Neck Anatomy PDF

 The neck is the transitional area between the cranium superiorly and the clavicles inferiorly that joins the head to the trunk and limbs. It serves as a major conduit for structures passing between them. Important organs with unique functions are located here: the larynx and the thyro...

 The neck is the transitional area between the cranium superiorly and the clavicles inferiorly that joins the head to the trunk and limbs. It serves as a major conduit for structures passing between them. Important organs with unique functions are located here: the larynx and the thyroid and parathyroid glands. Is a well-known region of vulnerability. Several vital structures, including the trachea, esophagus, and thyroid gland, lack the bony protection.  1. Bones of the Neck The skeleton of the neck is formed by the cervical vertebrae, hyoid bone, manubrium of the sternum, and clavicles. These bones are parts of the axial skeleton, except the clavicles, which are part of the superior appendicular skeleton 2. Cervical Vertebrae Seven cervical vertebrae form the cervical region of the vertebral column, which encloses the spinal cord and meninges. Centrally placed vertebral bodies support the head, provide the flexibility necessary to allow positioning of the head.  The four typical cervical vertebrae (3rd - 6th) have the following characteristics: The transverse processes possess a foramen transversarium for the passage of the vertebral artery and veins. NB: The vertebral artery passes through the transverse processes of C1 to 6 and not through C7). The spines are small and bifid.  The body is small and broad from side to side. The vertebral foramen is large and triangular. The superior articular processes have facets that face backward and upward; The inferior processes have facets that face downward and forward.  There are three atypical cervical vertebrae: The C1 vertebrae or atlas: A ring-like, kidney-shaped bone Lacking a spinous process or body. Consisting of two lateral masses connected by anterior and posterior arches. Its concave superior articular facets receive the occipital condyles.  The C2 vertebrae or axis: A peg-like dens (odontoid process) projects superiorly from its body. The C7 vertebra or vertebra prominens: So-named because of its long spinous process, which is not bifid. Its transverse processes are large, but its transverse foramina are small.  The Neck: Superficial Structures The first thing you will usually do during a physical examination is to palpate any superficial structure, So that, you can tell if abnormal changes have occurred. Example: Swollen lymph nodes will tell you if there is an infection in an area that is drained by the nodes. The superficial group of nodes in the neck drain the skin of the face & nose, scalp & external ear. The submental nodes also drain the tip of the tongue. Deeper regions of the head & neck drain into a deep group of lymph nodes and are less palpable. 9  The Neck: Superficial Structures In the anterior neck, you can palpate the cartilages of the larynx & trachea. The thyroid gland is closely associated with the cricoid cartilage & the tracheal rings and should always be palpated in a general physical examination of the neck. Another very important structure that palpable is the carotid artery. You should practice taking a carotid pulse since this is one site that is probably often used to check to see if a person is still alive. The carotid artery pulse can be felt by pushing lateral to the upper border of thyroid cartilage. 10  The Neck Region To allow clear communications regarding the location of structures, injuries, or pathologies, the neck is divided into regions. The four major regions are: 1). Sternocleidomastoid region, 2). Posterior cervical region, 3). Lateral cervical region, and 4). Anterior cervical region. 11  The Anterior Neck Region Major landmarks of the Anterior neck: Common carotid artery (cc) Internal carotid artery (ic) External carotid artery (ec) Carotid sinus (cs) Hyoid bone Thyroid & cricoid cartilage Thyroid gland Trachea 12  Triangles of the neck A. Anterior Cervical Region The anterior cervical region (anterior triangle of the neck) has: 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 tissue containing the Platysma. A floor: formed by the pharynx, larynx, and thyroid gland.  The anterior cervical region is subdivided into four smaller triangles, these are;  Submental triangle: unpaired and three small paired triangles: submandibular, carotid, and muscular) by the digastric and omohyoid muscles. A. The submental triangle Lies inferior to the chin, is an unpaired suprahyoid area. Bounded inferiorly by The body of the hyoid Laterally by the right and left anterior bellies of the digastric muscles. The floor is formed by the two mylohyoid muscles The triangle contains several small submental lymph nodes and small veins that are united to form the anterior jugular vein B. The submandibular triangle Is a glandular area between the inferior border of the mandible and the anterior and posterior bellies of the digastric muscle. The floor is formed by mylohyoid hyoglossus muscles middle constrictor muscle of the pharynx. C. The carotid 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. This triangle is important because of the common carotid artery ascends into it. D. The muscular triangle The triangle contains the infrahyoid muscles and viscera (e.g., the thyroid and parathyroid glands).  