Lecture 4 Brainstem and Sensory/Motor pathways Flashcards
(27 cards)
What are the major structures of the Midbrain?
- Cerebral Peduncles
- Superior colliculus
- Inferior colliculus
- (Substantia Nigra, Subthalamic nucleus) = Part of Basal Ganglia
- Red Nucleus
- Cranial Nerve Nuclei (Nerves 3 and 4)
What is the purpose of the Cerebral Peduncles
- Passage for Corticospinal fibers
What is the purpose of the Superior Colliculus? What do the neurons of the Superior Colliculus give rise to?
- Visual relay center for reflex eye and head movements
- SC gives rise to the Tectospinal Tract
What is the purpose of the Inferior Colliculus?
- Auditory relay center
- Adjust gaze relative to stimulus
What are the major structures of the Pons?
- Cerebellar Peduncles
- Pontine Nuclei
- Reticular Formation and Vestibular Nuclei
(Reticulospinal and Vestibulospinal tracts) - Cranial Nerve Nuclei (nerves 5-8)
What is the purpose of the Pons?
“Bridge” transfers information to and from the cerebellum
What is the purpose of the cerebellar Peduncles?
Connect Cerebellum to the brain and spinal cord
What is the purpose of the Pontine Nuclei?
Relay center for info traveling between the cortex and cerebellum
What are the major structures of the Medulla?
- Pyramids
- Reticular Formation and Vestibular Nuclei
(Reticulospinal and Vestibulospinal tracts) - Nucleus Gracilis and Cuneatus
- Cranial Nerve Nuclei (Nerves 9-12)
What are the Pyramids of the Medulla?
- Long Motor Tracts (Corticospinal tracts)
- Located ventrally in the Medulla
Where are the Olives (Olivary Nuclei) of the Medulla and what structures does it connect to?
- Located lateral to the Pyramids of the Medulla
- Form circuits with the Cerebellum
What is the Decussation of Pyramids?
- Point at which descending corticospinal fibers cross over to the contralateral side
In the Caudal portion of the Medulla, What is the purpose of the Internal Arcuate Fibers?
- Point of decussation of the Medial Lemniscus
(Medial Lemniscus = secondary sensory neurons in the brainstem that synapse to the Primary Fasciculus Cuneatus/Gracilis)
What is Brown-Sequard Syndrome?
- Hemisection (half damage) of the Spinal Cord
- causes motor and sensory loss below the level of the lesion
- contralateral loss of pain and temp
What happens to the body of someone with Brown-Sequard Syndrome
Dorsal Column
- Ipsilateral Paralysis (LCS)
- Ipsilateral loss of fine touch
Spinothalamic tract
- Contralateral loss of pain and temp
What parts of the spinal cord do the posterior spinal arteries feed?
- Feed the posterior one-third of respective sides of the spinal cord
- Includes the Dorsal Column and Dorsal Horn of the grey matter
What parts of the spinal cord do the Anterior Spinal Artery feed?
- Feeds the anterior two thirds of the spinal cord
- Includes the ventral horn of the grey matter and the ventral and lateral white matter Funiculi BILATERALLY
How is Anterior Cord Syndrome caused?
- Vertebral fracture or Dislocation, or Injury to the anterior spinal artery
What happens as a result of Anterior Cord Syndrome?
- Bilateral Paralysis (due to loss of lateral corticospinal tract BELOW the lesion)
- Bilateral loss of pain and temperature below lesion
- Fine touch and conscious proprioception are intact (dorsal column spared)
How is Dorsal Column Syndrome caused?
- Caused by Multiple Sclerosis or stoke of a posterior spinal artery
What happens as a result of Dorsal Column Syndrome?
- Ipsilateral (or bilateral if both sides diseased) loss of fine touch and conscious proprioception
- Pain and temp sensation NOT COMMONLY LOST (some dermatone overlap)
- Voluntary Motor Function is spared
How is blood flow to the anterior spinal artery reinforced?
- Segmental Medullary Arteries
What is the largest segmental medulary artery?
Artery of Adamkiewicz
- Reinforces blood supply to the entire lower half (T7 downwards)
What are watershed areas?
- Areas where blood flow meet between segmental medullary arteries
- Lowest Blood Pressure spots
- Most susceptible to stroke
