Articulatory I - Bones of the Skull

what are the two groups of skull bones?

neurocranium and viscerocranium

what is the neurocranium?

bones that encase the cranium (cranial skeleton)

what does the neurocranium do?

forms a vault for the skeleton

what is the floor of the neurocranium called?

the ‘cranial base’ or ‘base of skull’

what is the viscerocranium?

the skeletal face (facial skeleton)

what does the viscerocranium do?

supports the soft tissues of the face and provides skeletal framework for nasal cavities, oral cavity, and orbital cavities, and upper and lower jaws

what are the cranial features?

neurocranium, sutures, fossae, viscerocranium

how many bones make up the cranial skeleton (neurocranium)?

8 bones

how many bones make up the viscerocranium?

13 bones + the mandible

what are sutures?

fibrous joints between bones that make up the viscerocranium and the vault of the neurocranium, where bones ‘lock’ together

what are the cranial fossae?

spaces inside the skull housing the brain

how many cranial fossae are there?

3

what are the 8 bones of the neurocranium?

• frontal bone

• parietal bones (2)

• occipital bone

• temporal bones (2)

• ethmoid bone

• sphenoid bone

when does the frontal bone ossify?

ossifies in adulthood into a single bone

what does the frontal bone form?

forms bony forehead, anterior brain case and the roof of the orbital cavities

what does the frontal bone contain?

the frontal lobe

what are the features of the frontal bone

• supraorbital margin

• supraorbital foramen/notch

• superciliary arches

• glabella

• frontonasal suture

• frontal sinuses

what is the supraorbital margin?

where the vertical frontal bone becomes horizontal

what is the supraorbital foramen/notch?

where the nerve comnes out to innervate the skin

what are the superciliary arches?

where the eyebrows are

what does ciliary mean?

hair

what is the glabella?

space between the eyebrows

what is the frontonasal suture?

where the frontal bone connects

what are the frontal sinuses?

spongey, open space beneath glabella

why should we know the features of the frontal bone?

they are often points of muscle attachment

what are the parietal bones?

large,paired bones on the upper sides of the head

where do the parietal bones join with other bones?

the four largest sutures (sagittal, coronal, lambdoidal, squamousal)

what are the four largest sutures?

sagittal, coronal, lambdoidal, squamousal

what is the occipital bone?

most posterior and inferior surface of the brain case

which bones do the occipital bone articulate with?

temporal, parietal, and sphenoid bones (at base of skull)

what are the notable features iof the occipital bone?

• foramen magnum

• occipital condyles

• basioccipital bone

• external occipital crest

• external occipital protuberance

• nuchal lines

• cerebral & cerebellar fossae (next slide)

what is the foramen magnum?

where the spinal cord exits

what are the occipital condyles?

on either side of foramen magnum, where C1 connects, allow head to rock

what is a crest?

a ridge

what is a protuberance?

a bump

what are the temporal bones?

paired bones that form the lateral base and sides of the brain case

what do the temporal bones house?

the sensory mechanisms of the auditory (hearing) and vestibular (balance) systems

what are the four regions of the temporal bones?

squamous, tympanic, petrous, mastoid

what is the squamous portion of the temporal bones?

anterior/ upper portion

what are the notable features of the squamous portion of the temporal bones?

zygomatic process,articular eminence, mandibular fossa, roof of external auditory meadus

what is the tympanic portion of the temporal bones?

curved plate of bone

what are the notable features of the tympanic portion of the temporal bones?

external auditory meatus, tympanic plate, styloid process, petrotympanic fissure

what is the petrous portion of the temporal bones?

where the temporal lobe sits, projects into skull base between sphenoid and occipital bones

what are the notable features of the petrous portion of the temporal bones?

jugular foramen, internal acoustic meatus (IAM), trigeminal impression, tegmen tympani, carotid canal, foramen lacerum

what is the mastoid process of the temporal bones?

posterior, external portion

what are the notable features of the mastoid portion of the temporal bones?

mastoid process, stylomastoid foramen

what are foramen?

entry/exit for nerves

what are processes?

originates at one point and is named after the point it connects to

i.e. mastoid process of the temporal bone goes from temp bonbe to mastoid

what is the ethmoid bone?

complex, delicate structure at core of cranium; abuts the viscerocranium

what does the ethmoid bone form?

forms part of the walls of the cranial, nasal and orbital spaces

what are the notable features of the ethmoid bone?

