Vasclature of the head, face & brain

Question 1

Label the attached image which shows the vasculature of the scalp.

Answer 1

Question 2

There are two veins of the scalp which present a particular risk for infection from superior cranium to intercranial structures. What are these two veins called?

Answer 2

Supratrochlea v. & Supraorbital v. are valveless veins that drain into the cavernous sinus. This makes them a particular risk for infection from superior cranium to inter.

Question 3

Label the attached diagram of a superior view of the cranium.

Answer 3

Question 4

Label the attached diagram of a lateral view of the cranium.

Answer 4

Question 5

What is the Pterion?

Answer 5

The Pterion is the region where the temporal, frontal, sphenoid and parietal bones join.
It is a point of weakness of the cranium. On the interior surface of the pterion the middle meningeal vessels lie.

Question 6

What artery is likely to be damaged / ruptured in a Pterion fracture?

Answer 6

Middle meningeal a.

This would cause an extradural haematoma; these are expansile and thus a hole in the Pterion region of the skull would be required to minimise compression of surrounding cerebral tissue and to clamp the bleed.

Question 7

Identify the structures in this posterior view of the cranium

Answer 7

Question 8

Identify the structures in this internal view of the floor of the cranium.

Answer 8

Question 9

Fractures in what bone/s will cause CSF to leak through the nose?

Answer 9

Fractures to the frontal bone can see CSF leak through the cribriform plate > into the nasal cavity.

Fractures to the sphenoid bone can see CSF leak into the sphenoid sinus > into the nasal cavity.

Question 10

Fractures in what bone/s may cause CSF to leak into the middle ear / out of the auditory canal in the case of a perforated ear drum?

Answer 10

Fractures to the temporal bone can lead to leaking of CSF into the middle ear / out of the ear.

Question 11

What are the thickest areas of the cranium?

Answer 11

1. Mastoid process,
2. External occipital protuberance,
3. Glabella (frontal bone)

Question 12

What are the layers of the cranium?

Answer 12

Layer 1: Outer table / Lamina externa (thick)
Layer 2: Cancellous bone / Diploe (almost absent in region covered by temporalis muscle - prone to fracture).
Layer 3: Inner table / Lamina interna (thinner)

Question 13

The most common areas of skull fractures include:

Answer 13

The cranium vault: frontal, temporal and parietal bones.
The floor of the cranium: the anterior cranial fossa.

Question 14

Terminology for describing skull fractures includes:
1. Location
2. # Fracture lines
3. Displacement
4. Continuity to exterior
Provide the possible terms for each

Answer 14

Location = vault of skull or base of skull.

of fractures = Linear or comminuted.

Displacement = Depressed or non-displaced.

Continuity to exterior = Simple (closed) or Compound (open).

Question 15

Linear cranial fractures are the most common type of cranial fractures what is the most likely mechanism of injury?

Answer 15

Blunt forced trauma over a relatively wide area of the skull (ie along a flat surface).

Question 16

How does a linear cranial fracture appear in imaging?

Answer 16

Thin line, no depression, may or may not be associated with a suture line.
Significant if the fracture runs through a vascular channel, air sinus, CN foramina or a suture line.

Question 17

What is a diastatic cranial fracture?

Answer 17

A linear cranial fracture observed in infants with unclosed cranial bones.

Question 18

How does a depressed cranial fracture appear in imaging?

Answer 18

Fracture to cranium with effected region compressed in toward the brain tissue.
Can be comminuted as the mechanism of injury are the same.

Question 19

What is the most common mechanism of injury for a depressed fracture?

Answer 19

Blunt forced trauma over a small surface area.

Question 19

What is the most common mechanism of injury for a depressed fracture?

Answer 19

Blunt forced trauma over a small surface area.

Question 20

Why are depressed cranial fractures associated with increased risk of brain injury.

Answer 20

Fracture may damage tissue directly causing contusion / laceration and subsequent seizures and neurological deficits.

Question 21

In imaging what features allow for differentiation between a fracture and a suture line?

Answer 21

1. Width: fractures are greater than 3mm / sutures are less than 2mm wide.
2. Diameter throughout: fractures are wider in the centre and narrower at the ends of the fracture / sutures are the same diameter throughout.
3. Opacification: Fractures are typically darker than sutures.
4. Location: Fractures are common over the parietal and temporal bones / Sutures are located at specific anatomical sites.
5. Direction: Fractures commonly run in straight lines / sutures do not run in straight lines.

Question 22

What is a Pheumocephalus?

Answer 22

Air can enter into the cranial cavity.

Question 23

What is a Subcutaneous emphysema?

Answer 23

Air collects in the subcutaneous tissue.

Question 24

Signs of compound cranial fractures includes:

Answer 24

1. Presence of gas (air) in the cranial cavity.
2. Presence of a foreign body in the cranial cavity.
3. CSF rhinorrhoea (CSF leaking through nasal cavity).
4. CSF otorhoea (CSF leaking through the middle ear) - via eustachian tube or external ear canal in cases of perforated ear drum).

Question 25

Epistaxis means?

Answer 25

Bleeding from the nose. This can be a sign of a compound cranial fracture ONLY if it is mixed with CSF.

Question 26

What nerve runs between the Posterior Cerebral a. and the Superior Cerebella a. near to the level / parallel to the Posterior communicating a.?

Answer 26

The Oculomotor n. CN III

Question 27

Why do infarctions / lesions to the occipital pole and local area result in homonymous hemianopia with macula sparing?

Answer 27

The macular representing regions of the occipital cortex (1-4 in the attached image) receives dual blood supply therefore the macular region is spared.