WINDSOR UNIVERSITY SCHOOL OF MEDICINE DEPARTMENT OF ANATOMY Neck Dr. SREEKANTH THOTA

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 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.

Objectives 2. Fascia and Fascial spaces of the neck 1. To study Compartments of the neck. 2. Fascia and Fascial spaces of the neck 3. Anterior triangle of the neck 4. Posterior triangle of the neck 5. Bones of the Neck 6. Vasculatur of the neck 7. Nerves of the neck. 8. Lymphatics of the neck

Compartments of the neck Within the tube four compartments provide longitudinal organization 1. visceral compartment is anterior and contains parts of the digestive and respiratory systems, and several endocrine glands 2. vertebral compartment is posterior and contains the cervical vertebrae, spinal cord, cervical nerves, and muscles associated with the vertebral column 3. Two vascular compartments are lateral and contain the major blood vessels and the vagus nerve [X].

Fascia Superficial fascia: contains a thin sheet of muscle (the platysma) Deep cervical fascia: organized into several distinct layers 1. Investing layer 2. Prevertebral layer 3. Pretracheal layer 4. Carotid sheath

Fascial spaces 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. 1. Pretracheal space : passes between the neck and the anterior part of the superior mediastinum 2. Retropharyngeal space : extends from the base of the skull to the upper part of the posterior mediastinum

Triangles of the neck For descriptive purposes the neck is divided into anterior and posterior triangles 1.The anterior triangle of the neck is outlined by the anterior border of the sternocleidomastoid muscle laterally, the inferior border of the mandible superiorly, and the midline of the neck medially. 2. boundaries of the posterior triangle are the posterior border of the sternocleidomastoid muscle, the anterior border of the trapezius muscle, and the middle one-third of the clavicle

Anterior Triangle subdivided into smaller triangles by Posterior Triangle Submental Triangle Submandibular Triangle Carotid Triangle Anterior Triangle subdivided into smaller triangles by Digastric muscle Omohyoid muscle

Anterior triangle of the neck Subdivided into four smaller triangles 1. Submandibular triangle: outlined by the inferior border of the mandible superiorly and the anterior and posterior bellies of the digastric muscle inferiorly 2. Submental triangle: outlined by the hyoid bone inferiorly, the anterior belly of the digastric muscle laterally, and the midline

3.Muscular triangle: outlined by the hyoid bone superiorly, the superior belly of the omohyoid muscle, and the anterior border of the sternocleidomastoid muscle laterally, and the midline 4.Carotid triangle is outlined by the superior belly of the omohyoid muscle anteroinferiorly, the stylohyoid muscle and posterior belly of the digastric superiorly, and the anterior border of the sternocleidomastoid muscle posteriorly.

Contents of ant triangle

Posterior triangle of the neck

Bones of the Neck The skeleton of the neck is formed by the cervical vertebrae and hyoid bone

Cervical Vertebrae Seven cervical vertebrae form the cervical region of the vertebral column, which encloses the spinal cord and meninges.

C1 vertebrae or atlas Ring-like, kidney-shaped bone lacking a spinous process or body and consisting of two lateral masses connected by anterior and posterior arches. Its concave superior articular facets receive the occipital condyles.

C2 vertebrae or axis Peg-like dens (odontoid process) projects superiorly from its body

Four typical cervical vertebrae (3rd to 6th) Spinous processes are short and bifid. Transverse processes of all cervical vertebrae (typical or atypical) include transverse foramina for the vertebral vessel(except for C7, the vertebral artery).

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.

HYOID BONE Anterior neck C3 Suspended from the styloid process of the temporal bone by the stylohyoid ligament Serves as an attachment for suprahyoid and infrahyoid muscles and the investing deep fascia It serves as a prop to keep the airway open

Important Muscles of Neck

Superficial Muscles of the Neck 1. Sternocleidomastoid Muscle Origin:Sternal head: anterior surface of manubrium of sternum Clavicular head: superior surface of medial third of clavicle Insertion :Lateral surface of mastoid process of temporal bone and lateral half of superior nuchal line N. supply:Spinal accessory nerve (CN XI, motor) Action :Two muscles acting together extend head and flex neck; one muscle rotates head to opposite side

Congenital Torticollis Torticollis is a contraction of the cervical muscles that produces twisting of the neck and slanting of the head. The lesion, like a normal unilateral SCM contraction, causes the head to tilt toward, and the face to turn away from, the affected side

Spasmodic Torticollis Cervical dystonia commonly known as spasmodic torticollis, usually begins in adulthood. Characteristics of this disorder are sustained turning, tilting, flexing, or extending of the neck .

Muscles The muscles in the anterior triangle of the neck can be grouped according to their location relative to the hyoid bone: 1. Muscles superior to the hyoid are classified as suprahyoid muscles. 2. Muscles inferior to the hyoid are infrahyoid muscles.

