Chapter 20 Skull/Orbits
What landmark corresponds with the petrous ridges?
the TEA
What bone in the skull holds the auditory organs?
the temporal bone
If the patient cannot flex the neck to place the OML perpendicular to the IR for an AP Axial Townes projection, which line should be used instead?
IOML
What line should be placed parallel to the IR for the SMV?
IOML
A radiograph of a SMV projection of the cranium reveals that the mandibular condyles are projected into the petrous pyramids. What must be changed to produce an acceptable image?
Increase the extension of the skull.
What are the bones that make up the face?
Maxillae, Zygomatic, Palatine, Lacrimal, Mandible, Nasal inferior nasal concha
An average shaped skull with a 47 degree angle between the petrous pyramids and the MSP is classified as?
Mesocephalic
What is an average sized head called?
Mesocephalic.
What skull suture is located between the parietal bones?
Mid Sagittal Suture.
A radiograph of a lateral cranium reveals that the mentum was cut off from the bottom of the radiograph. A 10 x 12 image receptor was used and it was placed crosswise. What must be altered to repeat?
None, the mentum is not required on a cranium image.
In a PA projection of the skull, what line is perpendicular to the IR?
OML
Which line is placed perpendicular to the IR for the AP Axial Towne?
OML
What bone has condyles that articulate with the atlas of the c-spine.
Occipital
Which image demonstrates the petrous ridges in the orbits and the crista galli?
PA
What bones make up the floor?
R/L Temporal, ethmoid and sphenoid.
The bones of the cranium are joined together by fibrous joints called?
Sutures
The cranial bones are rigidly joined together by articulations called?
Sutures
The zygomatic arches are part of which bone?
Temporal
The petromastoid portion is a part of which bone?
Temporal Bone
The ethmoid notch is part of which cranial bone?
The Frontal bones.
For an SMV, the CR should always be perpedicular to the?
The IOML
Which of the following is true regarding the lateral projection of the skull?
The MSP is parallel to the IR and the IPL is perpendicular.
The pituitary gland is associated and protected by?
The Sphenoid Bone
The large aperture in the occipital bone, through which the medulla oblongata and spinal cord exit is called?
The foramen magnum.
What bones compose the bony orbit?
The frontal, sphenoid, ethmoid, palatine, lacrimal, zygomatic and maxillae
The suture located between the occiptal bone and the parietal bones is called?
The lambdoidal suture.
The posterior half of the base of the skull is formed by what bone?
The occipital bone?
What is demonstrated on the AP Acial Towne projection of the skull?
The open forman magmun, the occipital bone and the petrous pyramids.
The widest portion of the cranium is found at the level of?
The parietal tubercles.
What cranial bone contains the foramen ovale and spinosum?
The sphenoid.
The orbit is made up of ____ cranial bones and _____ facial bones.
Three and Four
How many bones make up the face?
14
What is the PA Axial Haas prejection CR angle?
25 degrees cephalic
Where is the CR centered for a lateral cranium?
3/4" anterior and 3/4" superior to the EAM.
If infraorbitomeatal line is placed perpendicular to the IR during an AP Axial Townes projection of the skull, how much is the central ray angled?
37 Degrees Caudad.
In a typically shaped head, the petrous pyramids project anteriorly and medially at what angle?
47 degrees
How many bones compose the bony orbit?
7
What is the difference in degrees between the IOML and the OML
7 to 8 degrees
How many bones make up the cranium?
8
What factor is most critical for demonstrating air-fluid levels?
A horizontal x-ray beam?
What cranial bone does not articulate with the parietal bone?
All but the ethmoid
Which skull suture is found between the frontal and parietal bones?
Coronal
What cranial bone contains the cribiform plate?
Ethmoid
How many cranial bones does the frontal bone articulate with?
Four, the r/l parietal bones, the ethmoid and the sphenoid.
What bones make up the Calvaria?
Frontal, R/L Parietal and Occipital
Name all of the cranial bones.
Frontal, sphenoid, ethmoid, R/L temporal, R/L parietal, occipital
What are wormian bones?
Wormian bones are a subset of the small intrasutural bones that lie between the cranial sutures formed by the bones of the skull vault. The title Wormian bones is reserved for abnormal intrasutural bones that are typically found around the lambdoid suture.
