Skull- procedures
What are the parts of the parietal bone?
2 squama and one eminence
cranial fossae
A cranial fossa is formed by the floor of the cranial cavity. A cranial fossa is formed by the floor of the cranial cavity.There are three distinct cranial fossae: anterior, middle, and posterior
Landmark: mentum/mental point/chin
Chin
Landmark: EAM (external acoustic meatus)
Opening of the external ear canal
lambdoid suture
between parietal bones and occipital bone
What sections of the frontal bone are there?
frontal: squama; glabella; supraorbital margin, groove, & foramina; superciliary arches, orbital plate, frontal sinus
supraorbital margin of frontal bone
A thickening over the eye.
Landmark: Lambda
Posterior end
What bones form the sphenoid
body; sinus; greater & lesser wings; sella turcica, tuberculum & dorsum sella, anterior & posterior clinoids; pterygoid processes; optic foramen, superior & inferior orbital fissures; foramen ovale, spinosum, rotundum.
What bones form occipital bone?
occipital: squama; inion; internal occipital protuberance; foramen magnum; basilar portion, clivus; condyles; jugular foramen.
Ethmoid Bone - Horizontal Portion
Also called cribiform plate
Landmark: Bregma
Anterior end of saggital suture
squamous suture
Between parietal and temporal bones
frontal sinus of the frontal bone
Cavity within the bone that is lined with muscosa and open to the exterior. It lightens the skull and alters vocal quality
mesocephalic skull
Considered the "typical skull". Petrous ridge forms 47 degree angle with MSP. The mesocephalic skull is 75-80% of its length
Frontal bone
Contributes to the formation of the forehead and the superior part of each orbit. Two parts; squamous or vertical portion and the orbital or horizontal portion. Forms the superior part of the orbit. Articulates with 4 bones; right and left parietals, sphenoid, and ethmoid.
sphenoid bone
Froms the anchor for the other seven cranial bones. Articulates with all seven cranial bones because it is in the center
identify the four bones composing the calvarium or "skull cap"
Frontal, Right parietal, Left Parietal, Occipital
R/L temporal bones
House delicate organs of hearing and balance. Situating between the greater wing of the sphenoid bone anteriorly and the occipital bone. Articulates with three cranial bones; parietal. occipital, and sphenoid. Also articulates with 2 facial bones.
Occipital bone
Inferoposterior portion of the calvarium is formed by the single occipital bone. Presents squamous portion. Articulates with six bones; two temporals, sphenoid, and atlas.
R/L parietal bones
Lateral walls of cranium and part of the roof are formed by the two parietal bones. Are roughly squared and have a concave internal surface. Articlates with each 5 bones; frontal, occipital, temporal, sphenoid, and opposite parietal
Ethmoid bone
Lies between nasal and sphenoid bones Forms most of the medial bony region between the nasal cavity and orbits. Articulates with 2 bones; frontal and sphenoid. Also articulates with 11 facial bones
meningeal grooves
One of several depressions on the internal surface of the cranial bones where blood vessels follow the meningeal and osseous structures of the skull.
List the eight cranial bones
R/L parietal bones, Frontal bone, Occipital bone, R/L temporal bones, sphenoid, ethmoid
Right Mastoid Fontanel
Right asterion
Right sphenoid fontanel
Right pterion
the four making up the "floor" of the cranium.
Right temporal, left temporal, sphenoid, ethmoid
Landmark: TEA (top of ear attachment)
Superior portion of the auricle where the ear attaches to the head. The TEA is an important landmark, as it is at the same level as the petrous ridges are internally
Identify the external landmarks which correspond to the level of the floor of the anterior cranium
Supraorbital groove (SOG)- just above the eyebrows, a ridge/arch. If you move your finger from your eyebrow to your forehead, you will feel a depression or groove. This is the SOG.
