FOCA 2023 Neck Anatomy Lecture 12 PDF

FOCA 2023 Neck Dr. Mark Hankin Professor & Senior Anatomist [email protected] Disclosures & Conflicts of Interest Authorship Anatomy & Physiology Revealed v4 2019, McGraw-Hill Clinical Anatomy: A Case Study Approach 2013, McGraw-Hill Test Prep for the USMLE® – Clinical Anatomy Q&A 2019, Thieme Medical...

FOCA 2023 Neck Dr. Mark Hankin Professor & Senior Anatomist [email protected] Disclosures & Conflicts of Interest Authorship Anatomy & Physiology Revealed v4 2019, McGraw-Hill Clinical Anatomy: A Case Study Approach 2013, McGraw-Hill Test Prep for the USMLE® – Clinical Anatomy Q&A 2019, Thieme Medical Publishers If you have used any of these resources, I hope you found them helpful. 2 Learning Objectives 1. Describe the skeleton and surface anatomy of the neck. 2. Describe the organization of the neck, including its fasciae, compartments, regions, and triangles. 3. Describe the muscles of the neck. 4. Describe the blood vessels and lymphatics of the neck. 5. Describe the nerves of the neck. 6. Describe the anatomy of the root of the neck, and list the structures that pass through this space. 7. Describe the anatomy of the thyroid and parathyroid glands. 3 The Neck – Definition and Contents Digestive system Pharynx & esophagus Respiratory system Pharynx, larynx & trachea Cardiovascular system Major vessels to head, neck & upper limb Muscular system Facial, neck & hyoid muscles CNS Spinal cord, peripheral & cranial nerves Endocrine system Thyroid & parathyroid Region between head, upper limbs & thorax Skeleton and Surface Anatomy Neck – Skeleton Bones Cervical vertebrae Hyoid Manubrium Clavicles Cartilages Larynx Trachea Neck – Hyoid Bone U-shaped bone Has no articulation with other bones or cartilages Lies at C3 level C3 C4 Parts Body, greater horn & lesser horn C5 Function C6 Muscle attachment Assists in keeping airway open Adam’s apple Surface Anatomy of the Neck Palpable landmarks Angle of mandible Laryngeal prominence Jugular notch Clavicle Soft tissue Greater supraclavicular fossa Sternocleidomastoid (lesser supraclavicular fossa between heads) Trapezius External jugular vein Organization Fascia, Compartments, Regions, and Triangles Cervical Fascia Deep Fascia & Compartments Investing fascia Surrounds entire neck & splits to enclose trapezius & SCM Pretracheal fascia Contains viscera: thyroid & parathyroid glands, trachea & esophagus Prevertebral fascia Muscular compartment around vertebral column Carotid sheath “Vascular” compartment: carotids, IJV, vagus nerve & sympathetic fibers, and deep cervical lymph nodes Retropharyngeal Space Potential space permits movement of neck viscera during swallowing Major pathway for spread of infection to mediastinum Pretracheal & prevertebral compartments Contains loose CT Buccopharyngeal fascia is posterior part of pretracheal fascia Subdivided by alar fascia Retropharyngeal Abscess Dysphagia (difficulty swallowing ) Dysarthria (difficulty speaking) Normal Retropharyngeal abcess Clinical Application Pus in retropharyngeal space can produce a bulge in the pharynx Cervical Regions & Triangles A Sternocleidomastoid region B Posterior cervical region 2 Posterior cervical triangle Anterior cervical triangle 4 Submandibular triangle 5 Submental triangle 6 Carotid triangle 7 Muscular triangle Accessory n. (CN XI) Stylohyoid m. 5 Digastric m. SCM Omohyoid m. Anterior midline Trapezius m. 7 Submental Triangle (Unpaired) Borders Anterior bellies of digastric m. Hyoid bone Floor Mylohyoid m. Contents – nodal Submental lymph nodes Tributaries of anterior jugular v. Submandibular Triangle (Paired) Borders Digastric muscle Mandible (inf border) Floor Mylohyoid m. Contents – glandular Submandibular gland Submandibular lymph nodes Hypoglossal nerve (CN XII) Mylohyoid nerve (CN V3) Parts of facial artery & vein Carotid Triangle (Paired) Borders SCM Omohyoid (superior belly) Digastric (posterior belly) Floor Inferior pharyngeal constrictor Major Contents Common carotid & bifurcation (ICA & ECA) Internal jugular vein Vagus nerve (CN X) Hypoglossal nerve (CN XII) Cervical plexus Larynx Muscular Triangle (Paired) Borders Midline of neck Omohyoid (superior belly) Floor Inferior pharyngeal constrictor Contents Infrahyoid muscles Thyroid & parathyroid glands Neck Muscles Groups of Neck Muscles Subcutaneous Platysma Superficial Sternocleidomastoid (SCM) & trapezius Hyoid Suprahyoid: mylohyoid, geniohyoid, stylohyoid, digastric Infrahyoid: sternohyoid, omohyoid, sternothyroid, thyrohyoid Vertebral Anterior: Longus colli & capitis Lateral: Scalenes Platysma – A Muscle of Facial Expression In subcutaneous tissue Origin: mandible, skin of cheek, angle of mouth, orbicularis oris m. Insertion: