lecture 4 Flashcards
the skull
how many bones is the skull comprised of?
22 bones
how is the skull divided so that we can better understand it?
general regions, secondary cavities of the skull, cranial fossae, sutures
how is the general regions divided up?
neurocranium and viscerocranium
what is the neurocranium?
portion that encloses the brain
what is the viscerocranium?
the facial bones
what comprises the secondary cavities of the skull?
the nasal cavity, orbits, middle and inner ear, paranasal sinuses
what is the middle and inner ear responsible for?
houses structures for hearing and equilibrium
what are the paranasal sinuses?
mucosa lined hollows within bones that drain into nasal cavity
how is the paranasal sinuses named?
for bone in which they are found
what are the functions of the paranasal sinuses?
1) form mucus in which they are found
2) warm air
3) provide resonance for voice
what is sinusitis?
inflammation of a paranasal sinus due to allergy or infection which can lead to blockage of the ostium
what are the different types of sinusitis?
infection of ethmoid cells and maxillary sinuses
why is the infection of ethmoid cells important to note as sinusitis?
potential for infection to break through thin wall into medial orbit and this can cause blindness due to proximity to optic canal
how is the infection of ethmoid cells subdivided?
into anterior, middle, posterior ethmoid sinuses each with own ostia or opening
why is the infection of maxillary sinuses important to note as sinusitis?
because its the most common location of sinusitis
where can we see the infection of the maxillary sinus?
ostia superiorly located with head erect, drainage cannot occur until full; ostia medially directed resulting in nights rolling from side to side if both maxillary sinuses inflamed; close proximity to maxillary molars
where is the maxillary sinus perceived?
within molars
what happens if you fracture the molar and you invade the maxillary sinus during extraction?
opening would allow for infection, very little separation between tooth and sinus and when infection happens, it feels a lot like a tooth ache.
what is the transillumination of sinuses called?
it allows for direct observation of fluid, mucous or masses within the maxillary and frontal sinuses
what is the cranial fossae or flattened surface?
depressions in the cranium floor that contain various brain structures like the anterior, middle and posterior cranial fossae
what are the sutures?
immovable joints that hold bone of the skull together
what are the different types of sutures called?
coronal suture, sagittal suture, lambdoid suture, squamous suture
what is coronal suture?
unites frontal bone to parietal bone
what is sagittal suture?
unites parietal bones
lambdoid suture?
unites occipital bone to parietal bones
what is the squamous suture?
unite parietal bones to temporal bones
what are the parts that make up the cranial bones?
frontal bone, parietal bone, temporal bone, occipital bone,the sphenoid bone, ethmoid bone
what is the frontal bone?
it forms the anterior portion of the cranium, roof of the orbits, and most of the anterior cranial fossa nonpaired bone of the skull
what does the frontal bone form after birth?
it forms two bones that fuse after brith and so you have the frontal suture which disappears around the age 6 and the metopic suture when the frontal suture is not obliterated
as part of the frontal bone, what is the frontal squama?
portion that forms the forehead
what makes up the frontal bone?
sutures (frontal and metopic), frontal squama, supraorbital margin, frontal sinus
where is the supraorbital margin located?
the thickening just superior to the orbits
what type of injury can happen to the supraorbital margin?
lid contusion
so, how does the aforementioned lid contusion happen?
a blow to supraorbital margin causes bruising, tissue fluid and blood leak into connective tissue and gravitates into superior eyelid and can be caused by bone fractures in region
where are the frontal sinuses of the frontal bone located?
located deep to frontal squama
where are the parietal bones?
paired bones that form bulk of sides and roof of calcium
where are the temporal bones?
paired bones that form inferolateral components of cranium plus portion of the cranial floor
what comprises the temporal bones?
temporal squama, zygomatic process, mastoid process, petrous portion, mandibular fossa and articular tubercle, the styloid process and stylomastoid foramen
where is the temporal squama?
thin flat portions that form anterosuperior portion of temple
where is the zygomatic process?
projection that articulates with temporal process of zygomatic bone to form the zygomatic arch
where is the mastoid process?
rounded process posterior to external auditory meatus and thus serves as attachment site for several muscles
what type of inflammation can affect the mastoid process?
mastoiditis which is the inflammation of mastoid air cells (mastoid sinus) via middle ear infection which can lead to the brain
where is the petrous portion?
triangular region of temporal bone in base of cranium (located between occipital and sphenoid bones
what else does the petrous portion hold?
it contains middle and inner ear plus external auditory meatus and also contains carotid canal and jugular foramen
what is the mandibular fossa and articular tubercle?
it articulates with the mandible to form the temporomandibular joint
what were the other features in the inferior aspect of the temporal bone again?
styloid process and stylomastoid foramen
what attaches to the styloid process?
attachment site for tongue and neck muscles/ligaments
where is the occipital bone?
forms posterior portion of cranium and posterior cranial fossa
what comprises the occipital bone?
external occipital protuberance, superior and inferior nuchal lines, foramen magnum, occipital condyle, hypoglossal canal
what attaches to the external occipital protuberance?
attachment site for ligamentum nuchae and extends to C7; also known as the Inion
what attaches to the superior and inferior nuchal lines?
sites of muscle attachment
what is the foramen magnum?
allows inferior portion of brain to connect to spinal cord + allows blood vessels to brain
what articulates with the occipital condyle?
