Podcast
Questions and Answers
How many separate bones compose the human skull?
How many separate bones compose the human skull?
How many cranial bones are there?
How many cranial bones are there?
8
How many facial bones are present in the human skull?
How many facial bones are present in the human skull?
14
Which of the following bones are part of the orbits?
Which of the following bones are part of the orbits?
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The anterior aspect of facial bones includes the __________.
The anterior aspect of facial bones includes the __________.
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What is the purpose of the infraorbital line (IOML)?
What is the purpose of the infraorbital line (IOML)?
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Hyposthenic patients generally require support at the chest to elevate the cervical spine.
Hyposthenic patients generally require support at the chest to elevate the cervical spine.
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Match the following skull landmarks:
Match the following skull landmarks:
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Which projection demonstrates fractures and tumors in the cranium?
Which projection demonstrates fractures and tumors in the cranium?
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What is the CR angle for the PA projection?
What is the CR angle for the PA projection?
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Study Notes
Skull Anatomy
- Comprised of 22 bones separated into two groups:
- Cranial bones: 8 bones
- Facial bones: 14 bones
Cranial Bones
- Divided into two categories:
- Calvaria: The roof of the skull
- Floor: The base of the skull
Facial Bones
- Have anterior and lateral aspects
Orbits
- Each orbit is formed by seven bones:
- Frontal bone
- Sphenoid bone
- Ethmoid bone
- Maxilla bone
- Zygoma bone
- Lacrimal bone
- Palatine bone
Paranasal Sinuses
- Air-filled cavities within the skull
Skull Topography (Landmarks)
- Key landmarks include:
- Glabella
- Inner canthus
- Outer canthus
- Nasion
- Infraorbital margin
- Acanthion
- Gonion
- Mental point
- External acoustic meatus (EAM)
- Auricular point
- Top of ear attachment (TEA)
Radiographic Reference Lines
- Essential lines used in positioning and image interpretation:
- Orbitomeatal line (OML)
- Infraorbital line (IOML)
- Glabellomeatal line (GML)
- Interpupillary line (IPL)
- Acanthiomeatal line (AML)
- Mentomeatal line (MML)
Facial Lines
- Lines used for facial imaging:
- Supraorbital margin
- Interpupillary line
- Infraorbital margin
- Median sagittal plane
- Orbitomeatal baseline (OMBL)
General Body Position for Cranial Imaging
- Both recumbent (table) and upright positions are used
- Body type may influence positioning to prevent MSP tilting:
- Hyposthenic/asthenic patients require chest support
- Hypersthenic patients require head support
Essential Cranial Radiographic Projections
- Multiple projections are required to visualize bone structures:
- PA or PA axial (Caldwell method): Fractures, tumors, metastasis, Paget disease
- PA axial (Haas method): Frontal sinus and ethmoid sinuses
- AP axial: Base of skill, foramen magnum
- AP axial (Towne method): Fractures of the occipital bone
- Lateral: Right or left lateral to view skull profile, dorsal decubitus to view foramen magnum
- Submento vertical (SMV): Cranial base
- Anteroposterior (AP): Used for sinuses
- Posteroanterior (PA): Used for sinuses
PA or PA Axial (Caldwell Method) Positioning
- Patient: Seated erect or prone with MSP centered on midline of grid
- Part: Head resting on table or upright Bucky, OML perpendicular to IR, MSP perpendicular to IR
- Central Ray (CR): 15-degree caudal angle, exits at Nasion
- Collimation: 10 X 12 inches (24 X 30 cm)
- Lead Shields: Use to protect sensitive areas
PA or PA Axial (Caldwell Method) Evaluation Criteria
- Image quality: ID, date, side marker visible, proper collimation, entire cranium without rotation or tilt, symmetric petrous ridges, MSP aligned with collimated field, orbits filled by petrous ridges, petrous pyramids in lower third of orbits, three distinct tables of squamous bone, penetration of frontal bone
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Description
Explore the fascinating structure of the skull, which includes 22 bones divided into cranial and facial categories. This quiz covers the details of cranial and facial bones, the orbits, paranasal sinuses, and key landmarks, along with essential radiographic reference lines used in interpretation. Test your knowledge on this critical aspect of human anatomy!
