Deep Neck & Pharynx - Student Notes PDF

Posterior Triangle of the Neck & Pharynx C H R I S T I W I L L I A M S , P T, D P T, O C S , C E R T. M D T Posterior Triangle of Neck  Regions of the Neck – Posterior Triangle Posterior Triangle Posterior triangle: - Trapezius - SCM - Clavicle A...

Posterior Triangle of the Neck & Pharynx C H R I S T I W I L L I A M S , P T, D P T, O C S , C E R T. M D T Posterior Triangle of Neck  Regions of the Neck – Posterior Triangle Posterior Triangle Posterior triangle: - Trapezius - SCM - Clavicle Anterior Triangle Anterior Triangle Boundaries: - SCM - Mandible - Median line of the neck  Cross-section of the neck at C7 What we’ve covered Where we are going Netter 8th ed. S-196 Fascial planes of the neck ▪ Fascia of the neck ▪ Important to contain muscles & viscera ▪ Allow structures to slide over one another (slippery) ▪ Serve as a conduit for the passage of neurovascular structures ▪ 2 major fascial compartments of the neck are separated by the retropharyngeal space ▪ Anterior – pretracheal fascia ▪ Posterior – prevertebral fascia ▪ These are both encased in the superficial layer of deep (investing) cervical fascia which encases the superficial muscles ▪ SCM & Trapezius Structures we have covered SCM Trapezius Netter 8th ed. S-196 Superficial layer of deep cervical (investing) fascia ◦ Encloses and covers the structures of the neck ◦ Splits around the sternocleidomastoid (SCM) and Trapezius ◦ Single sheet of fascia around the anterior and posterior triangles Netter 8th ed. S-196 Pretracheal fascia Anterior Compartment of neck  Pretracheal layer of deep cervical fascia Pretracheal fascia Encloses Infrahyoid muscles Thyroid gland Encloses the infrahyoids, (muscular portion) thyroid gland, Pretracheal Portion of larynx/trachea and Deep Cervical Fascia esophagus. Includes (Visceral portion) recurrent laryngeal nerve Trachea Larynx * Recurrent Laryngeal N Esophagus Netter 8th ed. S-196  Carotid sheath Common Carotid a. Carotid Sheath IJV ◦ Tubular fascial investment that extends from the base of the skull to the root of the neck ◦ Surrounds: ◦ Common carotid artery ◦ Internal jugular vein ◦ Vagus nerve (CN X) Vagus N Netter 8th ed. S-196 Prevertebral fascia Posterior Compartment of neck Prevertebral layer of cervical fascia ◦ Forms a tubular sheath for the vertebral column and associated muscles ◦ longus colli and capitis ◦ scalenes ◦ spinal nerves of the brachial plexus (C5-T1) ◦ sympathetic trunk embedded in this layer of fascia  Prevertebral Layer of Deep Cervical Fascia Longus colli Sympathetic & capitis * trunk Phrenic N Spinal nerves Brachial plexus Deep Cervical Scalenes Muscles Prevertebral Layer of Deep Cervical Fascia Netter 8th ed. S-196  The retropharyngeal space permits movement of the Retropharyngeal Space pharynx, esophagus, larynx, and trachea relative to the vertebral column during swallowing 7 Prevertebral fascia Netter 8th ed. S-196  Cervical Sympathetic Trunk & Ganglion ▪ Cervical sympathetic trunk ▪ Anterolateral to vertebral column ▪ Just medial & deep to the carotid sheath ▪ Superior cervical ganglion - fusion C1-4 ▪ Middle - fusion C5-6 ▪ Lower - fusion C7-8-T1= stellate ganglion Muscles of the Posterior Triangle of the Neck Scalenes Anterior Scalene O: Transverse processes (anterior tubercles) of cervical vertebrae I: First Rib N: C(3)4-6 spinal nerves A: Unilaterally: laterally flex the neck to same side. Bilaterally: elevate 1st rib during inhalation. Flex neck Trail Guide to the Body Anterior Scalene Trail Guide to the Body Middle Scalene O: Transverse processes of cervical vertebrae (posterior tubercles) I: First Rib N: C3-8 spinal nerves A: Unilaterally: