Anatomy of the Scalp Layers

Study Notes

Skin: Thick, hair-bearing, contains many sebaceous glands (sebaceous cysts can form)
Connective tissue: Lies beneath the skin, fibrous and fatty, connects the skin to the aponeurosis of the occipitofrontalis muscle, contains numerous arteries and veins.
- Arteries: Branches of external and internal carotid arteries, anastomose freely.
Aponeurosis (Epicranial): Thin tendinous sheet uniting the occipital and frontal bellies of the occipitofrontalis muscle, attaches to the temporal fascia laterally.
- Subaponeurotic space: Potential space beneath the aponeurosis, limited by origins of the occipitofrontalis muscle, extends laterally to the attachment of the aponeurosis to the temporal fascia.
Loose Areolar Tissue: Occupies the subaponeurotic space, connects the aponeurosis to the periosteum of the skull, contains small arteries and important emissary veins.
- Emissary Veins: Valveless, connect superficial scalp veins with diploic veins of the skull bones and intracranial sinuses, direction of blood flow determined by venous pressure outside and inside the skull, can allow passage of infection (Dangerous area of the scalp).
Pericranium: Periosteum covering the outer surface of the skull, continuous with the endosteum on the inner surface.
- The first 3 layers (skin, connective tissue, aponeurosis) move together as a unit.

Origin: 4 bellies (2 occipital and 2 frontal), connected by an aponeurosis (insertion)
- Occipital bellies: Highest nuchal line on the occipital bone
- Frontal bellies: Skin and superficial fascia of the eyebrow
Insertion: Aponeurosis
Nerve supply:
- Occipital belly: Posterior auricular branch of the facial nerve
- Frontal belly: Temporal branch of the facial nerve
Action: Movement of the first 3 layers of the scalp forward or backward, the loose connective tissue allows for movement of the aponeurosis on the pericranium. The frontal bellies raise eyebrows in surprise, horror, or frowning.

Supratrochlear nerve: Branch of the ophthalmic division of the trigeminal nerve, passes backward close to the median plane, reaches the vertex of the skull.
Supraorbital nerve: Branch of the ophthalmic division of the trigeminal nerve, supplies scalp as far backward as the vertex.
Zygomaticotemporal nerve: Branch of the maxillary division of the trigeminal nerve, supplies scalp over the temple.
Auriculotemporal nerve: Branch of the mandibular division of the trigeminal nerve, ascends over the side of the head from in front of the auricle, terminal branches supply skin over the temporal region.
Lesser occipital nerve: Branch of the cervical plexus (C2), supplies scalp over the lateral part of the occipital region and medial side of the auricle.
Greater occipital nerve: Branch of the posterior ramus of the 2nd cervical nerve, ascends over the back of the scalp, supplies skin as far as the vertex of the scalp.

Supratrochlear artery
Supraorbital artery: Branches of the ophthalmic artery, ascend with the supratrochlear and supraorbital nerves.
Superficial temporal artery: Smaller terminal branch of the external carotid artery, ascends in front of the auricle with the auriculotemporal nerve.
Posterior auricular artery: Branch of the external carotid artery, ascends behind the auricle.
Occipital artery: Branch of the external carotid artery, ascends from the apex of the posterior triangle, accompanies the greater occipital nerve, supplies skin over the back of the scalp as high as the vertex.

Supratrochlear vein
Supraorbital vein: Unite at the medial margin of the orbit to form the facial vein.
Superficial temporal vein: Unites with the maxillary vein in the parotid gland to form the retromandibular vein.
Posterior auricular vein: Unites with the posterior division of the retromandibular vein below the parotid gland to form the external jugular vein.
Occipital vein: Drains into the suboccipital venous plexus (lies beneath the floor of the upper part of the posterior triangle) or into the internal jugular vein. The suboccipital venous plexus drains into the vertebral veins.

Lymph vessels from:
- Anterior part of the scalp and forehead drain into: Submandibular nodes
- Lateral part of the scalp above the ear drain into: Superficial parotid (preauricular) nodes
- Part of the scalp above and behind the ear drains into: Mastoid nodes
- Back of the scalp drains into: Occipital nodes