cranium Flashcards
what are the 6 components of the axial skeleton
skull bones
auditory ossicles
hyoid bone
ribs
sternum
bones of vertebral column
how many cranial bones do we have
8
how many facial bones do we have
14
what is the purpose of the cranial bones
to enclose and protects the brain
what makes up the calvaria
1 frontal
1 occipital
2 parietal
2 outer plates of compact bone
what does calvaria mean
skull cap
what makes up the floor or base
1 ethmoid
1 sthenoid
1 occipital
1 frontal
2 temporal
what are the 2 division of the cranium
calvaria (skull cap) and the floor or base
what types of bones make up the calvaria
flat bones
what is contained by the bones of the calvaria
inner layer of spongy bone and red marrow, called diploe
what is diploe
the inner layer of spongy bone in the calvaria flat bones
what do we call the very top of the skull
the vertex
what are the internal regions of the skull (3)
anterior cranial fossa
middle cranial fossa
posterior fossa
what bones make up the anterior cranial fossa
frontal
ethmoid
sphenoid
what bones make up the middle cranial fossa
temporal
sphenoid
what bones make up the posterior cranial fossa
occipital
what sits in the A cranial fossa
the frontal lobe of cerebrum
what sits in the M cranial fossa
the temporal lobe of the cerebrum
what sits in the P cranial fossa
the cerebellum
what is the purpose of the cerebellum
balance and coordination
what is the vertical part of the frontal bone
frontal squama
what does the frontal squama contain
the frontal sinuses
what is the horizontal part of the frontal bone
the orbital plates
what are the orbital plates
form a big portion of the anterior cranial fossa
what do the orbital plates tell us
if there’s any TILT on a lateral skull projection
what are the 5 important landmarks of the frontal bone
frontal eminences
supraorbital margins
superciliary ridges
supraorbital foramina
glabella
what can you (visually) align to ensure no tilt
IPL inter pupillary line
what are the supraorbital margins
the part above the eyes ‘upper ridge of orbit’
what are the superciliary arches
ridges where your eyebrows are
what is the glabella
superior to where the eyebrows come together (bullet point)
(right above nasion)
what is the nasion
right where your nose ends at your forehead (inferior to glabella)
what are the 5 frontal articulations
parietals (L/R)
sphenoid
ethmoid
nasal bones
zygoma
what is the widest part of the skull
the distance between the parietal eminences
what does the parietal bone articulate with (5)
frontal
temporal
occipital
sphenoid
opposite parietal bone
where is the occipital bone
posteroinferior part of the skull
what forms most of the floor of the posterior cranial fossa
the occipital bone
what specific parts of the skull combine with C1 to form the atlantaloccipital joint
occipital condyles (NOT just occipital bone)
what is the foramen magnum
underneath is the spinal cord,
above is the brain stem
what happens when there is too much swelling in the brain
the brain stem herniates down through the foramen magnum
what are the nuchal lines
muscle attachment sites
what is the external occipital protuberance
the inion
what nerve passes through the foramen magnum
the 12th cranial nerve
what drains venous blood from the brain?
internal jugular vein
what parts of the skull do the temporal bones form
inferolateral portions of the skull
what are the main 4 parts of the temporal bones
squamous portion
tympanic portion
petrous ridges or pyramids
mastoid process
what is the opening of your ear called
external auditory meatus (EAM)
what is the line (for attachment) on the temporal bone
"”zygomatic process of the temporal bone””
EAM
external auditory meatus
what forms the TM joint
the condyle of mandible and the mandibular fossa (underside of zygomatic process of temporal)
what makes up the zygomatic arch
the zygomatic process of the temporal bone and the temporal process of the zygomatic bone
what is on the underside of the zygomatic process of the temporal bone
mandibular fossa
where is the tympanic portion situated on the temporal bone
inferior to the squamous
anterior to mastoid and petrous bones
where is the styloid process of the temporal bone
on the very inferior part
what vertebral level is associated with the tip of the mastoid process
C1
what do mastoid air cells do
communicate with space in the middle ear (**vary incredibly between people)
what do the petrous ridges contain
interior auditory canal
cochlea
where do the petrous ridges project
anteriorly and medially
what is the thockest, densest bone in the skull
the petrous ridges of the temporal bones
what is a landmark for the petrous ridges are
TEA top of ear attachment
which is the “average” skull tyoe
mesocephalic
47 degrees
what are the 3 skull types
mesocephalic
brachycephalic
dolichocephalic
brachycephalic skull type angle
54 degrees
what is the angle being measured for the different skull types
from the cranial midline to the petrous ridges
dolichocephalic skull type angle
40 degrees
what is the image where the petrous ridges are in the lower third of the orbits
caldwell
what is the image where the petrous ridges are by the top of the orbits
ruggle
what are the important foramina of the temporal bone (5)
carotid canal
jugular foramen
foramen lacerum
EAM
internal auditory canal
when do you repeat a (AP) skull image
when the petrous ridges aren’t in the right spot
what is A
petrous portion of the temporal bone
what travels through the carotid canal
the INTERNAL carotid artery
what is E
jugular foramen
what is C
carotid canal
what is B
foramen lacerum
what is D
EAM (external auditory meatus)
what is the keystone bone of the cranial floor ? why?