Muscular or Visceral Triangle The muscular triangle has the following boundaries: medially: mid line of neck Laterally: superior belly of omohyoid Superiorly: hyoid bone Inferiorly: sternomastoid & jugular notch Floor: sternohyoid & sternothyroid muscles Beneath sh, st, oh, & th (strap muscles) innervated by Ansa the floor lie: thyroid gland, larynx, cervicalis (C1, C2 & C3) & are trachea & esophagus depressors of hyoid & 20 Larynx.  Muscular or Visceral Triangle Contents of the triangle: 1. Infrahyoid muscles (strap muscles): (i). superficial layer: sternohyoid (sh) - content omohyoid (Sup. Belly) (oh)- border (ii). deep layer: sh, st, oh, & th (strap muscles) innervated by sternothyroid (st) - content Ansa cervicalis (C1, C2 & thyrohyoid (th) C3) & are depressors of hyoid & Larynx. 21 2. Thyroid & parathyroid glands. Suprahyoid muscles – found in submental & submandibular triangles.  raise the hyoid bone & larynx as in swallowing & talking. Viscera of the neck The cervical viscera are disposed in three layers. Superficial to deep, Endocrine layer: the thyroid and parathyroid glands. – thyroid gland produces thyroid hormone, which controls the rate of metabolism, and calcitonin, a hormone controlling calcium metabolism. – parathyroid glands produce parathormone (PTH), which controls the metabolism of phosphorus and calcium in the blood. Respiratory layer: the larynx and trachea. – contribute to the respiratory functions of the body – Routing air and food into the respiratory tract and esophagus, respectively. – Providing a patent airway & Producing voice.  Deep Dissection of Neck: Visceral Layers Alimentary Layer of Cervical Viscera: pharynx & esophagus: – digestive functions of the body. – Pharynx: its constrictor muscles direct food to the esophagus. – Esophagus, involved in food propulsion, is the beginning of the alimentary canal (digestive tract). 24  Larynx Is the complex organ of voice production (the voice box ). The larynx is a special part of the body that functions As an airway to the lungs as well as providing us with a way of communicating (vocalizing). Composed of nine cartilages connected by membranes and ligaments. Containing the vocal folds.  The Larynx Located in the anterior neck at the level of the bodies of C3 & C6 vertebrae. It connects the inferior part of the pharynx with the trachea These all functions are possible because of the skeletal components and the muscles that act on them.  Skeleton of the Larynx The skeleton of the larynx is made up of the hyoid bone & several cartilages. The thyroid cartilage is made up of two laminae that fuse anteriorly to form the laryngeal prominence (Adam's apple). The angle that they make is usually more acute in males & thus, more prominent.  The inferior horns articulate with the sides of the cricoid cartilage And form the cricothyroid joint where the thyroid cartilage rocks back & forth at this point. The cricoid cartilage is the only complete cartilage of the larynx. Anteriorly it forms the cricoid arch:  The arch expands posteriorly where it forms a square-shaped lamina.  Skeleton of the Larynx The arytenoid cartilages sit on Posterior View top of cricoid lamina, Posteriorly articulate at the cricoarytenoid joints. The arytenoid cartilages slide  medially & laterally, anteriorly & posteriorly & rotate at these joints.  The arytenoid cartilage is pyramidal in shape with the base being the triangular in shape appears with 3 processes:  The vocal process extends anteriorly,  The muscular process lies laterally and  third process is not well defined. The vocal ligament (cord) extends from the vocal process to the back side of the thyroid cartilage.  Skeleton of the Larynx Any movement of the arytenoid cartilage will have an effect on the placement of the vocal cords (making them loose or taut, And bring them together or spreading them apart). The epiglottis is attached inferiorly to the thyroid cartilage by a small stem. Its lateral & superior borders are free. The superior border can be seen through the oral cavity.  The Larynx Various parts of the larynx are closed by connective tissue membranes: Examples; A. The thyrohyoid membrane is pierced by the internal laryngeal nerve & superior laryngeal artery. It extends from the upper border of the thyroid cartilage to the greater wing of the hyoid bone. B. The quadrangular membrane is free at the top and bottom but attached posteriorly to the arytenoid cartilage and anteriorly to the side of the epiglottis. The lower free margin forms the false vocal cord (or vestibular fold).  The Larynx C. The cricothyroid membrane (conus elasticus) extends from the upper margin of the cricoid cartilage to attach to the back of the thyroid cartilage anteriorly and the arytenoid cartilage posteriorly. Its upper free margin is the vocal ligament (true vocal cord).  Laryngeal Skeleton Consists of nine cartilages: three are single (thyroid, cricoid, and epiglottic) and three are paired (arytenoid, corniculate, and cuneiform). A. The thyroid cartilage Is the largest of the cartilages; Its superior border lies opposite to the C4 vertebra. The inferior two thirds of its two plate-like laminae fuse anteriorly in the median plane to form the laryngeal prominence. This projection (Adam's apple) is well marked in men but seldom visible in women.  