Skull

Question 1

The skull base forms …

Answer 1

the floor of the cranial cavity, separates the brain from the other facial structures, its a complex anatomical region

Question 2

The 3 parts of the skull base are …

Answer 2

Endocranial (inner) skull base, Skull Base Foramina, Extracranial (outer) skull base

Question 3

Describe the Endocranial (inner) skull base

Answer 3

the inner surface of the skull, consists of the cranial cavity on which the brain rests

Question 4

The 4 types of bone forming the skull base are …

Answer 4

Frontal bone, Sphenoid bone, Temporal bone, Occipital bone

Question 5

Anatomically, the inner surface of the skull base is formed by …

Answer 5

The anterior cranial fossa, middle cranial fossa, posterior cranial fossa

Question 6

Describe the anterior cranial fossa - limits - 2 points

Answer 6

it’s limited anteriorly by frontal bone & by the posterior wall of the frontal sinus, limited posteriorly by the margin of the lesser wing of sphenoid bone

Question 7

What is the anterior cranial fossa formed by

Answer 7

ethmoid bone, sphenoid bone, frontal bone

Question 8

Describe what the lateral part of the anterior cranial fossa forms and what the median (central) part of the anterior cranial fossa is formed by

Answer 8

lateral part = form the roof of the orbits

median (central) part = formed by crista galli, the cribriform plate of the ethmoid plane and the sphenoid bone

Question 9

Describe the middle cranial fossa - formed by, limits - 3 points

Answer 9

formed by sphenoid and temporal bones, limited anteriorly by the lesser wings of the sphenoid bones, limited posteriorly by petrous bones

Question 10

Describe the posterior cranial fossa - formed by, limits - 3 points

Answer 10

formed by occipital bones, limited anteriorly by posterior walls of petrous bones, limited posteriorly by grooves of transverse sinuses

Question 11

Describe skull base foramina - 2 points

Answer 11

these are the several foramina which are in the bones of the skull base, nerves/arteries/veins pass through them

Question 12

Skull Base Foramina in the Ethmoid Bone

Answer 12

olfactory foramina

Question 13

Skull Base Foramina in Sphenoid Bone

Answer 13

optic canal, superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum, foramen lacerum

Question 14

Skull Base Foramina in Temporal Bone

Answer 14

internal acoustic meatus, jugular foramen

Question 15

Skull Base Foramina in Occipital Bone

Answer 15

hypoglossal canal, foramen magnum

Question 16

Describe the what forms the anterior part of the extracranial skull base

Answer 16

Zygomatic bone, Maxillary bone, Palatine bones

Question 17

Describe the remainder of what forms the extracranial skull base

Answer 17

Occipital bones, temporal bones, sphenoid bones

Question 18

Describe skull base fractures etc - 5 points

Answer 18

skull base fractures are of high importance in neurotrauma, often associated with cranial vault, mid face fractures occur in head injuries and are often related to brain injuries, involvement of nerves passing through a foramen in a respective region should always be considered, CT = gold standard for detecting these fractures

Question 19

What are the %’s of fractures which have occurred in various places

Answer 19

70% occur in anterior fossa
20% occur in the middle central skull base
5% occur in the middle or posterior fossa

Question 20

Clinical Signs - Battle’s Sign

Answer 20

bruising over the mastoid sinus (just behind auricle), delayed physical finding associated with base of skull fractures

Question 21

Clinical Signs - Hemotympanum =

Answer 21

blood behind ear drum, “racoon eyes” (periorbital bruising), other delayed findings

Question 22

Examples of what you should look for when keeping general close observations to ensure no late sequela

Answer 22

Delayed CSF leak - most relevant clinical sign, neurological symptoms - if deterioration then surgery may be considered

Question 23

monitoring must include … - 2 points

Answer 23

close clinical observation with regular neurological checks, re-scan

Question 24

Describe CSF leak

Answer 24

where cerebrospinal fluid leaks through the mouth/nose due to a tear in dura mater related to a traumatic brain injury, requires surgical intervention

Question 25

Surgical approaches to remove tumours from skull

Answer 25

range from traditional neurosurgery to minimally invasive endonasal/endoscopic surgery