it articulates with depressions on C1 to form atlanto-occipital joint
what does the hypoglossal canal do?
grip the skull by the occipital condyle
where is the sphenoid bone?
bat-shaped central bone of the cranium that articulates with all other central cranial bones
what comprises the sphenoid bone?
body, greater wings, and lesser wings
where is the body of the sphenoid bone located?
the cube like central portion located between ethmoid and occipital bone
what comprises the body of the sphenoid bone?
the sphenoid sinuses and the sella turcica
where is the greater wings of the sphenoid bone located?
they form the anterolateral floor of the cranium plus the lateral wall of the skull just anterior to the temporal bone
what comprises the greater wings of the sphenoid bone?
the foramen ovale
what comprises the lesser wings of the sphenoid bone?
they form the portion of floor of the cranium and posterior portion of the orbit
what are the other features of the sphenoid?
optic foramen, superior orbital fissure, pterygoid processes (lamina), foramen spinosum, foramen lacerum
where is the ethmoid bone located?
sponge like paired bones that lie in the anterior part of the cranial floor and medial to the orbits
what are the major structures formed by the ethmoids?
anterior portion of the cranial floor, medial wall of orbits, superior portion of the nasal septum, lateral walls of the nasal roof
what else do the ethmoids contain?
ethmoid sinuses, cribiform plate and the crista galli, superior and middle nasal concha
where is the cribiform plate located?
perforated feature located in the floor of the cranial cavity that allows dendrites from the olfactory to enter the nasal cavity and if damaged, we lose our sense of smell
where is the crista galli (cock’s comb)?
projects superiorly perpendicular to the cribiform plate and allows for the attachment of the meninges
*what is the superior and middle nasal concha?
cause turbulence of inspired air. Use to warm and filter air and so turbinates in the concha causes air turbulence so all air comes in contact with lining to filter air but no muscle attaches here, also called nasal turbinates
what comprises the facial bone?
nasal bones, maxilla, zygomatic bones, mandible, lacrimal bones, palatine bones, inferior nasal conchae, vomer
what is the nasal bone comprised of?
mostly cartilage
what are some clinical correlations of the nasal bone?
deviated nasal septum due to being congenital or from trauma and this can cause partial or complete blockage like chronic sinusitis, chronic sinus headaches, chronic nose bleeds
what can happen if trauma occurs to the nasal bone?
could be due to common sports or automobile injury, severe injuries may displace cartilage and or bones with potential to also fracture cribiform plate causing spinal fluid rhinohea
what happens if the cribiform gets damaged?
sense of smell is lost, meninges can also get damaged causing CSF damage
where is the maxilla located?
superior jaw bone
what does the maxilla contribute?
floors of the orbit, portion of lateral walls and floor of the nasal cavity, palatine process, alveolar arch
what also comprises the maxilla?
infraorbital foramen and inferior orbital fissure
where is the inferior orbital fissure located?
located between maxilla and the greater wing of the sphenoid
what happens when the maxilla does not fuse properly
the maxilla is formed by two bones that fuse prior to birth and improper fusion results in cleft lip/palate
what are the zygomatic bones located?
they form the prominence of the cheek and portion of floor of the orbits
what comprises the zygomatic bones?
temporal process of the zygomatic bone that articulates with the zygomatic process of the temporal bone and zygomaticofacial foramen; together the form the prominence of cheek and portion of floor orbits
where is the mandible located?
lower jaw bone
what comprises the mandible?
body, rami, and angle
what comprises the body of the mandible?
alveolar process containing alveoli, mental foramen (chin region), mental protuberance or the mental eminence
what happens to the body when loss of teeth occurs?
resorption of alveolar bone and the dental plates can press against the mental nerves producing pain and the decrease in vertical dimension of face and mandibular prognathism
what comprises the ramus?
condylar process, coronoid process, mandibular notch, mandibular foramen
what does the modified hinge joint facilitate?
it allows the movement in 3 planes including sliding action
how can the dislocation of the TMJ occur?
it occurs when attempting to take a large bite or when yawning
arthritis and crepitus of the joint can occur, T/F?
T
where does the coronoid process attach?
attachment of jaw muscle
what is the condylar process?
articulates with mandibular fossa and articular tubercle of temporal bone to form temporomandibular joint (TMJ)
where is the mandibular notch located?
located between condylar process and coronoid process
where is the mandibular foramen located?
beginning of mandibular canal which runs anteriorly to the root of each tooth»_space; most common site for dental anesthesia (mental foramen occasionally used as well)
what is the angle of the ramus?
where the ramus and body meet
where is the lacrimal bone?
resembles fingernail in size and shape, lateral and posterior to nasal bones within orbits and collects tears
what is the vertical fossa?
vertical groove between lacrimal bone and maxilla that houses lacrimal sacs and collects tears and passes them to nasal cavity
what are the craniometric points?
used as points in image based measurements of skull
where is the asteron?
located at junction of temporal, occipital and parietal bones
where is the bregma?
superior point of cranium at junction of sagittal and coronal suture
where is the glabella?
bony prominence located just superior to bridge of nose»_space; anterior-most region of forehead
where is the inion?
external occipital protuberance
where is the lambda?
located at junction of lambdoid and sagittal sutures
where is the nasion?
depression immediately superior to bridge of nose
where is the pterion?
located at junction of sphenoid, temporal, frontal and parietal bones
where is the vertex?
superior-most point of neurocranium»_space; located within sagittal suture
