Brainstem 2 Flashcards
What information does the trigemino-thalamic system carry?
Information from** the face, head and mouth **to the thalamus about pain, temp, touch, pressure, vibration and proprioception
What are the 3 nuclei of the trigeminal system?
What information does each carry?
Mesencephalic - proprioceptive information
Chief sensory - fine touch on face
Spinal trigeminal - pain, temp, proprioception, tactile/fine touch
The superior colliculus is collectively responsible for what functions?
Attending eyes to things they should be looking at
The inferior colliculus is collectively important for what task?
Hearing
- Describe how the corticobulbar facial nucleus innervates the muscles of facial expression.
- What would happen if there was a lesion in the UMN of the right side?
- What would happen if there were a lesion of the facial nerve (LMN)?
- The lower face LMN receives input ONLY from the contralateral UMN. The upper face LMN receives input from UMNs from both motor cortices.
- Weakness of contralateral lower face muslces only
- Weakness of whole ipsilateral half of face
What information does the dorsal and cuneospinocerebellar tracts carry?
Is it ascending or descending?
- Coordination of posture and movement of limbs
- Clarke’s nuclei and spinal accessory nuclei
- Inferior cerebellar peduncle
- Ascending
- What information does the ascending medial longitudinal fasiculus carry?
- Where does it receive information from?
- Where does it project information to?
- Information needed to coordinate eye movement and position eyes in relation to position of head
- Vestibular nuclei
- Nuclei controlling extraocular eye movements (3, 4, 6)
- What information does the corticobulbar tract convey?
- Is it ascending or descending?
- Where does it project?
- Voluntary and involuntary movement of facial muscles
- Descending
- Sensory
- Spinal trigeminal nucleus
- Nucleus solitarius
- Dorsal column nuclei (gracilis and cuneatus)
- Motor
- Oculomotor, trochlear, abducens, trigeminal motor, facial, ambiguus, hypoglossal, spinal accessory
- Reticular formation
- Where corticobulbar tract fibers terminate
What is the tectospinal tract?
Is this ascending or descending
Axons from superior colliculi
- Superior colliculus –> cross and descend with MLF in brain stem and spinal cord
- Involved in reflex and postural movements to visual and autitory stimuli
Descending
- What is the vestibulobulbar tract?
- Where are cell bodies in this tract?
- Is this ascending or descending?
- Involved in reflex and postural movements to visual and auditory stimuli
- vestibular nuclei
- Descending
*
What information does the mesencephalic nucleus (CN 5) convey?
Proprioceptive information about muscles of mastication (to thalamus)
What information does the chief sensory nucleus (CN 5) convey?
Fine touch on the face, pressure, proprioception (to thalamus)
What information does the spinal trigeminal nucleus convey (CN 5)?
Pain, temp, crude touch (to thalamus)
What is the trigeminal lemniscus?
The ascending tract from the chief sensory nucleus to the VPM of the thalamus that conveys information about fine touch, pressure and proprioception of the face. The fibers cross in the pons and ascend to the contralateral VPM of thalamus.
What is the trigemino-thalamic tract?
The ascending pathway that conveys information about pain, temp and crude touch from the spinal trigeminal nucleus to the VPM of the thalamus. Primary neuron cell bodies in trigeminal ganglion, descend to medulla, synapse with ascending neuron, which decussates at pontomedullary junction and then ascends to contralateral VPM of thalamus.
Why do primary sensory neuron axons in the spinal trigeminal nucleus descend from the trigeminal ganglion down to the medulla to synapse with a secondary sensory neuron?
Because this tract conveys pain, temp and some crude touch information to the VPM of thalamus. Other cranial nerves (7, 9, 10) also collect this type of information from other areas of the face / body and also send it up to VPM so CN 5 drops down to combine with these inputs from other cranial nerves in the spinal trigeminal nucleus before sending information up to VPM of thalamus.
Ascending MLF carries information about […].
Descending MLF carries […]
The direction the eye should move
Vestibulospinal tract to cervial spinal cord and innervates some muscles of neck/upper limb
What does the ascending MLF do? (2)
- Connect occulomotor nucleus, trochlear nucleus and abducens nucleus
- Integrate movements directed by gaze centers and information about head movement
Corticobublar Tract
- What does this tract do?
- Where are the 1st and 2nd order neurons located?
- Modulate sensory and motor nuclei of cranial nerves
- 1st = cerebral cortex
- 2nd = pontine, medullary, and reticular formation nuclei of cranial nerves
Most cranial nerve nuclei project and receive input from only one cranial nerve. Three exceptions exist. What are these exceptions?
