE NECK THE CERVICAL REGIONS THE CERVICAL TRIANGLES The neck is divided into four major regions based on the usually visible and/or palpable borders of the large and relarvely superficial SCM and trapezius muscles: Sternocleidomastoid region Posterior cervical region Lateral cervical region (posterior triangle) Anterior cervical region (anterior triangle) The neck is divided into: Sternocleidomastoid region Posterior cervical region Lateral cervical region (posterior triangle) Anterior cervical region (anterior triangle)

33 THE NECK THE CERVICAL REGIONS THE CERVICAL TRIANGLES The neck is divided into: Sternocleidomastoid region Posterior cervical region Lateral cervical region (posterior triangle) Anterior cervical region (anterior triangle)

34 THE NECK THE CERVICAL REGIONS THE STERNOCLEIDOMASTOID REGION The SCM visibly divides each side of the neck into the anterior and lateral cervical regions (anterior and posterior triangles). MAIN CONTENT: sternocleidomastoid muscle superior part of external jugular vein greater auricular nerve transverse cervical nerve The two heads (clavicle and sternal) of the SCM are separated inferiorly by a space, visible superficially as a small triangular depression, the lesser supraclavicular fossa.

35 THE NECK THE CERVICAL REGIONS THE STERNOCLEIDOMASTOID REGION MAIN CONTENT OF THE LESSER SUPRACLAVICULAR FOSSA inferior part of internal jugular vein The superior a_achment of the SCM is the mastoid process of the temporal bone and the superior nuchal line of the occipital bone. INNERVATION OF the SCMs: Spinal accessory nerve (CN XI, motor) C2 and C3 nerves (pain and propriocepron)

36 THE NECK THE CERVICAL REGIONS THE STERNOCLEIDOMASTOID REGION AcRng bilaterally, the SCMs can flex the neck. AcRng unilaterally, the SCM laterally flexes the neck (bends the neck sideways) and rotates the head so the ear approaches the shoulder of the ipsilateral (same) side while rotarng the head so that the chin is turned toward the contralateral (opposite) side and elevates. To test the SCM: the head is turned to the opposite side against resistance (hand against chin).

37 THE NECK THE CERVICAL REGIONS THE POSTERIOR CERVICAL REGION BORDERS of the suboccipital triangle: Obliquus capirs superior Obliquus capirs inferior Rectus capirs posterior major MAIN CONTENTS: trapezius muscle cutaneous branches of posterior rami of cervical spinal nerves suboccipital region or triangle lies deep to superior part of this region INNERVATION OF THE TAPEZIUS: Spinal accessory n. also receives some branches from C2 and C3, thought to be proprioceprve If the trapezius is paralyzed, the shoulder droops

38 THE NECK THE CERVICAL REGIONS THE LATERAL CERVICAL REGION The lateral cervical region (posterior triangle) is bounded: anteriorly by the posterior border of the SCM posteriorly by the anterior border of the trapezius inferiorly by the middle third of the clavicle between the trapezius and the SCM by an apex, where the SCM and trapezius meet on the superior nuchal line of the occipital bone by a roof, formed by the invesrng layer of deep cervical fascia by a floor, formed by muscles covered by the prevertebral layer of deep cervical fascia

39 THE NECK THE CERVICAL REGIONS THE LATERAL CERVICAL REGION The lateral cervical region is divided into: a large OCCIPITAL TRIANGLE superiorly and a small OMOCLAVICULAR TRIANGLE inferiorly by the inferior belly of the omohyoid The OCCIPITAL TRIANGLE is so called because the occipital artery appears in its apex. The most important nerve crossing the occipital triangle is the spinal accessory nerve (CN XI). MAIN CONTENTS OF THE OCCIPITAL TRIANGLE: part of external jugular vein (EJV) posterior branches of cervical plexus of nerves spinal accessory nerve (CN XI) trunks of brachial plexus cervicodorsal trunk cervical lymph nodes

40 THE NECK THE CERVICAL REGIONS THE LATERAL CERVICAL REGION MAIN CONTENTS OF THE OMOCLAVICULAR (SUBCLAVIAN) TRIANGLE: subclavian artery (third part) part of subclavian vein (somermes) suprascapular artery supraclavicular lymph nodes The inferior part of the EJV crosses this triangle superficially; the subclavian artery lies deep in it

41 THE NECK THE CERVICAL REGIONS THE ANTERIOR CERVICAL REGION The anterior cervical region (anterior triangle) has the following: an anterior boundary formed by the median line of the neck a posterior boundary formed by the anterior border of the SCM a superior boundary formed by the inferior border of the mandible an apex located at the jugular notch in the manubrium a roof formed by subcutaneous Rssue containing the platysma a floor formed by the pharynx, larynx, and thyroid gland

42 THE NECK THE CERVICAL REGIONS THE ANTERIOR CERVICAL REGION THE ANTERIOR CERVICAL REGION (ANTERIOR TRIANGLE): submandibular (digastric) triangle submental triangle carord triangle muscular (omotracheal) triangle

