Section 5, Part 3 Flashcards
What terminates in the gracile nucleus?
Dorsal column axons of the gracile fasciculus
What are arcuate fibers?
They are axons of the gracile and cuneate nuclei neurons that cross the midline and carry somatosensory and proprioceptive information from the upper and lower half of the body
Do arcuate fibers cross to the opposite side?
Yes they decussate
After arcuate fibers cross the midline, what are they renamed?
Medial Lemniscus
Do fibers ascend the medial lemniscus in a somatotopic fashion?
Yes they do
If you were to lesion the medial lemniscus…what would the symptoms be?
Epicritic deficits on the opposite side of the body
WHen does somatosensory information from the face join the medial lemniscus?
The pons
If you were to lesion the anterolateral tract in the medulla….what would the symptoms be?
loss of pain and temperature on the opposite side of teh body
When the anterolateral tract in the medulla is lesioned, what other structure is usually affected as well?
Spinal tract of nucleus V….so you get pain and temp loos on the same side of the head
AND
Vestibular area/ inferior cerebellar peduncle…so there are sometimes cerebellar and vestibular symptoms
what is the function of the inferior cerebellar peduncle?
Major cerebellar related pathway in the medulla that carries mainly afferent information to the cerebellum from several locations
What is the accessory cuneate nucleus?
A pateral protrusion of the cuneate nucleus that receives cuneate fasciculus axons carrying proprioceptive information from the upper half of the body
Where can the inferior olivary nucleus/ complex be found?
The ventrolateral portion of the open medulla and the rostral part of the closed medulla
What is the function of the inferior olivary nucleus?
It is a cerebellar relay
Where does the input of the inferior olivary nucleus come from?
The red nucleus, spinal cord and cerebral cortex
Where does the inferior olivary nucleus send axons to?
It sends axons to the inferior cerebellar peduncle
What are the symptoms of an inferior cerebellar peduncle lesion?
ataxia and intention tremor on the ipsilateral side of the body
Ex- patients lean to the side of the lesion and have clumsiness and a tremor when using the ipsilateral hand
What artery supplies the inferior cerebellar peduncle?
PICA
Where do the fibers of CN XII emerge from on the brainstem?
exit between the olive and the pyramid
If you were to lesion the left CN XII, what side would the tongue deviate to?
It would deviate to the left (damage is ipsilateral) i the lesion is to the nerve or the nucleus
If the lesion is in the cortex or anywhere rostral to the medulla it would deviate to the right (conralateral)
What is the nucleus ambiguous?
A long thin column of motor neurons that occur at most levels of the medulla
What do the axons of the nucleus ambiguous control?
They mainly project CN 9 and CN 10 to innervate the larynx and the pharynx
If there is a (unilateral) lesion to the nucleus ambiguous, what are the symptoms?
Hoarsness, impaired swallowing and asymmetry of the soft palate
What is the dorsal nucleus of the vagus made of?
Preganglionic parasympathetic neurons of teh vagus nerve
They terminate in the ganglia related to cardiac muscle and smooth muscle
What does the solitary nucleus recieve?
It receives afferent information from the pharynx and larynx and from the cardiovascular system and the GI system via cranial nerves 7, 9 and 10
What is the vestibular area?
It is an area that recieves vestibular information from CN 8 and has different projections to other nuclei for vestibular reflexes and to the cerebellum via the inferior cerebellar peduncle
Where are the dorsal and ventral cochlear nuclei found?
At the transition between the pons and medulla on the external surface of the inferior cerebellar peduncle
What is the function of the cochlear nuclei?
They recieve primary afferent input from the auditory portion of the CN 8 (the origin of the auditory pathway
If there is damage to the left cochlear nuclei….what symptoms are found?
Deafness of the ipsilateral ear
Damage to the vestibular nuclei results in what symptoms?
Nystagmus, vertigo ad problems with balance
What are the symptoms of a CN VIII lesion?
Deafness in ipsilateral ear, nystagmus, vertigo, problems with balance
What are the symptoms of a CN IX lesion?
Loss of gag reflex on the side of the oropharynx of the nerve injury (afferent loss to the solitary nucleus)
What are the symptoms of a CN X lesion?
Hoarseness due to loss of control of the larynx and difficulty swallowing, asymmetry of the soft palate
bilateral involvement can lead to chocking
What are the symptoms of a CN XI lesion?
inability to elevate the ipsilateral shoulder, difficulty to turn and tilt head, fasciculations and atrophy of the sternocleidomastoid and trapezius muscles
What are the symptoms of a CN XII lesion?
Paralysis of the ipsilateral tongue muscles, deviation towards the side of the weakness upon protrusion, atrophy, fasciculations of tongue muscles ipsilaterally
