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Extremely comprehensive notes and summary of what is needed for the third unit (head and neck). Memorizing these notes back and front is a guaranteed >90% on the exam, and it is the hardest exam of the course. Notes were taken mostly from the professor's mouth and heavily supplemented with the requi...

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Introduction The neck is a connector b/n things in the head and trunk. The principal contents of neck =upper portions of digestive system, respiratory sys, salivary glands, endocrine glands (thryoid and parathryoid), and major nerves and blood vessels coursing up and down the neck into the head and into the thorax, as well as the apices of the lungs. The apices of the lung and their cervical pleura extend about an inch above the medial end of the clavicle. The base of the neck has lungs apices, so wounds or putting catheters into vessels have the potential of creating a pneumothorax (collapsed lung). The anterior part of the neck has surface anatomy stuff. Starting with our finger at the chin and running a finger’s breadth below the chin, you should feel something hard at the midline, a u-shaped bone called the hyoid bone. You can feel a body (horizontal portion anteriorly), you can wrap your fingers around the greater bones of the hyoid, a U-shaped bone that projects posteriorly. The hyoid bone is typically located about the C3 level. Hyoid has body, greater horn, and lesser horn. Just below the hyoid bone in the midline, you can palpate (esp. in males) a projection of cartilage calle dthe Laryngeal prominance (Adam’s apple). If you push your finger just above the larygneal prominence, you can feel the thyroid notch. This is the superior border of the largest cartilage of the larynx, the thyroid cartilage. Note there is a soft tissue membrane between the hyoid bone and the superior border of the thyroid cartilage called the thyro-hyoid membrane. Structures penetrate thru the thyrohyoid membrane to get inside the larynx. The surface projection of vocal cords. The vocal cords are located just deep to the anterior border of the thyroid cartilage about its midpoint. (just behind the midline of the thyroid cartilage about its midpoint). IF you run your finger down the thyroid cartilage, you’ll feel a gap then another ridged structure – cricoid cartilage. Cricoid cartilage is a signant ring where there’s a lamina projected posteriorly and a band projected anteriorly which you can palpate. The membrane that spans the gap between the thyroid cartilag eand the cricoid cartilage is the cricoithyroid membrane. Inferior to the cricoid cartilage is the beginning of the tracheal rings. The lower border of the cricoid cartilage is the C6 level, which is the junction between the larynx above and the trachea below. The C6 level is also a transitional zone with the digestive system behind the larynx and the trachea. Behind the larynx lives the pharynx. Behind the trachea lives the esophagus. The junctoin b/n larynx and esophagus occurs at the C6 level. On the antero-lateral surfaces of the thyroid cartilag eand extending down into the neck is the thyroid gland. A finger’s breadth below the cricoid cartilage is a soft tissue mass that connects one lobe of the thyroid gland to the other (isthmus of the thyroid). Surface anatomy and landmarks in the neck The neck is subdivied into triangles bounded by muscles and/or bone. The anterior triangle of the neck is bounded by a line that goes from the chin to the jugular (suprasternal) notch. It runs up along the border of the sternocleidomastoid, a muscle that diagonally divides the neck. Then goes to the lower border of the mandible. The posterior triangle is bounded by the posterior border of the sternocleidomastoid, anterior border of trapezius, and the middle third of the clavicle. How is the neck organized?

The superficial fascia of the neck contains the platysma, cutaneous nerves, external jugular vein, and anterior jugular vein, whch are deep to the platysma. (shortened) The superficial fascia of the neck contains - Cutaneous nerves of cervical plexus - External jugular vein - Platysma muscle The platysma muscle lives in the superficial fascia and is in the family of muscles of fascial expression Deep fascia divides the neck into cylindrical compartments External jugular vein is seen coursing diagonally across sternocleidomastoid muscle to enter th eposterior triangle, and it descends the posterior triangle and is ultimately tributary to the subclavian vein. External jugular vein is formed by the union of the retromandibular vein and posterior auricular vein. Coursing with the upper part of the external jugular vein is the great auricular nerve, a cutaneous branch of the cervical plexus. If you see the nerve, look for the vein anterior to it. If you see the vein look for the nerve posterior to it. Lesser occipital nerve is coursing along the posterior border fot he SCM to the scalp behind the ear. Transverse cervical nerve crosses transversely across SCM to skin of anterior triangle. Branches of supraclavicilar nerves descend over the clavicle supplying skin on the base of the neck to the point of the shoulder. The point at which the cutaneous nerves comes out is ERB’s point. This is the emrgence of the cutaneous branches of the cervical plexus, it’s about midway along the posterior border of sternocleidomastoid. Spinal accessory nerve emerges just above Erb’s point, after supplied SCM and makes its way down the posterior triangle to the trapezius where it provides motor innervation. Superficial fascia Cutaneous/sensory branches of the cervical plexus Cervical plexus consists of VPR of cervical spinal nerves C1-C4. Lesser occipital (C2) – courses up posterior border of SCM, supplying skin on postero-lateral aspect of scalp. Greater auricular n. (C2/3) – courses in company with the upper protion of external jugular vein, supplies skin around the angle of the mandible, the lobule of the ear, and the skin behind the mastoid process Transverse cervical n. – crosses superficial to SCM supplying skin to anterior triangle Supraclavicular – crosses clavicle, supplies skin of base of neck to the tip of the shoulder, has a medial, intermediate, and lateral branch Cervical plexus block You can locate Erb’s point and put needle there and instill anesthesia there Surgeons will draw maps of underlying structures Superficial veins Some of the first veins you see when you reflect the skin ar eon the anterior part of the midline, which are the anterior jugular veins. Just belwo the chin in the submental region is where the anterior jugular veins begin. Anterior jugular veins coarse paramedially and diagonally down the anteiror part of the neck

