intro to brainstem Flashcards
The cerebellum is attached to the brainstem by what?
peduncles: inferior, middle and superior
function of inferior cerebellar peduncle
conveys spinal cord information to the cerebellum and interconnects the cerebellum
with the vestibular nuc. and inferior oliveconveys spinal cord information to the cerebellum and interconnects the cerebellum
with the vestibular nuc. and inferior olive
function of middle cerebellar peduncle
route by which information from the cerebral cortex gets to the cerebellum via the pontine nuclei
function of superior cerebellar peduncle
route by which the cerebellum gets information back to the cerebral cortex (via the thalamus).
- Locate and identify the attachment points of all the brainstem cranial nerves (CNIII – CNXII) {Fig. 2-17 to Fig. 2-22}
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Describe how the brainstem is divided into sensory and motor regions/ visceral and non visceral regions
The alar plate is located laterally and contains sensory nuclei and the basal plate is located medially and contains motor nuclei. These two plates are separated by the sulcus limitans. Additionally, within each plate, there is a visceral portion closest to the sulcans limitans and a non visceral portion farthest away from the sulcans.
What is the reticular formation
the core of the brainstem - performs diffuse functions such as keeping you awake and breathing
What do nuclei in the somatic motor zone innervate?
aka near midline in basal plate: They innervate extraocular muscles (III, IV, VI) or tongue (XII)
What is the medial longitudinal fasciculus
tract of the pons and upper medulla that connects motorneurons for extraocular muscles.
List the branches of the trigeminal nerve and their general functioins
ophthalmic: somatosensory. Maxillary: somatosensory. Mandibular: somatosensory and motor
where is the trigeminal nucleus?
There are two: trigeminal motor nucleus(aka spinal/descending trigeminal nucleus) and the principal (main) sensory nucleus. Both are in the midpons. Mesencephalic is a third nucleus with little importance
What kind of info does the principal sensory nucleus deal with and where do axons project from it
touch, vibration and position (analogous to dorsal column). Projects to the VPL in the contralateral thalamus
Where do the C and Ad fibers of trigeminal nerve project to
They turn caudally after entering the brainstem to form the descending root of the trigeminal nerve which terminate at the spinal trigeminal nucleus (which extends from the pons to the spinal cord). Carries pain and temp info
functions of lower and upper spinal trigeminal nucleus
lower: deals with pain and temp info (like the substantia gelatinosa of the spinal cord) Upper: trigeminally mediated reflexes (ie. Eye blink reflex)
What/where is the mesencephalic nucleus- what does it do and what happens if it is severed
This is a trigeminal nucleus that exists in the brainstem (pons) as a result of neural crest cells which become trapped in the brain during embryogenesis. It has one process that extends peripherally to proprioceptors of gums or jaw and a central process that terminates in the main sensory trigeminal nucleus. There are no deficits if it is severed
Which nuclei are in the branchiomotor nuclei group and what do they have in common
trigeminal motor nucleus, the facial (motor) nucleus and the nuc. ambiguus. What these have in common is that they innervate striate muscles derived from the branchial mesenchyme (of neural crest origin). (6-2)
Which nuclei are in the viscerosensory and autonomic nuclei
solitary nuc. and solitary tr. and the preganglionic
parasympathetic nuclei: dorsal motor nuc. of the vagus, superior and inferior salivatory nuc., and the Edinger-Westphal nuc., part of the oculomotor nuc.
What is the function of the dorsal motor nucleus of the vagus and where is it located
located in medulla (dosrally). Contains preganglionic parasympathetic neurons of the vagus nerve
where is the hypoglossal nucleus and what is its function
in medulla next to the dorsal motor nucleus of vagus and nucleus of solitary tract. Contains motor neurons that innervate the tongue.
Where is the nucleus of the solitary tract and what does it do
in medulla next to hypoglossal nucleus and dorsal motor nucleus of vagus. visceral sensory nucleus; farther rostrally, it would also deal with taste information
Which nuclei are included in the auditory system nuclei
including the cochlear nuc. and the ascending relay nuclei for audition including: Trapezoid body, superior olive, lateral lemniscus, inferior colliculus and medial geniculate nuc.
