RA Chapter 4, Skeletal anatomy

1.) *External Auditory Meatus:* ----> The opening/ passageway of the ear 2.) *Zygomatic Arch:* ----> The processes on the temporal and zygomatic bones; determines the widest part of the face. 3.) *Mandibular Fossa:* ---->The small oval depression on the zygomatic process of the temporal bone into which the condyle of the mandible articulates, just anterior to the ext. auditory meatus. 4.) *Mastoid Process:* ---->The rounded projection on the inferior portion of the temporal bones just posterior to the lobe of the ear.

*Anatomical structures to locate the ear:*

ZYGOMATIC BONES (2)

*Bones of the cheek;* the surface is on both the frontal and lateral planes of the face. ---->The surface is convex.

BODY: ----> Mental eminence ----> Alveolar processes ----> Incisive fossa RAMUS: ----> Coronoid process ----> Mandibular condyle ----> Mandibular notch ANGLE OF THE MANDIBLE

*Divisions of the mandible*

1.) Frontal eminences: ---->paired, prominences, 1 inch beneath the hairline. 2.) Supraorbital margins: ---->Superior rim of eye sockets 3.) Superciliary arches: ----> superior to the median ends of the eyebrows. 4.) Glabella: ----> bony prominence b/n the superciliary arches (brows).

*Eminences associated with the frontal bone:*

1. Vertical (forehead) 2. Horizontal (anterior portion of the crown)

*Surfaces of the frontal bone:*

1.) *Coronal:* -----> The junction b/n the frontal and parietal bones. 2.) *Lambdoidal:* -----> The junction b/n the parietal and occipital bones. 3.) *Squamosal:* -----> The junction b/n the parietal and temporal bones.

*The major suture of the cranium include:

*OCCIPITAL BONE (1)*

- Creates the lowest part of the back and base of the skull. - This bone serves as the cradle for the brain. - In the occipital bone, there is a large opening called the foramen magnum.

Foramen magnum (occipital bone)

-An opening in the occipital bone through which the spinal cord passes from the brain. ----> This is often utilized for the reattachment of decapitation by means of a dowel rod.

*TEMPORAL BONES (2)*

-Comprise the inferior portion of the sides and base of the cranium. -Their location is inferior to the parietal bones and anterior to the occipital bone.

Occipital protuberance

-The prominence at the center of the external surface of the occipital bone. ----> is a small jutting eminence in the occipital bone laying superior to the foramen magnum and may be used to find the foramen magnum.

Angle of mandible

A bony angle formed by the junction of the posterior edge of the ramus of the mandible and the inferior surface of the body of the mandible; ---->marks widest part of lower 1/3 of face.

Alveolar process (mandible and maxilla)

A bony ridge found on the inferior surface of the Maxilla and the superior surface of the Mandible which contains the sockets for the teeth.

MAXILLA (2)

A paired bone with several processes that form the skeletal base of most of the superior face, roof of the mouth, sides of the nasal cavity, and floor of the orbit

Mandibular notch

A relatively deep indentation between the condyle and coronoid process of the mandible

Mandibular condyle

A rounded prominence at the end of a bone-forming an articulation; the posterior process of the ramus of the mandible

Glabella

A single bony prominence of the frontal bone located between the superciliary arches in the inferior part of the frontal bone above the root of the nose.

BONES OF THE HEAD

Although different in size and form-the bony structures of the skull of all persons are similar enough to locate, with the exception of distortion or mutilation.

Sphenoid bone

An unpaired bone of the neurocranium. it is situated in the middle of the skull towards the front, in front of the basilar part of the occipital bone.

NASAL BONES (2)

Directly inferior to the glabella and forming a dome over the superior portion of the nasal cavity.

1.) Nasal spine of the maxilla 2.) Alveolar process 3.) Frontal process of maxilla

Eminences of the maxilla bone

7

How many bones does the infant skull have?