Superior to this prominence The laminae diverge to form a V- shaped superior thyroid notch. Lamina projects superiorly as the superior horn and inferiorly as the inferior horn. The superior horns attach to the hyoid by the thyrohyoid membrane. The inferior horns articulate with the cricoid cartilage at the cricothyroid joints  B. The cricoid cartilage Is shaped like a signet ring with its band facing anteriorly. This ring-like opening of the cartilage fits an average finger. Although much smaller than the thyroid cartilage, it is thicker and stronger And is the only complete ring of cartilage to encircle any part of the airway. It attaches to the inferior margin of the thyroid cartilage by the median cricothyroid ligament. And to the first tracheal ring by the cricotracheal ligament. C. The arytenoid cartilages are paired, three-sided pyramidal cartilages. articulate with the superior border of the cricoid cartilage lamina. Each cartilage has an apex superiorly, a vocal process anteriorly a large muscular process that projects laterally from its base.  The apex bears the corniculate cartilage and attaches to the aryepiglottic fold. The vocal process provides the posterior attachment for the vocal ligament. The muscular process serves as a lever to which the posterior and lateral cricoarytenoid muscles are attached. D. The epiglottic cartilage Consisting of elastic cartilage, gives flexibility to the epiglottis, A heart-shaped cartilage covered with mucous membrane. Situated posterior to the root of the tongue and the hyoid and anterior to the laryngeal inlet. Its inferior end is attached to thyroid laminae by the thyroepiglottic ligament.  Cont,… The hyoepiglottic ligament attaches the anterior surface of the epiglottic cartilage to the hyoid.  Muscles of the Larynx The muscles of the larynx can be difficult to clean and identify. They consist of muscles that change the opening of the glottis as well as the tenseness of the vocal cord, thereby keeping the larynx open for respiration and helps us vocalize. The cricothyroid muscle lies anterior and external to the larynx Anterior view It arises from the cricoid cartilage & attaches into the inferior horn & lower margin of the thyroid cartilage. When the cricothyroid muscle contracts, it pulls the thyroid cartilage forward, increasing the distance between the thyroid & arytenoid cartilages and tensing the vocal cord. It is supplied by the external laryngeal branch of the superior laryngeal nerve (X).  Muscles of the Larynx By removing one lamina of the thyroid cartilage, Anterior view Lateral view you can see the lateral- cricoarytenoid muscle. this muscle arises from the upper border of cricoid cartilage & inserts onto the muscular process of arytenoid cartilage (adduct arytenoid cartilages).  Muscles of the Larynx Located in the upper part of the aryepiglottic fold is the aryepiglottic muscle:  It is attached to the lateral border of the epiglottis and becomes the oblique arytenoid ,which then attaches into the arytenoid cartilage. Aryepiglottic muscle works as a purse string to close the opening of larynx when swallowing, protecting the larynx, (sphincter of laryngeal inlet).  Muscles of the Larynx Running from arytenoid to arytenoid cartilages is the transverse arytenoid muscle: This muscle pulls the arytenoid cartilages together when they contract  adducter. Lastly, we have the posterior- cricoarytenoid muscles. They arise from the expanse of cricoid lamina & insert into muscular process of arytenoid cartilages. These are the only muscles that open the space b/n the vocal cords (abduct).  Muscles of the Larynx Another muscle, not shown, is the thyroarytenoid  which extends from the back of thyroid cartilage to the front side of the arytenoid cartilage. It pulls the arytenoid cartilage forward when it contracts, thus loosening the vocal ligament (relaxor). The deep upper part of this muscle is the vocalis muscle:  vocalis muscle can change tenseness the vocal cord in order to vary tonal qualities of our voice.  Actions of Laryngeal Muscles The major function of the larynx is to keep the airway open. This means keeping the space b/n the vocal cords (rima glottidis) open If it isn't open, we don't breathe. The second important function is vocalization and this is a very complicated procedure that requires a variety of parts of the body to function together. Figure 1: points out the parts of the larynx involved in breathing and vocalization. arytenoid cartilage (ac): -vocal process (vp) Figure 1 -muscular process (mp)  Actions of Muscles of the Larynx Figure 2: shows the movements that take place between the arytenoid & cricoid cartilages (cricoarytenoid joints). The dot in the arytenoid cartilage is the vertical axis around which the arytenoid cartilage rotates. The movements include: adduction (AD) abduction (AB) anterior-posterior sliding (AP) Figure 2 medial-lateral sliding (ML) Figure 3: shows the action of the transverse arytenoid muscle. The arytenoid cartilages are pulled towards each other, thus closing the rima glottidis. Figure 3  Actions of Muscles of the Larynx Figure 4: shows that the lateral cricoarytenoid muscles adduct the arytenoid cartilages