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SF2 - Test 3 > 1 - Internal Anatomy of Brainstem (Cerebellum, Olfactory, Eye Movement, Respiration) > Flashcards

1 - Internal Anatomy of Brainstem (Cerebellum, Olfactory, Eye Movement, Respiration) Flashcards

1
Q

Cerebella Peduncles functions?

Inferior

Middle

Superior

A

Inferior Cerebellar Peduncle (Restiform body): Medulla

  • Major input pathway for most ascending somatosensory information, input form inerior olive

Middle Cerebellar Peduncle (brachium pontis): Pons

  • Input from pontine nuclei

Superior Cerebellar Peduncle (brachium conjunctivum): Pons, Midbrain

  • Output pathways from cerebellum
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2
Q

Dorsal (posterior) Spinocerebellar Tract

Function?

Route?

A

Function: Somatic sensation (uncoiscious proprioceptions) from lower limbs, trunk

Route: Primary (sensory) acons ascend gracile fasciculus, synapse in Clark’s Nucleus, 2o fibers run in dorsal spinocerebellar tract (lateral funiculus), remain lateral through medulla to inferior cerebellar peduncle

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3
Q

Cuneocerebellar Tract

Function?

A

Upper limb equivalent of dorsal spinocerebellar pathways

Uncrossed pathway, ascend Cuneate Fasciculus, Synapse in accessory cuneate nucleus, 2o fibers enter inferior cerebellar peduncle

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4
Q

Ventral (anterior) Spinocerebellar Tract

A

“Double Crossed” Pathway (Double Decussation)

Origin: Spinal interneurons (intermediate grey) - lumbar, lower thoracic level

Axons cross in ventral commissure, ascene in ventral spinocerebellar tract

Enter superior cerebellar peduncle and cross AGAIN to reach ipsilateral cerebellum

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5
Q

Olivocerebellar Pathway

A

Origin: Inferior Olivary Nuclei

Fibers cross, enter cerebellum through inferior cerebellar peduncles

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6
Q

Vestibulocerebellar pathway

A

Origin: Primary vestibular afferents and acons of secondary vestibular neurons

Enter cerebellum through inferior cerebellar peduncles (juxtarestiform body)

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7
Q

Corticopontine Pathway

Function?

Origin?

A

Function: Major input from motor, somatosensory, visual cortex–from most of cerebral cortex

Coordination of movements that we are conscious to

Pontocerebellar fibers cross and enter contralateral middle cerebellar peduncle to reach cerebellum

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8
Q

Cerebellar Output

A

Mostly occurs through the superior cerebellar peduncle

Fibers cross at inferior colliculi, project to red nuclei, and ventrolateral thalamus (VL)

**Some output from vestibular cerebellum goes through inferior peduncles

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9
Q

Clinical: Lesion of Cerebellar Peduncle

A

Produce signs/symptoms similar to cerebellar injury

Ataxia: Uncoordinated movements w/disordered contraction of agonist / antagonist muscles

Dysmetria: Over or under shooting of intended movements

Vertigo / Nausea if vestibular nuclei or vestubular connection to cerebellum affected

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10
Q

Gustatory Pathway

A

Afferents from CN VII, IX, X project to rostral solitary nucleus

2o fibers provide input to autonomic nervous system by projecting to:

Dorsal motor nucleus of X

Reticular formation/preganglionic sympathetic neurons in spinal cord

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11
Q

Ascending Pathway to Primary Gustatory Cortex

Pathway?

A

Conscious sensation in Gustatory Pathway

Pathway:

Central Tegmental Tract

Thalamus (VPM)

Insula, frontal operculum

Gustatory information also reaches hypothalamus (metabolic regulation, hunger, satiety) amygdala (emotional response to food)

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12
Q

Location of LMNs for extraocular muscles?

Types of eye movements?

Saccade

Smooth Pursuit

VErgence

Reflexive

A

Oculomotor, Trochlear, and Abducens Nuclei

Saccade: Very rapid (700 deg/s), voluntary movements to direct vision to objects of interest

Smooth Pursuit: Rapid (100 deg/s), non-voluntary to allow stable vision of moving objects

Vergence: Slower (20 deg/s) maintain vision for objects moving towards or away

Reflexive (OKR, VOR): Triggered by object movement (OKR) or head movement (VOR)

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13
Q

Generation of Horizontal eye movements?

How are conjugate eye movements accomplished?

What acts as the control center for horizontal gaze?

A

Horizontal movements are generated by Lateral Rectus (abducens nucleus) and medial rectus (oculomotor nucleus)

Medial Longitudinal Fasciculus (MLS) connects these nuclei to allow conjugate movements

Abducens functions as control center for horizontal gaze

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14
Q

Paramedian Pontine Reticular Formation (PPRF)

Location?

