The Neck - Anatomy PDF

Anterior & Posterior Triangles of the Neck DPM Program Learning Objectives: 1. Describe the fascial layers and spaces of the neck. 4.0 2. Explain the clinical significance of the cervical fasciae in the spread of infection to the thoracic cavity. 3.0 3. Explain the spread of the infections from the...

Anterior & Posterior Triangles of the Neck DPM Program Learning Objectives: 1. Describe the fascial layers and spaces of the neck. 4.0 2. Explain the clinical significance of the cervical fasciae in the spread of infection to the thoracic cavity. 3.0 3. Explain the spread of the infections from the oral cavity into the neck. 3.0 2. Describe the sternocleidomastoid, suprahyoid, and infrahyoid muscles, including their attachments, actions, and innervations. 3.0 3. Describe the boundaries and contents of the anterior and posterior triangles of the neck (including subtriangles). 4.0 4. Describe the major structures passing between the neck and the thorax. 3.0 5. Describe the relationship between the trachea and the esophagus. 3.0 6. Describe the location and anatomic relations of the thyroid and parathyroid glands. 3.0 7. Describe the dermatomes and the cutaneous innervation of the neck. 3.0 8. Describe the cervical plexus and its distribution. 3.0 9. Describe the autonomic nervous system in the neck. 3.0 10. Describe the courses of the accessory, vagus, and phrenic nerves in the neck. 3.0 11. Describe the courses and important relationships of the subclavian arteries and veins. 3.0 12. Describe the carotid sheath and its contents. 4.0 13. Describe the common carotid artery and its branches. 3.0 14. Describe the carotid sinus and carotid body. 3.0 15. Describe the branches of the external carotid artery 3.0 16. Describe the brachiocephalic, external jugular and internal jugular veins. 3.0 17. Describe the arrangement of the cervical lymph nodes and lymphatic drainage. 3.0 18. Locate the carotid pulse. 4.0 19. Describe the anterior scalene syndrome (scalenus anticus syndrome) as it relates to thoracic outlet syndrome. 3.0 20. Describe the clinical importance of the cervical pleura in relation to trauma at the base of the neck. 3.0 21. Identify the surface landmarks that are commonly used when inserting a central venous line. 4.0 22. Discuss the triangles of the neck in relation to penetrating neck trauma and surgical approaches. 4.0 23. Identify bony features and soft tissue structures of the head and neck on radiographs, MRI, CT, and angiograms. 4.0 24. Describe the origin, course, and termination of the vertebral artery. 3.0 1 Fascia of the Neck The neck is a tube providing continuity from the head to the trunk. It extends anteriorly from the lower border of the mandible to the upper surface of the manubrium of the sternum, and posteriorly from the superior nuchal line on the occipital bone of the skull to the intervertebral disc between the CVII and TI vertebrae. SUPERFICIAL FASCIA : Thin layer of subcutaneous connective tissue that lies between the dermis of the skin and the investing layer of deep cervical fascia. Surrounds and contains: Platysma muscle Cutaneous nerves Superficial veins DEEP FASCIA: Compartmentalizes the neck into visceral, vertebral, and vascular compartments. Helps to prevent the spread of infection Has fascial layers/sheaths: Investing layer (surrounds all structures in the neck) Prevertebral layer (surrounds the vertebral column and deep muscles associated with the back) Pretracheal layer (encloses the viscera of the neck) Carotid sheaths (surrounds the two major neurovascular bundles on either side of the neck) These layers of deep cervical fascia provide flexibility and slipperiness that allows structures in the neck to glide over one another with ease (i.e., swallowing and turning the head and neck) 2 Deep Cervical Fascia Investing Fascia: Completely surrounds the neck encloses the trapezius, sternocleidomastoid, submandibular, parotid glands, and infrahyoid muscles. Pretracheal Fascia (visceral compartment): From the hyoid bone to the thoracic cavity *named after the trachea, provides slippery surface for up and down gliding during swallowing and neck movements Surrounds the trachea, esophagus, and thyroid gland Posteriorly continues