sphenoid
because it articulate with all the other bones
what is F
foramen magnum
what does the sphenoid consist of
1 body
2 lesser wings
2 greater wings
2 perygoid processes
what does the body of the sphenoid contain (2)
2 sphenoid sinuses
sella turcica
how do you landmark the sella turcica on a lateral skull projection
1.9cm anterior and 1.9cm superior to the EAM
what is the sella turcica
encases the pituitary gland
what is the name for the posterior border of the sella turcica
dorsum sellae
what is the name of the anterior border of the sella turcica
tuberculum sellae
what are the 2 main parts of the dorsum sellae
posterior clinoid processes (top borders)
clivus
are the anterior clinoid processes part of the sella turcica
NO!!
they are part of the lesser wings
what sits against the clivus
the pons
describe the shape of the lesser wings
triangular and horizontal
compare the lesser to greater wings
smaller and more superior than the greater wings
what do the lesser wings form
posteromedial portion of the orbits
what foramen is part of the lesser wings
optic foramen (is a canal)
what do the greater wings of the sphenoid form
posterolateral walls of the orbits
what are the 3 foramen of the greater wings
foramen ovale
foramen rotundum
foramen spinosum
what is B
foramen spinosum
what passes through the superior orbital fissures
cranial nerves 3, 4, 6
what is A
foramen ovale
what is the yellow
superior orbital fssure
what is the blue
greater wing of the sphenoid
what is the red
the lesser wings of the sphenoid
what is this
what forms it
the innominate line
or lateral part of the greater wing
(edge of the greater wing of the sphenoid)
what do the pterygoid processes form
the posterolateral region of the nasal cavity
what 4 things make up the ethmoid
cribriform plate
Crista galli
perpendicular plate
lateral masses
what is in red (lateral)
lesser wing (from side)
what is in green (lateral)
sella turcica
what is the ethmoid mainly associated with
the nasal cavity
what does the cribriform plate contain
the olfactory foramina
what is the Crista galli for
attachment for the falx cerebri
what is the falx cerebri
membrane that separates the two hemispheres of the brain (part of the dura mater)
what does the perpendicular plates form
the SUPERIOR part of the bony nasal septum
does the ethmoid have a body
no, just lateral masses
do the lateral masses of the ethmoid bone form the inferior nasal conchae?
no, it is its own facial bone
what do the lateral masses of the ethmoid contain
ethmoid sinuses
what do the lateral masses of the ethmoid form
form the superior and middle nasal conchae
what are the 4 skull sutures
coronal suture
sagittal suture
lambodial suture
squamosal suture
what type of joints are skull sutures (in an adult)
fibrous, synarthrodial
where is the sagittal suture
superior midline between the parietal bones
what are the 4 important landmarks for the sutures
bregma
lambda
pterions
asterions
where is the squamosal suture
lateral part of the skull between the parietal and the temporal bones
what is the bregma
the anterior end of the sagittal suture
where is the coronal suture
between the frontal and parietal bones
where is the lambdoidal suture
posterior between the parietal and temporal bones
what is the lambda
posterior end of the sagittal suture
what are the pterions
(R/L) junction of the parietal, temporal, and greater wing of sphenoid
what are the asterions
(R/L) posterior to the ear where the squamosal and lambdoidal sutures meet
what are the pterions a landmark for
middle meningeal artery
what are the sutures in newborns
fontanels
(anterior, posterior, anterolateral, posterolateral)
dark blue
ethmoid
orange
sphenoid