to close the rima glottidis. Figure 5: demonstrates that the thyroarytenoids muscle pulls the Figure 4 arytenoid cartilages forward, thereby loosening the vocal cord. Figure 5  Actions of Muscles of the Larynx Figure 6: shows the only abductor, the posterior cricoarytenoid muscle. This muscle rotates the arytenoid cartilages laterally (abduct), causing the vocal cords to separate from one another, opening the rima glottidis. Figure 7: shows the cricothyroid muscle. Figure 6 This muscle is external to the larynx & can be seen in the muscular triangle of the neck. This muscle moves the thyroid cartilage forward around an axis through the cricothyroid joint. This action stretches the vocal cord, thereby tensing it. Figure 7 Actions of Muscles of the Larynx 53  Structures that take part in vocalization In considering the process of speech, sounds are produced by blowing air pass the vocal cords. The air produces vibrations in the vocal cords, forming the sounds that come out of the mouth. The air is pushed out of the lungs by relaxing the diaphragm and contracting muscles of the abdominal wall. The abdominal muscles are supplied by the lower inter- costal nerves & branches of L1.  The tonal and pitch variations occur when the vocal cord is made more tense or looser. Tense cords produce higher pitch, loose cords form lower pitch. The muscles involved are supplied by the recurrent laryngeal and external laryngeal nerves.  And also to change the vocal cords, the stylopharyngeus muscles pull the pharynx and larynx upward. This action shorten the tubal length of the air passage between the base of the skull (body of sphenoid) and the vocal cords. As found in an organ, longer pipes are low pitch and shorter pipes are high pitch. The stylopharyngeus are supplied by the glossopharyngeal nerves.  Structures that take part in vocalization The suprahyoid muscles (digastrics, mylohyoid, geniohyoid) pull the hyoid bone up and the larynx follows it. The anterior digastric is supplied by the nerve to mylohyoid (inf. Alveolar n.). The posterior belly of the digastric is supplied by the facial nerve. The geniohyoid muscle is supplied by C1. The infrahyoid muscles (sternothyroid, sternothyroid, sternohyoid, omohyoid) pull the larynx down. They are supplied by branches of the ansa cervicalis (C1- C3).  The tongue is used to add various modulations to our voice by varying its surface contour (intrinsic muscles) supplied by the hypoglossal nerve. Muscles of facial expression, especially around the mouth and cheeks, are also used to vary the quality of our speech, facial nerve. Finally, if you notice what must move when we speak, The mandible moves up and down by contraction of the muscles of mastication, mandibular division of trigeminal nerve.  Structures that take part in vocalization Another function of the muscles of the larynx is protection of the airway. The major muscle that performs this protection is the aryepiglottic & oblique arytenoid muscles.  When you swallow, the aryepiglottic muscle closes off the entrance to the larynx thru a purse-string(press or squeeze) action  It pulls the sides of the epiglottis back & narrows the inlet to the larynx. Muscle responsible is supplied by the recurrent laryngeal nerve.  To help in this protection, all muscles that adduct or tense the vocal cord; can also narrow the rima glottidis protecting trachea & lungs. The cough reflex is also designed to protect the air way.  Innervation of the Larynx Motor innervation: 1. external laryngeal branch of superior laryngeal n. (X) 2. recurrent laryngeal n. (X) Sensory innvervation: 1. internal laryngeal (X): sensory above the false vocal cords 2. recurrent laryngeal (X): sensory below the false vocal cords  Innervation of the Larynx Innervation of Intrinsic Muscles of the Larynx: Vagus nerve via: (a). Superior laryngeal nerve, and (b). Recurrent laryngeal nerve. A. Superior Laryngeal Nerve: Has two branches: internal laryngeal & external laryngeal branches – i). internal laryngeal branch, is a sensory nerve:  Gives sensory innervation to mucous membrane of larynx above the vocal folds/glottis (above false vocal cords);  sensory innervation to mucous membrane of larynx below the vocal folds/glottis is by the recurrent laryngeal nerve. ii). external laryngeal branch a motor nerve and supplies cricothyroid muscle. B. Recurrent Laryngeal Nerve: Has motor and sensory branches: i). The motor branch supplies all the intrinsic muscles except cricothyroid; ii). The sensory branch supplies sensory innervation to mucous membrane of larynx below the vocal folds/glottis.  Innervation & Blood Supply of the Larynx Most important intrinsic muscles of the larynx: Cricothyroids – superior laryngeal nerve – external laryngeal branch -  tense vocal cords Posterior cricoarytenoids – recurrent laryngeal nerve – abduct vocal cords Lateral cricoarytenoids – recurrent laryngeal nerve – adduct vocal cords Transverse arytenoids – recurrent laryngeal nerve – adducts vocal cords Thyroarytenoid – recurrent laryngeal nerve – relaxes vocal cord Aryepiglottus & Oblique arytenoid : recurrent laryngeal nerve  close laryngeal inlet. Blood Supply – a). superior laryngeal artery: branch of the superior thyroid artery, b). inferior laryngeal artery: branch of inferior thyroid artery.  