• crista galli

• cribriform plate

• perpendicular plate

• middle and superior nasal conchae

• orbital plates

what is crista galli?

where the dura mater attavhes to the skull via ethmoid bone

what is the cribriform plate?

holey plate at base of crista galli, olfactory nerve passes through the holes

what is the perpendicular plate?

separates the left and right nasal cavities

what are the middle/superior nasal conchae?

curled portions of the ethmoid bone

what are the orbital plates?

the latreral walls of each orbit

what is the shape of the ethmoid bone?

scarecrow

what is the shape of the sphenoid bone?

bat

what is the sphenoid bone?

very complex bone located at the base of the skull, significant contributor to cranial structure

what are the features of the sphenoid bone?

• body

• lesser wings

• greater wings

how is the body of the sphenoid bone described?

stella turcica (turkish saddle)

where are the lesser wings?

superior to body

where are the greater wings?

arise from posterior of body and continue to orbit (larger)

what are the medial and lateral pterygoid plates?

downward projections from body and greater wings

what are the formina of the sphenoid bone?

– optic canal and foramen

– superior orbital fissure

– foramen rotundum

– foramen ovale

– foramen spinosum

what are the features oof the sutures?

• bregma

• vertex

• lambda

• pterion

what is the bregma?

where coronal and saggital sutures meet (where you have bangs)

what is the vertex?

the highest point

what is the lambda?

where lambdoid and saggital sutures connect, shaped like greek lambda

what is the pterion?

where all 4 sutures meet, shaped like H

what are the cranial fossae?

spaces in cranial vault, like 3 level staircase

what are the 3 cranial fossae?

anterior, middle, posterior

what is the anterior cranial fossae?

fossae at front, shallowest, houses frontal lobe and all boney features at front

what is the middle cranial fossae?

middle fossae, middle deepest, houses temporal lobes of the brain and all the boney features of this lobe

what is the posterior cranial fossae?

back, largest, and deepeat of the 3 fossae, houses occipital lobe, cerebellum and brainstem, floor contains foramen magnum (passageway of spinal cord)

what does the uoper facial skeleton consist of?

the upper jaw (maxillae) and the orbital and nasal cavities

what does the viscerocranium consist of?

13 bones + the mandible

what are viscerocranium bones?

• maxillae (2)

• palatine (2)

• zygomatic (2)

• lacrimal (2)

• nasal bones (2)

• inferior nasal conchae (2)

• vomer

• mandible

what is the mnemonic for the viscerocranium bones?

• my

• pet

• zebra

• likes

• …

• it’s nose

• very

• much

what are the maxillaie?

paired; largest bones of the face (besides mandible)

where is the maxillae?

contributes to roof of mouth, nose, upper dental arch

what are the 5 processes of the maxillae?

– zygomatic process

– frontal process

– orbital process

– alveolar process

– palatine processes

what are the notable features of the maxillae?

• infraorbital foramen

• nasal notch

• anterior nasal spine

• nasal crest

what is meant by ‘spine’ in anterior nasal spine?

pokey piece of bone where things attach (here, it’s the palatine process)

what are the palatine bones?

paired bones, posterior to the maxillae, part of 3 cavities

what 3 cavities are the palatine bones part of?

nasal, orbital, and oral

what are the features of the palatine bones?

orbital plate, horozontal plate/process, sphenoidal process

what are the zygomatoc bones?

paired bones with quadralateral shaped body and 4 processes

what do the zygomatic bones articulate with?

maxilla, frontal, temporal and sphenoid bones

what are the 4 processes of the zygomatic bones?

– frontal process

– orbital process

– temporal process

– maxillary process

what are the lacrimal bones?

paired, smallest facial bones

what do the lacrimal bones articulate with?

maxillae, frontal bone, ethmoid, and inferior nasal conchae (in nasal cavity)

what do the lacrimal bones contain?

a depression that houses the nasolacrimal sac

what are the nasal bones?

paired bones forming the bony bridge of the nose

what do the nasal bones articulate with?

frontal, maxillae, perpendicular plate of ethmoid

what are the inferior nasal conchae?

paired, thin, curved bones projecting from the lateral wall of nasal cavity

what are the inferior nasal conchae also known as?

inferior turbinates

what is the largest conchae?

the inferior nasal conchae

what covers all 3 conchae?

thick, richly vascularized mucousa

what is the vomer?

single bone forming inferior and posterior portion of the nasal septum