Ear

Special Senses EAR

Learning objectives:
• Understand the bony and membranous labyrinths.
• In the vestibule be able to recognize and describe the function of the sensory end organs.
• Be able to recognize and describe the function of the components of the cochlea including the organ of Corti.
• Be able to distinguish the auditory parts of the inner ear from those of the vestibular system. What are their roles in hearing and balance?
• What are sensory hair cells?
• What is presently the only known "cure" for deafness besides hearing aids?

The Inner Ear:

bony labyrinth.
membranous labyrinth.


Hair Cells:

Sensory cells of the inner ear

Detect movement of endolymph

• acceleration (movement)
• gravity (position)
• sound (hearing)

The Cochlea:

Detection of Sound in the Inner Ear

Is there a difference in the innervation and function of the inner vs. outer hair cells?

The hair cells within the organ of Corti sense sound vibration. Is there any clinical significance to this other than hearing?

Vestibule:

• Maculae

two types of receptor cells (type I and type II hair cells)
supporting cells
afferent and efferent nerve endings.
• Type I hair cells are polygonal
• Type II hair cells are cylindrical
• The supporting cells are tall and columnar


Semicircular Canals:





In which of the following structures would you expect to find hairs cells without kinocilia?

a. Macula of utricle

b. Macula of saccule
c. Crista ampullaris of anterior semicircular duct
d. Crista ampullaris of lateral semicircular duct
e. Organ of Corti

In which of the following spaces would you expect to find endolymph?

a. Tympanic cavity
b. In the space between the bony labyrinth and membranous labyrinth
c. Scala media
d. Scala vestibuli
e. Scala tympani