laterally flex the neck to same side. Bilaterally: elevate 1st rib during inhalation. Flex neck Trail Guide to the Body Middle Scalene Trail Guide to the Body Posterior Scalene O: Transverse processes of cervical vertebrae (posterior tubercles) I: Second Rib N: C7-8 spinal nerves (COA) or C3 – 8 (Trail Guide) A: Unilaterally: laterally flex the neck to same side. Bilaterally: elevate 2nd rib during inhalation. Flex neck. Trail Guide to the Body Posterior Scalene Trail Guide to the Body  Anterior, Middle & Posterior Scalenes shown together/summary Anterior & Middle There is still discrepancy about scalene attach to the action of the scalenes as it 1st rib while relates to rotation: Trail Guide: rotate to opposite side Posterior scalene *Grays: Anterior scalene – rotates to attaches to 2nd rib opposite side while middle & posterior rotate to same side *JOSPT article: rotation is to same side COA and many others leave rotation out In general, the altogether innervation of the Bilateral: Flexion of neck scalenes is spinal Unilateral: Lateral Flexion to the nerves of C3-8 same side (ipsilateral lateral flexion) secondary motion of rotation is *ipsilateral rotation They are accessory muscles of respiration Trail Guide to the Body Roots of Brachial Plexus & Key relationships Trail Guide to the Body  Middle Scalene Anterior Scalene Posterior Scalene Roots of the brachial plexus What about the & Subclavian Subclavian vein? artery pass between the anterior & middle scalene Why does this matter? Trail Guide to the Body  Middle Scalene Anterior Scalene Posterior Scalene Dorsal scapular nerve pierces Brachial plexus middle scalene or passes under passes between the clavicle and middle & posterior pec minor scalene Why does this matter? Trail Guide to the Body  Thoracic Outlet Clinical Relevance The interscalene triangle – most typical site The costoclavicular triangle The subcoracoid space Scalene Muscles & Key Relationships 1st Rib Anterior Scalene Phrenic n. Over Anterior Scalene 1st Rib Middle Scalene 2nd Rib Posterior Scalene **Clinical note: interscalene block** Brachial Plexus B/w Anterior & Middle Scalene with Subclavian A *Dorsal Scapular n. pierces middle scalene or passes b/w middle & posterior scalene Subclavian Artery & Vein From Brachiocephalic a. on right & arch of aorta on left – changes name to axillary a. when crosses 1st rib Deep muscles of the neck (prevertebral muscles) Longus Colli O & I: Spans from anterior vertebral bodies & TP’s of C1- C6. N: Anterior primary rami C2-6 spinal nerves A: Unilaterally: laterally flex head & neck to same side, rotate head/neck to *same side. Bilaterally: Flex head & neck Trail Guide to the Body Longus Capitis O & I: Transverse processes of cervical verbebrae to occiput N: Anterior primary rami C1-3 spinal nerves A: Unilaterally: laterally flex head & neck to same side, rotate head/neck to same side. Bilaterally: Flex head & neck Trail Guide to the Body  Scalene Muscles & Deep Anterior Neck structures *Rectus Capitis Anterior Base of cranium *Longus Capitis (medial/central) -> TP of C1 Longus Colli Flexes head Think of these muscles as deep neck flexors and stabilizers *Rectus Capitis Lateralis *Note that the effectiveness of Base of cranium (lateral to stabilizing has been questioned as RCA attachment) -> TP of C1 well as whether they contribute to ipsilateral or contralateral rotation Flexes head & stabilizes Netter 8th ed. S-193 Nerves in the deep neck / posterior triangle  Cervical Plexus – Nerves in the posterior triangle of the neck Add photo from COA p. 1016 COA Fig. 9.14 Lateral Cervical Region (Posterior Triangle) - Nerves Great Auricular n. Lesser Occipital