Endocrine Layer of the Cervical Viscera A. Thyroid Gland Is the body's largest endocrine gland. Located anteriorly in the neck at the level of the C5 & T1 vertebrae. It consists primarily of right and left lobes, isthmus unites the lobes over the trachea.  Cont,… It produces thyroid hormone, which controls the rate of metabolism, and calcitonin, a hormone controlling calcium metabolism. Affects all areas of the body except itself and the spleen, testes, & uterus.  Arteries of the Thyroid Gland The highly vascular thyroid gland is supplied by the superior and inferior thyroid arteries. unpaired thyroid ima artery arises from the brachiocephalic trunk Veins of the Thyroid Gland Three pairs of thyroid veins usually form a thyroid plexus of veins. superior thyroid veins accompany the superior thyroid arteries; They drain the superior poles of the thyroid gland;  The middle thyroid veins do not accompany but run in parallel courses with the inferior thyroid arteries; they drain the middle of the lobes.  The usually independent inferior thyroid veins drain the inferior poles. The superior and middle thyroid veins drain into the IJVs; the inferior thyroid veins drain into the brachiocephalic veins  Lymphatic Drainage of the Thyroid Gland The lymphatic vessels of the thyroid gland Drain in to the superior & inferior deep cervical nodes, the brachiocephalic lymph nodes or the thoracic duct. Nerves of the Thyroid Gland Derived from the superior, middle, and inferior cervical sympathetic ganglia. Fibers are vasomotor, not secretomotor. They cause constriction of blood vessels. Endocrine secretion from the thyroid gland is hormonally regulated by the pituitary gland. Figure. Enlarged thyroid. A. A goiter is demonstrated. B. This scintigram shows a diffuse, enlarged thyroid gland.  B. Parathyroid Glands The superior parathyroid glands The inferior parathyroid glands Most people have four parathyroid glands. 5% of people have more; some have only two glands.  The hormone produced by the parathyroid glands, parathormone (PTH), controls the metabolism of phosphorus and calcium in the blood. The parathyroid glands target the skeleton, kidneys, and intestine.  Vessels of the Parathyroid Glands Inferior thyroid arteries The superior thyroid arteries The thyroid ima artery The laryngeal, tracheal, and esophageal arteries.  Parathyroid veins drain into the thyroid plexus of veins of the thyroid gland and trachea. Lymphatic vessels from the parathyroid glands drain with those from the thyroid gland into deep cervical lymph nodes and paratracheal lymph nodes  Trachea Is a fibrocartilaginous tube, supported by incomplete cartilaginous tracheal rings. Extending from the larynx into the thorax It transports air to and from the lungs. Its epithelium propels debris-laden mucus toward the pharynx for expulsion from the mouth. It ends at the level of the sternal angle or the T4 & T5 IV disc, where it divides into the right and left main bronchi  The tracheal rings keep the trachea patent; they are deficient posteriorly where the trachea is adjacent to the esophagus. The posterior gap in the tracheal rings is spanned by the involuntary trachealis muscle, smooth muscle connecting the ends of the rings. Hence the posterior wall of the trachea is flat  Alimentary Layer of the Cervical Viscera A. Pharynx A musculofascial posterior to the nasal and oral cavities. A common pathway for air and 'food'. Extends from the cranial base to the cricoid cartilage and level of C6 vertebra posteriorly. The pharynx has three parts A. Nasopharynx Has a respiratory function. Lies superior to the soft palate and behind the nasal cavities. In the roof is a collection of lymphoid tissue called the pharyngeal tonsil. It is called the adenoids when enlarged. And also tubal tonsil near the orifice of the pharyngotympanic tube B. Oropharynx Has a digestive function. Boundary by; Superiorly; the soft palate, Inferiorly; the base of the tongue, forms the floor. Laterally; the palatoglossal and palatopharyngeal arches. In the midline; the median glossoepiglottic fold.  Palatopharyngeal arch is a fold of mucous membrane covering the palatopharyngeus muscle. The same is for palatoglossal fold. The recess between the palatoglossal and palatopharyngeal arches is occupied by the palatine tonsil. C. The Laryngopharynx Lies posterior to the larynx. Extending from the superior border of the epiglottis to the inferior border of the cricoid cartilage. Related to the bodies of the C4 and C6 vertebrae. Communicates with the larynx through the laryngeal inlet on its anterior wall Pharyngeal Muscles 1. An external circular; fibers run in a circular direction. Consists of three pharyngeal constrictors : superior, middle, and inferior Pharyngotasilar fascia, internal fascia. Buccopharyngeal fascia, external fascia Contraction is involuntarily, takes place sequentially from the superior to the inferior propelling food into the esophagus.  The overlapping of constrictor muscles forms four gaps. The gaps provide a passage for muscles and neurovascular tissues. 1. Superior to the superior constrictor the levator veli palatini muscle pharyngotympanic tube, and ascending palatine artery 2. Between the superior and middle constrictors stylopharyngeus, glossopharyngeal nerve, stylohyoid ligament 3. Between the middle and inferior constrictors Internal laryngeal nerve Superior laryngeal artery and vein to pass to the larynx. 