1. Anatomy of scalp

Question 1

name the 5 layers of the scalp

Answer 1

1. skin 2. dense connective tissue 3. epicranial aponeurosis (tendon-like structure connecting occipitalis and frontalis) 4. loose areolar connective tissue 5. periosteum (outer table of cranium)

Question 2

which scalp layer contains most of the vasculature of the scalp

Answer 2

dense connective tissue

Question 3

why do scalp lacerations tend to bleed profusely

Answer 3

1. vessels in dense CT layer highly adherent to CT so unable to fully vasoconstrict 2. many anastamoses 3. pull of occipitofrontalis muscle in deep lacerations cuting across aponeurosis can cause wound gaping

Question 4

why is bleeding in scalp lacerations predominantly arterial

Answer 4

1. extremely low venous pressure in erect position 2. very rich blood supply from ECA branches

Question 5

why can head trauma cause a well circumscribed lump to appear

Answer 5

bleeding in the dense CT (mainly arterial) is limited by denseness of the CT in this layer which prevents it tracking far

Question 6

why can some cranial trauma cause bruising around the eye

Answer 6

if trauma affects the loose CT layer containing the emissary veins (that connect superficial scalp layer to deep dural venous sinuses), blood can track through this layer, under the frontalis muscle which inserts into obicularis occuli, allow blood to pool around eyes

Question 7

how can infections deep within scalp spread intracranially

Answer 7

via emissary veins running through loose CT to intracranial venous system

Question 8

what is a cephalohaematoma and does it pose any risk to infant brian

Answer 8

• traumatic subperiosteal haematoma - between periosteum (outer table) and bone - limited by suture lines where outer periosteum crosses bone to join inner periosteum - no risk to brain as bleed separated by bone

Question 9

describe the arterial supply to the scalp

Answer 9

3 branches of ECA: - superficial temporal - posterior auricular - occipital 2 branches of opthalmic a. (branch of ICA): - supraorbital - supratrochlear

Question 10

describe the venous drainage to the scalp

Answer 10

• superficial drainage following scalp arteries - valveless emissary vein drainage into intracranial venous sinuses

Question 11

describe the cutaneous innervation of the scalp

Answer 11

1. anterior to vertex and ears - branches of trigeminal n. (CN V):
   - anterior scalp: supratrochlear and supraorbital nn. (branches of CN Va)
   - lateral scalp: zygomaticotemporal n. (branch of CN Vb) and auriculotemporal n. (branch of CN Vc)
2. posterior to vertex and ears - cervical nn. (anterior rami C2-3): greater and lesser occipital nn.