n. 2 Cervical Plexus C2-C4 3 CN XI – Spinal Accessory 4 Phrenic n. Brachial Plexus C5-T1 Netter 8th ed. S-194  Motor Spinal Accessory nerve Sensory CN (XI) Hypoglossal nerve (CN XII) Great Auricular n. C1 to geniohyoid C1 Lesser & thyrohyoid Occipital n. muscles C2 Transverse cervical nerves C3 Ansa C4 cervicalis (to infrahyoids) Phrenic nerve Netter 8th ed. S-195 Supraclavicular nerves  Phrenic nerve C3, 4, 5 keep the diaphragm alive Phrenic n. Phenic n. innervating Diaphragm Netter 8th ed. S-194  Anterior Primary Rami from cervical plexus – C2, 3 Great Lesser Auricular Occipital n. n. (C2-3) (C2-3) C3 Occipital nerves G R E AT E R O C C I P I TA L L E S S E R O C C I P I TA L 3 R D O C C I P I TA L S U B O C C I P I TA L  Lesser Occipital n. Anterior Primary Rami from cervical plexus – C2, 3 Lesser Occipital n. (C2-3) C3  Lesser Occipital n. – sensory C2 & 3 ventral primary rami Lesser Occipital Nerve ▪ The LON originates from the ventral rami of the C2 and C3 spinal nerves and goes to the occipital region along the posterior margin of the sternocleidomastoid muscle. ▪ It pierces the deep cervical fascia close to the cranium and travels upward. ▪ Near the cranium, it penetrates the deep cervical fascia and goes superiorly above the occiput to innervate the skin and communicate with the GON. Greater Occipital n. & Third Occipital n. Dorsal Primary Rami from cervical plexus C2 – Greater Occipital C3 – Third (Least)Occipital  Greater Occipital Nerve (GON) C2 dorsal primary rami (sensory) The Greater Occipital Nerve ▪ It runs backward between the C1 and C2 vertebrae and traverses between the inferior capitis oblique and semispinalis capitis muscles from underneath the suboccipital triangle. ▪ Often pierces the semispinalis capitis muscle in most cases, and in some cases, the trapezius and the inferior oblique. ▪ This complex involvement with the nearby musculature may make the GON a potential source of nerve compression, entrapment, or irritation.  Third Occipital N. (TON) C3 dorsal primary rami (sensory) The Third Occipital Nerve ▪The TON is the dorsal ramus of the C3 spinal nerve. ▪ The TON travels through the dorsolateral surface of the C2-C3 facet joint. ▪ The TON also perforates the splenius capitis, trapezius, and semispinalis capitis. It then communicates with the GON and innervates the region of the skin below the superior nuchal line. What about C1? S U BOCCI P I TAL N. S UBOCCI P I TAL T R I ANGLE M OTOR TO MUS CL ES OF T HE S U BOCCI P ITA L T R I A NGLE DORSA L P R I MA RY R A M I OF C1  Suboccipital nerve (dorsal primary rami of C1) ▪ The suboccipital nerve arises from the posterior ramus of the C1 nerve. ▪ The primary function of the suboccipital nerve is the innervation of the suboccipital muscles. ▪ Rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis superior, obliquus capitis inferior ▪ These muscles are involved in postural control of the head, mainly functioning in head extension and rotation. ▪ The suboccipital nerve emerges inferior to the occipital bone and superior to the posterior arch of the C1 (atlas) vertebrae. ▪ It travels with the vertebral artery. ▪ Occasionally, the suboccipital nerve gives off a cutaneous branch that connects to either the greater or lesser occipital nerves, and this anatomical variation may play a role in occipital neuralgia and cervicogenic headaches. Occipital Neuralgia Vasculature in the deep neck  *Review* Common Carotid Artery ▪ Right common carotid a. begins at the bifurcation of the brachiocephalic trunk ▪ Left common carotid a. arises directly from arch of aorta ▪ Travel in carotid sheath with IJV & Vagus nerve before splitting into the ▪ Internal