TMJ & Mastication

TMJ

temporomandibular joint; articulation between the articular fossa of the temporal bone of the skull with the condyle of the mandible

TMJD

Temporal mandibular joint dysfunction

Frontal Bone

forms the forehead

Parietal Bone

either of two skull bones between the frontal and occipital bones and forming the top and sides of the cranium

Occipital Bone

The bone that protrudes at the base of the skull is the

Temporal Bone

bone that forms parts of the side of the skull and floor of the cranial activity. There is a right and left temporal bone.

Sphenoid Bone

Located at the lateral base of the skull anterior to the temporal bone.

Zygomatic Bone

cheekbone

Mandible

Jaw bone

Maxilla

upper jaw bone

Nasal Bone

Bridge of nose

Hyoid Bone

bone that is suspended in the mid neck region and provides a moveable base for the tongue

Mastoid Process

round projection on the temporal bone behind the ear

External Auditory Meatus

the opening of the exernal auditory canal of the outer ear

Styloid Process of the Temporal Bone

A slender projection positioned down and forward from the temporal bone on the inferior surface

Thyroid Cartilage

The largest of the 9 cartilages of the larynx; AKA Adam's apple; lies just inferior to the hyoid bon at about the level of C3-C4

TMJ Depression

Opening the mouth

TMJ Elevation

Closing the mouth

TMJ Lateral Deviation

Movement of the mandible from right to left and left to right sides

TMJ Protrusion

moving the mandible anteriorly

TMJ Retrustion

moving the mandible posteriorly

Resting Position of the Mandible

lips closed, teeth are several millimeters apart

TMJ prime movers

all innervated by the Trigeminal Nerve (cranial nerve V); temporalis, masseter, medial pterygoid, lateral pterygoid

Temporalis action

Bilateral: elevation of the mandible (closing the mouth); retrusion of the mandible

Unilateral: ipsilateral lateral deviation

Temporalis location

originates on the temporal fossa; inserts on the coronoid process and ramus of the mandible

Temporalis innervation

Trigeminal Nerve (cranial nerve V);

Masseter action

Bilateral: elevation of the mandible (closing the mouth);

Unilateral: ipsilateral lateral deviation

Masseter location

Located between the zygomatic arch of the temporal bone and the mandible

Masseter innervation

Trigeminal Nerve (cranial nerve V);

Medial Pterygoid action

Bilateral: elevation of the mandible (closing the mouth); protrusion of the mandible

Unilateral: contralateral lateral deviation

Medial Pterygoid location

internal angle of the ramus of the mandible

Medial Pterygoid innervation

Trigeminal Nerve (cranial nerve V);

Lateral Pterygoid action

Bilateral: depression of the mandible (opening the mouth); protrusion of the mandible

Unilateral: contralateral lateral deviation

Lateral Pterygoid location

inside the mouth near the condyle of the mandible

Lateral Pterygoid innervation

Trigeminal Nerve (cranial nerve V);

Suprahyoid Muscles

Mylohoid, Geniohyoid; Stylohyoid, Digastric; a group of muscles located superior to the hyoid bone; they connect the hyoid bone to the skull; their primary function is to elevate the hyoid and they also assist in mandibular depression (when the infrahyoid muscles stabilize the hyoid bone)

Infrahyoid Muscles

Sternohyoid, Sternothyroid, Thyrohyoid, Omohyoid; a group of muscles located inferior to the hyoid bone and function to depress the hyoid bone. They also stabilize the hyoid bone, thereby allowing the suprahyoid muscles to depress the mandible