Anatomy of the Scalp

Scalp Anatomy

• The scalp consists of five layers: skin, connective tissue, epicranial aponeurosis, loose areolar tissue, and periosteum.
• The skin layer is thick and contains sweat glands, sebaceous glands, and hair follicles.
• The connective tissue layer contains dense collagen fibers with blood vessels and nerves.

Muscles of the Scalp

• The main muscle of the scalp is the occipitofrontalis muscle, which consists of two pairs of bellies (occipital and frontal).
• The occipital bellies are shorter and narrower than the frontal bellies and are widely separated by the aponeurosis.
• The frontal bellies arise from the aponeurosis and are inserted into the skin of the eyebrows and nose, with no bony attachment.

Nerve Supply of the Scalp

• The nerve supply of the scalp is provided by branches of the trigeminal nerve and the upper three cervical nerves.
• Anterior to the pinna of the ear, the scalp is supplied by branches of the trigeminal nerve, including:
  • Supraorbital nerve, which arises from the frontal nerve of the ophthalmic division of the trigeminal nerve.
  • Supratrochlear nerve, which arises from the frontal nerve and emerges at the supra-orbital margin.
  • Zygomaticotemporal nerve, which supplies the skin of the anterior part of the temple.
  • Auriculotemporal nerve, which emerges from the upper end of the parotid gland close to the auricle at the root of the zygomatic arch.
• Posterior to the pinna of the ear, the scalp is supplied by the upper three cervical nerves, including:
  • Greater occipital nerve, which arises from C2 dorsal rami and enters the scalp with the occipital artery.
  • Third occipital nerve, which arises from C3 dorsal rami and supplies the nape of the neck.
  • Lesser occipital nerve, which arises from C2 ventral rami and sometimes C3, and supplies the scalp behind and above the ear.

Blood Supply of the Scalp

• The scalp is richly supplied by blood from the external and internal carotid arteries.
• Branches of the external carotid artery include:
  • Superficial temporal artery, which begins behind the neck of the mandible deep to the parotid gland.
  • Posterior auricular artery, which arises deep to the parotid gland and curves postero-superiorly below and behind the root of the auricle.
  • Occipital artery, which arises deep to the angle of the mandible and passes upward backward through the occipital groove of the mastoid bone.
• Branches of the internal carotid artery include:
  • Supraorbital artery, which arises from the ophthalmic artery of the internal carotid artery.
  • Supratrochlear artery, which passes through the upper medial angle of the orbit accompanied by the supratrochlear nerve.

Veins of the Scalp

• Supratrochlear and supraorbital veins unite at the medial angle of the eye to form the facial vein.
• Retromandibular vein forms by the union of superficial temporal vein and maxillary vein.
• Posterior auricular vein unites with the posterior branch of retromandibular vein to form the external jugular vein on the surface of sternocleidomastoid muscle.
• Occipital vein runs with the occipital artery in the scalp and drains to the suboccipital plexus of veins in the suboccipital triangle.
• Emissary veins pierce the skull and connect this system of veins with the venous sinuses inside the skull.