and unit and form a jugular venous arch, which provides tributaries posterior to SCM and they become tribuataries to distal end of external jugular vein. So the anterior jugular vein empties into the external jugular before it empties into subclavian. Define origin of EJV by posterior auricular and retromanidublar veins. Transverse cervical and suprascapular veins drain shoulders, becoming tributary to EJV before dumping into subclavian vein. Often there is an anterior communicating vein running on the anterior border of SCM connecting the anterior jugular vein with the common facial vein. Layers of deep cervical fasciae and cervical compartment Prevertebral compartment is the cervical spine and associated musculature. Levator scapuli, splenius capitus cervicis. Any muscle that attaches to the cervical spine is enclosed by prevertebral fascia. Cervical/visceral ciompartment lives in anterior central part of the neck, b/n SCM, containing cervical/visceral fascia. Either side of cervical/vixeral compt is cartoid sheath = common coratid artery, internal jugular vein, vagus nerve. Superficial layer of deep cervical fascia (investing) = the fascia you see after you reflect platysma. These fascial compts allow for movement of muscles and other compts when we talk, swallow, speak. They also represent surgical planes for separation out structures. Often we get infections, can be delimited by CT around that, or it can erode thorugh and enter another compt nearby. Cross-section at C7 level b/c at C6 level we should see cricoid cartilage and instead we see the trachea. Spinous process is long, our vertebra prominens. Investing fascia encloses SCM anteriorly and trapezius posteriorly. * = posterior triangle. Roof of posterior triangle is formed by investing layer of fasica. Floor is prevertebral fascia that overlies some muscles. Anterior central compatmnet of neck is cervical visceral fascia consist of two parts: tracheal fascia that encloses the trachea, larynx, and thyroid and bucco-pharygeal fascia, which seals off the compartment on the posterior side. Coratid sheath, principal contents = Internal jugular vein, common coratid artery, vagus nerve (cranial nerve X). Cervical sympathetic trunk lives posterior NOT within coratid sheath! Invesing fascia extends from lower border of mandlible, to mastoid process, to external occiptial proturbuerance, andd inferior it blends in with deep fascia overlying the manubrium, clavicle, scapula. Prevertebral compatment extends to base of skull, encloses cervical spinal column, muscles. Cervical compartment consists of pretracheal fascia anterolaterally and posteriorly our buccopharyngeal fascia. A potential space b/n buccopharyngeal fasica and prevertebral fascia, which is behind the pharynx/cervical visceral compt. It’s called retropharyngeal (retrovisceral) space, which contains loose CT which allows for sliding when we speak/swallow. Impt avenue for infections from oral cavity (nasal cavity) getting into retropharyngeal space and all the way to the mediastinum south of that. One can have mediastinitis in the mediastinum as a result of infections of head and neck b/c of this space and migrated south. Triangles of the neck Posterior cervical triangle is subdivided into the occipital triangle b/c at the apex of the triangle is the occipital artery (supplied posterior aspect of scalp). And a smaller subclavian triangle. As we look at the lower reaches there’s the inferior belly of omohyoid which arises from the superior border of the scapula just medial to the superscapular notch. It crosses the posterior triangle and attaches behind the SCM.

