Week 30 Lecture - Head and Neck

Potential complications of thyroid surgery?

1. Postoperative Haemorrhage 2. Recurrent Laryngeal Nerve Injury 3. External Laryngeal Nerve Injury 4. Post-operative Hypocalcaemaia

Triangles of the neck?

Anterior (Boundaries): - the median vertical line of the neck, - the inferior margin of the mandible, and - the anterior margin of the sternocleidomastoid muscle. • Posterior (Boundaries): - the middle one-third of the clavicle, - the anterior margin of the trapezius, and - theposteriormarginofthe sternocleidomastoid.

Why does a thyroid swelling move on swallowing?

Any thyroid gland swelling will move with the gland upwards on swallowing due to it being enclosed (with the gland itself) within the pre-tracheal fascia.

What are the arteries of the neck?

Common carotid artery: - Internal carotid artery (no branches in the neck) - External carotid artery (important branches are - sup thyroid, lingual, facial, and 2 terminal - maxillary & superficial temporal) Vertebral artery: no branches in the neck. Carotid pulse - felt lateral to upper border of thyroid cartilage.

Which nerve is in close proximity to the superior thyroid artery?

External laryngeal nerve. The external branch is susceptible to damage during thyroidectomy or cricothyrotomy, as it lies immediately deep to the superior thyroid artery. The ability to produce pitched sounds is then impaired along with easy voice fatigability, (usually mono-toned voice). Damage to the superior laryngeal nerve leaves the vocal cord abducted and poses an aspiration risk.

What are the groups of lymph nodes in the neck?

Groups: 1. Horizontal chain I. Upper II. Lower 2. Vertical I. Anterior II. Intermediate III. Posterior

What is the surface anatomy of the internal jugular?

Internal jugular - earlobe to sternoclavicular joint; External jugular - earlobe to mid clavicle.

What are the lymph node levels in the neck?

Level I - submental nodes, submandibular nodes Level II - internal jugular (deep cervical) chain, base of the skull to the inferior border of hyoid bone Level III internal jugular (deep cervical) chain lower margin of hyoid to lower margin of cricoid. Level IV internal jugular (deep cervical) chain lower margin of cricoid cartilage to level of the clavicle Level V posterior triangle (spinal accessory) nodes Level VI Prelaryngeal (Delphian node)/pretracheal Level VII superior mediastinal nodes N.B: Above does not include - the supraclavicular, parotid and retropharyngeal space nodes.

What is the sublingual salivary gland?

Lies between mylohyoid & side of the tongue (genioglossus muscle) under the mucosa of the floor of the mouth medial to the sublingual fossa of the mandible.

Salivary gland: how do they receive their secretomotor supply?

The auriculotemporal nerve is a branch of the mandibular nerve (V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head. This nerve as it courses posteriorly to the condylar head, is frequently injured in temporomandibular joint (TMJ) surgery, causing an ipsilateral parasthesia of the auricle and skin surrounding the ear. It is the main nerve that supplies the TMJ, along with branches of the masseteric nerve and the deep temporal. After a parotidectomy, the nerves from the Auriculotemporal Nerve that previously innervated the parotid gland can reattach to the sweat glands in the same region. The result is sweating along the cheek with the consumption of foods (Frey's syndrome). Treatment involves the application of an antiperspirant or glycopyrrolate to the cheek, Jacobsen's neurectomy along the middle ear promontory, and lifting of the skin flap with the placement of a tissue barrier (harvested or cadaveric) to interrupt the misguided innervation of the sweat glands. Pain from parotitis, a condition that can be caused by mumps, will be carried by the auriculotemporal nerve to the brain.

What are the strap muscles and what is their nerve supply?

The infrahyoid muscles (strap muscles) are a group of four pairs of muscles in the anterior (frontal) part of the neck. The four infrahyoid muscles are; the sternohyoid, sternothyroid, thyrohyoid and omohyoid muscles. The infrahyoid muscles either originate from or insert on to the hyoid bone. The term infrahyoid refers to the region below the hyoid bone, while the term strap muscles refers to the long and flat muscle shapes which resembles a strap. The stylopharyngeus muscle is considered by many to be one of the strap muscles, but is not an infrahyoid muscle. Innervation: All of the infrahyoid muscles are innervated by the ansa cervicalis from the cervical plexus (C1-C3) except the thyrohyoid muscle, which is innervated by fibers only from the first cervical spinal nerve travelling with the hypoglossal nerve.

Actions and innervation of sternocleidomastoid?

The sternocleidomastoid is innervated by the accessory nerve of the same side. It supplies only motor fibres. The cervical plexus supplies sensation, including proprioception, via the ventral primary rami of C2 and C3. The function of this muscle is to rotate the head to the opposite side or obliquely rotate the head. It also flexes the neck. When both sides of the muscle act together, it flexes the neck and extends the head. When one side acts alone, it causes the head to rotate to the opposite side and flexes laterally to the same side (ipsilaterally). It also acts as an accessory muscle of respiration, along with the scalene muscles of the neck.

Four compartments of the neck?

• Anterior visceral compartment - contains parts of the digestive and respiratory systems, and several endocrine glands. • Posterior vertebral compartment - contains the cervical vertebrae, spinal cord, cervical nerves, and muscles associated with the vertebral column. • Lateral vascular compartments, one on each side - contain the major blood vessels and the vagus nerve [X].

Thyroid vascular supply?

• Arterial - Superior & Inferior thyroid arteries - Arteria thyroidea ima (3%) *may replace inf thyroid artery • Venous - Superior, Middle and Inferior thyroid veins • Lymphatics - Deep cervical lymph nodes - Pre-laryngeal, Pre- and para-tracheal nodes - Directly to the thoracic duct

What are the nerves in the neck?

• Cervical plexus & branches • Cranial nerves: IX,X,XI, & XII • Cervical sympathetic trunk & ganglion

What are the veins of the neck?

• Internal jugular vein - from sigmoid sinus in cranium emerges at the jugular foramen and joins the subclavian vein to form brachiocephalic vein. • External jugular vein - formed behind angle of the mandible and terminates in the subclavian vein. • Anterior jugular vein - near the midline from the level of hyoid & ends in ext. jugular vein.

What is the parotid?

• Largest of the salivary glands Surface markings: • Superior - zygomatic arch • Posterior - ext auditory meatus, mastoid process & anterior border of SCM. • Inferior - line joining mastoid pr & gr cornu of hyoid • Anterior - overlaps masseter muscle Parotid duct -from ant part of the gland & opens opposite the 2nd upper molar tooth (middle third of the line between tragus to angle of mouth). Running within the gland - VII nv; Ext carotid art & Retromandibular vein. Running behind the gland - auriculotemporal nerve

What are the types of salivary glands?

• Parotid • Submandibular • Sublingual

Fascia of the neck?

• Superficial • Deep cervical fascia: - an investing layer, which surrounds all structures in the neck; - the pre-vertebral layer, which surrounds the vertebral column and the deep muscles associated with the back; - the pre-tracheal layer, which encloses the viscera of the neck; and - the carotid sheaths.

What is the submandibular salivary gland?

• Two lobes - demarcated by mylohyoid muscle. • Superficial lobe - in the submandibular triangle & deep lobe between mylohyoid & hyoglossus muscles • Submandibular duct opens on either side of the frenulum of the tongue.