43 THE NECK THE CERVICAL REGIONS THE ANTERIOR CERVICAL REGION THE SUBMANDIBULAR (DIGASTRIC) TRIANGLE MAIN CONTENTS: submandibular gland almost fills triangle submandibular lymph nodes hypoglossal nerve mylohyoid nerve parts of facial artery and vein THE SUBMENTAL TRIANGLE MAIN CONTENTS: submental lymph nodes and small veins that unite to form anterior jugular vein

44 THE NECK THE CERVICAL REGIONS THE ANTERIOR CERVICAL REGION THE CAROTID TRIANGLE The carord triangle is a vascular area bounded by: the superior belly of the omohyoid, the posterior belly of the digastric, the anterior border of the SCM The neurovascular structures in the carord triangle are surrounded by the caropd sheath: the caropd arteries medially the IJV laterally the vagus nerve posteriorly

45 THE NECK THE CERVICAL REGIONS THE ANTERIOR CERVICAL REGION THE CAROTID TRIANGLE MAIN CONTENTS: carord sheath containing common carord artery and its branches The neurovascular structures in the carord triangle are surrounded by the caropd sheath: the caropd arteries medially the IJV laterally the vagus nerve posteriorly

46 THE NECK THE CERVICAL REGIONS THE ANTERIOR CERVICAL REGION THE CAROTID TRIANGLE MAIN CONTENTS: carord sheath containing common carord artery and its branches internal jugular vein and its tributaries vagus nerve external carord artery and some of its branches hypoglossal nerve and superior root of ansa cervicalis spinal accessory nerve (CN XI) thyroid gland, larynx, and pharynx deep cervical lymph nodes branches of cervical plexus

47 THE NECK THE CERVICAL REGIONS THE ANTERIOR CERVICAL REGION THE CAROTID TRIANGLE The carord triangle is a vascular area bounded by: the superior belly of the omohyoid, the posterior belly of the digastric, the anterior border of the SCM THE MUSCULAR (OMOTRACHEAL) TRIANGLE MAIN CONTENTS: sternothyroid and sternohyoid muscles thyroid and parathyroid glands

48 THE NECK THE MUSCLES OF THE NECK THE CUTANEOUS AND SUPERFICIAL MUSCLES OF NECK Platysma - cervical branch of facial nerve (CN VII) Sternocleidomastoid (SCM) - spinal accessory nerve (CN XI, motor); C2 and C3 nerves (pain and propriocepron) Trapezius - spinal accessory nerve (CN XI; motor); C2 and C3 nerves (pain and propriocepron) THE MUSCLES IN LATERAL CERVICAL REGION splenius capirs levator scapulae anterior scalene middle scalene posterior scalene

49 THE NECK THE MUSCLES OF THE NECK THE MUSCLES IN ANTERIOR CERVICAL REGION The suprahyoid region contains 4 muscles: Mylohyoid - nerve to mylohyoid, CN V 3 Digastric - anterior belly CN V 3 ; posterior belly CN VII Stylohyoid - CN VII Geniohyoid C1 via hypoglossal nerve CN XII The infrahyoid region contains 4 muscles commonly called strap muscles: Omohyoid - C1 C3 by a branch of ansa cervicalis Sternohyoid - C1 C3 by a branch of ansa cervicalis Sternothyroid - C2 and C3 by a branch of ansa cervicalis Thyrohyoid - C1 via hypoglossal nerve (CNX II)

50 THE NECK THE ARTERIES OF THE NECK THE LATERAL CERVICAL REGION The arteries in the lateral cervical region include: the lateral branches of the thyrocervical trunk the third part of the subclavian artery part of the occipital artery The third part of the subclavian artery supplies blood to the upper limb. It is hidden in the inferior part of the lateral cervical region, posterosuperior to the subclavian vein. The third part of the artery is the longest and most superficial part. It lies on the 1st rib, and its pulsarons can be felt by applying deep pressure in the omoclavicular triangle.

51 THE NECK THE ARTERIES OF THE NECK THE ANTERIOR CERVICAL REGION The common caropd artery divides into: the internal carord artery the external carord artery C3-C4 JUNCTION SUPERIOR BORDER OF THYROID CARTILAGE The caropd sinus, a slight dilaron of the proximal part of the internal carord artery. Innervated principally by the glossopharyngeal nerve (CN IX) through the carord sinus nerve as well as by the vagus nerve (CN X), it is a baroreceptor (pressoreceptor) that reacts to changes in arterial blood pressure. The caropd body: a small, reddish brown ovoid mass of Rssue in life that lies on the medial (deep) side of the bifurcaron of the common carord artery. Supplied mainly by the carord sinus nerve (CN IX) and by CN X, it is a chemoreceptor that monitors the level of oxygen in the blood

52 THE NECK THE ARTERIES OF THE NECK THE ANTERIOR CERVICAL REGION Superiorly, the common caropd is replaced by the internal caropd artery. The internal caropd artery has NO BRANCHES in the neck. The external carord has several. The right common caropd artery begins at the bifurcaron of the brachiocephalic trunk. The right subclavian artery is the other branch of this brachiocephalic trunk. From the arch of the aorta, the lec common caropd artery ascends into the neck.