with buccopharyngeal fascia Carotid sheath (vascular compartment): Surrounds the common carotid artery, the internal carotid artery, the internal jugular vein, and the vagus nerve (CN X) Prevertebral Fascia (vertebral compartment): Cylindrical layer of fascia that surrounds Encloses the vertebral column and longus colli and capitis Extends laterally as axillary sheath (surrounding the axillary artery, vein, & brachial plexus) 3 The Retropharyngeal Space Between the fascial layers in the neck are spaces that may provide a conduit for the spread of infections from the neck to the mediastinum. We will focus primarily on the retropharyngeal space. Retropharyngeal space: travels between the base of the skull to the level of the 2nd thoracic vertebra -Infections (such as dental abscess) may pass into the DANGER SPACE -Space that connects the fascial spaces of the head and neck and superior mediastinum -Can carry an infection into the thorax. 4 Sternocleidomastoid Muscle The principal muscular landmark of the neck is the STERNOCLEIDOMASTOID (SCM) muscle. This bulging muscle bisects the neck diagonally from the sternum and clavicle to the mastoid process. As such, the SCM divides the neck into anterior and posterior triangles. ORIGIN: Sternal Head: manubrium of the sternum (―sterno‖) Clavicular Head: medial third of the clavicle (―cleido‖) INSERTION: Mastoid process of the temporal bone (―mastoid‖) Lateral one-half of the superior nuchal line of the occipital bone ACTIONS: Unilateral contraction: 1) Tilts (i.e., laterally bends or flexes) head toward the shoulder on the same (i.e., ipsilateral) side. 2) Rotates the head so the chin is turned upward, toward the opposite (i.e., contralateral) side. Bilateral contraction: 1) Flexes head. 2) When the head and neck are fixed, can assist in raising the thoracic cage (e.g., raises the sternum and consequently, the ribs, during deep and forced pulmonary ventilation). INNERVATION: ACCESSORY NERVE (CN XI): directly from branches of Ventral Rami (C2 and C3) 5 6 Subdivisions of the Anterior Triangle Boundaries of anterior triangle: Midline of the neck Inferior margin of mandible Anterior margin of SCM Roof = investing layers of deep cervical fascia **Further divided into smaller triangles by the omohyoid and digastric muscles Submandibular gland Hypoglossal n. (CN XII) n. To mylohyoid (CN V3) Facial a. & v. Carotid sheath and contents Internal carotid a. (ICA) Carotid sinus & body Ansa cervicalis Infrahyoid strap muscles 7 The Hyoid Bone The hyoid bone is a small U-shaped bone just superior to the larynx. Does not articulate with any other skeletal elements in the head and neck. Highly movable bone and strong bony anchor for a number of muscles and soft tissue structures in the head and neck. 8 Muscles of the Anterior Triangle -Suprahyoid and InfrahyoidAll of these muscles have an attachment to the hyoid bone. They can act synergistically to steady the hyoid bone in order to provide a firm base for the tongue (floor of the mouth). They also act to elevate/depress the viscera of the neck during speaking and swallowing. SUPRAHYOID MUSCLES: -Mylohyoid (CN V3) -Geniohyoid (C1) (not visible) -Stylohyoid (CN VII) -Digastric has anterior (CN V3) and posterior bellies (VII) Anterior belly of digastric Mylohyoid Posterior belly of digastric Hyoid bone Thyrohyoid muscle Thyroid cartilage Omohyoid muscle Cricoid cartilage INFRAHYOID (STRAP) MUSCLES: Superficial: -omohyoid (ansa cervicalis) -Sternohyoid (ansa cervicalis) Deep: -Sternothyroid (ansa cervicalis) -Thyrohyoid (C1) Stylohyoid muscle Sternothyroid muscle Sternohyoid muscle 9 Muscles of the Neck -Prevertebral Group- -Make up the floor of the anterior triangle of the neck -Extend from the cervical vertebrae to the occipital bone of skull or from cervical vertebrae to cervical vertebrae (Longus colli) -Flexion and rotation of the head -Ventral rami of cervical spinal nerves Longus capitus Longus colli Scalene muscles Anterior Middle Posterior **Make up the floor of posterior triangle will be discussed later 10 Digastric Stylohyoid Mylohyoid Geniohyoid 11 Sternohyoid Sternothyroid Thyrohyoid Omohyoid 12 Thyroid and Parathyroid Glands THYROID GLAND: Endocrine gland at C5 to C7 vertebral levels Arterial