Bones of the Cranium Flashcards
2 parts of the skull
Cranium and Face
Sutures
Immovable junction where two bones meet
Exception: moveable temporomandibular joint (Jaw)
Sinuses
Air filled cavities within bones that decrease weight of the skull
Forms anterior portion of cranium, anterior floor, and superior part of face
Frontal bone
Bone that forms the roof and lateral sides
Parietal bone
Bone that forms the floor and lateral sides
Temporal bone
Bone that forms the posterior portion of the cranium and posterior floor
Occipital bone
Foramen magnum is found in the inferior aspect of which bone
Occipital bone
3 portions of the sphenoid bone
Body (houses the pituitary gland in the depression called sella turcica)
Lesser wings project from the anterior aspect of the body
Greater wings project from lateral aspects of the body
4 portions of the Ethmoid bone
- Vertical perpendicular plate (forms the nasal septum)
- Horizontal cribriform plate (where olfactory nerves pass through)
- Labyrinths x2 (house ethmoid sinuses)
Palatine bone
Extends from the hard palate in the back of the mouth to the orbital floor
Lacrimal bone
Located along the medial wall of the orbit.
What is the orbit shaped as
A 4 sided pyramid with the apex of the pyramid posteriorly and slightly nasal.
What is the roof of the bony orbit formed by
Frontal bone and lesser wing of the sphenoid bone
The frontal bone makes up the majority of the roof
What is the floor of the bony orbit formed by
The floor is formed by the palatine bone, zygomatic bone, and maxillary bones.
What part of the bony cavity is the weakest and why
The floor is the weakest due to the infraorbital groove/canal in the maxillary bone and infraorbital foramen. There is also an air-filled maxillary sinus beneath the floor.
What is the lateral wall of the bony cavity formed by
Formed by the zygomatic and greater wing of the sphenoid bone. The rim or margin is the strongest area in the orbit because it is most exposed to possible injury.
What is the medial wall of the bony orbit formed by
Ethmoid, maxillary, lacrimal and body of the sphenoid bone
The majority of it is the ethmoid bone, which is the thinnest wall in the orbit.
The ethmoid bone is paper thin, which can also be referred to as
Lamina papyracea
If someone has an infection in their orbit, where did the infection likely spread from?
The infection likely spread from an infection in the ethmoid sinus and travel through the medial wall (thinnest wall).
Maxillary bone is apart of which two sides of the orbit
Medial and floor
The ___ bone is medial to the ethmoid bone
Lacrimal
What are the four paranasal sinuses and their purpose
- Frontal- superior to orbits
- Ethmoid- Medial and posterior to orbits
- Sphenoid- Medial and posterior to orbits
- Maxillary- inferior to orbits/under the floor
All connect to the nose
purpose to reduce weight of the skull and filter air we breathe.
Superior to inferior order of the 4 sinuses
FESM
- Frontal
- Ethmoid
- Sphenoid
- Maxillary
If patient complains of pressure behind eye
Could be due to sinusitis (infected air cavities)
What are the largest sinuses
Maxillary