4. A gap inferior to the inferior constrictor allows Recurrent laryngeal nerve Inferior laryngeal artery and vein to pass superiorly into the larynx. 2. The internal longitudinal layer Fibers run in longitudinal direction. Consists; the palatopharyngeus, stylopharyngeus, and salpingopharyngeus. Arteries Ascending pharyngeal artery; Ascending palatine and tonsillar branches of the facial artery; Branches of the maxillary and the lingual arteries. Venous Pharyngeal venous plexus. Pharyngeal Nerves Derives from the pharyngeal plexus of nerves. Motor fibers are derived from the vagus nerve (CN X). Supply all muscles of the pharynx and soft palate, Except the stylopharyngeus supplied by glossopharyngeal nerve. Sensory Nerve Supply of the Mucous Membrane Nasopharynx: The maxillary nerve Oropharynx: The glossopharyngeal nerve Laryngopharynx: The internal laryngeal branch of the vagus nerve  B. Esophagus A muscular tube that is continuous with the laryngopharynx at the pharyngoesophageal junction. Consists of striated (voluntary) muscle in its upper third, smooth (involuntary) muscle in its lower third, and a mixture of striated and smooth muscle in between. When the esophagus is empty, it has a slit-like lumen. Where as when a food bolus descends in it, the lumen expands, eliciting reflex peristalsis in the inferior two thirds of the esophagus.  Its first part, the cervical esophagus, is part of the voluntary upper third. The pharyngoesophageal junction appears as a constriction which is produced by the cricopharyngeal And is the narrowest part of the esophagus.  Vessels of the Cervical Esophagus Inferior thyroid arteries Inferior thyroid veins. Lymphatic vessels of the cervical part of the esophagus drain into the paratracheal lymph nodes and inferior deep cervical lymph nodes.  Muscles of the Anterior Cervical Region The suprahyoid muscles are superior to the hyoid and connect it to the cranium  The Lateral Neck Region A. Superficial structures: sternomastoid trapezius occipital lymph nodes (on) retroauricular lymph nodes (ran) superficial cervical lymph nodes (scn) submental lymph nodes (smn) buccal lymph nodes (bn) parotid lymph nodes (pn) submandibular lymph nodes (not labeled) 98  Posterior Triangle of Neck & Sternomastoid Region The anterior & posterior cervical triangles are interconnected through substernomastoid-space This space includes the following structures: 1. deep cervical lymph nodes: digastric node omohyoid node 2. ansa cervicalis (ac) ij cc 99 3. carotid sheath (cs) & contents: (i). internal jugular vein & tributaries (ij) (ii). common carotid artery (cc) & its bifurcation external carotid artery: occipital branch (oc) internal carotid artery (iii). vagus nerve (v)  Sternomastoid Region Contents of Carotid Sheath (cs): 1. internal jugular vein and tributaries. 2. common carotid artery (cc) & its bifurcation: 3. vagus nerve (v) deep cervical lymph nodes. The carotid sinus nerve. Sympathetic nerve fibers (carotid periarterial plexuses). 101 The infrahyoid muscles, often called strap muscles because of their ribbon-like appearance, are inferior to the hyoid  B. Lateral Cervical Region (posterior triangle of the neck is bounded by 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 investing layer of deep cervical fascia. By a floor, formed by muscles covered by the prevertebral layer of deep cervical fascia. 1. 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). 2. The omoclavicular (subclavian) triangle Is indicated on the surface of the neck by the supraclavicular fossa. The inferior part of the EJV crosses this triangle superficially.  The subclavian artery lies deep in it. Because the third part of the subclavian artery is located in this region, the omoclavicular triangle is often called the subclavian triangle Muscles in the Lateral Cervical Region The floor of the lateral cervical region is usually formed by the prevertebral fascia overlying four muscles:  splenius capitis levator scapulae middle scalene posterior scalene the inferior part of the anterior scalene appears in the inferomedial angle of the lateral cervical region  The Neck: Fascia of the Neck The fascia of the neck has a number of unique features. The superficial fascia in the neck contains a thin sheet of muscle called the platysma, which begins in the superficial fascia of the thorax, runs upwards to attach to the mandible & blend with the muscles on the face, It is innervated by the cervical branch of the facial nerve [VII]. 111  Deep to the superficial fascia, the deep cervical fascia is organized into several distinct layers: 1. an investing layer, which surrounds all structures in the neck; 2. prevertebral layer, which surrounds the vertebral column and the deep muscles associated with the neck/back; 3. the pretracheal layer, which encloses the viscera of the neck (thyroid gland, trachea, esophagus); 4. carotid sheaths, which receive fascia from the other three fascial layers, surround the two major neurovascular bundles on either side of the neck. Fascial Layers of the Neck 113  The Neck: Fascia of the Neck Layers of cervical fascia organizes the neck into four longitudinal compartments: 1. The first compartment consists of area surrounded by the investing layer; 2. the second compartment (vertebral compartment) consists of the vertebral column, the deep muscles associated with this structure & is area contained within the prevertebral layer; 114 3. The third compartment (visceral compartment) contains the pharynx, trachea, esophagus & the thyroid gland, which are surrounded by the pretracheal layer; 4. The compartment (the carotid sheath: neurovascular compartment) consisting of the neurovascular structures.  