The inferior belly of omahyoid is a boundary of subclavian triangle. If you run your fingers along the clavicle to where the clavicular head attaches to the medial third of the clavicle and push down, you should feel the subclavian pulse, so your fingers are in the subclavian triangle, where the subclavian vessesl are crossing the first rib. Anterior triangle – divided into… Submandibular triangle, which is bounded by anterior belly of digastric and posterior belly and the lower border of our mandible. Underneath the border of the mandible is the submandibular salivary gland, which largely fills the submandibular triangle. Submandibular triangle is paired (one on the left, one of the right). Submental triangle – below chin. Bounded by right and left anteiror digastric muscle and the body of the hyoid gland. Coratid triangle – bounded by the superior belly of omahyoid, a continuation of the inferior belly on its way to attach to the body of the hyoid bone. Muscular triangle – formed by a line from the hyoid bone to the supersternal notch in the midline and laterally by the superior belly of omahyoid and the anterior border of SCM. Muscles of the floor of the posterior triangle covered by pre-vertebral fascia are splenius capitis, levator scapuli, and scalene muscles (posterior, middle, anterior). Scale and prevertebral muscles Posterior and middle scalene muscles attach to posterior tubercles from C2 to C6 (trnsverse processes of cervical vertbra). Psterior scalene msucle attaches to 2nd rib. Anterior scalene muscle attach to 1st rib. Anterior and middle scalene muscles attach to transverse process of C3-C6. The anterior middle scalene muscles w/ the first rib form interscalene triangle. The roots and trunks of brahcial plexus and subclavian artery passes through interscalene triangle. Subclavian vein coarses in front of interscalene muscle (lies anterior to anterior scalene muscle). Axillary sheath is CT that is extension of prevertebral fascia that enclosed the contents of the axillary sheath, brachial plexus, axillary vessels. Superior thoracic aperture – see apices of lungs jutting through that, see subclavian vessesl coursing out and heading across first rib. Supraclavicular branches of the brachial plexus Above the clavicle, you see supraclavicular portion of brahcial plexus. Contents of posterior cervical triangle Termination of external jugular vein as it empties into subclavian Cutaneous branches of cervical plexus Spinal accessory nerve (cranial nerve 11) Muscles of the floor Phrenic nerve, which arises from C3/4/5 of cervical plexus. Id b/c it coarses diagonally across the anterior scalene muscle from lateral to medial before it enters the thorax. See portions of suprascapular artery and transverse cervical arteries as they cross from the neck towards the back where we saw them on the deep surface of trapezius, where we saw suprascapular artery in relationship to the transverse cervical ligament. Roots and trunks of brachial plexus Anterior cervical region

Divides neck into anterior and posterior triangle is SCM Origin = 2 heads, attaching to medial third of clavicle and manubrium (sternal head) Inserts on mastoid process Actoin = principal flexor on neck, unilateral contraction results in rotation of chin to opposite shoulder Coratid sheath Some of the things that you’ll see as you reflect the skin at the midline and reflect the platysma – lookout for anterior jugular veins as the descend in the neck and transception of SCM exposes the coratid sheath. Coratid sheath can be projected by line b/n angle of mandible and ipsilateral sternoclavicular joint… Covered and protected laregly by SCM Internal jugular vein, common coratid artery, and vagus nerve. Muscular triangle Strap muscles overlay cervical compartment Superficial and lateral layer is superior belly of omahyoid, arising from fascial sling of inferior belly w/ SCM on the medial end of the clavicle. Medial is sternohyoid, which attaches inferiorly to sternum and superiorly to body of hyoid bone. Behind these muscles is the sternothyroid muscle (attache sot inner surface of manubrium of sternum, and oblique line of theyroid cartilage) – this muscle prevents lobes of thyroid gland from growing superiorly. Growth typically heads south then. To find thyroid lobes transect sternothyroid. As a continuation (seemingly) is thyrohyoid muscle, which extends upward from the oblique line to the body of the hyoid. These muscles depress the larynx after swalling. Suprahyoid muscles elevate the larynx. B/c hyoid is attached to the thyroid cartialg eof larynx. Anterior cervical region Ansa cervicalis (C1-C3) – motor nerve into infrahyoid/strap muscles and a muscle ot the floor of the oral cavity. There’s a pair of roots that will unite , reprsenting superior (C1) root of ansa cervicalis. It’s not a cranial nerve, it’s a spinal nerve. It courses with the CT wrapping of hypoglossal nerve until it comes off. Superior root units with inferior root (C2/3) Look for inferior root wrapping around lateral surface of IJV. Ansa cervicalis branches supply infrahyoid muscles. Some C1 fibers will continue to coarse along w/ hypoglossal nerve, One is the nerve to the thyrohyoid muscle, then the nerve to the genohyoid muscle. Emergency crichothyrotomy Should palapate upper border of thyroid cartilage, soft connective tissue mass = thyrohyoid membrane, palpate anterior border of thyroid cartilage and at its midpoint is where vocal cords are located, also palpate band of cricoid cartilage, and cricothryoid membrane Vessels are paramidline, so we can access cricothryoid membrane via incision w/o hitting those As we look at a sagital view, canula enters below vocal cords. Oftentimes, an emergency cricothyrotomy in restaurant “café coronary” Landmark levels in the neck First see common coratid artery ascending up w/n coratid sheaths At C4 level (upper border of thryoid cartilage) the common coratid artery divides into two terminal branches, internal coratid artery (no branches in the neck) and external coratid artery (lotsa branches in

