W3: the skull and facial bones Flashcards
what is the cranium
complex bony structure that protects the brain, supports face and provides framework for sensory organs and pathways for nerves and vessels
consist of 22 bones (not including bones of middle ears)
divided into neurocranium (encases brain) and viscerocranium (forms skeleton of the face)
what is the neurocranium
structural framework for the cranial cavity
composed of 8 bones:
frontal bone
parietal bone (2)
occipital bone
ethmoid bone
temporal bone (2)
sphenoid bone
what is the frontal bone
forms forehead, roof of orbits and most of anterior part of cranial base
superior to the orbits, thickened bone is the supraorbital margin
has mucus membrane lined paranasal sinus (one of them is the frontal sinus)
what is the parietal bone
form superior and lateral aspects of the skull
contain protrusions and depressions for meningeal vessels
what is the temporal bones
form inferior lateral aspects of cranial cavity and part of base
features include:
external auditory meatus
internal acoustic meatus
mastoid process
zygomatic process
petrous ridge
jugular foramen
temporomandibular joints
what is the sphenoid bone
base of skull
features include:
sella turcica
greater and lesser wings
pterygoid processes (form part of nasal cavity)
what is the ethmoid bone
on roof of nasal cavity and medial walls of orbits
features include:
cribriform plate
perpendicular plate
ethmoidal air cells
crista galli
what is the occipital bone
posterior part of cavity and most of base
has foramen magnum in inferior part to allow spinal cord to connect with medulla oblongata
occipital condyles articulate with the alas to form atlantocciptal joint
external occipital protuberance can be felt as bony bump at back of head
what are the auditory ossicles
IN MIDDLE EAR: malleus, incus and stapes found within tympanic cavity (air filled space in temp bone)
transmit sound vibrations from eardrum to inner ear where they can convert into nerve signals that brain intercept as sounds
in petrous part of temp bone is a canal which allow for nerves and vessels that service the inner ear and parts of brain:
internal auditory meatus allow for passage of facial nerve, vestibulocochlear nerve and labyrinthine nerve
what are the lobes of the brain
each hemisphere has 4 main lobes
frontal lobe: attention, decision making, movement and speech
parietal lobe: spatial relationships, interpreting pain and touch and understanding spoken language
temporal lobe: stm, musical rhythm and smell recognition
occipital lobe: visual processing
what is the cranial cavity and fossae
the internal surface of the cranial base has 3 large fossae that form the base of cranial cavity
anterior cranial fossa - frontal lobes
middle cranial fossa - temporal lobes
posterior cranial fossa - cerebellum, medulla oblongata, pons
what are the cranial fontanelles
soft membranous regions of foetal and neonatal skulls
the corners of 3/4 developing flat bones meet and allow for growths of the skull over the developing brain
CONNECTIVE TISSUE AND FIBROUS MEMBRANE fills the gaps between
name the cranial fontanelles
anterior - becomes BREGMA
posterior - becomes LAMDA
sphenoid - becomes PTERION
mastoid - becomes ASTERION
what are cranial sutures
in adults they become ossified but still mark the boundaries between different bones of the skull
- fibrous joints that connect bones of skull
- serrated edges to interlock
- allow 4 movement during development enabling the skull to expand
MAIN SUTURES:
coronal - frontal and parietal
sagittal - parietal bone
lambdoid - occipital and parietal
what are the craniometric points of the cranium
anatomical landmarks on the skull from which measurements are taken
includes:
bregma
lambda
asterion
pterion
vertex
inion
nasion
glabella
what are the viscerocranium bones
facial bones the form structure of face
formed of 14 bones:
maxilla (2)
mandible
concha (inferior nasal) (2)
nasal bone (2)
vomer
lacrimal (2)
zygoma (2)
palatine (2)
what are the nasal bones
small flattened bones that from bridge of nose
unite in midline to form bony bridge
what are the zygomatic bones
cheekbones
form prominences of cheeks and lateral walls and floor of each orbit
features:
temporal process articulates with temporal bone to form the zygomatic arch
what is the maxillary
unite in midline to from upper jaw and anterior part of hard palate and forms part of the floor of the orbits and parts of nasal cavity
features:
maxillary sinus that empties into nasal cavity
infraorbital foramen
alveolar processes for teeth sockets
what is the inferior nasal conchae
scroll like
form the lateral wall as of nasal cavity (there’s superior, inferior and middle pairs)
helps filter air before passes into lungs
what are the palatine bones
2 L shaped bones from posterior part of the hard palate
part of nasal cavity and parts of orbits
what is the vomer
forms inferior part of nasal septum
triangular
what is the lacrimal bones
medial walls of the orbits
smallest facial bones
features:
lacrimal fossa for the lacrimal sac that gathers tears
what is the mandible
lower jaw, largest strongest facial bone
only movable skull bone
has a body, 2 rami, 2 angles, 2 condylar processes and mental foramen