supply from thyroid arteries PARATHYROID GLANDS (NOT PICTURED): 2 or more pairs of small endocrine gland, embedded in the posterior aspect of they thyroid gland Arterial supply from inferior thyroid artery **note the relationship between the esophagus and trachea 13 The Carotid Triangle The carotid triangle holds great importance for structures running through the neck. Some of these important structures are more superficial than others; carotid arteries, jugular veins, and vagus and hypoglossal nerves. These structures are often targets for various surgical approaches since they are relatively superficial. Hypoglossal n. Common Carotid a. (ICA also) Internal Jugular Vein Vagus n. (CNX) The carotid triangle also houses the carotid sinus or bulb. This structure contains baroreceptors which are responsible in detecting stretch caused by pressure within a vessel and have a role in maintaining blood pressure (baroreceptor reflex). These receptors are innervated by a branch of the glossopharyngeal nerve and part of homeostatic mechanisms. Carotid body is a highly vascularized mass located posterior to the bifurcation in the wall of the ICA. Involved in the regulation of respiration and cardiac function. Also supplied by glossopharyngeal nerve. The contents of the carotid sheath are IJV, Vagus n. and Common Carotid a. (including ICA). 14 Vasculature of the Neck In general, blood supply to the head and neck comes from branches of the subclavian and common carotid arteries. Venous drainage is primarily by the internal and external jugular veins (the latter of which drains to the subclavian vein) Brachiocephalic trunk: –1st branch of the arch of aorta - divides into right common carotid and right subclavian arteries Subclavian artery: neck, shoulder, brain, thoracic wall (becomes axillary a.) right: comes from brachiocephalic trunk left: comes from arch of the aorta (3rd branch) - passes posterior to the anterior scalene muscle - changes its name to axillary artery at the lateral border of the first rib Common Carotid Artery (anterior triangle of the neck): right: comes from brachiocephalic trunk left: comes from arch of the aorta (2nd branch) -divides into the internal and external carotid arteries at about the C4 vertebral level. Internal carotid: - Ascends through neck within the carotid sheath - Gives off NO branches in the neck - Enters cranial cavity through the carotid canal -Supplies the brain and structures in the orbit, scalp & part of the nasal cavity External carotid (8 branches): neck, viscera of neck, oral & nasal cavities, face, deep face (ITF), scalp -Comes off the common carotid artery and exits the carotid sheath -Supplies majority of structures of the head external to the cranial cavity -Also supplies many structures in the neck 15 Vertebral a. External Carotid Artery Branches -Supply the structures of the face Vertebral Artery arises from the subclavian artery bilaterally -ascends up through the transverse foramina to the base of the skull traveling through the foramen magnum -Supplies the cerebellum, brainstem and occipital lobe of the cerebrum Internal Carotid Artery -Arises as a branch of the common carotid artery -Supplies the brain (frontal, temporal, and parietal lobe of the cerebrum along the midline 16 The external carotid artery (ECA) arises from the common carotid artery in the carotid triangle. It is the major source of blood to structures in the head and neck external to the cranial cavity. Superficial temporal artery Posterior auricular artery Facial artery Lingual artery There are eight branches of the external carotid artery: - superior thyroid – larynx, thyroid gland, infrahyoid muscles Maxillary artery - ascending pharyngeal – pharynx, prevertebral muscles, middle ear -lingual – tongue, oral cavity - facial – face, muscles of facial expression, palatine tonsils, nasal cavity, oral cavity - occipital – back of scalp- posterior auricular – side of scalp - maxillary – infratemporal fossa, muscles of mastication, nasal cavity, palate, teeth, Meninges: - superficial temporal – scalp, face Submental artery Internal carotid artery External carotid artery Superior thyroid artery Common carotid artery 17 18 19 20 Venous Drainage -major tributaries to the major