Week 1 (A&P Review, Intro Substrates) Flashcards
Sensory Cortex: Function and Efferents
Fx: somatic sensation, visual stimuli, and movement planning
Efferents: Primary Motor Cortex, Brainstem
Motor Cortex: Function and Efferents
Fx: Involved in planning of goal-directed movement.
External target of movement needed.
Efferents to: motor strip, brainstem
Define: motor homonculus
cortical map involved in the execution of movement
Function of cingulate gyrus
sensorimotor integration
Function of insular cortex (a.k.a. insula)
sensory-cued but stereotyped motor behaviors or habits
Define: direct activation pathway
Also referred to as the Pyramidal Tract
Has direct connection on the final common pathway
Forms part of the upper motor neuron system
Effect is primarily facilitative – leads to movement – not inhibition of movement
Direct activation is divided into what 2 tracts?
Corticospinal and corticobulbar tract
Explain: DAP division into CS and CB tracts
Axons descend from the cortex
Terminate in the brainstem/spinal cord
Synapse with cranial/spinal nerves
3 effects of damage to the direct activation pathway
Loss or reduction of skilled movement
Normal reflexes
Because CN supply to V, IX, X, XI are bilateral, unilateral UMN lesions are usually minor
Deifne: indirect activation pathway
Also referred to as the Extrapyramidal Tract
Has indirect connection on the final common pathway
There are multiple synapses between the origin in the cortex and its arrival and activation of the FCP
Functions for speech poorly understood
This pathway is a source to lower motor neurons, whereas the control circuits are not.
Indirect activation pathway is divided into what 2 tracts?
Corticoreticular and corticorubral
Define: corticoreticular
cortex to reticular formation
Define: corticorubral
cortex to red nucleus
Effects of damage to indirect activation pathway
spasticity and hyperreflexia
Explain: corticoreticular tract
From cortex to reticular formation (brainstem)
Reticular formation: Set of interconnected nuclei that are located throughout the brain stem
Intermingled with corticospinal and corticobulbar fibers
Descend to midbrain, medulla and pons
Fibers then distributed bilaterally
Mediates ascending sensory information
Corticoreticular tract has ______ and _______ influences
facilitatory and inhibitory
explain: facilitatory and inhibitory influences
Crucial for regulation of muscle tone
Excites extensor motor neurons and inhibits flexor motor neurons
Explain: corticorubral tract
Fibers sent from the cortex to the red nucleus
Explain: 4 important facts about the red nucleus
Oval mass of cells in the midbrain
Serves as a relay station between a pathway from the cerebellum to thalamus and cortex
Major influence is on flexor muscle groups in the limbs
Role involved in speech is unclear
Effects of damage to corticorubral tract
spasticity and hyperreflexia
5 main points: direct pyramidal tract
- voluntary
- conscious
- movements generated by cognitive activity
- corticospinal and corticobulbar tract division
- damage: loss or reduction of skilled movement. Unilateral: weakness on contralateral side
7 main points: indirect pyramidal tract
- involuntary
- subconscious
- Gives the direct pathway a framework to accomplish the skilled movement
- Regulates reflexes
- Maintain posture, tone
- corticoreticular and corticorubral tract division
- damage: affect muscle tone and reflexes (spasticity and hyperreflexia)
Define and explain: final common pathway
Referred to as lower motor neuron system
Peripheral mechanism through which all motor activity is mediated
Last link in the chain of neural events that lead to movement
Generates activity in skeletal or somatic muscles
The final common pathway includes what 3 things?
nuclei/cell bodies of cranial and peripheral nerves; their axons; and neuromuscular junction
Primary cranial and peripheral nerves for: respiration
- spinal (cervical and thoracic)
2. phrenic nerve, intercostals
Primary cranial and peripheral nerves for: phonation
Vagus (CNX)- larynx
Primary cranial and peripheral nerves for: resonance
Vagus (x) + (IX and XI) velopharynx and larynx
Primary cranial and peripheral nerves for: articulation
- trigeminal (CNV)- jaw
- facial (CNVII)- face
- hypoglossal (CNXII)- tongue
4 subcortical structures
caudate, internal capsule, putamen, globus pallidus
Thalamus provides connections to and from
To: Primary Motor cortex Premotor cortex Supplemental Motor cortex Insula From: Basal Ganglia, Cerebellum, Brainstem
Function of the thalamus
relaying sensory and motor signals to the cerebral cortex, regulation of consciousness, sleep, and alertness
Define and explain: control circuits
Basal ganglia and cerebellum large collections of nuclei that modify movement on a minute-to-minute basis.
Motor cortex sends information to both
Both send information right back to cortex via thalamus
Do not have direct contact with LMN’s (like the direct and indirect pathways)
Cerebellum output = _________
excitatory
Basal ganglia output = __________
inhibitory
Effects of balance vs. disturbance of control circuits
balance = smooth coordinated movement disturbance = movement disorder
Basal ganglia includes what 3 structures?
caudate nucleus, putamen, and globus pallidus