Anatomy: Scalp Extension Layers

What is the most posterior boundary of the scalp extension?

Which layer of the scalp contains the nerves, vessels, and lymphatics?

Why is bleeding from the scalp profuse and needs compression to stop?

What is the function of the epicranial aponeurosis layer of the scalp?

Which muscle is found within the epicranial aponeurosis layer of the scalp?

What is the function of the aponeurosis in relation to the eyebrows?

Which nerve supplies the aponeurosis?

What is the clinical significance of cutting the aponeurosis in a deep scalp wound?

What is the clinical significance of a subperiosteal hemorrhage (cephalic hematoma)?

Which layer of the scalp is most dangerous for hematoma formation, resulting in a "black eye"?

Scalp Extension and Layers

Scalp extension: from the eyebrows (supra orbital margin) to the highest nuchal line posteriorly and laterally to the superior temporal line
Five layers of the scalp: skin, connective tissue, aponeurosis, loose areolar connective tissue, and periosteum

Skin

Hairy and full of sebaceous glands
Most common site of sebaceous cysts

Connective Tissue

Formed of compact, dense CT fibers
Contains many septa that connect this layer with the layers above and below
Contains nerve, vessels, and lymphatics of the scalp (neurovascular plane)
Bleeding from the scalp is profuse and needs compression to stop due to CT septa attached to the wall of blood vessels and rich vascularity

Aponeurosis

Epicranial Aponeurosis
Only layer with bony attachment to limit scalp movement
Contains the muscle "Occipito-Frontalis" with four bellies:
- 2 Occipital Bellies (origin: highest nuchal line, insertion: the aponeurosis)
- 2 Frontal Bellies (extension: from the forehead, near the parotid gland, called muscles of expression)
Clinical Anatomy: cutting the aponeurosis in any deep wound of the scalp will lead to wound gapping, which requires sutures due to traction of the aponeurosis

Loose Areolar Connective Tissue

Contains loose CT elements continuous anteriorly with connective tissue of the upper eyelids
Most dangerous: hematoma in this layer will cause "Black Eye"

Periosteum

Pericranium, confined to each bone
Clinical Anatomy: subperiosteal hemorrhage (Cephale hematoma) takes the shape of the underlying bone

Learn about the layers of the scalp extension, including the skin layer with sebaceous glands and connective tissue forming septa. Explore clinical anatomy insights like common sebaceous cyst sites.