veinssuperficial temporal v. starts in the scalp and joins the maxillary v. to form the retromandibular v. RETROMANDIBULAR VEIN: scalp, deep face (ITF) -Travels through the parotid gland along the posterior aspect of the mandibular ramus -terminates by dividing into anterior and posterior divisions -the anterior division of the retromandibular v. joins the facial vein to become the common facial v. (a tributary of the IJV) -the posterior division of the retromandibular v. joins the posterior auricular v. to become the external jugular vein (EJV) EXTERNAL JUGULAR VEIN (EJV): scalp, neck, (half of retromandibular) -one of the most superficial structures passing through the posterior triangle of the neck -formed by union of posterior division of retromandibular v. & the Posterior auricular v., descends neck superficial to SCM, drains to subclavian INTERNAL JUGULAR VEIN (IJV) – brain, face, neck, (half of retromandibular) - formed by sigmoid sinus after it leaves the cranial cavity -NOTE: deep cervical lymph nodes travel along the course of the internal jugular v. – they receive lymph from the entirety of the head and neck and drain to the JUGULAR LYMPHATIC TRUNK SUBCLAVIAN (begins at the lateral border of the 1st rib as a continuation of the axillary v. ) Receives: -External jugular v. BRACHIOCEPHALIC VEIN (formed by union of the IJV and subclavian vv) - unite to form the SVC 21 22 Venous Drainage of the Head and Neck The venous drainage of the head and neck occurs through valve less veins. This is important as the flow of the blood inside the vein is not one-way but the flow depends on the pressure of one region as compared to another. The majority of veins follow the same naming pattern as the arteries. External Jugular Vein -forms from the venous elements draining from the posterior aspect of the head and the posterior aspect of the jaw -located superficial to the sternocleidomastoid -drains blood into the subclavian Retromandibular Vein -drains blood from the lateral aspect of the head and from the structures deeper in the face, into the external jugular vein -retromandibular vein can also drain blood into the facial vein to then drain blood into the internal jugular vein 23 Venous Drainage of the Brain Venous blood in the Internal Jugular Vein comes from: -dural venous sinuses that collect cerebral veins (responsible for draining the brain) -the internal jugular vein begins as a dilated continuation of the sigmoid sinus, which is a dural venous sinus. -Sigmoid sinus exits the skull through the jugular foramen associated with the glossopharyngeal [IX], vagus [X], and accessory [XI] nerves, and enters the carotid sheath. 24 25 Nerves in Anterior Triangle Muscular branches of the CERVICAL PLEXUS innervate: -Infrahyoid strap muscles, primarily via the ANSA CERVICALIS -Geniohyoid -Prevertebral muscles -Diaphragm via the PHRENIC N. -HYPOGLOSSAL (CNXII) -Travelling toward the oral cavity & tongue -VAGUS (CNX) -Inside the carotid sheath -Branches to the larynx and pharynx Hypoglossal n. Posterior belly of the digastric m. External and Internal Carotid a. Ansa cervicalis Internal jugular v. Common carotid a. Vagus n. Phrenic n. 26 Nerves in Anterior Triangle Continued In the neck, the first four cervical spinal nerves receive gray rami communicantes from the superior cervical ganglion. The fifth and sixth cervical nerves from the middle cervical ganglion and the seventh and eighth from the inferior cervical ganglion. Remember there are NO WHITE RAMI COMMUNICANTES present in the cervical region. 27 Posterior Triangle of the Neck BOUNDARIES: Posterior border of SCM Anterior border of Trapezius Middle third of the clavicle Roof = investing layers of deep cervical fascia Floor = prevertebral fascia covering muscles: splenius capitis, levator scapulae(anterior), middle and posterior scalene muscles CONTENTS: -inferior belly of omohyoid m. VESSELS: -Transverse cervical and suprascaular arteries & venis (arteries are branches of the thyrocervical trunk) -Occipital artery & v. (artery is a branch of the external carotid a.) -Third part of the subclavian artery & the subclavian v. -External jugular v. NERVES: Spinal accessory (CN XI) Roots of brachial plexus (ventral rami C5-T1) & suprascapular