Cranium Anatomy / Bony Markings

Frontal bone

Forms the forehead and anterior portion of the cranial vault

Parietal bones

Paired bones forming much of the sides and roof of the skull

Occipital bone

Forms the posterior and inferior portion of the skull

Temporal bones

Paired bones forming portions of the lateral skull

Sphenoid bone

Irregular bone forming part of the cranial floor; contains the sella turcica

Ethmoid bone

Bone located between the orbits; contributes to the nasal cavity and cranial floor

Sella turcica

Saddle-shaped depression in the sphenoid bone containing the pituitary gland

Foramen magnum

Large opening in the occipital bone through which the spinal cord passes

External auditory meatus / EAM

Opening of the ear canal; very important positioning landmark

Mastoid process

Projection of the temporal bone located behind the ear

Styloid process

Thin pointed projection extending inferiorly from the temporal bone

Zygomatic process

Projection involved in forming the zygomatic arch

Zygomatic arch

Bony arch on the lateral side of the skull

Mandibular condyle

Rounded superior portion of the mandible that articulates with the temporal bone

Mandibular ramus

Vertical portion of the mandible

Mandibular angle

Junction between the body and ramus of the mandible

Mental protuberance

Anterior prominence of the mandible forming the chin

Glabella

Smooth prominence between the eyebrows

Nasion

Junction of the frontal bone and nasal bones

Acanthion

Point at the base of the anterior nasal spine

Mental point

Most anterior point of the chin

Outer canthus

Outer corner of the eye; positioning landmark

Infraorbitomeatal line / IOML

Line from the infraorbital margin to the EAM

Orbitomeatal line / OML

Line from the outer canthus of the eye to the EAM

Interpupillary line / IPL

Line connecting the pupils

Midsagittal plane / MSP

Plane dividing the body into equal right and left halves

Coronal suture

Junction between the frontal and parietal bones

Sagittal suture

Junction between the two parietal bones

Lambdoid suture

Junction between the parietal and occipital bones

Squamosal suture

Junction between the temporal and parietal bone