The Scalp

Question 1

what does the scalp refer to?

Answer 1

layers of skin and subcutaneous tissue that cover the bones of cranial vault

Question 2

what are the layers of the scalp?

Answer 2

Skin
dense Ct
epicranial Aponeurosis
Loose areolar ct
Periosteum

Question 3

which layers are tightly bound together?

Answer 3

first 3 - move together as a unit

skin, dense Ct, epicranial Aponeurosis

Question 4

what does the skin contain?

Answer 4

numerous hair follicles and sebaceous glands - site for sebaceous cysts

Question 5

what does the dense Ct do?

Answer 5

connects the skin to the epicranial aponeurosis

richly vascularised and inervated

Question 6

why can the scalp be a site of profuse bleeding?

Answer 6

the blood vessels within the dense Ct are high adherent to the Ct
this renders them unable to fully constrict if lacerated

Question 7

what is the epicranial aponeurosis?

Answer 7

a thin, tendon-like structure that connects the occipitalis and frontalis muscle

Question 8

describe the loose areolar ct

Answer 8

a thin ct layer that separates the periosteum of the skull form the epicranial aponeurosis

Question 9

what does the loose areolar ct consist of?

Answer 9

numerous blood vessels - including emissary veins which connect the veins of the scalp to the diploic veins and intracranial venous sinuses

Question 10

describe the periosteum

Answer 10

outer layer of skull bones

Question 11

what does the periosteum become continuous with? where?

Answer 11

becomes continuous with the endosteum at the suture lines

Question 12

Clinical: scalp infections, where is the danger area of the scalp?

Answer 12

loose CT

Question 13

clinical: why is the loose CT the danger area of the scalp?

Answer 13

because pus and blood spreads easily within it, and can pass into the cranial cavity along the EMISSARY veins
therefore, infection can spread from scalp to meninges - can lead to meningitis

Question 14

where does the scalp receives its rich blood supply via?

Answer 14

external carotid artery and opthalmic artery

Question 15

what is the opthalmic artery a branch of?

Answer 15

internal carotid

Question 16

how many branches of the external carotid artery are involved? what are they?

Answer 16

3
superficial temporal
posterior auricular
occipital

Question 17

what is the mnemonic for remember the branches of the external carotid artery?

Answer 17

some anatomists like freaking out poor medical students

Question 18

what are the all the branches of the external carotid artery?

Answer 18

S: superior thyroid artery
A: ascending pharyngeal artery
L: lingual artery
F: facial artery
O: occipital artery
P: posterior auricular artery
M: maxillary artery
S: superficial temporal artery

Question 19

what does the superficial temporal artery supply?

Answer 19

frontal and temporal regions

Question 20

what does the posterior auricular artery supply?

Answer 20

area superiorly and posteriorly to the auricle

Question 21

what does the occipital artery supply?

Answer 21

back of the scalp

Question 22

anterior and superiorly, where else does the scalp receive blood supply from?

Answer 22

2 branches of the opthalmic artery:
supraorbital artery
supratrochlear artery

Question 23

how is the venous drainage of the scalp divided?

Answer 23

into superficial and deep components

Question 24

what does the superficial venous drainage follow?

Answer 24

the arteries: (SOP,SS)
superficial temporal
occipital
posterior auricular
supraorbital 
supratrochlear

Question 25

what is the deep region of the skull drained by?

Answer 25

deep (temporal) region

drained by pterygoid venous plexus

Question 26

what does the pterygoid venous plexus drain to?

Answer 26

maxillary vein

Question 27

where is the pterygoid venous plexus situated?

Answer 27

between the temporalis and lateral pterygoid muscles

Question 28

what is the innervation of the scalp?

Answer 28

cutaneous innervation from 6 main nerves

arise from trigeminal or cervical nerves

Question 29

what are the branches of the trigeminal nerve which innervates the scalp?

Answer 29

supratrochlear nerve
supraorbital nerve
zygomaticotemporal nerve
auriculotemporal nerve

Question 30

what are the branches of the cervical nerve which innervates the scalp?

Answer 30

lesser occipital nerve

greater occipital nerve

Question 31

what are main branches of the trigeminal nerve?

Answer 31

tri = 3 (OMM)
ophthalmic nerve (V1)
maxillary nerve (V2) 
mandibular nerve (V3)
(all converge on the trigeminal ganglion)

Question 32

what is the supratrochlear nerve (trigeminal) a branch of? supplying where?

Answer 32

branch of opthalmic nerve (V1)

supplies anteromedial forehead

Question 33

what is the supraorbital nerve (trigeminal) a branch of? supplying where?

Answer 33

branch of opthalmic nerve (V1)

supplies large portion of scalp between anterolateral forehead and vertex

Question 34

what is the zygomaticotemporal nerve (trigeminal) a branch of? supplying where?

Answer 34

branch of maxillary nerve (V2)

supplies temple

Question 35

what is the auriculotemporal nerve (trigeminal) a branch of? supplying where?

Answer 35

branch of mandibular nerve (V3)

supplies skin anterosuperior to the auricle

Question 36

what is the lesser occipital nerve (cranial) a branch of? supplying where?

Answer 36

branch of anterior rami of C2 & C3

supplies behind the ear

Question 37

what is the greater occipital nerve (cranial) a branch of? supplying where?

Answer 37

branch of anterior rami of C2 & C3

supplies posterior scalp up to vertex (top)

Question 38

clinical: why do lacerations to the scalp bleed profusely?

Answer 38

1. pull of occipitofrontalis muscle prevents the closure of the bleeding vessel and surrounding skin
2. blood vessels to the scalp are adhered to dense CT, preventing vasoconstriction that normally occurs in damage response
3. blood supply to the scalp is made up of many anastomoses - contribute to profuse bleeding

Question 39

what can loss of blood supply to scalp lead to? why?

Answer 39

bone necrosis

as most of blood supply to skull comes from middle meningeal artery