Revision 3 for 'Scalp'All Revisions
The scalp is the skin and subcutaneous tissue covering the neurocranium.
The scalp is composed of five layers which are easily remember with this mnemonic. From external to internal the layers are:
- Skin: thin, except in the occipital region, contains many sweat and sebaceous glands and hair follicles. It has an abundant arterial supply and good venous and lymphatic drainage.
- Connective tissue: forms the thick, dense, richly vascular- ized subcutaneous layer that is well supplied with cutane- ous nerves.
- Aponeurosis (Galeal or epicranial aponeurosis): the broad, strong, tendinous sheet that covers the calvaria and serves as the attachment for muscle bellies converg- ing from the forehead and occiput (occipitofrontalis muscle) (Fig. 7.15B) and from the temporal bones on each side (temporoparietalis and superior auricular muscles). Collectively, these structures constitute the musculo-aponeurotic epicranius. The frontal belly of the occipitofrontalis pulls the scalp anteriorly, wrinkles the forehead, and elevates the eyebrows; the occipital belly of the occipitofrontalis pulls the scalp posteriorly, smoothing the skin of the forehead. The superior auric- ular muscle (actually a specialized posterior part of the temporoparietalis) elevates the auricle of the external ear. All parts of the epicranius (muscle and aponeurosis) are innervated by the facial nerve.
- , the first three of which are connected intimately and move as a unit
- Loose areolar tissue: a sponge-like layer including poten- tial spaces that may distend with fluid as a result of injury or infection. This layer allows free movement of the scalp proper (the first three layers—skin, connective tissue, and epicranial aponeurosis) over the underlying calvaria.
- Pericranium: a dense layer of connective tissue that forms the external periosteum of the neurocranium. It is firmly attached but can be stripped fairly easily from the crania of living persons, except where the pericranium is con- tinuous with the fibrous tissue in the cranial sutures.
- posterior: superior nuchal lines of the occipital bone
- anterior: supra-orbital margins of the frontal bone
- lateral: zygomas