Radiology-Wilson Flashcards
What supplies the brainstem at the pontomedullary junction?
AICA
What occurs if the inferior cerebellar peduncle is lesioned?
ICP is formed by pathways passing in both directions between the medulla and cerebellum
- will have cerebellar signs
- ataxia
- lack of coordination
- positive Romberg test (the side to which you fall will indicate cerebellar ataxia)
What is interesting about the cerebellum compared to other parts of the brain?
if lesioned, the symptoms will be on the same side
dorsal and ventral cochlear nucleus
- In terms of the relay of sensory information auditory information up to cortex
- it is a parallel multi tract pathway
- In terms of having a monaural auditory loss, it is the last sight where you can have a loss; it either the auditory nerve of the these nuclei
- at that stage these fibers are auditory information goes up bilaterally and everything gets mixed in together
- you lesion the left and right hand side????
dorsal cochlear nucleus
is one of the relay nuclei for the auditory fibres of the vestibulocochlear nerve (CN VIII) and functions to modify inputs to the higher auditory structures
ventral cochlear nucleus
is one of the relay nuclei for auditory fibres of the vestibulocochlear nerve (CN VIII) and functions to modify inputs to the higher auditory structures
Spinothalamic Tract
transmits pain and temperature sensations from the spinal cord to the thalamus
-usually running with this pathway is the descending hypothalamic fibers going to the sympathetic nervous system
A lesion in the spinothalamic tract near the pontomedullary junction will usually produce what syndrome?
Horner’s syndrome will be on one side of the head and the loss of pain and temp will be on the other side
-alternating cranial and body pattern of loss either sensory/ motor function
Trapezoid body
- is formed by decussating auditory fibers and provides for bilateral projections to the auditory cortex
- where the cochlear nucleus one side will project to the other side to the superior olivary nucleus
Superior olivary nucleus
- modifies the transmission of auditory signals to higher centres and is important in the localization of sound and in reducing background noise
- very important for sound localization
Corticospinal tract
controls the precision and speed of skilled movements involving the distal muscles of the contralateral limbs particularly those of the hands and fingers
at the middle of pons it will be FUTL but as you go more caudal the fiber bundles come together to form the pyramidal tract
Facial nucleus
-controls the activity of the muscles of facial expression, stapedius m. and most of the glands of the head (except the parotid gland). It also carries taste sensation from the anterior two-thirds of the tongue and general sensation
is one of the structures related to lateral pontine syndrome
both of the lower and upper half of the face is affected if you have a lesion in this nucleus at the lateral pontine area
-located laterally in the pons but has fibers (internal genu of CN VII) that run around the abducens nucleus laterally
Medial lemniscus
-transmits sensations of discriminative touch, vibration, proprioception and stereognosis from the gracile and cuneate nuclei to the ventral posterior nucleus of the thalamus
with lesion, will get contralateral hemisensory loss for fine touch and vibration
Abducens nucleus
-contains the cell bodies of fibers in the ipsilateral abducens nerve which supplies the lateral rectus muscle of the eye
Abducens nucleus fibers!!
-run medially from the abducens nucleus
paralysis to lateral gaze of one eye only you will expect
- medial lesion of the pons
- contralateral hemisensory loss due to the medial lemniscus; loss of fine touch, vibration
- you have the beginning of the corticospinal tract
Lateral lemniscus
-transmits auditory information from the superior olivary and cochlear nuclei to the inferior colliculus
In the pons what is the order of the medial lemniscus, lateral lemniscus, and spinothalamic tract from most medial to most lateral?
medial lemniscus
spinothalamic tract (sandwiched in between the two)
lateral lemniscus
Trigeminal nucleus
a dorsolateral lesion of the middle or rostral pons you will hit the trigeminal nerve or the trigeminal motor nucleus
- is the major nerve transmitting general sensations (GSA) from structures in the head to the brainstem.
- it also contains motor (GVE) fibres which supply the muscles of mastication
Trigeminal motor nucleus
- controls the activity of the muscle of mastication
- located medial to the trigeminal nerve
Principal Trigeminal Nucleus
- processes vibration, stereognosis, and discriminative touch sensations from the head and neck and then relays them to the thalamus
- located lateral to the trigeminal nerve
