Lecture: 3 Head and neck Dr. Omar Riadh
11-10-2017
The neck
The neck is divided by sternocleidomastoid muscle into anterior triangle in front of the muscle and posterior triangle behind the muscle.Sternocleidomastoid muscle:-
Origin:- it has two heads: a- sternal head arise from manubrium sterni. b- clavicular head arise from the upper surface of medial 1/3 of clavicle.Insertion:- anterior part inserted into mastoid process, while posterior part inserted into the lateral part of superior nuchal line.
Nerve supply:- motor by spinal part of accessory nerve, while sensory by ventral rami of C2.
Action:- acting alone, it tilts the head to its own side and rotates it, so the face turned towards the opposite side, two muscles acting together flex the neck, but raise the sternum and assisted in forced inspiration.
The posterior triangle:-
Boundaries:-Anteriorly:- posterior border of sternocleidomastoid muscle.
Posteriorly:- anterior border of trapezius muscle.
Inferiorly:- by intermediate third of clavivle.
Roof:- covered by skin, superficial fascia, platysma muscle and deep fascia, in addition to supraclavicular nerve and lymph vessels run in these fascia.
Floor:- is formed by muscles which are covered by prevertebral fascia these muscles from above downward are semispinalis capitis, splenius capitis, levator scapulae and scalenus medius muscle.
The posterior triangle is divided by inferior belly of omohyoid muscle in to occipital triangle and supraclavicular triangle.
Contents:
Arteries:- 3rd part of subclavian artery, transverse cervical artery, suprascapular artery and occipital artery.
Veins:- external jugular vein, subclavian vein.
Muscle:- inferior belly of omohyoid muscle.
Nerve:- spinal part of accessory nerve, cutaneous branches of cervical plexus, upper root of brachial plexus between scalenus anterior and scalenus medius muscles, phrenic nerve and dorsal scapular nerve.
Accessory nerve:-
Is 11th cranial nerve arises by two roots, spinal roots from the upper five cervical segments which ascends upward through foramen magnum to join the cranial root which arises from medulla oblongata, both roots united together and leave the skull through jugular foramen with the vagus (10th cranial nerve) and glossopharyngeal (9th cranial nerve). In the jugular foramen the cranial part separates and joining the vagus nerve, while the spinal part passes posteriorly under sternocleidomastoid muscle supplies it and ends under trapezius muscle which also supplied by this nerve. With the accessory nerve runs branches from C2,C3 and C4 as sensory to these muscles.
Cutaneous branches of cervical plexus:-
The cervical plexus is formed deeply inside scalenus medius by the ventral rami of upper four cervical nerves, this plexus gives rise to the followings:-
Cutaneous branches of cervical plexus.
Ansa cervicalis.
Phrenic nerve.
Direct muscular branches.
Contribution to accessory nerve.
Cutaneous branches of cervical plexus are:-
Great auricular nerve:- arises under posterior border of sternocleidomastoid muscle and turned upward in front of the auricle supplies the skin of auricle and the skin over the parotid gland.
Lesser occipital:- passes upward along the posterior border of sternocleidomastoid muscle supplies the skin of the auricle and scalp posteriorly.
Transverse cervical branch of the neck:- which crosses sternocleidomastoid muscle and runs anteriorly to the skin of the neck.
Supraclavicular nerve:- arises from C3 and C4 , this nerve divided into medial, intermediate and lateral branches supplies the skin over the chest, breast and over the shoulder joint.
Phrenic nerve:-
Arises from C3,C4 andC5, it appears on the lateral surface of scalenus anterior muscle, this nerve is motor to the diaphragm and sensory to the central part of the diaphragm.
The anterior triangle:-
Boundaries:-
Anteriorly:- by midline of the neck.
Posteriorly:- by anterior border of sternocleidomastoid muscle.
Superiorly:- by lower margin of the body of mandible.
Roof:- skin, superficial fascia, platysma muscle and the investing layer of the deep facsia.
The anterior triangle is subdivided by anterior and posterior bellies of digastric muscle and superior belly of omohyoid muscle into triangles which are:-
Submental triangle.
Digastric triangle (submandibular).
Carotid triangle.
Muscular triangle.
Submental triangle:-
Lies under the chin, bounded by midline, anterior belly of digastric muscle and inferiorly by the hyoid bone. The floor is formed by mylohyoid muscle.
Contents:- submental artery(branch of facial artery), nerve to mylohyoid (from mandibular division of trigeminal nerve) and submental lymph nodes.
Digastric triangle:-
It lies under the mandible.
Boundaries:-
Superiorly:- the body of mandible.
Anteriorly:- anterior belly of digastric muscle.
Posteriorly:- posterior belly of digastric muscle.
Floor:- by mylohyoid and hyoglossus muscles.
Contents:-
Submandibular salivary gland.
Submandibular lymph nodes.
Submandibular ganglia which is a parasympathetic ganglia connects to the lingual nerve.
Facial artery and vein.
Hypoglossal nerve (12th cranial nerve).
Lingual artery and vein.
Nerve and artery to mylohyoid.
Lower part of parotid gland.
Sometimes carotid sheath lies on its posterior part.
Carotid triangle:-
Boundaries:-
Superiorly:- posterior belly of digastric muscle.
Inferiorly:- superior belly of omohyoid.
Posteriorly:- anterior border of sternocleidomastoid muscle.
Floor:- hyoglossus, thyrohyoid muscle, middle and inferior constrictor muscles.
Contents:-
Carotid sheath:- which contains common carotid artery, internal jugular vein and vagus nerve.
Branches of external carotid artery:- superior thyroid, facial, lingual, ascending pharyngeal and occipital arteries.
At the bifurcation of common carotid artery , also there is carotid bodies and carotid sinus.
Ansa cervicalis anterior to the carotid sheath.
Sympathetic trunk posterior to the carotid sheath.
Hypoglossal nerve.
Accessory nerve.
Deep cervical lymph nodes.
Muscular triangle:-
Boundaries:-
Anteriorly: is the midline.
Superiorly:- by superior belly of omohyoid.
Posteriorly:- by anterior border of sternocleidomastoid muscle.
Contents:-
Infrahyoid muscles:- which are sternohyoid, sternothyroid, thyrohyoid and omohyoid muscles.Branches of ansa cervicalis.
Thyroid gland.
Branches of superior thyroid artery.
Trachea.
Esophagus.