Skull & Cranial Vault Flashcards
What is the pterion?
What is its clinical significance?
H-shaped suture between the frontal, parietal, sphenoid & temporal bones
Bone here is thin & susceptible to fracture
Anterior division of the middle meningeal artery grooves it, thus a blow to the petrion can rupture the artery - leading to extradural haematoma
What are important cranial sutures?
Coronal - frontal & parietal bones in coronal plane
Sagittal suture - left & right parietal bones
Lamboid - coronal plane, occipital & parietal bones
What are the important parts of the temporal bone?
Squamous - anterior & superior flat part of the bone which articulates with sphenoid & parietal bone
Mastoid process - thick, inferior & posterior projection - full of air cells
Styloid process - thin projection from lower medial border - attachment for structures in oropharynx
Zygomatic process - projects laterally & then anteriorly to articulate with the zygomatic bone to form the zygomatic arch
Petrosus part - inward wedge shaped
What are features of the occipital bone?
Superior & inferior nucal lines
External occipital protuberance - important land mark, i.e. occipitofrontalis attaches here
What are important features of the sphenoid bone?
What separates its greater & lesser wings?
Centrally (within the body) contains the turkish saddle (sella turcica) - where the pituitary gland sits
The greater & lesser wings are separated by the superior orbital fissure
What bones make up the anterior cranial fossa?
What lobe of the brain sits in it?
What foramina are found here?
Frontal bone + lesser wing of sphenoid bone + cribiform plate of ethmoid bone
Ventral side of the frontal lobe
Cribiform plate - formaina for projections of olfactory bulb
Only olfactory foramina
What bones make up the middle cranial fossa?
What lobe of the brain sits in it?
What foramina are found here?
Greater wing & body of sphenoid + Temporal bone (petrous part - forms border with posterior fossa)
Temporal pole
Superior orbital fissure, orbital canal
Foramen rotundum, ovale & spinosum
Foramina for eye structures + trigeminal divisions & MMA
What bones make up the Posterior cranial fossa?
What lobe of the brain sits in it?
What foramina are found here?
Occipital bone (+ part of petrus bone as it forms the border b/w middle & posterior fossa)
Occipital lobe and cerebellum
Foramen magnum (occipital bone) Hypoglossal canal (occipital bone) Jugular foramen (between occipital & petrous) Internal acoustic meatus (petrous part of temporal bone) - DROPS DOWN INTO POSTERIOR FOSSA
What is significant about the petrous part of the temporal bone?
Inward, wedge shaped projection making up part of the middle cranial fossa
Contains internal acoustic meatus
What structure exits through the cribiform plate?
Afferents from olfactory bulb CN 1 (olfactory nerve)
What structure exits through the superior orbital fissure?
CN3 (occulomotor), CN4 (trochlear), CN5 V1 (opthalmic division of trigeminal) & CN6 (abducens)
All NERVES to the eye (muscles) except optic nerve
What structure exits through the optic canal?
CN1 (optic nerve) + opthalmic artery
Nerve + artery to actual EYEBALL
What structure exits through the hypoglossal canal?
CN 12 (hypoglossal)
What structure exits through the jugular foramen?
CN 9 (glossopharyngeal) , 10 (vagus), 11 (Spinal accessory) & internal jugular vein
What structure exits through the foramen magnus?
Spinal cord
CN11 (spinal accessory) ENTRES (exists via jugular foramen)
What structure exits through the internal auditory meatus?
CN VII (facial) ENTRES + CN VIII (vestibulocochlear)
What foramina & canals doesCN VII pass through?
Enters petrousal part of temporal bone at internal acoustic meatus, passes through facial canal, exits through stylomastoid canal
What structure exits through the foramen rotundum, ovale & spinosum?
Rotundum - CN5 V1 (maxillary division)
Ovale - CN5 V2 (mandibular division)
Spinosum - middle meningeal artery
What fossa within which part of a cranial bone does the pituitary gland sit?
Hypophysial fossa - within the salle turcica of the body of the sphenoid bone
Dura Mater
What are their general features?
What potential space do they create?
What can collect in these spaces?
- Touch, fibrous outer meningeal layer
- Has two components - periosteal (adherent to skull) & meningeal (close contact with arachnoid mater & continuous with dura of spinal cord)
- Creates the extradural space (between skull & meningeal dura layer) + subdural space (between menigeal dura & arachnoid mater)
- Extradural - blood from meningeal artery i.e. extradural haematoma
- Subdural - venous blood i.e. subdural haematoma
Arachnoid mater
What are their general features?
What potential space do they create?
What can collect in these spaces?
Middle meningeal layer
- More delicate/fine, fibrous
- Lines the meningeal layer of the dura mater
Subarachnoid space - space between arachnoid mater & pia mater
- Real space as CSF flows through it
Pia mater
What are their general features?
What potential space do they create?
What can collect in these spaces?
Innermost meningeal layer
Envelopes the brain, difficult to separate
Thin and fragile
No space associated with it as it is adherent to the brain tissue
What are dural partitions & their function?
Separation of the periosteal & meningeal layers of dura mater at various points to form inward projections that separate certain structures & form dural venous sinuses
What are 4 important dural partitions?
Falx cerebri
Falx cerebelli
Tentorium cerebelli
Diaphragma sellae
