Ch 20 - Skull Flashcards
Rests on the superior aspect of the vertebral columns; composed of 22 separate bones divided into 2 groups
Skull
Bones that form a protective house for the brain
Cranial
2 groups the of cranial bones
Calvaria Floor
Bones that provide structure, shape and support the face and form protective housing for the upper ends of the respiratory and digestive tracts and with several of the cranial bones, form the orbital sockets for protection of the organs of sight
Facial
8 cranial bones
(Calvaria) Frontal 1 Occipital 1 Right parietal 1 Left parietal 1 (Floor) Ethmoid 1 Sphenoid 1 Right temporal 1 Left temporal 1
4 calvaria bones
Frontal 1 Occipital 1 Right parietal 1 Left parietal 1
4 floor bones
Ethmoid 1 Sphenoid 1 Right temporal 1 Left temporal 1
14 facial bones
Nasal (right and left) 2 Lacrimal (right and left) 2 Maxillary (right and left) 2 Zygomatic (right and left) 2 Palatine (right and left) 2 Inferior nasal conchae (right and left) 2 Vomer 1 Mandible 1
Fibrous joints that connect the bones of the skull (except mandible)
Sutures
With what bone(s) does the sphenoid bone articulate?
Sphenoid bone articulates with all other cranial bones
4 sutures
Coronal Sagittal Squamosal Lambdoidal
Suture between frontal and parietal bones
Coronal
Suture on top of head between two parietal bones
Sagittal
Suture between temporal bone and parietal bones
Squamosal
Suture between occipital and parietal bones
Lamboidal
Junction of coronal and sagittal sutures
Bregma
Junction of sagittal and lambdoidal sutures
Lambda
Areas of incomplete ossification in infant skulls (ex: soft spots)
Fontanels
At what age is adult cranial size usually achieved?
12
At what angle does a mesocephalic skull’s petrous pyramids project anteriorly and medially from the midsagittal plane?
47 degree angle
Typical skull
Mesocephalic
At what angle does a brachycephalic skull’s petrous pyramids project anteriorly and medially from the midsagittal plane?
54 degree angle
At what angle does a dolichocephalic skull’s petrous pyramids project anteriorly and medially from the midsagittal plane?
40 degree angle
Skull that is short from front to back and broad from side to side
Brachycephalic
3 regions cranial floor is internally divided into
Anterior cranial fossa Middle cranial fossa Posterior cranial fossa
Extends from the anterior frontal bone to the lesser wings of the sphenoid; associated mainly with the frontal lobes of the cerebrum
Anterior cranial fossa
Accommodates the temporal lobes and associated nuerovascular structures and extends from the lesser wings of the sphenoid bone to the apices of petrous portions of the temporal bones
Middle cranial fossa
Deep depression posterior to the petrous portions of the temporal bones, protects cerebellum, pons and medulla oblongata
Posterior cranial fossa
Vertical portion of frontal bone, forms forehead and anterior part of cranial vault
Frontal squama
Has vertical portion (frontal squama) and horizontal portions
Frontal bone
3 things frontal bone forms
Orbital plates Part of the roof of the naval cavity Greater part of anterior cranial fossa
Roofs of the orbits
Orbital plates
6 landmarks on the frontal bone
Frontal eminences Supraorbital margins Supraciliary arches Supraorbital foramina Glabella Nasal spine
Rounded elevations on each side of the midsagittal plane of the superior portion of the squama of the frontal bone
Frontal eminences
Two arched ridges below the frontal eminences and just above the supraorbital margins that correspond in position to the eyebrows
Supraciliary arches
Two openings for nerves and blood vessels in the center of the supraorbital margin (frontal bone)
Supraorbital foramina
Smooth elevation between the superciliary arches of the frontal bone used as centering mark
Glabella
Small inferior projection of bone at the anterior edge of the ethmoidal notch of the frontal bone; superior-most component of the bony nasal septum
Nasal spine
Situated between the two tables of the squama of the frontal bone on each side of the midsagittal plane These irregularly shaped sinuses are separated by a bony wall which may be incomplete and usually deviates from the midline
Frontal sinuses
3 things the frontal squama articulates with
Parietal bones at the coronal suture Greater wing of these sphenoid bone at the frontosphenoidal suture Nasal bones at the frontonasal suture
Midpoint of the frontonasal suture
Nasion
5 things the frontal bone articulates with
Right and left parietals Sphenoid Ethmoid Nasal bones Zygoma
Small, cube-shaped bone at the midsagittal plane located between the orbits
Ethmoid bone
3 things the ethmoid bone consists of
Horizontal plate Vertical plate Labyrinths
4 things the ethmoid bone forms
Part of anterior cranial fossa Nasal cavity Orbital walls Bony nasal septum
Horizontal portion of the ethmoid bone that is received into the ethmoidal notch of the frontal bone; perforated by many foramina for the transmission of olfactory nerves
Cribriform plate
Thick, conical process on cribriform plate of the ethmoid bone that projects superiorly from its anterior midline and serves as the anterior attachment for the falx cerebri
Crista galli
Vertical portion of the ethmoid bone; thin flat bone that projects inferiorly from the inferior surface of the cribriform plate and, with the nasal spine, forms the superior portion of the bony septum of the nose
Perpendicular plate
Two light, spongy lateral masses of the ethmoid bone Contain ethmoid sinuses or air cells
Labyrinths
3 groups cells of each side of the ethmoid sinuses are divided into in the labyrinths
Anterior Middle Posterior ethmoidal air cells
Two thin, scroll shaped processes the project inferiorly from each medial wall of the labyrinths of the ethmoid bone
Superior and middle nasal conchae
5 bones the ethmoid bone articulates with
Frontal Sphenoid Lacrimal Maxilla Vomer
Two square-shaped bones that have a convex external surface and a concave internal surface Form a large portion of the sides of the cranium and the posterior portion of the cranial roof by their articulation with each other at the sagittal suture in the MSP
Parietal bones
Prominent bulge on each parietal bone near the center of external surface of each bone Point where the width of the skull should be measured to set technique because it’s the widest point of the head
Parietal eminence
5 bones the parietal bones articulate with
With each other at sagittal suture in MSP Frontal Temporal Occipital Sphenoid
Irregular, wedge-shaped bone that resembles a bat with its wings extended (somewhat) Located in base of cranium anterior to temporal bones and basilar portion of occipital Body contains two sphenoid sinuses (incompletely separated by a median septum) and anterior surface forms posterior bony wall of nasal cavity
Sphenoid bone
7 things the sphenoid bone consists of
Body 2 lesser wings 2 greater wings 2 pterygoid process
Deep depression (saddle) on superior surface of body of the sphenoid bone that houses pituitary gland
Sella turcica
Where is the sella turcica located?
Located on sphenoid bone in MSP of cranium 3/4 in (1.9 cm) anterior and superior to the level of the external acoustic meatus (EAM)
Anterior border of sella of the sphenoid
Tuberculum sellae
Posterior border of sella of the sphenoid that bears the posterior clinoid processes
Dorsum sellae