Neck Anatomy PDF

Neck The muscles of neck Superficial group Platysma ，a thin sheet-like muscle of facial expression Sternocleidomastoid Suprahyoid muscles Digastric Stylohyoid Mylohyoid Geniohyoid Elevate (raise) hyoid bone and depress mandible. Infrahyoid muscle Sternohyoid Sternothyroid Thyrohyoid Omohyoid Depres...

Neck The muscles of neck Superficial group Platysma ，a thin sheet-like muscle of facial expression Sternocleidomastoid Suprahyoid muscles Digastric Stylohyoid Mylohyoid Geniohyoid Elevate (raise) hyoid bone and depress mandible. Infrahyoid muscle Sternohyoid Sternothyroid Thyrohyoid Omohyoid Depress hyoid or larynx after elevation Deep group Lateral Scalenus anterior Scalenus medius Scalenus posterior Medial longus capitis longus colli Flex the head, bends the neck forward Major muscles of the neck Sternocleidomastoid Origin: manubrium and sternal end of clavicle Insertion: mastoid process of temporal bone Action: contraction of one muscle draws head toward the same side, and turn face to opposite side; both muscles act together to draw head backward Torticollis: tortion of neck (collis) congenital or acquired Scalenus anterior Origin: transverse processes of C3C6. Insertion: tubercle for scalenus anterior Action: unilateral, bends neck laterally; bilateral, elevate first rib, an accessory muscle of inspiration; if rib is fixed, flex neck anteriorly The arteries of neck Common carotid artery Origin (arises from) Brachiocephalic trunk on the right Aortic arch on the left Ascends in neck to upper border of thyroid cartilage; bifurcates into internal and external carotid arteries Carotid sinus (baroreceptor), located at a localizes dilation of terminal part of common carotid artery or beginning of internal carotid artery, sensitive to blood pressure changes Carotid glomus (chemoreceptor), lies posterior to the point of bifurcation of common carotid artery, senses changes in blood carbon dioxide (oxygen) levels Branches of external carotid artery Superior thyroid a. descends to supply upper pole of thyroid gland and larynx Lingual a. Facial a. Occipital a. Posterior auricular a. Maxillary a. Superficial temporal a. Veins draining the neck Internal jugular vein Begin at jugular foramen, descending to join the subclavian vein to form brachiocephalic vein Lies lateral first to internal and then to common carotid a. within carotid sheath Chief extracranial tributaries Facial vein Lingual v. Pharyngeal v. Superior thyroid v. Middle thyroid v. Subclavian vein It is a continuation of axillary vein at the lateral border of first rib Joins internal jugular vein to form the brachiocephalic vein. Angle of union is termed venous angle External jugular vein Formed behind angle of mandible by union of posterior auricular, posterior branch of retromandibular and occipital vein Crossing sternocleidomastoid to enter subclavian vein Anterior jugular vein Drains submandibular and anterior neck regions Descends near midline, runs posterior to sternal end of sternocleidomastoid to drain into external jugular vein or subclavian vein Lymph nodes of neck Anterior cervical lymph nodes Superficial anterior cervical lymph nodes Deep anterior cervical lymph nodes Lateral cervical lymph nodes Superficial lateral cervical lymph nodes－lie along the external jugular vein Deep lateral cervical lymph nodes Extend along the internal jugular vein Receive lymphatic vessels from head, neck, tongue, larynx, cervical parts of esophagus and trachea, thyroid gland, upper parts of the thoracic wall and breast Right lymphatic duct Formed by union of right jugular, subclavian, and bronchomediastinal trunks Ends by entering the right venous angle Receives lymph from right half of head, neck, thorax and right upper limb Thoracic duct At the roof of the neck, it turns laterally and arches forwards and descends to enter the left venous angle Just before termination, it receives the left jugular, subclavian and bronchomediastinal trunks Cervical plexus Formation: formed by anterior rami of C1-C4 spinal nerves Position: lies in front of the origin of levator scapulae and scalenus medius and deep to the superior part of the sternocleidomastoid Branches Cutaneous branches: emerge around middle of posterior border of sternocleidomastoid, to supply skin of neck and scalp between auricle and external occipital protuberance Lesser occipital n. Great auricular n. Transverse nerve of neck Supraclavicular n. Muscular branches: supply the deep muscles of neck Phrenic nerve (anterior rami of C3C5) Lies on anterior scalene, deep to fascia To diaphragm (motor and sensory) Ansa cervicalis : Hypoglossal nerve gives off superior root of ansa composed of fibers picked up from nerve C1 Joins inferior root of ansa (C2and C3) to form a loop, the ansa cervicalis, which supplies infrahyoid muscles Vagus nerve (Ⅹ) Leaves skull via jugular foramen Descends in the neck in carotid sheath between internal (or common) carotid artery and internal jugular vein Branches Superior laryngeal nerve passes down side of pharynx and given rise to Internal branch which pierces thyrohyoid membrane to innervates mucous membrane of larynx above fissure of glottis External branch which innervates cricothyroid Cervical cardiac branches : descending to terminate in cardiac plexus Recurrent laryngeal nerves Ascend in tracheo-esophageal groove Enter larynx posterior to cricothyroid joint, the nerve is now called inferior laryngeal nerve Innervations: laryngeal mucosa below fissure of glottis , all laryngeal laryngeal muscles except cricothyroid Accessory n. (Ⅺ ) Deep to posterior belly of digastric Supplies sternoclidomastoid and trapezius muscle Hypoglossal n.