Spinal Cord/brainstem Flashcards
Crus cerebri
on the outer midbrain, cling to the forebrain and hold it to the midbrain
Why is the pons so much larger
because within the pons there is a larger number of cranial nerve nuclei , carrying info to/from cortex and other nuclei. There are so many of these that the main pathway carrying motor info breaks up and forms ‘pontine nuclei’.
Pons is a bridge that holds the two cerebral hemispheres together via cerebellar Peduncles
Pontine Nuclei
White matter tracts that carry information through the pons.
Medullary Pyramids
Paired white matter structures of the brainstem’s medulla oblongata that contain motor fibers of the corticospinal and corticobulbar tracts – known together as the pyramidal tracts. The lower limit of the pyramids is marked when most of the fibers cross (90% decussate) to the opposing side of the spinal cord to the lateral horn as the lateral corticospinal tract. Remaining travels do to the spinal level as the anterior CS tract.
Corticobulbar terminates here with cranial nuclei.
What lies dorsal to the midbrain (crus), Pons (cranial nuclei) and Medullary (pyramids)
Tegmentum: responsible for carrying the sensory info coming up from the spinal cord
What are the 2 pathways of the tegmentum
1) Pain + temp (ventrally)
2) Discriminative: from the gracile and cuneate nuclei > tegmentum
Substantia Nigra. Function and location
Located in the midbrain
- Largest producer of Dopamine
- Sends fibres up to the basal ganglia, and hlds motor neurons of BG just at firing stage
- Smooths out motor control for controlled voluntary movement
What happens if the substantia Nigra is damaged and there’s less dopamine?
Motor neurons cannot be activated, movement control is diminished and movement control cannot occur.
PARKINSONS DISEASE
What are the subdivisions of the Corpora Quadryenina
Superior Colliculus
Inferior Colliculus
Superior colliculus role?
Primarily responsible for head and eye reflexes towards a visual stimulus.
Inferior Colliculus
Slightly less precise, but responsible for head and ear reflexes towards an auditory stimulus
Cerebellar Peduncle (3x)
all of the white matter tracts that go to/from the cerebellum.
Requires huge amount of fibres
Inferior Olivery Complex
- in the medullary tegmentum.
- Looks like a shrivelled olive
The 2 Motor Pathways
1) Corticospinal Pathway
2) Corticobulbar (facial control)
The 2 Sensory Pathways
1) Dorsal column-medial lemniscal pathway (touch and pressure)
2) Spinothalamic Tract (pain and temp)
