A&P 2.8. spinal versus cranial nerves Flashcards
(30 cards)
Stimulus
Pain from myofascia
Pathophysiological reflex
PAIN SPASM PAIN CYCLE
Sensory receptor
Nocicepter
Free nerve ending sensitive to damage or potential damage
Sensory neuron
Conducts a nerve impulse from nocicepters to the CNS
Integrating center
Sensory neurons synapse with an INTERNEURON that synapses with a ….
Motor neuron
To the MUSCLE WITH THE RECEPTOR, while the antagonist is inhibited
Effector
Muscle in pain
Response
Muscle in pain contracts
Renewed stimulus
Repeated firing of the motor neuron and repeated contraction of the muscle use a lot of energy - more than normal- creating an energy crisis.
The muscle and the motor neuron secrete chemicals in response to the energy crisis that stimulate nocicepters
Go back to step 2 and REPEAT IN A VISCOUS CYCLE
Facilitation
Any neuronal pathway that is used repeatedly develops a lower threshold, and will fire more easily in the future
“Wearing a groove”
Spreading
Large amounts of nociceptive input to the spinal cord cause additional interneurons to fire, spreading the chronic contractions to other muscles
First in motor neurons in the same segment, then on the other side, then up and down the cord and eventually stimulating the reticular formation, increasing global muscle tone and spreading myofascial pain throughout larger body regions.
Spinal nerves
31 pairs of spinal nerves that are numbered not named according to t he level of the vertebral column at which they emerge from the spinal cavity.
Spinal nerves ARE ALWAYS MIXED (they have both sensory and motor axions)
Cervical nerve pairs
8 pairs
C1-C7 emerge superior to their respective vertebrae
C8 emerges between T1-C7 vertebrae
Thoracic nerve pairs
12 pairs
All emerge inferior to their respective vertebrae
Lumbar nerve pairs
5 pairs
L1-5. All emerge inferior to their respective vertebrae
Sacral nerve pairs
5 Pairs
S1-5 all emerge from foramina in the sacrum
A branch of each sacral nerve travels anterior lay into th e pelvis, while another branch travels posteriorly to the myofascia and skin over the sacrum
Coccygeal nerve pair
1 pair
Emerges between the sacrum and the coccyx
Cranial nerves
12 pairs identified by both ROMAN NUMERALS AND NAMES.
The numbers indicate the order in which they connect to the brain from anterior to posterior while the names suggest. Either their distribution or function. Like all peripheral nerves, cranial nerves are made up of bundles of axions, unlike other they connect to the under surface of the brain. Unlike spinal nerves, cranial nerves are either mixed, sensory or mostly motor. Mostly motor also contain proprioceptive fibers that carry information regarding muscle tension in the muscle controlled by the motor fibers of the same motor nerve.
Cranial nerves
I
I
Name: Olfactory
Class : sensory
Function: smell
Cranial nerves
II
II
Name: optic
Class: sensory
Function: vision
Cranial nerves
III
III
name: oculomotor
Class: mostly motor
Function: eye movement
Cranial nerves
IV
IV
Name : troclear
Class: mostly motor
Function: eye movement
Cranial nerves
VI
VI
Name: abducens
Class: mostly motor
Function: eye movement (abducts the eye)
Conus medullaris
CONE MIDDLE
The inferior end of the spinal cord (cone shaped) usually ends at L1, but can vary between T12 & L3