superficial fascia of pectoral & deltoid regions Innervation: Facial n. (CN VII) Sternocleidomastoid Muscle Inferior attachment Clavicle & manubrium Superior attachment Mastoid process Innervation: Accessory (CN XI) Cervical Dystonia Idiopathic Spasmodic torticollis Signs & symptoms Head can twist spasmodically Neck pain radiating to shoulders (pain may increase over time & can be exhausting and disabling) Headache No cure May resolve without treatment; sustained remissions uncommon Control: botulinum toxin injected into affected muscles; Parkinson’s drugs can be used in combination Clinical Application Onset 30-60 years; more frequent in females Prevalence: 3:10,000 in U.S. Hyoid Muscles Suprahyoid Digastric Geniohyoid Mylohyoid Stylohyoid Infrahyoid Sternohyoid Omohyoid Sternothryoid Thyrohyoid Suprahyoid Muscles Digastric – Anterior & posterior Intermediate tendon (fascial sling connects tendon to hyoid) Geniohyoid Mylohyoid Stylohyoid Actions Elevate hyoid bone Mylohyoid also elevates floor of mouth Innervation Posterior digastric (Facial – CN VII) Stylohyoid (Facial – CN VII) Anterior digastric (Mandibular – CN V3) Mylohyoid (Mandibular – CN V3) Geniohyoid (C1 – Cervical plexus) Infrahyoid Muscles Superficial Sternohyoid (S) Omohyoid (O) Deep Sternothryoid (S) Thyrohyoid (T) SOS+T Innervation: Cervical plexus SOS: Ansa cervicalis T: Thyrohyoid nerve Action Depress hyoid Prevertebral Muscles Longus capitis muscles Actions Flexion & lateral flexion of head Longus colli muscles Actions Flexion & lateral flexion of neck Innervation Cervical plexus (ventral rami) Lateral Vertebral Muscles = Scalenes Anterior & middle Cervical TVP to Rib 1 Posterior Cervical TVP to Rib 2 Actions Lateral flexion of neck Elevate ribs (forced inspiration) Innervation Cervical plexus (ventral rami) Cervical Blood Vessels Superficial Veins Subcutaneous On SCM Formed by Retromandibular Posterior auricular Other tributaries Anterior jugular Superficial cervical Suprascapular Termination Subclavian v. Deep Veins Continuation of sigmoid (dural venous) sinus in cranial cavity Tributaries Many in the neck, including EJV Termination Joins subclavian to form brachiocephalic Inferior bulb of IJV Bicuspid valve Prevents backflow into neck IJV Catheterization Right side preferred because IJV larger and straighter than left SCM Lesser supraclavicular fossa Jugular notch EJV Applications Measurements of central venous pressure Administration of meds Venous access when peripheral access not available Clinical Application Landmarks External Carotid Artery Begins at bifurcation of CCA, which is at C4 vertebral level ECA & branches leave carotid sheath S.A.L.F.O.A.M.S. Superior thyroid Ascending pharyngeal Lingual Facial Occipital Posterior Auricular Maxillary Superficial temporal Carotid Sinus & Body Carotid sinus: dilation in proximal ICA or distal CCA Baroreceptors: RXN Δ arterial BP Carotid body: mass at carotid bifurcation Chemoreceptors: RXN Δ arterial O2 Afferent innervation Carotid sinus nerve (CN IX) Parasympathetic (CN X): vasodilatory Sympathetic: vasoconstrictor Cervical Lymphatics Lymphatic Drainage of the Head & Neck Superficial cervical nodes Along external jugular vein Drain most superficial tissues of head & neck These nodes drain to inferior deep cervical nodes Deep cervical nodes Along internal jugular vein Drain to supraclavicular nodes, which are palpable Efferent lymphatics from cervical deep nodes form jugular lymph trunks Superficial cervical nodes Along EJV & superficial to SCM EJV Deep cervical nodes Along IJV & deep to SCM M SC IJV Peri-cervical Nodes (Collar) Peri-cervical (superficial cervical) lymph nodes form a collar at junction of head & neck Submental, submandibular, parotid, mastoid & occipital nodes No lymph nodes in scalp or face (exception: parotid-buccal region) Mastoid nodes Occipital nodes Parotid nodes Submental nodes Submandibular nodes Lymphatic vessels of the face accompany facial blood vessels 41 Virchow’s Node & Trosier Sign Enlargement of these nodes (known as a Trosier sign) may be sign of metastasis to the neck, especially from GI viscera Jugulodigastric node Tumor embolization from GI cancers via thoracic duct usually leads to enlargement of left supraclavicular node Trosier sign may also be seen in lymphoma, breast, esophageal, pelvic & testicular CAs Deep cervical nodes Jugulo-omohyoid node Jugular lymph trunk Supraclavicular nodes Thoracic duct Clinical Application Supraclavicular nodes (AKA Virchow's nodes) are located near venous angles A 52-year-old man presents to his primary care physician with postprandial epigastric pain. Physical exam shows an enlarged, firm left supraclavicular mass. Which surface anatomy feature is associated