Function?

A

Location: Pontine tegmentum (reticular formation) near abducens nucleus

Higher level horizontal gaze center, receives input from higher level eye movement control centers

Projects to ipsilateral abducens

Triggers ipsilateral horizonal gaze

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15
Q

Clinical: Lesion of Abducens Nerve

A

Impaired abduction of ipsilateral eye

  • Looking straight ahead with ipsilateral eye when attempting to look towards lesion
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16
Q

Clinical: Lesion of Abducens Nucleus

A

Ipsilateral gaze palsy (both eyes affected)

Cause: Loss of connection (via MLF) by contralateral oculomotor nucleus

Both eyes look straight ahead when attempting to look toward lesion

17
Q

Clinical: Lesion of Paramedian Pontine Reticular Formation (PPRF)

A

Causes ipsilateral gaze palsy (both eyes affected)

Prevents gaze toward lesion in both eyes (same as Abducens NUCLEUS)

18
Q

Clinical: Lesion of Medial Longitudinal Fasciculus (MLF)

A

Faiure of adduction in ipsilateral eye

Abduction in contralateral accompanied by nystagmus (rhythmic oscillating eye movement)

Intranuclear Ophthalmoplegia (INO)

***MLF = Nystagmus (INO) contralateral of lesion***

19
Q

Clinical: What may be spared in lesions of MLF?

A

Eye adduction may be spared during convergence

LMNs for medial rectus are intact

These movements are “programmed” by control center in midbrain

20
Q

Clinical: Lesion of Abducens (or PPRF) + MLF

A

Combinaytion of ipsilateral lateral gaze palsy + INO

One-and-a-half Syndrome

Symptoms:

  1. Ipsilateral eye can’t move horizontal (loses ALL horizontal movement, “one”)
  2. Contralateral eye can only abduct (the “half”)
    - - -

Contralateral eye may have Nystagmus when looking away from lesion

***Key difference is IPSILATERAL eye can’t move horizontal AT ALL***

21
Q

Brainstem circuits for vertical eye movements:

Mediated by what regions/muscles?

A

Muscles: Superior / Inferior Rectus, Superior / Inferior Oblique

Regions: Midbrain Reticular Formation, Pretectal Area

22
Q

Clinical: Lesion of dorsal midbrain

Clinical: Lesion of ventral midbrain

A

Dorsal - May impair upgaze

Ventral - May impair downgaze

Ex: Pineal Tumor, Hydrocephalus

23
Q

Frontal Eye Fields

Project to?

Movements generated?

Clinical: Lesion?

A

Project to contralateral PPRF

Movements: Saccades in contralateral direction

Lesion: Gaze Preference towards side of lesion

Receive input from visual cortical areas

24
Q

Parietal-Occipital-Temporal Area

Connect to?

Movements Generated?

A

Connect to: PPRF, other eye movement control centers

Movements Generated: Smooth Pursuit in ipsilateral direction

Receive input from visual cortical areas

25
Q

Respiratory Control (not in brainstem)

Medulla

Pons/Midbrain

Forebrain

Caudal Solitary Nucleus

Pre-Bötzinger Complex

A

Medulla: Automatic g_eneration of respiratory rhythms_ (inspiration/expiration); project to cervical and thoracic spinal levels to LMNs

Rostral Pons/Midbrain: Respiratory rhythm modulation

Forebrain: Can override, and exert voluntary control

Caudal Solitary Nucleus: Receives visceral sensory input (O2, pH in blood)

Pre-Bötzinger Complex: Pacemaker center for respiration; ventro-lateral medullary reticular formation

26
Q

Clinical: Damage to medulla and respiration

A

Damage to medulla may disrupt respiration

Respiratory Arrest (central apnea) and death

Ataxic respiration (irregular breathing), may progress to respiratory arrest

27
Q

Clinical: Lesions of Kölliker-Fuse Area

A

Apneustic Respiration (breif respiratory pauses at full inspiration)

28
Q

Respiration:

Inpspiration Centers

Expiration Centers

Modulation Centers

A

Inspiration: Pre-Bötzinger Complex, Rostral Ventral Respiratory Group, Phrenic Nerve, Thoracic Inpspiratory Nerve, Dorsal Respiratory Group

Expiration: Bötzinger Complex, Caudal Ventral Respiratory Group, Thoracic Expiratory Nerve

Modulation: Kölliker-Fuse Area, Nucelus Solitarius

29
Q

Clinical: What can be compressed in tonsillar herniation?

A

Respiratory centers in medulla

Inspiration, Expiration, and Modulation all at risk

30
Q
A

SF2 - Test 3 (25 decks)

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