Zygomatic arch depression

One of the lesser concavities of the face located on the lateral portion of the cheek inferior to the zygomatic arch

Frontal eminences (frontal bone)

Paired, rounded, unmargined prominences of the frontal bone found approx. 1 inch beneath the normal hairline.

-being oval in shape, like an egg

THE SKULL CAN BE DESCRIBED AS WHAT?

1. nasal (2) 2. zygomatic (2) 3. Maxilla (2) 4. mandible (1)

THE SURFACE BONES OF FACE ARE AS FOLLOWS

1. occipital (1) 2. parietal (2) 3. temporal (2) 4. frontal (1)

THE SURFACE BONES OF THE CRANIUM ARE AS FOLLOWS:

*FRONTAL BONE (1)*

The anterior third of the cranium, forming the forehead and the anterior portion of the roof of the skull. -----> It is convex in shape, extending from the eyesockets to two bony prominences known as the Frontal eminences.

Coronoid process (mandible)

The anterior, non-articulating process of the ramus of the mandible which serves as the insertion for the temporalis muscle.

Frontal process of maxilla

The ascending part of the upper jaw which gradually protrudes as it rises beside the nasal bone to meet the frontal bone; *the ascending process of the upper jaw.*

Temporal cavity

The concave surface of the head overlying the temporal bone.

Incisive processes (mandible/maxilla)

The depression between the mental eminence and the mandibular incisors

1.) *MALE:* ----> Larger, heavier, the bone is thicker. ----> The areas of muscle attachment (temporal line) = has a more pronounced ridge. 2.) *FEMALE:* ----> Lighter, smaller, exhibits thinner walls and has less pronounced muscular ridges. ----> Overall, more round.

The difference b/n male and female craniums:

MANDIBLE (1)

The horseshoe-shaped bone forming the inferior jaw.

Superciliary arches (frontal bone)

The inferior part of the forehead just superior to the median ends of the brows.

Zygomaticofrontal Process

The lateral rim of the eye socket formed by a process of the frontal bone and a process of the zygomatic bone.

-Until puberty.

The male and female bones are similar until when?

Nasal cavity

The orifice in the bony face bounded by the margins of the nasal bones and the maxilla.

Zygomatic arch (temporal and zygomatic)

The process on the temporal and zygomatic bones; determines the widest part of the face. ----> projects from the lower part of the squama and is used to locate the correct position of the modeled ear..

Mastoid process (temporal)

The round projection on the temporal bone behind the ear/ on the inferior portion of the temporal bones, just posterior to the lobe of the ear.

Parietal eminence

The rounded peak of the external convexity of the parietal bones; determines the widest part of the cranium. -----> Located just above the posterior borders of the ears. -----> Helpful when attaching the modeled ear to the side of the cranium.

Nasal spine of the maxilla

The sharp, bony projection located medially at the inferior margin of the nasal cavity.

Supraorbital margins (frontal bone)

The superior rim of the eye socket.

Vertical (forehead) = frontal bone

The surface extends from the upper margin of the eye sockets to the level of the two frontal eminences. ----> the forehead is defined as that part of the face above the eyes.

Squama (temporal)

The vertical surface of the temporal bone. -----> smooth and convex; creates the widest part of the face and is used to locate the correct position of the modeled ear

Ethmoid bone

This bone is an anterior cranial bone located between the eyes. ---> It contributes to the medial wall of the orbit, the nasal cavity, and the nasal septum. ----> 3 parts: cribriform plate, ethmoidal labyrinth, and the perpendicular plate.

Horizontal (anterior portion of the crown) = frontal bone

This surface continues to ascend superiorly until it reaches the parietal bones. ---->The topmost part of the head (crown)

*PARIETAL BONES (2)*

Two bones that form the posterior 2/3 of the vault of the cranium and part of the *sides of the skull.* ---->create the greater part of the cranium and articulate with all other cranial bones.

Occipital condyles

Two rounded knobs on the occipital bone that form a joint with the first cervical vertebra (atlas).

Mental eminence (mandible)

a triangular projection on the inferior portion of the anterior mandible