External Bones of the Cranium/Face

Incisive Fossa

A depression between the mental eminence and the incisive teeth.

External Occipital Protuberance

Also known as the E.O.P., it is located at the base of the skull, lying midway between the foramen magnum and the summit of the occipital bone.

Mental Eminence

Also known as the chin, it is closed by a symphysis (line of union). It is triangular and slightly concave at the base. At each end is a prominent tubercle (nodule or eminence), which together influence the form of the inferior border of the chin and jaw line.

Dental Prognathism

An oblique insertion of the teeth.

Zygomatic Arch

Comprised of the the zygomatic process of the temporal bone and the temporal process of the zygomatic bone. The widest part of the face is measured from one zygomatic arch to the other zygomatic arch.

Mastoid Process

Conical projection posterior and inferior to the mandibular fossa. It serves as a point of attachment for the sternocleidomastoid muscle.

Alveolar Process of the Maxilla

Contains 16 sockets for the teeth. The alveolar arch is formed by the alveolar process and the teeth it contains.

Central Plane of the Face

Covers the four incisor teeth

Mandibular Fossa

Depression in the temporal bone that articulates with the mandibular condyle.

Frontal Process of the Maxilla

Each extends superiorly and anteriorly beside a nasal bone to articulate with the frontal bone. Makes the medial margin of the eye socket.

External Auditory Meatus

Ear passage (meatus means "passageway"). The most accurate location of the ear. It is protected by a small flap of skin called the tragus.

Superior Nuchal Line

Extends laterally on both sides of the E.O.P. This is the origin of the occipitofrontalis muscle.

Medial Margin of the Eye Orbit

Formed by the frontal process of the maxilla, it ascends superiorly to join the frontal and nasal bones. It is the second most anterior portion of the eye orbit.

Occipital Bone

Forms the back and base of the skull and is the cradle for the brain. It articulates with C1 (the atlas), the parietal bones, and temporal bones. Its opening is the foramen magnum.

Frontal Bone

Forms the forehead and anterior portion of the roof of the skull. In infancy, the frontal bone is in two parts, right and left. In a few years, the two parts unite and the suture disappears, becoming one bone. The surface is convex and goes in two directions. The crown is the horizontal part and ascends superiorly until it articulates with the parietal bones. The forehead is the vertical portion. It extends from the eye sockets to the frontal eminences.

Palatine Process of the Maxilla

Forms the greater part of the roof of the mouth and floor of the nasal cavity.

Ramus of the Mandible

It is the vertical portion of the mandible. Each ramus is a wide, flat quadrilateral bone. The posterior border is the thicker border, smooth and rounded. The anterior border is thin and thickens as it goes downward. The angle of the mandible is where the ramus meets the body of the mandible.

Alveolar Prognathism

Lips move forward while the chin recedes.

Nasal Spine of the Maxilla

Located where the two bones join at the inferior margin of the nasal cavity to create a small, sharp spur. This creates the bony anatomical limit of the nose.

Inferior Margin of the Eye Orbit

Lower margin of the eye socket created by the cheekbone (zygomatic) and upper jaw (maxilla). On direct view, it is slightly concave and the medial end is superior to the lateral end. In profile or bilateral view, the inferior margin surface simulates an S-curve.

Parietal Bones

Makes up the superior portion of the sides and back of the cranium. Comprises two thirds of the roof of the skull and articulates with the temporal, occipital, and frontal bones. The parietal bones go in two directions, vertical at the sides and horizontal at the top. The parietal bone changes direction at the parietal eminences.

Mandibular Prognathism

Mandible juts out beyond the upper part of the face.

Maxillary Prognathism

Maxilla juts out beyond the upper part of the face.

Bones of the Cranium

Occipital bone (1) Parietal bones (2) Temporal bones (2) Frontal bone (1)

Alveolar Process of the Mandible

On the body of the mandible is the alveolar process, which holds the same 16 teeth as are on the upper jaw (maxilla). The teeth on the mandible are slightly within those of the upper jaw.

Prognathism

Projection of the jaw beyond the upper part of the face.

Eye Orbits

Quadrilateral, pyramid-shaped cavities located at the upper anterior part of the face. The margins are created by the frontal, zygomatic, and maxillary bones.

