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