with this enlarged lymph node? A. B. C. D. E. Greater supraclavicular Infraclavicular Lesser supraclavicular Sternal angle Sternal (jugular) notch Clinical Application Test your Understanding Test your Understanding A 52-year-old man presents to his primary care physician with postprandial epigastric pain. Physical exam shows an enlarged, firm left supraclavicular mass. Which surface anatomy feature is associated with this enlarged lymph node? A. B. C. D. E. Greater supraclavicular Infraclavicular Lesser supraclavicular Sternal angle Sternal (jugular) notch Nerves in the Neck Cervical Plexus formed by C1-C4 Ventral Rami Cutaneous branches (C2-C4) Lesser occipital Great auricular Transverse cervical Supraclavicular Motor branches (C1-C4) Ansa cervicalis (C1-3) Phrenic (C3, C4) Deep branches to cervical muscles Cervical Plexus – Cutaneous Distribution Cutaneous branches (C2-C4) Lesser occipital Vertex CN V1 Great auricular Ophthalmic n. Transverse cervical Supraclavicular CN V2 Maxillary n. CN V3 Mandibular n. Dorsal rami (C2-C3) Ventral rami Cervical plexus (also C2-C3) Nerve Point of the Neck Nexus (central location) where cutaneous branches of cervical plexus enter posterior triangle Located along posterior border of SCM Approx. half-way between mastoid process & clavicle Accessory nerve (CN XI) also near this point Cervical Plexus – Motor Distribution Ansa cervicalis Superior root “hitchhikes” on CN XII to thyrohyoid (infrahyoid) & geniohyoid (suprahyoid) muscles Inferior root supplies “SOS” infrahyoid muscles Phrenic nerve Chiefly from C4 (less from C3 & C5) Descends on anterior scalene muscle Anatomical Relationships & Scalenes Phrenic nerve On anterior scalene muscle Subclavian vein Arches over 1st rib, anterior to anterior scalene muscle Brachial Plexus Passes through space between anterior & middle scalene muscles (interscalene space) Subclavian artery Passes through interscalene space & arches over 1st rib Accessory Nerve (CN XI) Motor nerve from C1-C5 spinal cord Axons form the spinal root (between and separate from the dorsal & ventral roots) Enters cranial cavity via foramen magnum Exits cranial cavity via jugular foramen (with CN IX & X) Motor to trapezius & SCM Hypoglossal Nerve (CN XII) Motor to the tongue Courses along posterior digastric muscle, just superior to the hyoid bone C1 fibers “hitchhike” on CN XII Thyrohyoid nerve Geniohyoid nerve Superior root of ansa cervicalis Cervical Sympathetics Three cervical sympathetic ganglia 1. Superior (C1-C2 vertebral level) 2. Middle (C6 vertebral level) 3. Inferior (C7 vertebral level) ⎼ Usually fused with the T1 ganglion to form the stellate (cervicothoracic) ganglion Cervical Sympathetics Fibers from T1-T3 spinal cord ascend in sympathetic chain to cervical ganglia…synapse! Inferior cervical ganglion (at C7) Postganglionics follow gray rami into lower brachial plexus Middle cervical ganglion (at C6) Postganglionics follow gray rami into upper brachial plexus Superior cervical ganglion (at C1-2) Postganglionics follow gray rami into cervical plexus and onto internal carotid peri-arterial plexus Root of the Neck Root of the Neck Junction between neck & thorax Boundaries 1st ribs & costal cartilages Manubrium T1 vertebral body Root of the Neck Nerves, vessels & viscera pass through the root of the neck Neurovasculature Brachiocephalic trunk Subclavian arteries ⎼ Notable branches: vertebral, internal thoracic & thyrocervical trunk EJV & IJV terminate at venous angles Vagus & recurrent laryngeal nerves Phrenic nerve Sympathetic trunks Viscera Trachea & esophagus Thyroid & Parathyroid Glands Thyroid Gland Location C6-T1 vertebra level Lobes Right & left Isthmus (anterior to tracheal rings 2-3) 50% may have pyramidal lobe (remnant of thyroglossal duct) Function Controls metabolism & contributes to Ca metabolism Parathyroid Glands Usually four glands Location Posterior thyroid gland (outside thyroid capsule) Blood supply Inferior thyroid a. Veins drain to thyroid venous plexus Function Controls blood Ca and P Blood Supply for Thyroid Gland Usually 2 arteries Superior thyroid (from ECA) Superior thyroid (from subclavian) Usually 3 veins Superior & middle veins (to IJV) Inferior veins (to left brachiocephalic) Thyroid – Anatomical Relationships Inferior thyroid artery crosses recurrent laryngeal nerve Recurrent laryngeal nerve ascends in tracheo-esophageal groove Esophagus Inferior thyroid artery (branch of thyrocervical trunk from subclavian) usually passes posterior to the nerve During thyroidectomy, or parathyroidectomy, the nerve needs to be protected while ligating this artery. Trachea Recurrent laryngeal nerve T Tracheo-esophageal groove E Clinical Application Inferior thyroid artery END 63