The Neck: Fascia of the Neck There are three spaces between the fascial layers in the neck that may provide a conduit for the spread of infections from the neck to the mediastinum: 1. The pretracheal space: b/n investing layer of cervical fascia (covering posterior surface of infrahyoid muscles) & the pretracheal fascia (covering the anterior surface of the trachea and the thyroid gland), which passes b/n the neck & the anterior part of the superior mediastinum; 116 2. The retropharyngeal space b/n the buccopharyngeal fascia (on the posterior surface of the pharynx & esophagus) & the prevertebral fascia. It is the largest & most important because it is the major pathway for the spread of infection 3. The third space is within the prevertebral layer & extends thru the posterior mediastinum to the diaphragm. Fascial Layers of the Neck 118  Superficial Structures of the Neck Superficial venous drainage: The external jugular & anterior jugular veins are the primary venous channels for superficial venous drainage of the neck. The external jugular vein is formed posterior to the angle of mandible as the posterior auricular vein & the retromandibular vein join. 119  Table of Muscles of the Neck Muscle Origin Insertion Action Nerve Supply sternal head-- manubrium of rotates, extends sternum; clavicular mastoid process, spinal sternomastoid head; flexes head--medial superior nuchal line head accessory 1/3rd of clavicle superior part-- lateral 1/3rd of superior nuchal clavicle; middle elevates shoulder; line; nuchal part-acromion rotates scapula spinal trapezius ligament; spinous process & spine of laterally to help accessory; processes of C7 scapula; inferior raise shoulder; C2-C3 & all of thoracic part--spine of retracts scapula scapula (middle part) spinous processes mastoid process & extends & rotates dorsal rami of splenius capitis of upper thoracic superior nuchal vertebrae line head thoracic nerves upper medial levator transverse border raises scapula dorsal scapular scapulae processes of C1-C4 of scapula raises 2nd rib; scalene transverse upper surface of ventral rami of bends neck to posterior processes of C5-C7 2nd rib the side C7-C8 transverse upper surface raises 1st rib; ventral rami of scalene medius processes of C1-C6 of 1st & 2nd ribs bends neck to side C3- C8 transverse scalene tubercle of raises 1st rib; ventral rami of scalene anterior processes of C3-C6 1st rib bends to side C6-C8 120  Table of Muscles of the Neck Nerve Muscle Origin Insertion Action supply scaphoid fossa elevates & aponeurosis tensor palati of pterygoid tenses soft of soft palate V3 (CN V) fossa palate apex of petrous pulls soft aponeurosis of levator palati temporal bone palate soft palate CN X & auditory tube up & back aponeurosis of elevates palatopharyngeus wall of pharynx soft palate pharynx CN X cartilage of elevates salpingopharyngeus wall of pharynx auditory tube pharynx CN X 121  Table of Muscles of the Neck Nerve Muscle Origin Insertion Action Supply merges with draws tongue up hyoglossus & styloglossus styloid process and back to aid XII genioglossus swallowing food muscles in tongue merges with greater horn of styloglossus & draws side of hyoglossus hyoid bone tongue down XII genioglossus muscles fans out in the pulls tongue genial tubercle tongue to make genioglossus of mandible forward, sticking XII up the bulk of the the tongue out tongue produce small intrinsic tissues of changes in the tissues of tongue XII muscles tongue contour of the surface of tongue elevates hyoid nerve to mylohyoid line hyoid bone and bone and floor of mylohyoid of mandible raphe mylohyoid mouth to aid in (V3) swallowing lower genial elevate hyoid body of hyoid geniohyoid tubercle of bone bone or depress C1 mandible mandible 122  Major Arteries in the Neck Branches of the external carotid artery: 1. Superior thyroid artery: Thyrohyoid muscle, internal structures of the larynx, sternocleidomastoid and cricothyroid muscles, thyroid gland 2. Ascending pharyngeal artery: Pharyngeal constrictors and stylopharyngeus muscle, palate, tonsil, pharyngotympanic tube, meninges in posterior cranial fossa 3. Lingual artery: Muscles of the tongue, palatine tonsil, soft palate, epiglottis, floor of mouth, sublingual gland 4. Facial artery: All structures in the face from the inferior border of the mandible anterior to the masseter muscle to the medial corner of the eye, the soft palate, palatine tonsil, pharyngotympanic tube, submandibular gland 123 5. Occipital artery: Sternocleidomastoid muscle, meninges in posterior cranial fossa, mastoid cells, deep muscles of the back, posterior scalp 6. Posterior auricular artery: Parotid gland & nearby muscles, external ear & scalp posterior to ear, middle & inner ear structures 7. Superficial temporal artery: Parotid gland and duct, masseter muscle, lateral face, anterior part of external ear, temporalis muscle, parietal