Solitarius
- 7, 9, 10
Ambiguus
- 9, 10
Trigeminal
- 5, 7, 9, 10
What level is this?
How can you tell?
What are the highlighted structures?
Midbrain
Red nuclei are visible, pyramids are long and diffuse along inferior lateral section, superior colliculi are visible on top
What level is this?
How can you tell?
What is the labeled structure?
Midbrain
Inferior colliculus visible (eyeliner)
What level of the brainstem is this?
How can you tell?
What is the highlighted structures?
Medulla
Inferior olive
What level of the brainstem is shown?
How can you tell?
Pons
Pontine striations
What structures are shown?
What are their functions / what do they innervate?
What level of the brainstem is shown?
How can you tell?
What are the labeled structures?
How can you tell?
Medulla
Inferior olive
Nucleus solitarius
Eye of sauron appearance
Where does the vestibular nerve project to?
The output of the vestibular nu. is to the spinal cord, cerebellum, thalamus, nu. of extracocular movement, and more
What level of the brainstem is this?
How can you tell?
What are the labeled structures?
Medulla
Inferior olive
Label each nucleus and explain the function that each one provides for CN 9.
Label each nucleus and explain the function that each one provides for CN 10.
What nucleus is shown?
What does it innervate?
What is the function of the things it innervates?
- What effect would upper motor neuron lesion result in for the tongue?
- What effect would lower motor neuron lesion result in for the tongue?
What level of the brainstem is shown?
How do you know?
What are the labeled structures?
Medulla
Inferior olive
Explain this diagram.
- What artery supplies the area with polka dots?
- What condition would result if blood supply to the brain by this artery were disrupted?
- What artery supplies the area with polka dots?
- What condition would result if blood supply to the brain by this artery were disrupted?
What do the dorsal spinocerebellar and cuneocerebellar pathways convey to the brain?
Fine coordination of posture and movement of limb muscles
Where are the neurons / synapses for the dorsal spinocerebellar tract?
1st order is myelinated fibers of DRG for sacral and lumbar levels
2nd order is in Clarke nu., C8-L2
3rd order is in cerebellum via inferior cerebellar peduncle
Where are the neurons / synapses for the cuneocerebellar tract?
1st order is myelinated fibers
of DRG for cervical and thoracic levels
2nd order is accessary cuneate nu. of medulla
What information do the tectospinal and vestibulospinal tracts convey to the brain?
- Tectospinal: for reflex & postural movement to visual & auditory stimuli
- Vestibulospinal: stability of head and eyes
Where are the neurons / synapses in the tectospinal tract?
1st order in Superior Colliculus
2nd order tectospinal in cervical ventral horn layers
3rd order in motor neurons crosses at midbrain
Where are the neurons / synapses in the vestibulospinal tract?
1st order in Vestibular nu.
2nd order in cervical interneurons of ventral horn
3rd order motor neurons of layer IX
Lateral VS crosses at midbrain and medial VS is bilatera
What are the symptoms of CN3 palsy?
Affected eye moves down and out
Ptosis
Dilated pupil
Disrupted lateral gaze
What are the symptoms of CN 4 Palsy?
Vertical diplopia
Double vision that is aggravated when looking contralaterally downward while descending stairs
Corrected by head tilt AWAY from affected eye
Fractures of the face can damage peripheral branches of [….] resulting in a loss of feeling
CN 5 - trigeminal neuralgia
Cells of the […] are the only primary sensory neurons in the brain
Mesencephalic nucleus of trigeminal nerve
In lateral medullary syndrome (AKA Wallenberg syndrome), there is a loss of pain and temp on the […] side of the body and the […] side of the face.
Contralateral
Ipsilateral
How can you distinguish between lesions to the abducens nerve and the abducens nucleus?
- Lesion to nerve –> paralysis of lateral rectus on same side as lesion (i.e. inability to ABduct affected eye)
- Lesion to nucleus –> paralysis of horizontal conjugate gaze on same side as lesion (i.e. inability to turn BOTH eyes toward the side that has the lesion)
What is the mass effect with regards to lesions of the abducens nerve?
A cerebellar tumor growing into the 4th ventricle can compress the abducens nerve
If there is a lesion or loss of blood supply to the abducens nucleus, what other symptoms would a person almost always present with?
Paralysis of muscles of facial expression on same side as lesion (damage to LMN of CN 7)
What is the blood supply to the abducens nucleus?
PICA, basilar artery, internal carotid
What are the symptoms of CN 6 palsy?