Which nuclei are in the vestibular system and what do they do
vestibular nuclear complex- connect with motorneurons via the MLF to innervate the extraocular muscles and vestibular nuclei send long descending axons to the spinal cord to trigger postural reflexes to changes in perceived direction of gravity.
where is the cochlear nucelus located
medulla
list the cerebellum associated tracts and nuclei
pontine nuclei, inferior olivary nuc. (= Principal olivary nuc.), red nuc., and superior cerebellar peduncle
Where is the dentate nucleus and what does it do
squiggly lines in the cerebellum- send axons out the superior cerebellar peduncle to end in the contralateral VA/VL nucleus of the thalamus
Where is the vestibular nucleus located
medulla- just medial to the inferior cerebellar peduncle
where is the middle cerebellar peduncle and where do its fibers originate
pons- axons from the contralateral pontine nuclei project to the deep cerebellar nuclei and to granule cells of the cerebellar cortex through the midde cerebellar peduncle
where is the facialnucleus, what is its function, route of axons
innervates muscles of facial expression. Axons go up towards abducens, around in front of abducens then back past the facial nucleus to exit the brainstem
where is the abducens nucleus and where do fibers project
pons- motor neurons and interneurons that project via the MLF to nuc III and innervate the lateral rectus
Where is the superior olivary nucleus, function and fiber paths
auditory- input from both ipsilateral and contralateral cochlear nucleus. Projects to inferior colliculus
- Locate and identify the following features on the intact brainstem: approximate dividing lines between medulla, pons and midbrain; optic chiasm, mammillary body, superior and inferior colliculi; crus cerebri (cerebral peduncle), basal pons, superior, middle and inferior cerebellar peduncles, pyramid and olive. {Figs. 2-17, 2-20, 2-21; 2-31; 2-33}
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What symptoms occur when the pyramidal tract is cut, where do these tracts cross midline? Where are they located throughout the brainstem
spastic paralysis- located anteriorly in medulla/ pons, then anterior-lateral in midbrain. Fibers cross at the pyramidal decussation in the medulla
What symptoms occur when the anterolateral/ spinothalamic tract is cut- where do these tracts cross midline?
loss of pain and temperature- tracts are located laterally in medulla, lateral and more posterior in pons, then even more posterior in the midbrain. The fibers cross in spinal cord at the level of enrty
What symptoms occur when the dorsal column/medial lemniscus tract is cut, where do these tracts cross midline?
loss of 2-pt discrimination, fine touch, and concious proprioception. Tracts are located dorsally until mid-medulla, then they cross as the internal arcuate in the medulla are located medially as the medial lemniscus in the medulla, cental but more lateral in the pons, anterior/lateral in the midbrain
What symptoms occur when the spinal trigeminal tract and nucleus is cut, where do these tracts cross midline?
loss of pain and temp for the head. Tract fibers are located just dorsal to the anterolateral tract in the medulla (dorso-lateral), CNV is located btw the pons and the medulla, the fibers become the trigeminothalamic tract just dorsal to the medial lemniscus in the pons and midbrain
damage to the brainstem and cerebellum show up on which side of the body
ipsilateral side (as opposed to the cerebrum)
Where is the inferior olive located and what fibers does it carry
in the medulla (anterior)- squiggly lines. These cells project via the contralateral inferior cerebellar peduncle to the cerebellar cortex where they end as climbing fibers.
Give location of cell bodies of origin and destination of fibers from the pyramids
originates from ipsilateral motor and premotor cortex; terminates in the contralateral spinal cord
Give location of cell bodies of origin and destination of fibers from the medial lemniscus
originates from the contralateral nuc. gracilis and cuneatus; terminates in the ipsilateral VPL.
Give location of cell bodies of origin and destination of fibers from the inferior cerebellar peduncle
originates from the contralateral inferior olive and from neurons of the ipsilateral Clarke’s column (spiinocerebellar tr.). More rostrally, the peduncle also will contain fibers from the ipsilateral vestibular nerve and nuclei. These axons end in the ipsilateral cerebellum.
