Nerves of the Head and Neck

Question 1

Facial Nerve - Surgical Landmarks for Identification of the facial nerve during Parotid Surgery

Answer 1

1. Tragal Pointer - F.N. is 1 to 1.5cm deep to and just anterior and inferior to the lateral edge of the external canal cartilage
2. Tympanomastoid Fissure - F.N. can be identified 6 - 8mm below the inferior ‘drop off’ of the fissure
3. Posterior Belly of Digastric muscle at its insertion to the mastoid process - f.n. exits the stylomastoid foramen just anterior to this
4. Proximal dissection of peripheral f.n. branches through the parotid gland: allows the surgeon to localize the nerve when its proximal extratemporal anatomy is distorted or parotid neoplasm is present
5. Identification in the Mastoid: Perform mastoidectomy and trace f.n. to the stylomastoid foramen.

Question 2

Facial Nerve - Surgical landmarks for identification of the intratemporal facial nerve

Answer 2

1. Cochleariform process - tympanic segment of the f.n. is just deep and superior to this
2. Lateral Semicircular Canal - second gentiles inferior and medial to this
3. Digastric ridge - stylomastoid foramen located at anterior edge of ridge

Question 3

Intratemporal facial nerve dehiscence: Incidence and site of injury during surgery

Answer 3

1. 30% incidence of f.n. dehiscence in the middle ear
2. Most common site of dehiscence of and injury to f.n. during middle ear surgery is the tympanic segment near the oval window