Skull Osteology Flashcards
what makes up the skull
cranium + mandible
what 2 parts make up the cranium
-neurocranium
-viscerocranium
skull bones are organized into
-cranial
-facial
whats the function of cranial bones
-theyre the site for head muscle attachment
-encase brain and particular sense organs
whats the function of facial bones
-site for facial muscle attachment
-contain cavities for particular sense organs i.e. gustation, olfaction, vision
-form the framework for the face
-contain openings for air and food passage
-secure teeth
the neurocranium can be divided into
calvaria & cranial base
the calvaria forms what aspects of the skull and forehead
the superior, lateral, posterior aspects of the skull and the forehead
calvaria looks like
dome shaped roof (skullcap)
the cranial base forms what
floor of the skull
the cranial base consists of what bones
ethmoid, sphenoid and parts of the temporal and occipital bones
whats a cranial cavity
its the cavity covered by the calvaria and cranial base
what cavities are in the skull
-cranial (contains brain)
-orbits (contains eyeballs)
-nasal ( contains paranasal sinuses)
-middle and inner ear
what are depressions and openings of the cranium
-fissure
-foramen
-fossa
-sulcus
-meatus
whats a fissure
whats a foramen
whats a fossa
whats a sulcus
whats a meatus
-a narrow opening between adjacent parts of bones for nerves and vessels
-a hole/opening
-a shallow depression
-a groove
-a tubelike passageway
whats a suture
connections (joints) between bones of skull
where can you find sutures
at all bones of the skull except mandible
what are the cranial bone sutures
-coronal
-sagittal
-squamous
-lambdoid
how are sutures of facial bones named
based on name of bones that are connected
what are fetal bones like at birth
unfused
fetal skull bones are joined by
membranes called fontanelle
whats a fontanelle
area of fibrous tissue membrane separating the bones of the calvaria
what are major fontanelles
-anterior
-posterior
-anterolateral (sphenoidal)
-posterolateral (mastoid)
what do fontanelles allow for
why do infants have open fontanelles
rapid stretching and deformation of the neurocranium as the brain expands faster than the surrounding bones grow
to allow for brain growth
what 6 fontanelles are present at birth
-anterior (1)
-posterior (1)
-mastoid (2)
-sphenoid (2)
whats the shape of anterior fontanelle
diamond/ rhomboid
where is anterior fontanelle located
junction of the sagittal, coronal and frontal sutures
anterior fontanelle is the future site of
bregma
when does the anterior fontanelle close (ossify)
18 months of age
what forms the posterior fontanelle
junction of 3 suture lines i.e. sagittal suture anteriorly and lambdoid suture on either side
shape of posterior fontanelle
triangular
when does posterior fontanelle close
first 2-3 months after birth
when do cranial sutures start to ossify
8 years ( sutures on facial skeleton ossify earlier)
obliteration of cranial sutures progresses usually at what age
20-30 yrs (often before age 40)
obliteration of sutures begins with which suture
coronal suture and then extends into sagittal and lambdoid sutures
ossification of the cartilaginous neurocranium begins in which bones
-occipital bone
-basisphenoid
-ethmoid bone
what is craniosynostosis
premature closure of one or more sutures
what causes scaphocephaly (boat head)
early closure of sagittal suture
what causes brachycephaly (short head)
the premature closure of the coronal and lambdoid sutures
what are types of craniosynostosis
-scaphocephaly
-brachycephaly
-plagiocephaly
what causes plagiocephaly (asymmetry head)
unilateral closure of coronal suture/ lambdoid suture
how many cranial bones are there
8
what are the paired cranial bones
-parietal
-temporal
what are the unpaired cranial bones
-frontal
-occipital
-sphenoid
-ethmoid
where is the frontal bone located
anterior cranial fossa
the frontal bone has what structural contribution
anterior portion of cranium
roofs of the orbits
anterior cranial fossa
what are the parts of the frontal bone
frontal squama
supraorbital margins
glabella
what are the articulations of the frontal bone
coronal suture i.e. parietal bones
frontonasal suture
what are the sinuses and openings of the frontal bone
frontal sinus
supraorbital foramen
what are the marks of the frontal bone
frontal squama ( forehead)
supra-orbital margin (protects eye)
lacrimal foosa (for tear ducts)
frontal sinuses
what makes up the foramina of the frontal bone
supra-orbital foramen
supra-orbital notch
the supra-orbital foramen allows for passage for what
for blood vessels of eyebrows, eyelids and frontal sinuses
whats the supra-orbital notch
an incomplete supra-orbital foramen
what are the major associated sutures of the parietal bones
1 coronal
1 lambdoid
2 squamous
1 sagittal
what are sutural bones
tiny irregularly shaped bones which appear within sutures
whats the structural contribution of the parietal bone
superior and lateral aspects of the skull
what are the articulations of the parietal bone
coronal- anterior; frontal bone
sagittal- midline; parietal bones
lambdoid- posterior; occipital bone
squamous- lateral; temporal bones
whats the structural contribution of the temporal bone
lateral surface
inferior to parietal
(inferolateral aspects of skull)
what are the articulations of the temporal bone
squamous i.e. parietal
what are the 4 regions of the temporal bone that make its shape
squamous region
tympanic region
mastoid region
petrous region
what happens at the squamous region of the temporal bone
-zygomatic process meets the zygomatic bone and forms the zygomatic arch
-mandibular fossa and condyle of mandible form the temporomandibular joint
what’s it like at the tympanic region of the temporal bone
-it’s the region which surrounds the external auditory meatus
-has the styloid process which is a needle like projection for muscle attachment
what’s does the mastoid region (mastoid process) of the temporal bone do
-forms the mastoid process which is an anchoring point for neck muscles and contains the mastoid sinuses
what’s the petrous region (mountain range) of the temporal bone
-is part of the cranial base
-is between occipital and sphenoid bones
-it forms middle cranial fossa
-it houses middle and inner ear cavities
what’s the foramen of the temporal bone
jugular- contains jugular veins and 3 cranial nerves
carotid canal
internal acoustic meatus- contains cranial nerves 7 & 8
what’s the structural contribution of the occipital bone
posterior wall and base of skull
walls of posterior cranial fossa
what are the articulations of the occipital bone
lambdoid i.e. parietal bones
occipitomastoid i.e. temporal bones
basioccipital i.e. sphenoid bone
what’s the opening of the occipital bone
foramen magnum- where brain connects with spinal cord
what are the protrusions of the occipital bone
occipital condyles-which articulates with the first vertebrae
what’s the location of the occipital bone
posterior cranial fossa