and temporal fossae  Maxillary artery: External acoustic meatus, lateral & medial surface of tympanic membrane, temporomandibular joint, dura mater And inner table of cranial bones, trigeminal ganglion and dura in vicinity, mylohyoid muscle, mandibular teeth, skin on chin, temporalis muscle, outer table of bones of skull in temporal fossa, structures in infratemporal fossa, maxillary sinus, upper teeth and gingivae, infra- orbital skin, palate, roof of pharynx, nasal cavity. Major Arteries in the Neck 126  Prevertebral Region In order to view the prevertebral region, the skull and cervical viscera must be reflected forward. The dotted line is the plane of separation. pharynx (ph) longus colli (lc) scalene anterior (sa) scalene medius (sm)  Prevertebral Region The background for the prevertebral region is the cervical vertebral column. The viscera of the neck (pharynx- esophagus & larynx-trachea) lie just anterior to:  bodies of cervical vertebrae anterior longitudinal ligament (all)  Prevertebral Region The next layer is made up of muscles that act to move the vertebrae, forward and laterally flexing the neck: 1. rectus lateralis 2. rectus anterior 3. longus capitis 4. longus cervicis (longus colli) 5. scalene medius 6. scalene anterior 7. scalene posterior 8. anterior longitudinal ligament  Also at the muscular layer, the nerves that Prevertebral Region make up the cervical plexus (1-4) are the roots of phrenic nerve & brachial plexus: 1. anterior ramus of C1 2. C2 3. C3 4. C4 5. C5 6. C6 7. C7 8. C8 9. T1 In the upper limb: C5 & C6 merge to form the upper trunk of the brachial plexus, C7 forms the middle trunk and C8 & T1 form the lower trunk. C3-C5 form the phrenic nerve  Prevertebral Region The cervical part of sympathetic chain runs along the prevertebral region and consist of the: superior cervical ganglion (1) middle cervical ganglion (2) inferior cervical ganglion (3) 1st thoracic ganglion (4) Notice that the cupola of the lung (5) extends up into the root of the neck  Prevertebral Region: Root of the Neck At the root of the neck, we can see the large arteries emerging from the thorax: 1. common carotid 2. subclavian 3. vertebral 4. internal mammary 5. thyrocervical trunk 6. suprascapular 7. transverse cervical 8. ascending cervical The terminal branch of the thyrocervical trunk is the inferior thyroid artery (not labeled)  Root of the Neck Finally, the remaining items at the root of the neck are: 1. brachiocephalic vein 2. vertebral vein 3. internal jugular vein 4. external jugular vein 5. thoracic duct 6. right lymphatic duct  Structures found at the Root of the Neck The root of the neck is bounded by the manubrium of the sternum anteriorly, the first rib laterally and the first thoracic vertebra posteriorly. All structures passing from the head thru the neck to lower regions pass thru this area as well as structures arising in the thoracic cavity and passing out thru this region. I. Most anterior structures: 1. brachiocephalic vein 2. vertebral vein 3. internal jugular vein 4. subclavian vein 6. thoracic duct 7. thymus gland  Structures Found at the Root of the Neck II. The next layer can be considered the artery-nerve layer: 1. lung 2. vagus nerve 3. common carotid artery 4. subclavian artery 5. ansa subclavius 6. thyrocervical trunk 7. vertebral artery 8. internal thoracic artery The upper lobe of the lung (1): extends into the 9. trachea neck region. This is clinically important for anyone entering this region surgically since the 10.esophagus lung can be punctured if the surgeon isn't careful.  Structures Found at the Root of the Neck III. The posterior part of the root of the neck: is made up of the anterior surface of the body of the 1st thoracic vertebra with its anterior longitudinal ligament (in gray) & contains the following Nerves : 1. ventral ramus of C8 2. ventral ramus of T1 3. lower trunk of brachial plexus 4. stellate ganglion (inferior cervical (C8) + 1st thoracic ganglia)  CLINICAL CONSIDERATIONS 1. Superficial cervical plexus nerve block: is done by injecting anaesthetic solution at multiple points along the posterior border of the sternocleidomastoid muscle. The main point of injection is at the junction of the upper and middle third of the posterior border of the sternomastoid muscle. 2. Brachial plexus nerve block: is carried out by inserting the needle above the midportion of the clavicle, directing it medially and downwards towards the first rib. The finger is usually placed at the upper border of the clavicle to depress the subclavian artery. Right and left sides. 137  Anatomy of the Neck: Clinical Conditions CLINICAL CONSIDERATIONS: 3. Cervical rib: incidence 1-2%, mostly bilateral. When the cervical rib is well developed, both the subclavian artery and the brachial plexus groove the upper surface of the rib giving rise to symptoms of vascular and nerve compression. Treatment ranges from conservative muscular re- education to scalenotomy with or without resection of the rib. 4. Scalenus anticus syndrome: symptoms resemble that seen in cervical rib, due to spasm or hypertrophy of scalenus anterior muscle. Alleviation of the condition is by transaction of the scalene at its insertion. The anterior relation of the subclavian vein and phrenic nerve to the muscle is to be kept in mind during the operation.