Scalp

Question 1

What are the boundaries of the scalp?

Answer 1

• Anterior: Supercilliary arches
• Posterior: External occipital protuberance and superior nuchal line
• Lateral: Zygomatic arches

Question 2

What are the layers of the scalp?

Answer 2

1. Skin
2. Connective tissue (dense)
3. Aponeurosis
4. Loose connective tissue
5. Pericranium

SCALP

Question 3

What is the structure of the skin layer of the scalp?

Answer 3

• Similar to skin in other areas of the body
• Contains large amounts of hair follicles and sebaceous glands

Question 4

What is the structure of the connective tissue (dense) layer of the scalp?

Answer 4

• Contains all the blood vessels and nerves that supply the scalp
• Tough and is tightly anchored to the skin above and the aponeurosis below (does not allow movement between 2 layers)

Question 5

What is the structure of the aponeurosis layer of the scalp?

Answer 5

• Contains the occipitofrontalis muscle that has anterior (frontal) and posterior (occipital) bellies connected by aponeurosis

Question 6

What are the functions and innervation of the occipitofrontalis?

Answer 6

• Functions of the occipitofrontalis include:
  1. Movement of the scalp
  2. Wrinkling of the forehead
  3. Raising of the eyebrows
• Innervation of the occipitofrontalis:
  1. Frontal belly: Temporal branches of facial nerve [VII]
  2. Occipital belly: Posteriorauricular branches of facial nerve [VII]

Question 7

What is the structure of the loose connective tissue layer of the scalp?

Answer 7

• Superficial to the pericranium and deep to the aponeurosis (both of which it is attached to)
• Loosest layer of the scalp and facilitates all movements of scalp over the skull

Question 8

What is the structure of the pericranium layer of the scalp?

Answer 8

• Forms the periosteum of the calvaria
• Removable apart from at sutures where it is continuous with the periosteum of the inner surface of calvaria

Question 9

What is the clinical significance of the loose connective tissue layer of the scalp?

Answer 9

• Tearing of the scalp occurs in this layer
• Infections most easily spread through the scalp in this layer

Question 10

What is the blood supply of the scalp?

Answer 10

• Anterior & superior aspects (up to vertex) of the scalp supplied by branches of the opthalmic artery (from ICA):
  1. Supratrochlear artery
  2. Supra-orbital artery
• Lateral & posterior aspects of the scalp supplied by branches of the ECA:
  1. Posterior auricular artery: Supplies area posterior to pinna and pinna itself
  2. Occipital artery: Supplies posterior aspects of scalp
  3. Superficial temporal artery: Supplies lateral aspects of scalp

Question 11

What is the nature of anastomoses in the scalp?

Answer 11

• Arteries supplying the scalp freely anastomose throughout the whole of the scalp
• Anastomoses are most numerous on the lateral aspects so lateral cuts result in most bleeding

Question 12

What is the nature of venous drainage in the scalp?

Answer 12

Follows arterial supply

Question 13

What is the innervation of the scalp?

Answer 13

Anterior:

• Supratrochlear nerve (branch of Va)
• Supra-orbital nerve (branch of Va)
• Zygomaticotemporal nerve (branch of Vb)

Lateral:

• Lesser occipital nerve (posterior ramus of C2)
• Auriculotemporal nerve (branch of Vc)

Posterior:

• Greater occipital nerve (posterior ramus of C2)
• Third occipital nerve (posterior ramus of C3)
• Greater auricular nerve (anteiror rami of C2/3)
• Lesser occipital nerve (anterior ramus of C2)

Question 14

What is the general pattern of innervation of the scalp?

Answer 14

• Anterior aspects of the scalp innervated by branches of the trigeminal nerve [V]
• Posterior aspects of the scalp innervated by branches of C2,3 spinal roots