Lecture 19: Descending supraspinal (upper motor neuron) pathways Flashcards
Ready – BLANK cortex
Set – BLANK cortex
Go – BLANK motor cortex
Ready – supplementary cortex
Set – premotor cortex
Go – primary motor cortex
A: just random Movement
B: Give and task and do it
C: just give a task
Premotor cortex
BLANK: organizes postural adjustments required to make a movement
- Brodmann area 6 (BLANK)
receives input from sensory processing areas in the BLANK mainly related to proprioception; projects to
BLANK (and to reticular formation to activate reticulospinal tracts)
- neurons active before M1 cells; acts on proximal limb muscles to set the proper posture for initiation of the BLANK movement
- limb movements are guided by sensory input (e.g., tactile or visual) rather than BLANK
Preparation to move: organizes postural adjustments required to make a movement
- Brodmann area 6 (inferior)
receives input from sensory processing areas in the parietal lobe mainly related to proprioception; projects to
M1 (and to reticular formation to activate reticulospinal tracts)
- neurons active before M1 cells; acts on proximal limb muscles to set the proper posture for initiation of the intended movement
- limb movements are guided by sensory input (e.g., tactile or visual) rather than memory-guided experience
Parietal association cortex
- Brodmann area 5
- integrates afferents from BLANK and BLANK
- contains arm projection neurons active only when reaching for a BLANK
- BLANKneurons active when manually exploring object of interest
- Brodmann area 5
- integrates afferents from somatosensory cortex and vestibular system
- contains arm projection neurons active only when reaching for a specific object of interest
- hand manipulation neurons active when manually exploring object of interest
Parietal association cortex
- Brodmann area 7
- afferents from BLANK; processes visual information related to the location of objects in space
- contains neurons involved with BLANK; active when reaching for a BLANK identified target
- Brodmann area 7
- afferents from visual system; processes visual information related to the location of objects in space
- contains neurons involved with eye-hand coordination; active when reaching for a visually identified target
Brodmann area 5 and 7 both project to
supplementary and premotor cortex but not M1
Clinical connection: lesions to motor cortices (outside BLANK) result
in BLANK - an inability to produce voluntary movements despite
normal muscle power and tone
Clinical connection: lesions to motor cortices (outside M1) result
in apraxia - an inability to produce voluntary movements despite
normal muscle power and tone
- Brodmann area 24 (and 32?)
- two separate clusters of neurons on superior and inferior banks
of BLANK (inferior to BLANK) - controls movements and gestures that occur in an BLANK context
- Brodmann area 24 (and 32?)
- two separate clusters of neurons on superior and inferior banks
of cingulate sulcus (inferior to supplementary motor cortex) - controls movements and gestures that occur in an emotional context
Primary motor cortex (M1)
- Brodmann area 4; BLANK and BLANK
- agranular heterotyical cortex: expanded layers BLANK and BLANK with reduced
layer BLANK - vertical columns of cells organized by muscles associated with joint
actions involved in purposeful movements - function: execution of fractionated movements of BLANK
(controls independent finger movements)
- Brodmann area 4; precentral gyrus and anterior paracentral lobule
- agranular heterotyical cortex: expanded layers III and V with reduced
layer IV - vertical columns of cells organized by muscles associated with joint
actions involved in purposeful movements - function: execution of fractionated movements of distal extremities
(controls independent finger movements)
Corticospinal tract
Origin: pyramidal neurons in layer BLANK of primary motor cortex (some neurons in BA 6 and parietal cortex (BA 5,7) also project in CST)
- BLANK (giant pyramidal neurons)synapse directly on LMNs especially those that innervate forearm and hand muscles; other CST cells synapse on interneurons that synapse on LMNs associated with more proximal musculature
Origin: pyramidal neurons in layer V of primary motor cortex (some neurons in BA 6 and parietal cortex (BA 5,7) also project in CST)
- Betz cells (giant pyramidal neurons)synapse directly on LMNs especially those that innervate forearm and hand muscles; other CST cells synapse on interneurons that synapse on LMNs associated with more proximal musculature
Corticospinal tract
Corticospinal tract
Blood supply_internal capsule (posterior limb)
Occulsion of either vessles
CST (occupies middle 1/3 of crus cerebri) thus is supplied by
both paramedian branches (medial crus cerebri) and quadrigeminal a. (lateral crus cerebri) in midbrain
Paramedian
ASA
ASA
