Chapter 14 Definitions

Question 1

Define Accommodation

Answer 1

Adjustments of the eyes to view a near object: the pupils constrict, the eyes converge (adduct), and the lens becomes more convex. The optic nerve is the afferent (sensory) limb of the reflex, and the oculomotor nerve provides the efferent (motor) limb.

Question 2

Define Bell’s palsy

Answer 2

Paralysis or paresis of the muscles of facial expression on one side of the face; is caused by a lesion of the facial nerve.

Question 3

Define Cochlea

Answer 3

Snail shell–shaped organ, formed by a spiraling, fluid-filled tube. The cochlea contains a mechanism, the organ of Corti, which converts mechanical vibrations into the neural impulses that produce hearing.

Question 4

Define Conductive deafness

Answer 4

Hearing defect as a result of the inability to transmit vibrations in the outer or middle ear.

Question 5

Define Consensual reflex

Answer 5

Constriction of the pupil in the opposite eye when a bright light is shined into one eye. The optic nerve is the afferent (sensory) limb of the reflex, and the oculomotor nerve provides the efferent (motor) limb.

Question 6

Define Dysarthria

Answer 6

Speech disorder resulting from paralysis, incoordination, or spasticity of muscles used for speaking; due to upper or lower motor neuron lesions or muscle dysfunction. Comprehension of spoken language, writing, and reading are not affected by dysarthria. Three types of dysarthria may be distinguished: (1) spastic, as a result of damage to the upper motor neurons; and (2) flaccid, as a result of damage to the lower motor neurons; and (3) ataxic, as a result of cerebellar damage.

Question 7

Define Labyrinth

Answer 7

Inner ear that consists of the cochlea and vestibular apparatus.

Question 8

Define Main sensory nucleus of the trigeminal nerve

Answer 8

Site of synapse between first- and second-order discriminative touch neurons in the trigeminothalamic pathway.

Question 9

Define Medial longitudinal fasciculus (MLF)

Answer 9

Brainstem tract that coordinates head and eye movements by providing bilateral connections among vestibular, oculomotor, and accessory nerve nuclei and the superior colliculus.

Question 10

Define Medial geniculate body

Answer 10

Thalamic relay station for auditory information to the primary auditory cortex.

Question 11

Define Mesencephalic nucleus

Answer 11

Collection of cell bodies that process proprioceptive information from the face.

Question 12

Define Optic chiasm

Answer 12

Site where the optic nerve fibers from the nasal half of the retina cross the midline.

Question 13

Define Optic tract

Answer 13

Axons conveying visual information from the optic chiasm to the lateral geniculate body of the thalamus.

Question 14

Define Organ of Corti

Answer 14

Organ of hearing; is located within the cochlea.

Question 15

Define Pupillary reflex

Answer 15

Pupil constriction in the eye directly stimulated by a bright light. The optic nerve is the afferent (sensory) limb of the reflex, and the oculomotor nerve provides the efferent (motor) limb.

Question 16

Define Sensorineural deafness

Answer 16

Hearing defect as a result of damage to the receptor cells or the cochlear nerve.

Question 17

Define Spinal trigeminal nucleus

Answer 17

Site of synapse between first- and second-order neurons conveying nociceptive information from the face; it located in the lower pons and medulla.

Question 18

Define Trigeminal neuralgia

Answer 18

Trigeminal nerve dysfunction that produces severe, sharp, stabbing pain in the distribution of one or more branches of the
trigeminal nerve. Pain is triggered by normally innocuous noxious, including eating, talking, or touching the face. The pain begins and ends abruptly, lasts less than 2 minutes, and is not associated with sensory loss.