(Ⅻ) Descends between internal carotid a. and internal jugular v., hooks around external carotid a., to lie on the hyoglossus before entering tongue Supplies muscles of tongue Cervical part of sympathetic trunk Formed by superior , middle and inferior cervical ganglia and interganglionic branches Superior cervical ganglion: largest, situated in front of transverse processes of C1~C3 vertebra Middle cervical ganglion: smallest, is at level of transverse processes of C6 vertebra Inferior cervical ganglion: situated at level of C7 vertebra, and may be fused with first thoracic ganglion to form cervicothoracic ganglion Regional anatomy of neck Parts and regions of the neck Boundaries Superior－inferior border of mandible, angle of mandible, tip of mastoid process, superior nuchal line, external occipital protuberance Inferior－jugular notch, sternoclavicular joint, superior border of clavicle, acromion, spinous processes of C7 Regions Neck Anterior region of neck Lateral region of neck Sternocleidomastoid Anterior region of neck Submental triangle Submandibular triangle Carotid triangle Muscular triangle Lateral region of neck Occipital triangle Supraclavicular triangle Superficial fascia Consists of fat and connective tissue Contents Platysma Superficial veins Anterior jugular v. External jugular v. Cutaneous nerves Lesser occipital n. Greet auricular n. Transverse nerve of neck Supraclavicular n. Cervical branch of facial n. Submental triangle Lies below the chin and is bounded laterally by anterior bellies of digastric, and inferiorly by the body of hyoid bone Covered by skin, superficial fascia and investing fascia Floor－mylohyoid muscles Contents－submental lymph nodes Submandibular triangle Bounded by anterior and posterior bellies of digastric and lower border of the body of the mandible Covered by skin, superficial fascia, platysma and investing fascia Floor－ mylohyoid, hyoglossus and middle constrictor of pharynx Contents－submandibular gland, facial a., v., hypoglossal n. and v., lingual n., submandibular ganglion and submandibular lymph nodes Carotid triangle Bounded by anterior border of sternocleidomastoid, superior belly of omohyoid and posterior belly of digastic muscles Covered by skin, superficial fascia, platysma and investing fascia Floor－prevertebral fascia and lateral wall of pharynx Contents－common carotid a. and its branches, internal jugular v. and its tributaries, hypoglossal n. with its descending branches, vagus nerve, and part of the chain of deep cervical lymph nodes Muscular triangle Bounded by midline of the neck, superior belly of the omohyoid and anterior border of the sternocleidomastoid. Covered by skin, superficial fascia, platysma, anterior jugular v., cutaneous n. and investing fascia Floor－prevertebral fascia Contents－sternohyoid, superior belly of omohyoid, sternothyroid, thyrohyoid, thyroid gland, parathyroid gland, cervical part of trachea and esophagus Sternocleidomastoid region Covered by sternocleidomastoid Contents Ansa cervicalis Carotid sheath Cervical plexus Cervical part of sympathetic trunk Lateral region of neck Bounded by posterior border of sternocleidomastoid, anterior border of trapezius and middle third of clavicle Divided by inferior belly of omohyoid into occipital and supraclavicular triangles Occipital triangle Bounded by posterior border of sternocleidomastoid, anterior border of trapezius and superior border of inferior belly of omohyoid Covered by skin, superficial fascia, and investing fascia Floor－prevertebral fascia and scalenus anterior, scalenus medius, scalenus posterior, splenius capitis and levator scapulae Conents Accessory n.－emerges above the middle of the posterior border of sternocleidomastoid and crosses the occipital triangle to trapezius Cervical and brachial plexuses Supraclavicular triangle Bounded by posterior border of sternocleidomastoid, inferior belly of omohyoid and middle third of clavicle Covered by skin, superficial fascia, and investing fascia Floor－prevertebral fascia and inferior parts of scalenus Conents Subclavian v. and venous angle Subclavian a. Brachial plexus Dissection Platysma Cutaneous nerves and superficial veins Lesser occipital n. External jugular vein Transverse nerve of neck Anterior jugular vein Greet auricular n. Supraclavicular n. Submandibular gland Digastric Accessory n. Hypoglossal n. Superior thyroid a. Ansa cervicalis Sternothyroid Sternohyoid Vagus n. Cervical plexus Phrenic n. Omohyoid