carotid a. -> main artery to the brain ▪ External carotid a. -> supplies most structures external to cranium (several branches to face, head & neck)  Internal Carotid Artery ▪ICA has no branches in the head/face, but travels directly to the brain ▪ Enters the skull through the carotid canals ▪ Feeds into the circle of Willis COA Figure 8..39 External Carotid Artery  External Carotid Artery – for completeness Some Anatomists Like Freaking Out Poor Medical Students Superficial Temporal a. “Students” Posterior Auricular a. “Poor” Maxillary a. “Medical” Facial a. “Freaking” Occipital a. Lingual a. “Out” “Like” Ascending Pharyngeal a. “Anatomists” Superior Thyroid a. “Some” *Key Branches of ECA (aka what you need to know) ▪ Superficial Temporal artery ▪Maxillary artery ▪ *Middle Meningeal a. ▪ Inferior alveolar a. ▪ Sphenopalatine a. ▪ Facial artery Trail Guide to the Body  Subclavian artery ▪ From the brachiocephalic trunk on the right and direct branch off arch of aorta on the left ▪ Has 3 parts in relation to the anterior scalene ▪ (anterior scalene is over the 2nd part) ▪ Continues into UE as the Axillary artery ▪ Changes names as it crosses the first rib  Subclavian Artery 3 2 1 1st Part 2nd Part *Vertebral artery - C1-6 Costocervical trunk 3rd Part transverse foramen ◦ *Dorsal scapular Supreme artery intercostal artery *Internal thoracic artery Deep cervical artery Thyrocervical trunk ◦ Transverse cervical artery ◦ *Suprascapular artery ◦ Inferior thyroid artery ◦ Ascending cervical artery  Subclavian Artery – for completeness Ascending Cervical Inferior Thyroid Section 1 (medial to anterior scalene) Transverse Cervical Vertebral Artery Suprascapular Internal Thoracic Thyrocervical Trunk Section 3 - Inferior Thyroid (lateral to anterior scalene - Ascending Cervical to 1st rib) - Suprascapular - Transverse Cervical Dorsal Scapular Section 2 (Under anterior scalene) Costocervical Trunk Trunk - Superior intercostal - deep cervical Netter 8th ed. S-195  Subclavian Artery – *Key Branches (aka what you need to know) Section 1 (medial to anterior scalene) *Vertebral Artery *Suprascapular Section 3 (lateral to anterior scalene to 1st rib) *Internal Thoracic *Dorsal Scapular Section 2 (Under anterior scalene) Netter 8th ed. S-195 Vertebral artery Netter 8th ed. S-44  Subclavian Vein ▪ Direct continuation of the axillary vein ▪ Begins at lateral border of 1st rib ▪ Separated from Subclavian a by ant scalene ▪ Joins with Internal jugular vein = venous angle How does lymph enter the venous system? Right Lymphatic Duct Drains lymph from the right upper quadrant (right side of the head, neck and thorax as well as the right upper limb) Empties into the right venous angle Junction of the right internal jugular vn and right subclavian vn Thoracic Duct Drains lymph from the remainder of the body Empties into the left venous angle Junction of the left internal jugular vn and left subclavian vn  Right & Left Venous Angles Left Right Venous Venous Angle Angle Netter 8th ed. plate S-348 R Lymphatic Duct Thoracic Duct RUE, R head, neck & thorax Left side and both LE’s Pharynx & Larynx Larynx  Laryngeal Cartilages Hyoid bone Thyrohyoid membrane Epiglottis Thyroid Cartilage Arytenoid Cartilage Cricothyroid ligament Cricoid Cartilage Netter 8th ed. S-375 Laryngeal Cartilages Epiglottis Thyroid Cartilage Arytenoid Cartilage Cricoid Vocal Cartilage Ligament Netter 8th ed. S-375  Vagus Nerve & Recurrent Laryngeal nerves ▪ Vagus nerve travels with CCA & IJV in the carotid sheath ▪ Right Vagus nerve loops around the subclavian artery and continues to the larynx as the recurrent laryngeal n. ▪ Left Vagus nerve loops around the arch of the aorta