Line of the Temple

Slightly raised, curving ridge on the surface of the frontal bone that marks the end of the forehead and the beginning of the temporal region. It is continuous with the lateral line of the eye socket. The anterior region of the temporal cavity is created by the line of the temple and the lateral line of the eye socket.

Zygomatic Process of the Maxilla

Small, elevated, roughly triangular structure that juts forward to join the more prominent surface of the zygomatic bone.

Glabella

Small, smooth elevation that lies between the supercilliary arches and is located immediately above the root of the nose. The lateral margins of the glabella form a part of the orbital cavity and converge medially to meet the nasal bone.

Squamous Portion of the Temporal Bone

Smooth and convex, it extends medially and deep behind the zygomatic arch. Also considered the vertical portion of the bone, it is the anterior and superior portion of the bone.

Lateral Plane of the Face

Starts at each canine tooth and extends posteriorly and laterally (back and out) to, and including, the first molar.

Teeth

The (normal) mouth has a total of 32 teeth: Incisors (8) Canines (4) Premolars (8) Molars (12)

Mandible

The body is the horizontal portion and the ramus is the vertical portion. Direction changes at the angle where the body and ramus unite. There is a regressive change in the angle of the mandible as we age. At birth the angle is 175º. At 4 years old, the angle is 140º. The adult has an angle of 110-120º. In old age, the angle is 140º.

Temporal Cavity

The greatest depth of the temporal cavity is located posterior to the lateral rim of the eye socket.

Lateral Margin of the Eye Orbit

The lateral rim is formed by extensions of the frontal bone and zygomatic bone (zygomaticofrontal process). It has three characteristics: It lies on the side of the head. Its anterior edge dips concavely between the forehead and cheek. The edge of the lateral rim is posterior to the medial rim due to the bilateral curvature of the face. The most posterior of margins.

Infranasal Prognathism

The shaft of the nose inclines forward at an angle greater than normal.

Temporal Bones

The thinnest bones protecting the brain. Located behind the lateral borders of the eye sockets. The temporal bones create the inferior portion of the sides and base of the skull and articulate with the parietal and occipital bones.

Nasal Bones

The two bones lie inferiorly to the glabella and articulate with each other. They create the dome over the superior part of the nasal cavity. Along with the width of the nasal cavity, nasal bones are indicators of the general dimensions and mass of the nose.

Coronoid Process and Condyle

The two vertical portions of the mandible terminate superiorly in two processes: the coronoid process (anterior) and the condyle (posterior), which rests in the mandibular fossa of each temporal bone.

External Bones of the Face

There are seven surface bones of the face: Zygomatic Bones (2) Nasal Bones (2) Mandible (1) Maxilla (2)

Zygomatic Bones

They create the bony prominences of the cheeks and major portions of the inferior and lateral margins of the eye orbits. They are diamond shaped and have two directions, anterior and posterior. The center of the bone is where the change in direction takes place. From one center to the opposite center is the widest part of the central plane of the face.

Maxilla

Two bones that appear as one and articulate at the medial line below the nasal cavity. Pyramidal in form, each bone has a sinus.

Superciliary Arches

Two in number, they are located above the eyebrow arches.

Nasal Cavities

Two in number, they are orifices bounded by the margins of the body of the nasal bones and the maxilla. They are irregular in shape, like a pear, and extend from the base of the cranial vault to the roof of the mouth. The two cavities are separated by the septum. Since the bones supporting the septum are not symmetrical, the nose tends to bend to one side (usually to the left), which means that air passages are also unequal.

Supraorbital Margins

Two in number, they form the upper rim of the eye socket, inferior to the superciliary arches. The medial portion of the eye socket is rounded and the lateral portion is sharp (almond-shaped). The distance between the apex of each eye socket is used to determine the width of the medial plane of the face in Restoration.

Frontal Eminences

Two prominences on the upper part of the forehead. They can vary in size, may be asymmetrical, or may be continuous. The normal hairline lies just above the frontal eminences, on the crown portion of the frontal bone. Shading between the eminences on men with red will bring out shadow and shape to make them more prominent.

Horseshore Curvatures

Upper integumentary lip, cheeks, forehead, and the lower jaw.

Parietal Eminences

Where the parietal bones change direction. The distance between the two parietal eminences marks the widest portion of the skull.