Anatomy - Interior Of The Skull Flashcards
The roof of the cranial cavity is formed by the
Calvaria
Anterior: Frontal
Middle: Parietal
Posterior: Occipital
Attachment of falx cerebri?
What is falx cerebri?
Frontal crest
Falx cerebri is part of the dura mater
Frontal crest terminates at the beginning of the __
Groove for the superior sagittal sinus
which is the intradural venous structure
Parietal bones have grooves from which artery?
Middle meningeal a.
What are granular foveolae?
Small pits and depressions in the calvaria that host arachnoid granulations
The floor of the cranial cavity has 3 large depressions:
Anterior
Middle
Posterior cranial fossa
Anterior cranial fossa
Shallowest and most superior of the 3 depressions on the cranial cavity
Bones: frontal, ethmoid, sphenoid
Features:
Foramen cecum
Cribriform foramina
Anterior and posterior ethmoidal foramina
Foramen cecum
In the frontal bone on the border with the ethmoid
For the passage of nasal emissary veins
Cribriform foramina
In the cribriform plate
For the passage of axons of olfactory nerves
Anterior and posterior ethmoidal foramina
For passage of ethmoid a. and v.
The ethmoid forms a ___, and a ___ for ___.
The ethmoid forms a cribriform plate and a median crest, crista galli, for the attachment of the falx cerebri
Middle cranial fossa
Posterior and inferior to anterior cranial fossa.
Bones: sphenoid, temporal
Foramina of the Middle Cranial Fossa
Carotid canal Optic canal Foramen rotundum Foramen lacerum Foramen ovale Foramen spinosum Superior orbital fissure
ROLS SOC
What is the Sella Turcica?
“Turkish saddle”
centrally located upper part of body of the sphenoid
The limbus of the sphenoid forms the __
Anterior boundary of the chiasmatic sulcus, which is formed as the continuation of the optic canals where the optic nerves cross
What is the sella turcica formed by?
- Tuberculum sellae - elevation at the posterior aspect of chiasmatic sulcus
- Hypophysial fossa - depression housing pituitary gland
- Dorsum sellae - bony ridge projecting superior with posterior clinoid processes as lateral edges
Optic canal
Goes through lesser wing of sphenoid, found in the base
Opens into orbit
For passage of CN II and ophthalmic a.
Superior orbital fissure
Located between greater and lesser wings of sphenoid
Opens into the orbit
For passage of: CN III CN IV CN V1 (ophthalmic n.) CN VI ophthalmic veins
Foramen rotundum
Located posterior to the medial end of he superior orbital fissure
Opens externally into the pterygopalatine fossa
For passage of CN V2 (maxillary n.)
Foramen ovale
Opens inferiorly into the infratemporal fossa
For passage of:
CN V3 (mandibular n.)
Lesser petrosal n.
Accessory meningeal a.
Foramen spinosum
Located posterolateral to f. ovale
Opens into infratemporal fossa
For passage of middle meningeal a.
Blood supply to dura mater?
Middle meningeal a.
Carotid canal
Opens into the cranium posteromedial to f. ovale
For passage of internal carotid a. and nerve plexus
Foramen lacerum
Posterolateral to hypophyseal fossa
Partially filled with cartilage during life
Posterior cranial fossa
Largest, deepest, and most inferior of the 3 cranial fossa
The posterior cranial fossa is limited by___
Anteriorly
Laterally
Inferiorly/posteriorly
A: on the midline by dorsum sellae
L: superior border of the petrous part of temporal bone
I/P: occipital bone
Bony features of posterior cranial fossa
Clivus - -a shallow depression formed by sphenoid body and basilar part of occipital bone. Slopes posteriorly
Internal occipital crest - runs along midline from f. magnum to internal occ. protuberance. Divides posterior cranial fossa into 2 bilateral depressions, the deep cerebellar fossae
Foramen of the posterior cranial fossa
- Foramen magnum
- Jugular foramen
- Internal acoustic meatus
- Hypoglossal canal
- Sinuses
A. Inferior petrosal
B. Sigmoid
C. Transverse
Foramen magnum
Largest foramen in the skull
Within occipital bone
For passage of:
Brainstem/spinal cord with meninges
Vertebral arteries
CN XI (spinal accessory n.)
Jugular foramen
At the base of the petrous ridge of the temporal bone
For passage of: CN IX CN X CN XI sigmoid sinus as it becomes the superior bulb of the internal jugular vein
Internal acoustic meatus
Anterosuperior to jugular foramen within petrous portion
For passage of:
CN VII
CN VIII
Labyrinthine a.
Hypoglossal canal
Anterolaterally within the foramen magnum
For passage of:
CN XII
Location of sinuses found in posterior cranial fossa
- Inferior petrosal sinus
- lateral to clivus - Sigmoid sinus
- between temporal and occipital bones running towards jugular foramen - Transverse sinuses
- extend laterally from internal occipital protuberance to join sigmoid sinuses