n. Cervical plexus (ventral rami of C1-C4) -cutaneous branches (from NERVE POINT OF NECK) -motor branches 28 29 Muscles of the Neck -Posterolateral Group- Trapezius Sternocleidomastoid Splenius Levator scapulae -Lateral flexion of the neck -accessory muscles of respiration Omohyoid (inferior belly) 30 Interscalene Triangle The space between the anterior and middle scalene muscles is called the interscalene triangle. C5 C6 Phrenic nerve C7 The roots of the brachial plexus (C5-T1 ventral rami) and the subclavian artery both pass through the interscalene triangle and leave grooves on the superior border of the first rib. The subclavian vein crosses the superior surface of the first rib anterior to the anterior scalene muscle. **phrenic nerve courses superficial to the anterior scalene muscle Anterior Scalene muscle C8 T1 Superior trunk of brachial plexus Middle trunk of brachial plexus Clavicle Lower trunk of brachial plexus Cords of brachial plexus First rib Subclavian artery Subclavian vein 31 Subclavian Artery and Thyrocervical Trunk SUBCLAVIN ARTERIES Divided into three parts by the anterior scalene muscle Ends at the lateral border of the first rib to become the axillary aa. 1st part-proximal to anterior scalene m. Vertebral aa. ascends and enters the foramen in the transverse process of vertebra CVI passes through the foramen magnum to contribute to the arterial supply of the brain Thyrocervical trunk divides into three branches-inferior thyroid, transverse cervical, suprascapualr aa. Internal Thoracic aa. enters the thoracic cavity posterior to the ribs 2nd part-deep to anterior scalene Costocervial trunk 3rd part-distal to anterior scalene Dorsal scapular artery 32 33 Nerves in Posterior Triangle THE CERVICAL PLEXUS: -composed of ventral rami of C1-C4 -Lies deep to SCM -Cutaneous branches emerge from the middle of the posterior border of SCM at the nerve point of the neck along with CN XI. -Lesser occipital (C2) -Great Auricular (C2,C3) -Transverse Cervical (C2,C3) -Supraclavicular (C3,C4) -Most muscular branches pass anteroinferiorly and are best seen in the anterior triangle. SPINAL ACCESSORY (CNXI): -innervates SCM & trapezius -lies on superficial surface of levator scapulae m. ROOTS OF BRACHIAL PLEXUS: -ventral rami of C5-T1 34 35 Lymphatic Drainage of the Neck Posterior triangle: • Thoracic duct (only on left side) enters neck posterior to left subclavian artery. • Passes through posterior triangle on its way to the junction of the left IJV and left subclavian vein Anterior triangle: Drains by superficial cervical nodes that parallel the EJV and deep cervical nodes along the IJV Superficial cervical nodes receive: Occipital, parotid, and anterior cervical nodes Deep cervical nodes receive: Submandibular nodes, submental nodes Jugular trunk formed from the deep lymphatics in the root of the neck. On right drains into right venous angle. On left drains into thoracic duct. 36 Carotid pulse— -the common or external carotid artery can be palpated in the anterior triangle of the neck -one of the strongest pulses in the body -The pulse can be obtained by palpating either the: -common carotid artery posterolateral to the larynx -external carotid artery immediately lateral to the pharynx midway between the superior margin of the thyroid cartilage below and the greater horn of the hyoid bone above. 37 Anterior Scalene Syndrome Because of the relationship of the trunks of the brachial plexus and the subclavian artery to the anterior scalene muscles (i.e., these structures pass posterior to the Scalenus anterior muscle, between the muscle and first rib), hypertrophy of the anterior scalene or the presence of a cervical rib (refer back to your syllabus from the Fall Semester in the chapter on the Thoracic Cage) may cause compression of the structures behind the muscle (i.e., subclavian artery and the brachial plexus, particularly the lower trunk). Signs and symptoms resulting from compressive lesions include: -coldness and cyanosis, numbness, paresthesia, and pain of the hand. -Muscle weakness and atrophy may occur. These symptoms are collectively referred to as the anterior scalene syndrome and the reasons for these specific manifestations will become clear when we cover the upper