Lecture 26 - Cranial nerve nuclei Flashcards
What are the four major components of the brainstem?
Midbrain, pons, cerebellum, and medulla
What CN nuclei are in the midbrain?
CN III and IV
What CN nuclei are in the pons?
CN V and VI
What CN nuclei are in the medulla?
CN VII, VIII, IX, X, XI, and XII
What is the basic function of the brainstem?
Conduit between brain and spinal cord, motor and sensory tracts carried here
What dysfunction is caused by CN I lesion?
Dysosmia
What dysfunction is caused by CN III lesion?
Anisocoria, miosis, or mydriasis (also SNS lesion)
What dysfunction is caused by CN III, VI, and (IV)
Strabismus
What dysfunction is caused by CN IX or X?
Dysphagia
What nerves are involved in the corneal blink reflex?
CN V1 and VII
What is dysosmia?
Any qualitative or distortion of the perception of smell
What can cause dysosmia?
Mechanical damage to area, encephalitis in canines, disease of the cribiriform plate
What would you do to test for dysosmia?
Ability to find food
What is anisocoria?
Unequal sized pupils
What is miosis?
Pathological constriction of the pupil
What would miosis mean?
Possible disruption of SNS to eye
What is mydriasis?
Pathological dilated pupils
What could caused mydriasis?
Possible disruption of PNS to eye
Where do the optic nerve fibers synapes?
Pretectal area
Where do pretectal nerve fibers synapse?
E-W nuclei
Where do the E-W nuclei synapse?
Ciliary ganglia
Where do ciliary ganglia nerves synapse?
Pupillary sphincter muscle
What is the direct light reflex?
Pupils constrict in eye, stimulated by light
What is the consensual light reflex?
Pupil contricts in contralateral eye
Where do the nerve fibers involved in the pupillary dilation reflex come from?
Posterior hypothalamus synapse at C8 to T1 lateral horn
Where do the preganglionic SNS fiber synapse in the PD reflex?
IN superior portion of sympathetic trunk
Where do the postganglionic SNS fiber synapse in PD reflex?
Pupillary dilator muscle
What is a strabismus?
Two eyes do not line up in the same direction, and do not look at the same object at the same time
What strabismus is caused by a lesion of CN III or midbrain?
Ventrolateral strabismus
What is the cause of a ventrolateral strabismus?
Dorsal oblique and lateral rectus are unopposed
What strabismus is caused by a lesion of IV or midbrain?
Dorsomedial strabismus
What is the cause of a dorsomedial strabismus?
Ventral oblique unopposed
What strabismus is caused by a lesion of CN IV or rostral midbrain?
Medial strabismus
What is the cause of a medial strabismus?
Medial rectus is unopposed
What is dysphagia?
Trouble swallowing
What can cause dysphagia?
Lesion of the glossopharyngeal and vagus nerve or caudal medulla oblongata
How do you test for dysphagia?
Hyoid pinch or cotton swab to back of throat
What is the sensory component of the blink reflex?
CN V1
What is the motor component of the blink reflex?
CN VII
How do you test for a deficit in the blink reflex?
Touching the medial and lateral canthi or eyelid
