Oral anatomy terminology – Part 1

| April 18, 2012 | 0 Comments

Oral anatomy terminology – Part 1

Bony Elevations

Tubercle, Eminence, or Tuberosity. All of these words describe rather small, somewhat circular areas that are raised above the general level of the surrounding bone. An elevation of bone that falls in this category was specifically labeled as an eminence, a tuberosity, or a tubercle by the person who originally described it. There might be little to distinguish among these kinds of elevations as far as relative shape and size are concerned. They just have to be memorized according to the names they carry.
Ridge. A linear elevation on the surface of a bone.
Process. A very prominent projection from the central mass of a bone.
Condyle. A rounded, convex, smooth surface on one of the bones that forms a movable joint.

Bone Depressions and Channels

Fovea. A shallow, cup-shaped depression or pit.
Fossa. A more or less longitudinal, rounded depression in the surface of a bone.
Canal. A tubular channel through bone. The channel has at least one entrance and one exit hole. A canal’s entrance or exit hole is called a foramen.

Joints

Joints can be classified in a number of ways, one of the ways being the kind of movement that the structure of the joint allows. There are three kinds of joints found in the human skull.

Synarthrosis or Immovable Joint. Most bones of the skull are joined together along highly irregular, jigsaw puzzle-like lines called sutures. A suture joint is classified as a synarthrosis. Bones joined along suture lines in the skull are not totally immobile. Movement occurs, but it is very limited.
Ginglymodiarthrodial Joint. Literally defined, this is a freely movable, gliding, hinge joint. This relationship of one bone to another allows the greatest range of movement of any joint type. The term ginglymodiarthrodial specifically describes the temporomandibular joint that unites the lower jaw with the rest of the skull.
Ellipsoidal Joint. The type of joint that exists between the occipital bone of the skull and the first vertebra of the spinal column. There are two axes of motion at right angles to each other in this joint, and both axes pass through the same bone. This arrangement enables you to nod your head and rotate it from side-to-side.

Muscles

The mass of a muscle is composed of many individual cells that are capable of contracting. The force generated by the muscle as a whole depends on how many cells in the muscle’s mass are contracting at any given time. Muscles can pull (contract or shorten); they cannot push. A relaxed muscle cannot get any longer unless another contracting muscle somewhere else is forcing the extension. It should be obvious that a simple act like flexing and extending a finger requires at least two different muscles. The muscles used in flexing and extending a finger perform actions that are opposite one another. The performance of an action by one muscle that is opposed to the action of another is called antagonism. Besides having definite names, muscles are described in terms of:

Origin. A structure where a muscle attaches that moves the least when a muscle contracts.
Insertion. A structure where a muscle attaches that has the greater movement during contraction.
Action. The performance expected when a particular muscle contracts.

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Category: Oral Anatomy, WIKI

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