Nervous System Flashcards
Motor Planning vs. Motor Learning
Both part of Motor Control.
MOTOR PLANNING= ability to plan and perform purposeful movement (also called “PRAXIS”); Dyspraxia=inability
MOTOR LEARNING= Acquisition and modification of learned movement patterns over time (repetition). Motor control is the outcome of motor learning.
MOTOR CONTROL = PLAN > EXECUTE > REFINE
Two parts of the nervous system
1) CNS: central nervous system (control)
2) PNS: peripheral nervous system (action)
CNS
Central Nervous System
• Brain and spinal cord
• Controls/integrates functions, regulates consciousness/ awareness, interprets stimuli, executes thought
• Brain exerts centralized control over organs
Homunculi
Image that represents the amount of sensory or motor brain function is dedicated to a body part (figure with large hands, face, etc.)
PNS
Peripheral nervous system. **More of the focus for OT!
• Consists of nerve cells outside CNS
• Regulated by CNS
• 12 pair Cranial nerves and 31 pair spinal nerves considered PNS
• Divided into AFFERENT and EFFERENT systems
• Further divided into SOMATIC and AUTONOMIC systems
• Then, autonomic even further divided into SYMPATHETIC and PARASYMPATHETIC
Afferent vs. Efferent Systems
These are the two systems of the PNS.
AFFERENT= impulses TOWARD the CNS, transferring sensory info to brain from body
EFFERENT= impulses AWAY from CNS, activating/controlling body
Cranial vs. Spinal Nerves
Nerves of the PNS.
CRANIAL = 12 pairs; carry impulses directly to/from the brain (not involved with spinal cord)
SPINAL = 31 pairs; carry impulses to/from spinal cord; link spinal cord with sensory receptors elsewhere in body
Somatic vs. Autonomic Systems
These are two systems of the PNS.
SOMATIC = the VOLUNTARY system; supplies skeletal muscles, controls conscious movement
AUTONOMIC = the INVOLUNTARY system; regulates body functions that are involuntary (cardiac muscle, glands, organs). This is further divided into Sympathetic and Parasympathetic systems.
Sympathetic vs. Parasympathetic Systems
Two systems of the AUTONOMIC system of PNS.
SYMPATHETIC = deals with stress, stimulations, fight/flight
PARASYMPATHETIC = deals with conserving energy; functions during rest
Neuron
Part of nerves that transmits signals through body. Requires oxygen and glucose to rebuild, but may last a lifetime. Specialized by location/function.
Composed of:
• Dendrite (the “hair”-receives impulses)
• Cell body (the “head”-processes impulses)
• Axon (the “tail”-conducts impulses to next neuron)
• Some axons are coated with MYELIN, which acts as protective coating, separating impulses. Lack of myelin leads to MS, etc.
Dermatome
Afferent sensory receptors located in the skin responsible for sensations like pain, light touch, temperature. Each dorsal nerve root is associated with specific area of the skin. (Graphic of skin divided into sections)
Spinal Cord (Roots)
Spinal cord composed of tracts that communicate afferent/efferent impulses to/from brain.
• Tracts go in 2 directions:
- DORSAL roots: Ascending; sensory tracts; transmit sensory input
- VENTRAL roots: Descending; motor tracts; direct/control motor responses
Spinal Cord (Segments)
• Divided into segments corresponding to vertebrae:
- CERVICAL: 8 total; come out ABOVE the vertebra C1-C8 (Note: one more nerve than the 7 cervical vertebrae. Only roots that emerge above vertebrae.)
- THORACIC: 12 total; come out below vertebra T1-T12
- LUMBAR: 5 total; come out below L1-L5
- SACRAL: 5 total; come out below S1-S5
- COCCYGEAL: 1 total; from coccyx
*Often injuries to spine affect all nerves below injury, but not always!
Plexuses
Groupings of spinal nerves that join together and branch out in different areas of body.
• CERVICAL (C1-C4)
• BRACHIAL (C5-T1)*Important for OT!
• LUMBOSACRAL (L1-S3)
Erb’s Palsy
Occurs usually at birth from traction on brachial plexus (stretched to pull baby out). Presents as inward-rotated arm; often heals.
Scapular Winging
Caused by injury to long thoracic nerve, causing scapula to jut out behind the body.
Wrist Drop
Caused by injury to the radial nerve, causing inability to extend wrist.
Ape-Hand
Caused by injury to median nerve, causing thumb to be stuck in the plane of the hand (not opposable)
Claw Hand
Caused by injury to the ulnar nerve. Last two fingers stuck in flex position.
Foot Drop
Caused by injury to the common peroneal nerve. The foot cannot be lifted (dorsiflexed) when walking.
Upper Motor Neuron (UMN)
Motor neurons in the CNS. Cerebral cortex and brainstem house the cell bodies for UMNs. Originate in cortex and synapse with lower motor neurons (LMNs), then exit through brainstem or spinal cord.
- Lesions can cause paralysis, loss of/hyperactive reflexes, hypertonia.
Lower Motor Neurons (LMN)
Motor neurons found in PNS; connect UMN with PNS.
- Lesions can cause paralysis, hypotonia, atrophy.
Interoceptors vs. Exteroceptors
INTEROCEPTORS: “internal receivers”; afferent nerve endings that respond to stimuli from within body (organs).
EXTEROCEPTORS: “external receivers”; afferent nerve endings that respond to stimuli by external agents/from external environment (ie: eyes).
Chorea
Irregular, involuntary movement of limb/facial muscles.
Clonus
Caused by hyperactive stretch reflex as result of UMN lesion; rapid alteration of contractions betw agonist/antagonist groups.
Innervation of skeletal muscles of trunk vs. extremities
Trunk innervations are SEGMENTAL.
Extremities are via a PLEXUS. Plexus provides redundancy (protection by way of multiple nerves on muscles).
Lumbosacral Plexus
Combination of lumbar and sacral plexuses. Nerve roots L1 through S3. Innervates lower extremities through the femoral (anterior thigh) and sciatic nerves (posterior leg).