the neck). Internal coratid artery shoots up into the base of the skull and is a major blood supply to the brain Where the common coratid bifurcates, there’s a swelling of wall of proximal part called coratid sinus, which contains baro-receptors (monitor pressure w/n lumen, innervated sensory by cranial nerve 9 – glossopharyngeal nerve).On the medial side at the junction is the coratid body, which contains chemoreceptors, which monitor O2, CO2 levels in the blood, reflexly supplied by glossopharyngeal nerve system as well. Often an area for plaque buildup. Remove plaque surgically by carotid endartectomy. Branches of external carotid artery Anterior – superior thyroid artery, lingual artery (blood supply to tongue), fascial artery (splenic artery of the face) Posterior – ascending pharyngeal (hardly ever see, don’t care about), occipital artery (supplies posterior scalp), posteiror auricular Terminal – superficial temporal, maxillary artery A variation that occurs fairly frequently – as we progress up the external coratid, you may see a lingualfascial trunk that gives rise to lingual artery and fascial artery. Tributaries of the itnernal jugular vein Blood from brain leaves base of skull and enter internal jugular vein, which receives tributaries from face and neck as it descedns in neck, it units w/ subclavian vein to form the brachiocephalic veins.

NECK 2 Erb’s point = sensory portion of the cervical plexus Lesser occipital nerve, Greater occipital nerve crosses SCM (C2/3), transverse cervical (C2/3), supraclavicuar (C3/4) Cord levels correspond w/ cord levels of phrenic nerve (motor and senosry to diaphragm) Irritation of the diaphragm can be referred pain to the neck via supraclaviculars Motor portion of cervical plexus = ansa cervicalis, it sits outside the carotid sheath In the carotid sheath is internal jugular vein, common carotid, CN X (runs b/n vein and artery), and deep cervical lymph nodes associated with IJV The common carotid artery is divided into the internal and external portion at C4 Internal carotid enters skull through carotid canal External carotid leaves and has brances (anterior and posterior branches) Superior thyroid artery Thyrohyroid membrane Superior laryngeal artery goes thru thyrohyoid membrane to supply superior portion of the larynx. Lingual artery = it’s close to the hyoid bone. It’s just above C3 vertebra Arteries with CNX (superior laryngeal nerve, which has two branches. The internal branch runs with thryoid artery. It pierces the thyrohyoid membrane and is sensory in the larynx above the two vocal cords It will always be ABOVE the arteries.)

Running with the superior thyroid artery is the external branch of the superior laryngeal nerve. Supplies muscle of larynx, motor to cricothyroid muscle (small muscle of the larynx, runs b/n cricoid cartilage and thyroid cartilage. Tenses true vocal cords, causing increase in pitch) All the muscles of the larynx are innervated by recurrent branches of laryngeal nerve except cricothryoid IF you do thyroidectomy, you can damage the external branch of superior larygenal nerve, so person loses ability to increase pitch. Submandibulary gland Hypoglossal nerve CNXII supplies muscles of tongue except one (something glossis) CNXII As you follow it superiorly it starts to turn at the elbow and picks up smlal muscular branch from occipital artery, and leads you back to occipital artery Leads us to superior root of ansa (motor root of cervical plexus, supplies infrahyoid muscles except one, the thyrohyoid musclet Suprahyoid muscles elevate hyoid, elevate the larynx (when you swallow) Digstric (posterior) = digastric fossa, mastoid process Diagastric (anterior) = digastric fossa, mandible Mylohyoid forms floor of mouth. It runs off the myohyloid line in the mandible. Posterior fibers attach to hyoid and meets fibers from muscle on the other side Geniohyoid (spine) – runs from mandible to spines. Has motor innervation from C1 from motro poriton of cervical plexus. Stylohyoid runs from styloid process out to the hyoid bone. Fibers become fleshy. Tendon of posterior belly of digastric goes through these fibers. In between the mastoid proces and styloid prcess is an opening of the skull is the stylomastoid foramen, CN VII fascial nerve innervates sty...