53 THE NECK THE ARTERIES OF THE NECK THE ANTERIOR CERVICAL REGION The internal caropd arteries are direct conrnuarons of the common carords superior to the origin of the external carord artery, at the level of the superior border of the thyroid carrlage. C3-C4 JUNCTION level of upper border of thyroid carrlage and bifurcaron of common carord artery. The external caropd arteries supply most structures external to the cranium. The orbit and the part of the forehead and scalp supplied by the supraorbital artery are the major exceprons.

54 THE NECK THE ARTERIES OF THE NECK THE ANTERIOR CERVICAL REGION The external caropd arteries - six arteries arise from the external carord artery: ascending pharyngeal artery occipital artery posterior auricular artery superior thyroid artery lingual artery facial artery maxillary artery (T) superficial temporal a. (T) The inferior thyroid is a branch of the subclavian artery.

55 THE NECK THE ARTERIES OF THE NECK THE ANTERIOR CERVICAL REGION The ascending pharyngeal artery sends branches to the pharynx, prevertebral muscles, middle ear, and cranial meninges. The occipital artery ends by dividing into numerous branches in the posterior part of the scalp. The posterior auricular artery supplies the adjacent muscles; parord gland; facial nerve; and structures in the temporal bone, auricle, and scalp. The superior thyroid artery gives off branches to thyroid gland, the infrahyoid muscles and the SCM and gives rise to the superior laryngeal artery, supplying the larynx. The lingual artery divides into the deep lingual and sublingual arteries. The external caropd arteries is dividing into two terminal branches: the maxillary artery the superficial temporal artery

56 THE NECK THE ARTERIES OF THE NECK THE ANTERIOR CERVICAL REGION The subclavian artery: right from the brachiocephalic trunk lec from the aorrc arch The subclavian artery supplies blood to the upper limb. 1. medial part 2. posterior part 3. lateral part The subclavian artery branches: 1. thyrocervical trunk a. inferior thyroid b. ascending cervical c. suprascapular 2. costocervical trunk

57 THE NECK THE VEINS OF THE NECK THE LATERAL CERVICAL REGION The external jugular vein (EJV) begins near the angle of the mandible by the union of the posterior division of the retromandibular vein with the posterior auricular vein. The external jugular vein (EJV) descends to the inferior part of the lateral cervical region and terminates in the subclavian vein The subclavian vein unites with the internal jugular vein (IJV) to form the brachiocephalic vein. Most veins in the anterior cervical region are tributaries of the IJV, typically the largest vein in the neck. The IJV drains blood from the brain, anterior face, cervical viscera, and deep muscles of the neck.

58 THE NECK THE VEINS OF THE NECK THE ANTERIOR CERVICAL REGION The IJV commences at the jugular foramen in the posterior cranial fossa as the direct conrnuaron of the sigmoid sinus From a dilaron at its origin, the superior bulb of the IJV, the vein descends in the carord sheath The inferior end of the IJV dilates to form the inferior bulb of the IJV. This bulb has a bicuspid valve that permits blood to flow toward the heart while prevenrng backflow into the vein.

59 THE NECK THE VISCERA OF THE NECK THE THYROID GLAND Development of the thyroid gland begins in the floor of the embryonic pharynx at the site indicated by a small pit, the foramen cecum, in the dorsum of the postnatal tongue. The developing gland relocates from the tongue into the neck, passing anterior to the hyoid and thyroid carrlages to reach its final posiron anterolateral to the superior part of the trachea. During this relocaron, the thyroid gland is a_ached to the foramen cecum by the thyroglossal duct.

60 THE NECK THE VISCERA OF THE NECK THE THYROID GLAND The thyroid gland lies deep to the sternothyroid and sternohyoid muscles, located anteriorly in the neck at the level of the C5 T1 vertebrae. It consists primarily of right and lel lobes, anterolateral to the larynx and trachea. The thyroid gland is surrounded by a thin fibrous capsule The highly vascular thyroid gland is supplied by the superior and inferior thyroid arteries Usually the first branches of the external carord arteries, the superior thyroid arteries divide into anterior and posterior branches supplying mainly the anterosuperior aspect of the gland. The inferior thyroid arteries, the largest branches of the thyrocervical trunks arising from the subclavian arteries.

61 THE NECK THE VISCERA OF THE NECK THE THYROID GLAND The lympharc vessels of the thyroid gland run in the interlobular connecrve Rssue The vessels pass inirally to prelaryngeal, pretracheal, and paratracheal lymph nodes. NERVES OF THYROID GLAND These fibers are vasomotor, not secretomotor. They cause constricron of blood vessels. Endocrine secreron from the thyroid gland is hormonally regulated by the pituitary gland.

62 THE NECK THE VISCERA OF THE NECK THE PARATHYROID GLANDS The small fla_ened, oval parathyroid glands usually lie external to the thyroid capsule on the medial half of the posterior surface of each lobe of the thyroid gland, inside its sheath. Most people have four parathyroid glands. Approximately 5% of people have more; some have only two glands.