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Scalp, From Wikipedia, the free encyclopedia

The scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly. It is usually described as having five layers.

• S: The skin on the head from which head hair grows. It is richly supplied with blood vessels and can be subject to such conditions as dandruff and cutis verticis gyrata.
• C: Connective tissue. a thin layer of fat and fibrous tissue lies beneath the skin
• A: The aponeurosis (or galea aponeurotica) is the next layer. It is a tough layer of dense fibrous tissue which runs from the frontalis muscle anteriorly to the occipitalis posteriorly
• L: The loose connective tissue layer provides an easy plane of separation between the upper three layers and the pericranium. In the barbaric practice of scalping the scalp is torn off through this layer. It also provides a plane of access in craniofacial surgery and neurosurgery.
• P: The pericranium is the periosteum of the skull bones and provides nutrition to the bone and the capacity for repair. It may be lifted from the bone to allow removal of bone windows (craniotomy).

The blood supply of the scalp is via four pairs of arteries, two from the external carotid and two from the internal carotid:

• the supratrochlea artery to the midline forehead
• the supraorbital artery to the lateral forehead and scalp as far up as the vertex
• the superficial temporal artery which gives frontal and parietal branches to supply much of the scalp
• the occipital artery which runs from posteriorly to supply much of the back of the scalp.

The scalp is innervated by the:

• Supratrochlea nerve and the supraorbital nerve from the ophthalmic division of the trigeminal nerve
• Greater occipital nerve (C2) posteriorly up to the vertex
• Lesser occipital nerve (C3) behind the ear.

The scalp plays an important role in the aesthetics of the face. Androgenic alopecia, or male pattern hair loss, is a common cause of concern to men. It may be treated by medication (eg finasteride) or hair transplantation with variable success. If the scalp is heavy and loose, a common change with aging, the forehead may be low, heave and deeply lined. The brow lift procedure aims to address these concerns.

The scalp is a common site for the development of tumours including:

• epidermoid cyst
• pilar cyst
• actinic keratosis and squamous cell carcinoma
• basal cell carcinoma
• merkel cell tumours