Procedures II: Quiz 4 (Skull Anatomy and Radiography)

petrous pyramids

(temporal bone) project anteriorly and toward the midline from the area of the EAM

PA Caldwell Skull

*SID* 40" *IR Size* 24 x 30 cm LW *Tube angle* 15 degrees caudal *CR* Center at the nasion (nose bridge) *Collimation* Collimate to both sides *Positioning* Place patient's forehead and nose against IR with OML and MSP perpendicular to IR *Breathing* Suspend *Additional Comments* Mark correct side

AP Axial (Towne Method) skull

*SID* 40" *IR Size* 24 x 30 cm LW *Tube angle* 30 degrees caudal to OML *CR* Center 2.5" above glabella *Collimation* Collimate on 4 sides *Positioning* Have patient tuck chin to place OML and MSP perpendicular to IR *Breathing* Suspend *Additional Comments* Place a small sponge behind patients head to help tuck chin. Angle 37 degrees if IOML is perpendicular to IR

Haas (Reverse Townes) Skull

*SID* 40" *IR Size* 24x30 cm LW *Tube Angle* 25 degrees cephalic to OML *CR* Center 1.5" below inion (between EAM) *Collimation* Four sides *Positioning* PA: Have patient tuck chin to place OML and MSP perpendicular to IR *Breathing* Suspend *Additional Comments* Angle 32 degrees if IOML is perpendicular to IR

PA skull

*SID* 40" *IR Size* 24x30 cm LW *Tube angle* None *CR* Center to glabella (between eyebrows) *Collimation* Collimate on 4 sides *Positioning* Place pt's forehead and nose against IR with OML and MSP perpendicular to IR *Breathing* Suspend *Additional Comments* The patient's arms and hands are by their head for support if done on the table. Can also be done AP. Mark correct side.

Lateral skull

*SID* 40" *IR size* 24 x 30 cm CW *Tube angle* None *CR* Center 2" above EAM (may need to move pt. anterior/posterior to ensure all of skull is in light field) *Collimation* Collimate on 4 sides *Positioning* Oblique pt. & place affected side against IR in a true lateral position. Interpupillary line is perpendicular to IR. MSP is parallel to IR. IOML is perpendicular to edge of IR. *Breathing* Suspend *Additional Comments* Use sponge under chin or head to prevent tilt

PA skull positioning accuracy

1. Petrous ridges must fill the orbits 2. Distance from outer canthus and lateral margin of skull must be equal on both sides

How many facial bones are there?

14

At what age do all sinuses become aerated?

17 or 18

floor of the cranium

2 Temporals Sphenoid Ethmoid

What are the facial bones?

2 maxillae 2 zygomas 2 lacrimals 2 nasal bones 2 inferior nasal conchae 2 palatine bones vomer mandible (My Mouth's Palate Never Liked Zucchini In Vinegar)

What angle does a mesocephalic head form?

47

What degree of difference is there between OML and MML?

53 degrees

What angle does a brachycephalic skull form?

54

How many bones of the orbit are there?

7

What degree of difference is there between the OML and IOML?

7 degrees

How many cranial bones are there?

8

What degree of difference is there between the GML and OML?

8 degree

AML

Acanthiomeatal line; line between mustache area and ear hole

Why are supine positions not ideal for viewing sinuses?

Because supine will cause all the sinus fluid to drain and you won't get proper idea of air/fluid levels

tragus

Cartilaginous projection anterior to the external opening of the ear

What are the bones of the orbit?

Cranial -frontal -sphenoid -ethmoid Facial bones -maxilla -zygoma -lacrimal -palatine (My Little Eye Sits Facing Zac Posen)

Calvarium (skull cap)

Frontal 2 Parietals Occipital

brachycephalic

Having a short, wide head (Big=Brachy=54 deg) Petrous pyramids form a 54 degree angle (>47) to the midline of body

interpupillary line

Line between the pupils, used to ensure true lateral position of skull

dolichocephalic

Long narrow head 40 degree angle (<47) from petrous pyramids to midline

mesocephalic

Medium sized head 47 degree angle between petrous pyramids and midline

inion

Most prominent point of external occipital protuberance

Lateral Sella Turcica

Same as a lateral skull but center 3/4" anterior and superior to EAM

Towne's sella turcica

Same as for a skull but cone down (make collimation smaller)

supraorbital groove

Slight depression above each eyebrow

superciliary ridge (arch)

The prominent ridge of bone beneath each eyebrow

supraorbital margin

The superior rim of the eye socket located on the frontal bone.

gonion

angle of mandible

occiput

back part of the skull

glabella

between eyebrows

nasion

bridge of nose; where nose meets forehead

mentum

chin

Ethmoid sinus

consists of many air cells within the labrynth

bony nasal septum

consists of perpendicular plate of the ethmoid and the vomer

If the patient must be supine, how can you view sinuses?

decubitus x-ray

sella turcica

depression in the sphenoid bone where the pituitary gland is located

skull tilt

ear to shoulder

EAM

external auditory/acoustic meatus; ear hole

auricle

external portion of the ear

What are the 8 cranial bones?

frontal, 2 parietal, 2 temporal, occipital, sphenoid, ethmoid (STEP OF 6)

GML

glabellomeatal line; line from eyebrow to earhole

IOML (Reid's Base Line)

infraorbitalmeatal line; line from just under eye to ear hole

inner canthus

inner corner of eye

What is the best position for viewing sinuses?

lateral

skull rotation

looking left and right

infraorbital margin

lower rim of orbit

paranasal sinuses

maxillary, frontal, ethmoid, sphenoid

MML

mentomeatal line; line between chin and ear hole

OML

orbitomeatal line; line from eyes to ear hole

outer canthus

outer corner of eye

dorsum sellae

ridge of bone at posterior edge of sella turcica (sphenoid)

sphenoid sinus

sinus above and behind the nose; 1 or 2 sinuses

TEA

top of ear attachment

vertex

top of head

maxillary sinus

two sinuses; AKA antra of highmore Located near cheekbones

frontal sinus

usually 2 sinuses; become aerated at age 6 Located on forehead

acanthion

where the nose and upper lip meet, "mustache"

lateral skull positioning accuracy

1. Orbital plates must be superimposed 2. Angles of the mandible must be superimposed

routine skull

1. PA 2. AP Axial/Towne Method 3. Both Laterals -all skull radiography best done upright

Optional skull positions

1. PA Caldwell 2. Haas (Reverse Towne's) 3. Sella Turcica Positioning -Lateral -Towne's

AP Axial (Towne Method) Skull positioning accuracy

1. Petrous ridges must be symmetrical 2. Dorsum sellae must be found within the foramen magnum

Haas (Reverse Townes) Skull positioning accuracy

1. Petrous ridges must be symmetrical 2. Dorsum sellae must be found within the foramen magnum

PA Caldwell skull positioning accuracy

1. Petrous ridges must fill the lower 1/3 of orbits 2. Distance from outer canthus and lateral margin of skull must be equal on both sides