Face, scalp & Parotid

Question 1

What are the 5 layers of the scalp how are these different in the face?

Answer 1

Skin, Connective tissue, Aponeurosis (of occipital-frontalis muscle) Loose connective tissue, Pericranium/periosteum. Face has no layer 4 (loose connective tissue) and has muscles instead of aponeurosis (layer 3).

Question 2

What are the boundaries of the scalp?

Answer 2

From the External occipital protuberance posteriorly to the supraorbital margins (ie includes the forehead)

Question 3

Why do scalp wounds bleed profusely?

Answer 3

1. rich anastomoses of blood vessels within the connective tissue layer
2. Scalp wounds gape as wound margins are pulled apart by the attachments of occipitalis and frontalis muscle bellies to the underlying aponeurosis
3. Vasoconstriction of arteries is prevented via attachments to fibrous septa - this impedes clotting.

Question 4

Muscles of the face are derived from which pharyngeal arch embryologically? what nerve are they innervated by?

Answer 4

2nd pharyngeal arch -> innervated by Facial Nerve (CNVII)

Question 5

What is the sensory innervation to the face? how does this differ anteriorly and posteriorly to the ears?

Answer 5

Ant = 3 branches of Trigeminal Nerve (V1 Opthalmic, V2 Maxillary, V3. Mandibular). Posterior to the ears the skin is innervated by the dorsal rami of cervical spinal nerves

Question 6

What is the blood supply to the face?

Answer 6

Majority of face is supplied by branches of the external carotid artery -> gives off the facial artery which runs a tortuous course to the medial border of the eye, superficial temporal artery supplies the lateral scalp. The middle forehead region is supplied by the Supratrochlear and Supraorbital branches of from the Opthalmic artery (a branch of the internal carotid)

Question 7

What is the blood supply to the scalp?

Answer 7

1. superficial temporal artery
2. posterior auricular artery
3. occipital artery
   => ALL from ext carotid

Question 8

How can infection spread from the face to the brain?

Answer 8

most of the blood from the face drains via the facial vein however it can also drain via the opthalmic vein into the cavernous sinus

Question 9

What are the LN of the face/scalp?

Answer 9

1. submental nodes (below the chin)
2. Submandibular nodes
3. Pre-auricular and parotid nodes
4. Mastoid nodes
5. Occipital nodes
   - > all drain to the upper deep cervical nodes

Question 10

Describe the course of the parotid duct

Answer 10

Emerges from the anterior border of the parotid gland and runs on the masseter muscle until it turns inwards (at the anterior border of masseter) and pierces Buccinator and enters the oral cavity in the vestibule near the 2nd upper molar

Question 11

What 4 structures are contained within the substance of the parotid gland?

Answer 11

1. facial nerve (most superficial)
2. retromandibular vein
3. ext carotid artery (deepest)
4. parotid LN -> scattered throughout

Question 12

Describe the course of the facial nerve in relation to the parotid gland

Answer 12

forms a plexiform arrangment within the substance of the parotid gland (pes anserinus) giving off its 5 terminal branches (Temporal, Zygomatic, Buccal, Mandibular, Cervical)

Question 13

After the external carotid artery enters the parotid gland what branches does it give off?

Answer 13

divides into its two terminal branches - maxillary and superficial temporal arteries

Question 14

What important branch does the maxillary artery give off?

Answer 14

Middle meningeal artery

Question 15

What common pathologies are associated with the facial nerve?

Answer 15

can be damaged during surgery to the parotid gland/face, can be affected by unknown mechanisms to cause Bell’s palsy