Head & Neck Unit – Lecture15 د. حيدر جليل الأعسم Root of the Neck Head & Neck Unit – Lecture15 د. حيدر جليل الأعسم

Root of Neck It is the area immediately superior to upper thoracic aperture and axillary inlet. It contains structures passing between neck, thorax, and upper limb. It is bounded by: Anteriorly: Top of manubrium and superior margin of the clavicle Posteriorly: Top of T1 thoracic vertebra and superior margin of the scapula to the coracoid process. There is also an extension of the thoracic cavity projecting into the root of the neck. This consists of an upward projection of the pleural cavity, on both sides, and includes the cervical part of the parietal pleura (copula), and the apical part of the superior lobe of each lung.

Muscles of Root of the Neck Scalenus Anterior Muscle It is key muscle of root of neck. It is deeply placed & descends vertically from vertebral column to first rib. Origin: Transverse processes of 3rd, 4th, 5th & 6th cervical vertebrae Insertion: 1st rib Action: Elevates 1st rib; laterally flexes & rotates cervical vertebrae. Nerve Supply: C4, C5 & C6. Important Relations Anteriorly: carotid arteries, vagus nerve, internal jugular vein, deep cervical lymph nodes, Transverse cervical, suprascapular arteries. Prevertebral layer of deep cervical fascia bind phrenic nerve to muscle. Posteriorly: pleura, origin of brachial plexus, second part of subclavian artery & Scalenus medius Medially: vertebral artery & vein & sympathetic trunk. left side medial border is related to thoracic duct. Laterally: cervical plexus, roots of brachial plexus & third part of subclavian artery.

Root of Neck Scalenus Medius It lies behind scalenus anterior and extends from transverse process of atlas and transverse processes of next five cervical vertebrae to be inserted into upper surface of first rib behind the groove for subclavian artery. It lies behind roots of the brachial plexus and subclavian artery.

Vessels at the root of Neck Subclavian Arteries Subclavian arteries on both sides arch upwards out of thorax to enter root of neck Right subclavian artery begins posterior to sternoclavicular joint as one of two terminal branches of brachiocephalic trunk. It arches superiorly and laterally to pass anterior to cervical pleural and posterior to anterior scalene muscle. Continuing laterally across the 1st rib, it becomes the axillary artery. Left subclavian artery begins in thorax as a direct branch of aortic arch. Lying posterior to left common carotid artery & lateral to trachea, it ascends & arches laterally, passing anterior to cervical pleural and posterior to anterior scalene muscle. Continuing laterally across 1st rib, it becomes axillary artery.

Subclavian Arteries Subclavian artery is divided into three parts by anterior scalene : First part: from origin of artery to anterior scalene muscle; Second part is the part posterior to anterior scalene muscle; Third part is the part lateral to anterior scalene muscle before lateral border of first rib. All branches from right and left subclavian arteries arise from the first part. Branches include vertebral artery, thyrocervical trunk, internal thoracic artery & costocervical trunk.

Subclavian Veins They begin at lateral margin of 1st rib as continuations of axillary veins. Passing medially on each side, just anterior to anterior scalene muscles, each subclavian vein is joined by internal jugular vein to form brachiocephalic veins. The only tributary to subclavian veins are external jugular veins.

Autonomic Nervous System of Head & Neck Sympathetic Part: Cervical Sympathetic Trunk Cervical part of sympathetic trunk extends upward to base of skull and below to neck of 1st rib, where it becomes continuous with thoracic sympathetic trunk. It lies directly behind internal & common carotid arteries & is embedded in deep fascia between carotid sheath & prevertebral deep fascia. It has 3 ganglia: Superior Cervical Ganglion: lies immediately below skull Branches: Internal carotid nerve: (internal carotid artery- Plexus) Gray rami: (upper four anterior rami of cervical nerves) Arterial branches: (common & external carotid aa. Plexus) Cranial nerve branches: 9th, 10th & 12th cranial nerves Pharyngeal branches: join pharyngeal branches of glossopharyngeal & vagus n. & form pharyngeal plexus. Superior cardiac branch: ends in cardiac plexus in thorax.

Autonomic Nervous System of Head & Neck 2. Middle Cervical Ganglion: lies at level of cricoid Branches: Gray rami: (ant. rami of 5th & 6th cervical nerves) Thyroid branches: along inferior thyroid artery. Middle cardiac branch: ends in cardiac plexus. 3. Inferior Cervical Ganglion: fused with 1st thoracic ganglion to form stellate ganglion. It lies in interval between transverse process of C7 & neck of 1st rib. Branches: Gray rami: (ant. rami of 7th & 8th cervical nerves Arterial branches: subclavian & vertebral arteries Inferior cardiac branch: join cardiac plexus. Sympathetic trunk connecting middle cervical ganglion to inferior or stellate ganglion is represented by two or more nerve bundles. The most anterior bundle crosses in front of 1st part of subclavian artery and then turns upward behind it. This anterior bundle is called ansa subclavia.

Parasympathetic Part Parasympathetic part of autonomic nervous system is located in nuclei of oculomotor (3rd), facial (7th), glossopharyngeal (9th), and vagus (10th) cranial nerves. Axons from these nuclei are myelinated preganglionic fibers and synapse in peripheral ganglia located close to viscera they innervate. Cranial parasympathetic ganglia are ciliary, pterygopalatine, submandibular & otic. The postganglionic fibers are nonmyelinated, and they are short in length.

Lymphatics of Neck They include superficial nodes around the head, superficial cervical nodes along external jugular vein & deep cervical nodes forming a chain along internal jugular vein. Superficial lymph nodes around the head 5 groups of lymph nodes form a ring around head and are primarily responsible for lymphatic drainage of face & scalp. Their pattern of drainage is very similar to area of distribution of arteries near them. 1. Occipital nodes near attachment of trapezius muscle to skull and associated with occipital artery. 2. Mastoid nodes (retroauricular / posterior auricular nodes) posterior to ear near attachment of sternocleidomastoid and associated with posterior auricular artery. 3. Pre-auricular & Parotid nodes anterior to ear & associated with superficial temporal & transverse facial artery. 4. Submandibular nodes inferior to body of mandible and associated with facial artery. 5. Submental nodes inf. & post. to the chin. Lymphatic flow: Drainage from occipital & mastoid LN= to superficial cervical nodes along external jugular vein; Drainage from pre-auricular & parotid, submandibular & submental LN= to deep cervical nodes.

Root of Neck Superficial cervical lymph nodes: They lie along external jugular vein on superficial surface of sternocleido-mastoid muscle. They primarily receive lymphatic drainage from posterior and posterolateral regions of scalp through occipital & mastoid nodes. Deep cervical lymph nodes They form a chain of LNs along internal jugular vein. They are divided into upper & lower groups by intermediate tendon of omohyoid muscle. The most superior node in upper deep cervical group is jugulodigastric node. Another large node at or just inferior to intermediate tendon of omohyoid muscle, is jugulo-omohyoid node. This receives lymphatic drainage from the tongue. They eventually receive all lymphatics of head & neck.

End of the Lecture GOOD LUCK