Localizing lines: GML (glabellomeatal line)
This is a line between the glabella and the EAM
Localizing lines: GAL (glabelloalveolar line)
This is a line between the glabella and the alveolar processes of the maxilla/mandible. Alveolar processes are the spots where the teeth go into the maxilla or mandible.
Localizing line: IOML (Reid's baseline) (Infraorbitomeatal line)
This is a line between the inferior orbital margin and the EAM
Localizing lines: MML (Mentomeatal line)
This is a line between the mentum of the mandible and the EAM.
Localizing lines: OML (orbitomeatal line)
This is a line between the outer canthus and the EAM
Localizing lines: AML (acanthiomeatal line)
This is the line between the acanthion and the EAM.
orbital plate of the frontal bone
This section of the Frontal bone forms the upper portion of the eye socket.
Identify the external landmarks at the level of the petrous ridge
Top of ear attachment (TEA)- Superior portion of the auricle where the ear attaches to the head. The TEA is an important landmark, as it is at the same level as the petrous ridges are internally.
Localizing lines: IPL (interpupillary, interorbital line)
an imaginary line drawn between the pupils. This line is frequently used for lateral positions of the skull and facial bones.
Temporal bone (petrous portion)
anterior and inferior walls of external auditory meatus
superciliary arches of the frontal bone
arches lie deep to the eyebrows
Temporal bone (zygomatic process)
articulates with zygomatic bone to form zygomatic arch
ethmoid bone: crista galli
attachment for falx cerebri
temporal bone: styloid process
attachment for muscles of the tongue, throat, and hyoid bone
posterior fontanel
back soft spot on fetal skull between parietal and occipital bone
anterior fontanel
closes at 12-18 months
Landmark: inner/outer canthus
either corner of the eye where the upper and lower eyelids meet
What sections of bone are apart of the ethmoid bone?
ethmoid: horizontal portion; crista galli, perpendicular plate; lateral masses (labyrinth); superior & middle nasal conchae (turbinates); ethmoid sinuses;
Cranial sutures are classified as being _____ joints.
fibrous, synarthrodial
Sphenoid bone: lesser wings
form part of the floor of the anterior cranial fossa and part of the orbit
Ethmoid Bone (perpendicular plate)
forms superior part of nasal septum
Squamous frontal bone
forms the forehead
Landmark: Vertex
highest point of the head
sphenoid bone: sella turcica
holds pituitary gland
sphenoid bone: foramen ovale
hole on the side of saddle section (large middle hole to saddle)
temporal bone: carotid canal
internal carotid artery
Landmark: Nasion
junction of the two nasal bones and the frontal bone
left mastoid fontanel
left asterion
Left sphenoid fontanel
left pterion
Landmark: Acanthion
midline point of juncton of the upper lip and nasal septum. Where nose and upper lip meet
Sphenoid bone: greater wings
project laterally from the sphenoid body, forming parts of the middle cranial fossa and the orbits
Landmark: Gonion/angle
refers to the lower posterior angle on each side of the jaw or mandible
saggital suture
separates the left and right parietal bone
brachycephalic skull
short and wide. Its width is 80% or more of its length. In this type of skull, the petrous ridges form an angle of more than 47 degrees from MSP (usually 54 degrees)
(sphenoid bone) optic foramen
small hole into eye at saddle
Landmark: Tragus
small, liplike structure located anterior to the EAM
Landmark: glabella
smooth, slightly raised trian
What parts of the temporal bone are there?
temporal: (2) squama; mastoid portion, process, air cells; tympanic portion; petous portion; zygomatic process; mandibular fossa; EAM; IAM; styloid, carotid canal & foramen.
Temporal Bone: Mandibular Fossa
the depression in the temporal bone that articulates with the mandible
coronal suture
the suture between the parietal and frontal bones of the skull
Landmark: alveolar process
thickened ridge of bone that contains the tooth sockets on the jaw bones that hold teeth
glabella of frontal bone
unibrow
Landmark: auricle/pinna
visible portion of the external ear
