wk 5- nervous system Flashcards
(38 cards)
major sub divisions of the nervous system and what is included in them?
CNS- brain and spinal cord+
PNS- nervous tissue outside of CNS structures
where are sensory receptors found, what is their function and what types are there?
Where are sensory receptors found?
– Skin, joint capsules, ligaments, tendons, along muscle fibres
• What is the general function of sensory receptors?
– To detect a stimulus
• What types of sensory receptors are there?
– Pain
– Mechanical (touch, pressure, vibration)
– Temperature
– Stretch
– Force
types of skin sensory receptors 3
pain, thermoreceptors, mechanoreceptors
sensory receptors of lower limb 3
stretch receptors (in muscle belly)
force receptors (in tendons)
mechanoreceptors (in joint capsule and ligaments)
different spinal nerves and how many pairs in each region and total
Cervical nerves 8 pairs
Thoracic nerves 12 pairs
Lumbar nerves 5 pairs
Sacral nerves 5 pairs
Coccygeal nerves 1 pair
total = 31 pairs
what is a nerve composed of?
main component is axons of neurons
what type of neuron fibers may be found in nerves? 3 and what do they do?
- (Somatic) Motor neurons axons carrying instructions from the
CNS to skeletal muscles
– (Autonomic) Motor neurons axons carrying instructions from CNS
to smooth muscle and glands
– Sensory neurons process carrying information from sensory
receptors to CNS
sensory neuronal pathway 6
- Brain
Spinal cord
Spinal nerve
Nerve plexus
Peripheral nerve - Receptor
main function of nerves 2
-Highway connecting peripheral organs to spinal cord
– Carries bidirectional traffic
where do majority of lower limb nerves arise from?
All major peripheral nerves of the
lower limb arise from the lumbar &
sacral plexuses
what parts of the body does the posterior ramus innervate?
all tissues of back
region/dorsum of
body (posterior to
vertebral column)
What parts of the
body does the
Anterior ramus
innervate?
All tissues anterior to
vertebral column
including trunk
(thorax/abdomen/
pelvis) and upper &
lower limb
what are ascending tracts
sensory information traveling to brain, functionally localised
motor neuronal pathway
Brain
Spinal cord
Spinal nerve
Nerve plexus
Peripheral nerve
Neuromuscular
junction
motor pathway through CNS
white matter of spinal cord descending tracts sending motor messages from brain to muscles
upper motor neuron lesions 4
Cell body in cerebral cortex
– Corticospinal tract involvement
• Varying degrees of paralysis (severest
in upper limb)
• Spasticity with exaggerated tendon
reflexes
• Sign of Babinski – upturning and
spreading of the toes on stroking sole
of foot (extensor plantar response)
instead of normal babinski reflex
lower motor neuron lesions 4
• Cell bodies within ventral horn of
spinal cord
• Flaccid paralysis of affected muscles
• Diminished or absent tendon reflexes
• Progressive atrophy of deprived
muscles
poliomyelitis
-infantile paralysis
-viral infection of lower motor neuron
-LMN syndrome at level of lesion
-lower motor neuron disease
motor unit of skeletal muscles are
one motor neuron and all muscle fibers inverted by it
types of spinal reflex arcs 2
• Stretch Reflex:
– Acts to maintain posture and prevent falling to the
ground
– Prevents excessive tension building up in a muscle
• Withdrawal/Pain Reflex
– Acts to remove painful stimulus and protect body from
further injury
• Extremely fast response
• No input from brain
do lumbar nerve plexus lie in the belly of the posts major muscle?
yes
nerves that arise from the lumbar plexus
genitofemoral, lateral femoral cutaneous, femoral nerve, obturator
nerves that arise from the sacral plexus
superior/inferior gluteal, sciatic, posterior femoral cutaneous
nerves that pass through the lesser sciatic foramen
pudendal nerve