and continues to the larynx as the recurrent laryngeal n. ▪ Branches of the vagus continue into the thorax Laryngeal Nerves – CN X Internal branch -Sensory Superior Laryngeal N. (from Vagus) External branch -Cricothyroid m. Recurrent Laryngeal n. (from Vagus) continues as inferior laryngeal n. - Motor to muscles of Larynx (except cricothyroid which is innervated by the external branch of the superior laryngeal n.) Netter 8th ed. S-378  Muscles of the Larynx v v v Cricothyroid m. Posterior Cricoarytenoid m. Transverse Arytenoid m. v v v Thyroarytenoid m. Lateral Cricoarytenoid m. Oblique Arytenoid m. Netter 8th ed. S-377 Pharynx  The Pharynx ▪ Musculomembranous tube shared by the nasal and oral cavities above and respiratory and digestive channels below ▪ Extends from the base of the skull to the lower border of the cricoid cartilage (C6)  The Pharynx Nasopharynx Subsections Oropharynx ◦ nasal pharynx ◦ posterior to the nose and superior to the soft palate Laryngopharynx ◦ oral pharynx ◦ Posterior to the mouth ◦ laryngeal pharynx ◦ Posterior to the larynx Netter 8th ed. S-372  Pharynx Nasal Pharynx - respiratory function ◦ pharyngotympanic tubes (auditory, Eustachian) ◦ Connects the nasopharynx to tympanic cavity ◦ Function – equalize pressure in the middle ear (allows air to enter & leave tympanic cavity) ◦ Opened via soft palate muscles ◦ Tensor veli palatini – CN V3 ◦ Levator veli palatini – CN X Netter 8th ed. S-373  Cartilaginous part of pharyngotympanic tube Levator veli palatini Tensor veli palatini (CN X) (CN V3) Netter 8th ed. S-398  Pharynx Oral Pharynx ◦ air and food pathways cross Laryngeal pharynx ◦ continuation of oral part ◦ epiglottis is connected to root of tongue Netter 8th ed. S-373  Pharyngeal Musculature Internal musculature: External musculature ◦ Palatopharyngeus - CNX ◦ Superior constrictor – CN X ◦ Salpingopharyngeus – CN X ◦ Middle constrictor– CN X ◦ Stylopharyngeus – *CN IX ◦ Inferior constrictor– CN X Collectively, these muscles elevate Collectively, these muscles the larynx and shorten the contract sequentially, to ensure pharynx during swallowing that food is propelled correctly down into the esophagus Innervated by CN X (except stylopharyngeus which is CN IX) Innervated by CN X - Vagus  Musculature of the Pharynx Salpingopharyngeus m – CN X. Palatopharyngeus m. – CN X Sensory of pharynx: Glossopharyngeal n. (CN IX) & **Superior Pharyngeal Constrictor Vagus (CN X)) Motor of pharynx: Vagus (CN X) and **Middle Pharyngeal Constrictor (CN IX) for stylopharyngeous **Inferior Pharyngeal Constrictor Stylopharyngeus m. - CN IX **External musculature – CN X (Vagus) – collectively contract sequentially to propel food *Internal musculature – CN X (except Stylopharyngeus CN IX) – collectively elevate larynx & shorten pharynx during swallowing Lab Today ▪ Dissect the deep structures of the neck ▪ Remove middle 3rd of clavicle ▪ Roots & Trunks of brachial plexus ▪ Scalenes / phrenic n. ▪ Subclavian a. ▪ Review Larynx on models ▪ **Review previous labs** References Actions of the Scalene Muscles for Rotation of the Cervical Spine in Macaque and Human John A. Buford, Stephanie M. Yoder, Deborah Givens Heiss, and John V. Chidley. Journal of Orthopaedic & Sports Physical Therapy 2002 32:10, 488-496 Kennedy, E., Albert, M., & Nicholson, H. (2017). Do longus capitis and colli really stabilise the cervical spine? A study of their fascicular anatomy and peak force capabilities. Musculoskeletal science & practice, 32, 104–113. https://doi.org/10.1016/j.msksp.2017.10.005 Yu M, Wang SM. Anatomy, Head and Neck, Occipital Nerves. [Updated 2021 Nov 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542213/