extremity. Positive Adson Test: -indicates Scalenus anticus syndrome. Performed by doing the following: 1) patient sits with the head and neck in the anatomic position and the forearms resting pronated on the thighs, the examiner first establishes a baseline radial pulse during deep inspiration (i.e., when the patient takes a deep breath of air inward and holds it in) 2) The examiner then monitors the radial pulse during deep inspiration with the patient’s head extended backward and turned to the side being tested. The head extension and rotation maneuver narrows the interval between the Scalenus anterior and medius muscles and thus manifests or increases any compression of the subclavian artery and/or brachial plexus within the interval. Maintenance of deep inspiration imposes increased traction on the subclavian artery and the brachial plexus through elevation of the first rib. 3. The test is positive if the head extension and rotation maneuver diminishes or obliterates the radial pulse and also reproduces or aggravates the patient’s neurological symptoms. A positive test suggests that the patient’s neurological symptoms are attributable to entrapment and compression of the subclavian artery and brachial plexus between the Scalenus anterior and medius muscles 38 39 Central Venous Line A central line is a large-bore central venous catheter that is typically placed using a sterile technique unless a patient is unstable, in which case sterility may be a secondary concern. Some indications for central venous line placement include: -fluid resuscitation, blood transfusion, drug infusion, central venous pressure monitoring, pulmonary artery catheterization, emergency venous access for patients in which peripheral access cannot be obtained, and transvenous pacing wire placement. Central venous catheter access utilizes the following vein choices: · Internal Jugular/External Jugular · Subclavian · Axillary · Femoral Each of these will be discussed in detail in the following slides. 40 Central Venous Line Internal Jugular Vein The internal jugular approach allows for ultrasound guidance or landmark approach. It is large, easy to locate and has easy access to the superior vena cava (SVC). -Advantages: Insertion-related complication rates are reduced when ultrasound guidance is used. -Disadvantages of the internal jugular approach include inadvertent arterial puncture, increased risk of infection, discomfort due to location, and difficulty maintaining dressing at site. This site is compressible for patients with coagulation disorders and is associated with an overall lower risk of pneumothorax. Landmarks include: · Angle of the mandible · Two heads of sternocleidomastoid muscle · Clavicle · External jugular vein · Trachea Adjacent anatomy includes: · Carotid artery · Phrenic and vagus nerves · Pulmonary apex · Thoracic duct (left side approach) 41 Central Venous Line External Jugular Vein The external jugular lies outside the SCM. It is visible from the surface making it easy to locate. Use of the external jugular vein is considered an advanced skill, due to the close proximity to the carotid artery. Use of the external jugular vein for CVC is relatively uncommon, and is limited primarily by difficulty advancing the guidewire into the SVC. Disadvantages of the external jugular include inadvertent arterial puncture, increased risk of infection, discomfort due to location and difficulty maintaining an occlusive dressing at insertion site. Like the internal jugular site, the external jugular would not be the first site of choice in patients with tracheostomies or neck stabilization devices. Adjacent anatomy includes: · Carotid artery · Phrenic and vagus nerves · Pulmonary apex · Thoracic duct (left side approach) 42 Central Venous Line Subclavian Vein The subclavian vein, as its name suggests, lies below the clavicle, which is directly above the first rib. An extension of the large axillary vein, it begins at the outer border of the first rib, passes over the rib and extends to the inner end of the clavicle. There, it unites with the internal jugular vein forming the innominate (or brachiocephalic) vein. It is a large vessel with a high flow rate of 800-1200 cc blood flow per minute. While the