What are the five layers of the scalp?

The scalp has five layers, remembered by the mnemonic SCALP: Skin (thick and hairy), Connective tissue (dense layer with vessels and nerves), Aponeurosis (epicranial aponeurosis from the occipitofrontalis muscle), Loose areolar tissue (allows mobility and contains emissary veins), and Pericranium (periosteum of the skull bones).

How is the scalp innervated?

Sensory innervation is divided: in front of the auricle, it's from the trigeminal nerve (e.g., supratrochlear, supraorbital); behind the auricle, it's from spinal nerves C2–C3 (e.g., greater occipital). Motor innervation to the occipitofrontalis muscle comes from the facial nerve: frontal belly by the temporal branch, occipital belly by the posterior auricular branch.

What arteries supply blood to the scalp?

The scalp has a rich arterial supply from both internal and external carotid arteries. In front of the auricle, arteries include the supratrochlear and supraorbital (from the ophthalmic artery) and the superficial temporal (from the external carotid). Behind the auricle, it's supplied by the posterior auricular and occipital arteries (from the external carotid).

Why is the loose areolar tissue layer considered dangerous?

The loose areolar tissue is called the dangerous layer because infections here can spread to intracranial dural venous sinuses via emissary veins, potentially causing serious complications like meningitis or brain abscesses.

What is the difference between caput succedaneum and cephalhematoma?

Caput succedaneum is subcutaneous edema over the scalp at birth that crosses suture lines, while cephalhematoma is a subperiosteal blood collection confined by sutures, often appearing after birth.

How does the occipitofrontalis muscle function?

The occipitofrontalis muscle moves the scalp and is involved in facial expressions. Its actions include raising the eyebrows (as in surprise) and creating forehead wrinkles (as in fright). It consists of frontal and occipital bellies connected by the epicranial aponeurosis.

How is a scalp hemorrhage typically controlled?

Scalp hemorrhage is controlled by applying pressure around the ears and eyebrows, which compresses the arteries supplying the scalp, such as the superficial temporal and occipital arteries, to reduce bleeding.

What is the extent of the scalp anatomically?

The scalp covers the vault of the skull, extending anteriorly to the eyebrows (superciliary arches), posteriorly to the superior nuchal lines, and laterally to the superior temporal lines (some sources include up to the zygomatic arches).

Scalp Anatomy – SCALP Layers, Vessels & Nerves

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