Blood Supply to the Scalp

Study Notes

The scalp receives blood supply from the external carotid artery, which has three branches: superficial temporal, posterior auricular, and occipital.
The superficial temporal artery supplies the frontal and temporal regions.
The posterior auricular artery supplies the area superiorly and posteriorly to the auricle.
The occipital artery supplies the back of the scalp.
Additionally, the scalp receives supply from two branches of the ophthalmic artery: the supraorbital and supratrochlear arteries.

The venous drainage of the scalp can be divided into superficial and deep components.
The superficial drainage follows the arterial supply, including superficial temporal, occipital, posterior auricular, supraorbital, and supratrochlear veins.
The deep (temporal) region of the skull is drained by the pterygoid venous plexus, which drains into the maxillary vein.
The veins of the scalp connect to the diploic veins of the skull via valveless emissary veins.

The part of the scalp that is anterior to the auricles is drained to the parotid, submandibular, and deep cervical lymph nodes.
The posterior part of the scalp is drained to the posterior auricular (mastoid) and occipital lymph nodes.

The scalp receives cutaneous innervation from branches of the trigeminal nerve or the cervical nerve roots.
The trigeminal nerve supplies the scalp through the following branches:
- Supratrochlear nerve: supplies the anteromedial forehead.
- Supraorbital nerve: supplies a large portion of the scalp between the anterolateral forehead and the vertex.
- Zygomaticotemporal nerve: supplies the temple.
- Auriculotemporal nerve: supplies the skin anterosuperior to the auricle.

Facial clefts can result in facial disfigurement, difficulties hearing, speaking, eating, swallowing, and breathing.
Cleft lip occurs when there is a partial or complete lack of fusion of the maxillary prominence with the medial nasal prominence on one or both sides.
Cleft palate can be divided into primary and secondary depending on whether they are in front of or behind the incisive foramen respectively.

The cervical nerves also supply the scalp, including:
- Lesser occipital nerve: supplies the skin posterior to the ear.
- Greater occipital nerve: supplies the skin of the occipital region.
- Great auricular nerve: supplies the skin posterior to the ear and over the angle of the mandible.
- Third occipital nerve: supplies the skin of the inferior occipital region.

The connective tissue layer of the scalp is considered the "danger area" because it contains valveless emissary veins, which are a potential pathway for the spread of infection from the scalp to the intracranial space.
Deep lacerations to the scalp tend to bleed profusely due to the pull of the occipitofrontalis muscle, the adherence of blood vessels to dense connective tissue, and the many anastomoses that contribute to profuse bleeding.
Cephalohematoma is a collection of blood that occurs between the neonate's pericranium and calvaria, usually over one parietal bone, due to a rupture of multiple minute periosteal arteries.
The scalp is one of the most common sites for sebaceous cysts due to the presence of numerous sebaceous glands.

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