subclavian approach provides consistent landmarks and has the lowest associated risk of infection for chest access, the subclavian approach should be avoided in patients with coagulation disorders due to the inability to compress the subclavian site effectively. This site is associated with the highest risk for pneumothorax, a risk that should be considered prior to insertion. Rarely, patients can also experience "pinch-off syndrome," in which devices in the subclavian vein become compressed between the clavicle and first rib. Landmarks include: · Clavicle · Sternocleidomastoid muscle (SCM) · Suprasternal notch, or visible dip between the clavicular notch and the manubriosternal junction Adjacent anatomy includes: · Right lymphatic duct · Costoclavicular ligament, first rib 43 Central Venous Line Axillary Vein The axillary vein is a continuation of the brachial and basilic veins and continues to become the subclavian vein at the lateral border of the first rib. The infraclavicular axillary vein is located in the delto-pectoral groove, deep to the pectoralis minor muscle. As the vein traverses lateral to the second rib, it begins to separate from the chest wall and the underlying pleural cavity. The axillary vein is situated inferior to the axillary artery. The separation between the artery and vein is variable. Sometimes there is no space between the artery and vein, and other times there is 1-3 cm of space The delto-pectoral groove also serves as a major landmark for the axillary vein. In the middle section of the groove, there is a relatively large gap formed between the vein and the rib cage providing some advantage to using the axillary vein for CVC insertion. Even further laterally, the vein is relatively free of vulnerable structures including the axillary artery. However, close to the site of CVC placement, the vein does come into close proximity to the brachial plexus; the vein, artery and brachial plexus travel in a neurovascular bundle. Landmarks include: · Delto-pectoral groove Adjacent anatomy includes: · Cephalic vein · Subclavian vein · First rib · Clavicle 44 Clinical Importance of Cervical Pleura The esophagus: -retopharyngeal space and the prevertebral fascia separate the esophagus from the bodies of the vertebrae. On the right side: -in contact with the cervical pleura (the cupula); the parietal pleura covering the apex of the lung. This comes above the level of the first rib on either side and thus is located in the neck. -it can be punctured during injections and other surgical procedures at the root of the neck 45 Neck Trauma For descriptive and clinical management purposes, the neck is divided into three zones: zones 1, 2, and 3. In penetrating trauma, zone designations have anatomic, diagnostic, and management implications. Since the zone system is helpful in guiding management decisions, it is preferable to employ the zone system when describing traumatic injuries. Understanding the anatomy of the neck, especially the location of important structures, is essential to providing optimal care. Zone 1: -This is the area between the clavicles and the cricoid cartilage. -This zone contains vital structures which include the innominate vessels, the origin of the common carotid artery, the subclavian vessels and the vertebral artery, the brachial plexus, the trachea, the esophagus, the apex of the lung, and the thoracic duct. -Surgical exposure and access can be difficult in this zone, because of the presence of the clavicle and bony structures of the thoracic inlet. Zone II: -This is the area between the cricoid cartilage and the angle of the mandible. -The following structures are located here: the carotid and vertebral arteries, the internal jugular veins, the trachea, and the esophagus. -This zone has comparatively easy access for clinical examination and surgical exploration. It is the largest zone and the most commonly injured in the neck. Zone III: -This is the area between the angle of the mandible and the base of the skull. -This area contains the distal carotid and vertebral arteries and the pharynx. -Since it is very close to the base of the skull, this area is less amenable to physical examination and difficult to explore during surgical evaluation. 46 47