Suprahyoid muscles Digastric Stylohyoid Geniohyoid Mylohyoid Styloid process to hyoid bone Geniohyoid Inferior mental spine (on back of symphysis menti) to hyoid bone Mylohyoid Mandible to hyoid bone Stylohyoid muscle- With post belly of digastric muscle supplied with facial nerve. Geniohyoid- C1 running with hypoglossal nerve. Mylohyoid muscle- With anterior belly of digastric muscle supplied with mylohyoid nerve (arises from mandibular division of trigeminal nerve). 38

Action of Supra & Infrahyoid Muscles Direction of pull; effect on hyoid; swallowing: epiglottis closes over larynx; Function of elevators and depressors is therefore v. imp!

Infrahyoid Muscles Strap muscles Sternothyroid Sternohyoid Thyrohyoid Sternum to thyroid cartilage Sternohyoid Sternum to hyoid bone Thyrohyoid Thyroid cartilage to hyoid bone Omohyoid Superior border of scapula to hyoid bone All infrahyoid muscles are innervated by ansa cervicalis from cervical plexus (C1-3) EXCEPT for thyrohyoid muscle, which is innervated by C1 fibers running with hypoglossal nerve 41

Scalene Muscles Elevation of rib I and II Anterior, middle, and posterior scalene muscles Attach to transverse processes of cervical vertebrae and to rib 1 and 2 Action Elevation of rib I and II Innervated by spinal nerves C3-C8 Also called lateral vertebral muscles 43

Subclavian artery Common carotid artery ICA ECA Arteries of the Neck Subclavian artery Common carotid artery ICA ECA

Subclavian Arises from Right side- brachiocephalic trunk Left side- arch of aorta Arches laterally over cervical pleura and apex of lung and grooves on 1st rib between anterior and middle scalene muscles Divided into three parts in relation to anterior scalene muscle Becomes axillary artery at lateral border of 1st rib

First part of Subclavian artery The first part extends from the origin of the artery to the anterior scalene muscle. 1. Vertebral artery 2. Thyrocervical trunk 3. Internal thoracic artery Thyrocervical trunk Inferior thyroid artery Transverse cervical artery Suprascapular artery

Second part of the subclavian artery. Costocervical trunk 1. Deep cervical artery 2. Supreme intercostal artery

Common carotid artery Arises from Brachiocephalic trunk on right Arch of aorta on left Divides into internal & external carotid arteries At superior border of thyroid cartilage (C4)

Carotid Pulse Important site for pulse taking Pulsation in common carotid artery are felt just below its bifurcation Bifurcation happens at the level of superior border of thyroid cartilage Against transverse process of 6th cervical vertebra (carotid tubercle)

Internal carotid artery No branches in neck External carotid artery Gives eight branches Four or five arise in carotid triangle Ends within parotid gland by dividing into maxillary and superficial temporal arteries

Superficial venous drainage The external jugular and anterior jugular veins are the primary venous channels for superficial venous drainage of the neck

Nerves Several nerves and components of the nervous system pass through the neck. 1. Cervical plexus 2.Phrenic nerves 3. Vagus nerves [X] 4. Recurrent laryngeal nerves 5. Sympathetic nervous system

Cervical plexus The cervical plexus is formed by the anterior rami of cervical nerves C2 to C4, and possibly a contribution from the anterior ramus of cervical nerve C1. Muscular (or deep) branches Cutaneous (or superficial) branches

Phrenic nerve The phrenic nerves are branches of the cervical plexus and arise on each side as contributions from the anterior rami of cervical nerves C3 to C5 come together.

Vagus nerves [X] The vagus nerves [X] descend through the neck within the carotid sheath, posterior to and just between the common carotid artery and the internal jugular vein. In the root of the neck, each vagus nerve [X] passes anterior to the subclavian artery and posterior to the subclavian vein as it enters the thorax

Recurrent laryngeal nerves The right recurrent laryngeal nerve is a branch of the right vagus nerve [X] on reaching the lower edge of the first part of the subclavian artery in the root of the neck The left recurrent laryngeal nerve is a branch of the left vagus nerve [X] as it crosses the arch of the aorta in the superior mediastinum. It passes below and behind the arch of the aorta and ascends beside the trachea to the larynx.

Sympathetic nervous system Various components of the sympathetic nervous system are visible as they pass through the root of the neck. These include: 1. cervical part of the sympathetic trunk; 2. ganglia associated with the cervical part of the sympathetic trunk; 3.cardiac nerves branching from the cervical part of the sympathetic trunk

Lymphatics Thoracic duct The thoracic duct is a major lymphatic channel that begins in the abdomen, passes superiorly through the thorax, and ends in the venous channels in the neck.

Termination of lymphatic trunks in the root of the neck. 1.Jugular trunk from the head and neck 2.Subclavian trunk from the right upper limb 3.Bronchomediastinal trunk

Lymphatics of the neck 1. occipital nodes 2. mastoid nodes (retroauricular/posteri or auricular nodes) 3. pre-auricular and parotid nodes 4. submandibular nodes 5. submental nodes Superficial cervical lymph nodes Deep cervical lymph nodes

Deep cervical lymph nodes From the deep cervical nodes, lymphatic vessels form the right and left jugular trunks, which empty into the right lymphatic duct on the right side or the thoracic duct on the left side.