Anatomy of Scalp in a Nutshell

Anatomy of Scalp

Scalp: A structure that begins at the supraorbital margins (superior aspect of the orbit)

• Includes the eyebrows, forehead, and continues till reaching the level of the occipital protuberance.
• Laterally, it blends with the fascia around the temporalis muscles (temple region).
• 5 layers of the scalp: “SCALP”
  • S: Skin

1. 1. • Has sebaceous and sweat glands, is covered with hair
      • Tightly bound to underlying CT

1. • C: Connective tissue

1. 1. • Dense, tightly affixed to skin
      • Is where we find the nerves and blood vessels supplying the scalp
      • Bands of collagen in the CT cause vessels to remain patent- clinically important as this causes extensive bleeding during scalp lacerations.

1. • A: Aponeurosis

1. 1. • Flat tendinous sheet
      • Run between the frontalis muscle (anterior muscle of facial expression) and the occipitalis muscle (posterior lying)

• • • Galea Aponeurotica: aponeurotic helmet.

• • • All three layers (skin, CT, aponeurosis) are fused together

1. • L: Loose areolar tissue
   • P: Periosteum

1. 1. • Also known as pericranium
      • Periosteum on the internal aspect is the endocranium

• This arrangement of layers makes operations on scalp easy
  • Relevant to surgery for easy manipulation in opening / closing
  • Also relevant to scalping- after making incision, scalp can be pulled away easily due to loose areolar tissue.
• Blood supply to the scalp
  • Branches of the ophthalmic artery (branch of internal carotid coming off in orbit) supplies anterior portion

1. 1. • Supratrochlear artery
      • Supraorbital artery

1. • External carotid branches: supplies posterior portion

1. 1. • Superficial temporal
      • Posterior auricular
      • Occipital artery

• • All of these branches form large anastomotic network. Surgery to scalp repairs well due to great collateral circulation
• Veins: follow the exact same path as the arteries (there is a named vein for each artery as well as a venous anastomosis)
  • Primary venous drainage is via vein by the same name
  • Emissary veins:

1. 1. • Another system (not the primary system) of small veins provide a pathway from the scalp to the dural venous sinuses (go through bone)
      • Function similar to diploic veins in providing this conduit

• • • Blood may go in either direction (no valves), thus infection may find a pathway back / forth from dural venous sinuses to scalp.

• Innervation of the scalp
  • CN V1: First division of trigeminal (ophthalmic)

• • • Supertrochlear nerve (medial
    • Superorbital nerve (lateral)
      1. Goes through superorbital foramen
      2. Both go on to superior aspect of scalp up past vertex

1. • CN V2: zygomaticotemporal

1. 1. • Second division of trigeminal
      • Along the temple

1. • CN V3: auriculotemporal nerve

1. 1. • Third part of trigeminal
      • Supplies temple region

1. • Lesser occipital nerve

1. 1. • From the cervical plexus
      • A ventral ramus combination from C2 + C3

1. • Greater occipital nerve (C2)

1. 1. • Is a dorsal ramus
      • Innervates posterior scalp

1. • Third occipital nerve- is a dorsal ramus
   • Dermatome does not include C1 (has no sensory component).

1. 1. • C2 supplies posterior scalp, back of head (overlaps with C3)
      • C4 supplies back of neck / shoulder (also overlaps with C3)

• • • C3 supplies nearly the same as C2 + C4 plus small area on it’s own in between neck / shoulder

• • • Branches of trigeminal nerve supply face
      1. V1 = forehead / nose
      2. V2 = cheek / upper lip
      3. V3 = chin / lower cheek

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