Skull Flashcards
The skull base forms …
the floor of the cranial cavity, separates the brain from the other facial structures, its a complex anatomical region
The 3 parts of the skull base are …
Endocranial (inner) skull base, Skull Base Foramina, Extracranial (outer) skull base
Describe the Endocranial (inner) skull base
the inner surface of the skull, consists of the cranial cavity on which the brain rests
The 4 types of bone forming the skull base are …
Frontal bone, Sphenoid bone, Temporal bone, Occipital bone
Anatomically, the inner surface of the skull base is formed by …
The anterior cranial fossa, middle cranial fossa, posterior cranial fossa
Describe the anterior cranial fossa - limits - 2 points
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
What is the anterior cranial fossa formed by
ethmoid bone, sphenoid bone, frontal bone
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
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
Describe the middle cranial fossa - formed by, limits - 3 points
formed by sphenoid and temporal bones, limited anteriorly by the lesser wings of the sphenoid bones, limited posteriorly by petrous bones
Describe the posterior cranial fossa - formed by, limits - 3 points
formed by occipital bones, limited anteriorly by posterior walls of petrous bones, limited posteriorly by grooves of transverse sinuses
Describe skull base foramina - 2 points
these are the several foramina which are in the bones of the skull base, nerves/arteries/veins pass through them
Skull Base Foramina in the Ethmoid Bone
olfactory foramina
Skull Base Foramina in Sphenoid Bone
optic canal, superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum, foramen lacerum
Skull Base Foramina in Temporal Bone
internal acoustic meatus, jugular foramen
Skull Base Foramina in Occipital Bone
hypoglossal canal, foramen magnum
Describe the what forms the anterior part of the extracranial skull base
Zygomatic bone, Maxillary bone, Palatine bones
Describe the remainder of what forms the extracranial skull base
Occipital bones, temporal bones, sphenoid bones
Describe skull base fractures etc - 5 points
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
What are the %’s of fractures which have occurred in various places
70% occur in anterior fossa
20% occur in the middle central skull base
5% occur in the middle or posterior fossa
Clinical Signs - Battle’s Sign
bruising over the mastoid sinus (just behind auricle), delayed physical finding associated with base of skull fractures
Clinical Signs - Hemotympanum =
blood behind ear drum, “racoon eyes” (periorbital bruising), other delayed findings
Examples of what you should look for when keeping general close observations to ensure no late sequela
Delayed CSF leak - most relevant clinical sign, neurological symptoms - if deterioration then surgery may be considered
monitoring must include … - 2 points
close clinical observation with regular neurological checks, re-scan
Describe CSF leak
where cerebrospinal fluid leaks through the mouth/nose due to a tear in dura mater related to a traumatic brain injury, requires surgical intervention
