Detailed Exploration of the Skull Flashcards
Orbital plates of frontal bone
Ant Cranial Fossa
Convex elevations to either side of cribriform plates.
- Form roof of bony orbit below
Crista galli of ethmoid bone
Ant Cranial Fossa
projects upward in midline. Also provides attachment for falx cerebri
Cribriform plate
Ant Fossa
Ethmoid bone, perforated areas on either side of crista Galli.
- Small perforations communicate with roof of nasal cavity below and transmit olfactory n (CNI)
Lesser wing of sphenoid
Posterior aspect of anterior cranial fossa
Anterior clinic processes
Middle cranial fossa
Extend posteriorly from lesser wing of sphenoid bone and provide attachments for dura
Petrous portion of temporal bone
SP
Sella turcica of sphenoid bone
“Turkish saddle” (within circle)
Tuberculum sellae
front of “saddle”
Hypophyseal (pituitary) fossa
Concavity that resembles rider’s seat in saddle and accommodates pituitary gland
Dorsum sellae
Back of “saddle”
Posterior clinoid processes
Extend posteriorly from either end of dorsum sellae and provide dural attachments
Optic canals
Pass forward to orbits and transmit optic nerves and ophthalmic arteries
Optic canals
Pass forward to orbits and transmit optic nerves and ophthalmic arteries
Superior orbital fissure
Inverted, comma-shaped gap between greater and lesser wings of sphenoid bone found under cover of lesser wing that communicates w/ orbit anteriorly and through which pass ophthalmic veins and CN 3, 4, 6, V1
Foramen rotundum
Round opening posterior to inferior orbital fissure that transmits maxillary nerve (CN V2)
Foramen ovale
oval-shaped opening posterior to foramen rotundum, that leads to infra temporal region below skull and transmits mandibular nerve (CN V3)
Foramen spinosum
Immediately behind and lateral to foramen oval; small round opening leading from infratemporal region below that transmits middle meningeal artery
Foramen lacerum
Opening on either side of hypophyseal fossa for entrance of ICA
Carotid canal
Junction of greater wing of sphenoid and petrous portion of temporal bone
Hiatus for greater petrosal n
Exits from anterior slope of petrous temporal ridge (groove can be followed to foramen lacer)
H
Hiatus for greater petrosal n
Exits from anterior slope of petrous temporal ridge (groove can be followed to foramen lacerum)
Hiatus and groove transmit greater petrosal n
Hiatus and groove for lesser petrosal n
Run parallel and inferior to greater hiatus and groove, which leads toward foramen ovale and transmits lesser petrosal n
Petrous ridge of temporal bone
Posterior cranial fossa
Clivus
body of sphenoid bone behind dorsum sellae which becomes fused with a portion of occipital bone anterior to foramen magnum
Slopes posteriorly and inferiorly to end as anterior margin of foramen magnum
Foramen magnum
Spinal cord continuous with brainstem above
Hypoglossal canal
Found on lateral margin of foramen magnum anterior to occipital condyle
Runs obliquely anteriorly and laterally, transmits hypoglossal n (CN12)
Internal auditory meatus (IAM)
posterior slope of petrous temporal ridge just above jugular foramen.
Passing through opening to middle ear region within temporal bone = CN7, CN8
Jugular foramen (JF)
large opening lateral to foramen magnum that leads to base of skull below.
Transmits the IJV and cranial 9,10,11
Internal occipital protuberance
Internal projection of bone at bone at posterior pole of internal aspect of skull (IOP)
Normal Basalis
Anterior transverse line: joins right and left articular eminence
articular eminence: rounded ridge of bone, runs transversely across anterior limit of mandibular fossa
Posterior transverse line: joins anterior aspects of right and left mastoid processes
Normal Basalis: Anterior Region
Each side of hard palate consists of 2 bones:
- Palatine process of maxilla (Mx) forms anterior 2/3 of palate
- Horizontal plate of palatine bone (P) forms posterior 1/3 of palate, ending posteriorly as double crescentshaped free border
Posterior nasal spine
Midline posterior projection from posterior border of bony palate
Incisive foramen
Mouth of incisive canal behind central incisor.
Foramen is common opening for right and left incisive canals
–Transmits nasopalatine nerve and vessels
Greater palatine canal opens as
- Greater palatine foramen onto palatal process of palatine bone in line with last maxillary molar.
* transmits greater palatine n and vessels - Lesser palatine foramen - posterior to greater palatine foramen
* lesser palatine nerve and vessels
Posterior choanae or posterior nasal apertures
posterior limits of nasal cavity
Vomer
free edge of bony nasal septum separated
Pterygoid processes of sphenoid bone : Lateral plate
Attachment for lateral and medial pterygoid muscles
Medial pterygoid plate
Posterior limit of lateral wall of nasal cavity
- ends inferiorly as hamulus
Scaphoid fossa
canoe-shaped shallow depression @ base of medial pterygoid plate
*tensor palatini muscle originates here
Palatovaginal canal
still anterior
Near base of Vomer
Pterygoid canal
still anterior
Passes base of pterygoid process.
Mouth of canal medial to scaphoid fossa, passing anterior margin of foramen lacerum
Mandibular fossa
INTERMEDIATE region
Accomodates condyle of mandible
Tympanic plate
Forms anterior wall of EAM and posterior, nonfunctioning wall of mandibular fossa
EAM
int’d region
behind mandibular fossa
Squamotympanic fissure/petrotympanic fissure
transmits chorda tympani
Spine of sphenoid
projection medial to mandibular fossa; ligament joins spine to lingula of mandible
Foramen spinosum
opening anterior to spine of sphenoid, transmits middle meningeal a from base of skull to interior of skull
Foramen lacerum
usually occupied by cartilage in life
Foramen ovale
Int’d region
Mastoid process
of temporal bone *posterior line
Stylomastoid foramen
Between styloid and mastoid processes, passage of facial n from within temporal bone
Styloid process
downward, forward and medial, joined to lesser horn of hyoid bone by stylohyoid ligament
Jugular formen
Internal jugular vein and CN 9, 10, 11 pass
Entrance to carotid canal
Anterior immediately anterior to jugular foramen
separated via wedge of bone
tympanic canaliculus
inferiorly on wedge of bone separating carotid canal/jugular foramen
transmits tympanic branch of glossopharyngeal nerve (IX)
Other posterior structures
occipital condyles
hypoglossal canal
foramen magnum (FM)
