IV.C.5 Head: Internal Ear Page 1 of 2

Objectives:

4.5.1 Identify the components of the organs of balance.

4.5.2 Identify the relationship of the semicircular canals with the cochlea.

Assigned Readings:

Moore's COA: Pages 974-985. See the blue boxes on page 988 for clinical correlations. See the yellow box on page 989 for "The Bottom Line."

Neuroanatomy page: 62, 538.

Step 1: Begin with the right side of the cadaver's head.

The organs of balance are encased in a bony labrynth.

	What sensory nerve innervates the organs of balance?
The vestibular branch of the vestibulocohlear nerve CN VIII. They are composed of three semicircular canals. These are the anterior, posterior and lateral semicircular canals.
	What is their orientation to one another?
They are at right angles to one another.
	What is the significance of this orientation?
The three planes that are created give our brains a sense of orientation of the x, y, and z axes.