Spinal Cord, Spinal Nerves, And Somatic Reflexes

Front 1

-starts at foramen magnum and ends at L1
--conduction/communication
-locomotion
-reflexes
-neural integration

Back 1

Spinal Cord: CNS

Front 2

1. communicates with the brain and rest of the body by info up and down spinal cord

2. pools of spinal neurons receive input from multiple sources, integrate the info, and execute an approp. output

Back 2

1. conduction


2. neural integration

Front 3

1. central pattern generators; for simple repetetive motions

2. involuntary stereotyped responses to stimuli, such as withdrawal of hand to pain

Back 3

1. locomotion


2. relexes

Front 4

2 areas where the SC has enlargement/thicker

Back 4

1. cervical enlargement
2. lumbar enlargement

Front 5

1. enlargment that gives rise to the nerves of upper limbs

2. enlargement that gives rise to pelvic region and lower limbs

Back 5

1. cervical enlargement

2. lumbar enlargement

Front 6

1. inferior to lumbar enlargement, where the cord tapes to a point

2. bundle of nerve roots that occup the vertebral canal from L2-S5

Back 6

1. Medullary Cone

2. Cauda Equina

Front 7

1. SC and brain are enclose in 3 fibrous CT membranes

2. forms loose fitting sleeve/sheath around the SC

Back 7

1. meninges

2. dura matter/dural sheath

Front 8

1. space between dural sheath and vetebral bones
-occupied by blood vessels, adipose tissues, and loose CT

2. consists of simple squamous epithelium, membrane, adheres to inside of dura, and a loose mesh of collagenous and elastic fibers spanning the gap between membrane and pia mater

Back 8

1. epidural space

2. arachnoid mater

Front 9

1. -gap between arachnoid membrane and pia mater
-filled with CSF and involved with lumbar punctures

2. delicate, transparent membrane that closely follows the countours of the SC

Back 9

1. subarachnoid space

2. pia mater

Front 10

-type of nervous tissue
-H shaped/butterfly pattern
-contains somas, dendrites, and procimal parts of axons (unmyelinated)
-site of synaptic contact between neurons so site of all neural integration in the SC

Back 10

gray matter

Front 11

-type of nervous tissue
-has abundance of myelin
-composed of bundles of axons/tracts that go up and down the SC and arranged into 3 colums
-involved with communication between different levels of the CNS

Back 11

white matter

Front 12

1) part of gray matter involved with motor activity

2.) part of gray matter invovled with sensory activity

Back 12

1. anterior/ventral horn

2. posterior/dorsal horn

Front 13

1. -destroys the nuerons of the anterior horn

2. -gray SC inflammation
-muscles do not receive innervation
-muscle pain, weakness, atrophy, paralysis, loss of some reflexes, and sometimes respiratory arrest

Back 13

1. polio virus

2. poliomyelitis

Front 14

-Lou Gehrig disease
-degeneration of motor neurons and atrophy of muscle, also sclerosis of the lateral regions of the SC
-upper and lower neurons degenerate
-sensory tracts intact
-muscular weakness, difficulty speaking, swallowing, and using the hands

Back 14

ALS

Front 15

-cause by varicella-zoster virus
-itchy rash
-remains for life in the posterior root ganglia
-if stressed, virus emerges and travels down sensory nerve fibers to cause painful itchy sores and often fluid filled vesicles along path of nerve

Back 15

shingles

Front 16

1. bundle of axons that communicate between spinal cord and brain

2. gateway to the cerebral cortex

Back 16

1. tracts

2. thalamus

Front 17

-carry sensory information up the cord
-sensory pathways
-receptor to brain
-involves 1st, 2nd, and 3rd order neurons
-names are "spine+destination"
ex: spinothalamic tract

Back 17

ascending pathways

Front 18

1. -receptor to SC/brainstem involves this

2. spinal cord to thalamus involves this

3. thalamus to cerebral cortex/primary somestetic cortex

Back 18

1. 1st order neuron

2. 2nd order neuron

3. 3rd order neuron

Front 19

1. as passing up or down brainstem and spinal cord tracts cross to opposite side

2. origin and destination of a tract are on opposite side of the body

Back 19

1. decussation

2. contralateral

Front 20

1. tract does not decussate, its origin and destination are on the same side of the body

1. how the SC communicates with the rest of the body
-sensory+motor info=seperated upon entering/exiting SC

Back 20

1. ipsilateral

2. spinal nerves

Front 21

-conduct motor impulses down the SC
-motor pathways
-brain to effector (consist of 2 neurons)
-involves upper and lower motor neurons

Back 21

descending pathways

Front 22

1. cerebral cortex(primary motor cortex) to spinal cord

2. spinal cord to muscle/gland
-axon of this leads from the SC to the muscle or other target organ

Back 22

1. upper motor neuron

2. lower motor neuron

Front 23

1. type of descending pathway
-carry motor signals from the cerebral cortex for precise, finely coordinated limb movements

2. -type of ascending pathway
-carries signals for pain, temp, pressure, touch, tickle, or itch

Back 23

1. corticospinal tract

2. spinothalamic tract

Front 24

1. -cordlike organ composed of numerous nerve fibers/axons bound together by CT
-cable

2. -wire
-axon

Back 24

1. nerve

2. nerve fiber

Front 25

-consist of both afferent (sensory) and efferent (motor) fibers
-conduct signals in 2 directions
-most are this

Back 25

mixed nerves

Front 26

1. -dense CT that surrounds the whole nerve

2. wraps around each fascicle (bundle of nerve fibers)

3. loose CT that wraps around each nerve fiber

Back 26

1. epineurium

2. perineueum

3. endoneurium

Front 27

1. number of cervical spinal nerves

2. number of thoracic spinal nerves

Back 27

1. 8 (C1-C8)

2. 12 (T1-T12)

Front 28

1. number of lumbar spinal nerves

2. number of sacral spinal nerves

3. number of coccygeal spinal nerves

Back 28

1. 5 (L1-L5)

2. 5 (S1-S5)

3. 1 (Co)

Front 29

1. contains the neurosomas of sensory neurons

2. come together to form the spinal nerve

Back 29

1. posterior/dorsal root ganglion

2. posterior and anterior roots

Front 30

1. anterior surface; goes toward muscle, skin

2. goes to doral surfaces

3. what the spinal nerve travels through before branching

Back 30

1. anterior ramus

2. posterior ramus

3. intervetebral foramina

Front 31

how a spinal nerves branches (the 3 flows)

Back 31

spinal nerve (mixed)--> DRG --> dorsal root --> spinal cord --> ventral root --> spinal nerve (mixed)

spinal nerve (mixed) <--> dorsal ramus <--> individual neruons innervate spinal region and back

spinal nerve (mixed) <--> ventral ramus <--> plexus <--> individual neurons innvervate anterior body

Front 32

nerve networks

Back 32

plexuses

Front 33

1. cervic plexus

2. brachial plexus

Back 33

1. C1-C5

2. C5-T1

Front 34

1. lumbar plexus

2. sacral plexus

Back 34

1. L1-L4

2. L4-S4

Front 35

1. number cervical neve pairs

2. number thoracic nerve pairs

Back 35

1. 8

2. 12

Front 36

1. number lumbar nerve pairs

2. number sacral nerve pairs

Back 36

1. 5

2. 5

Front 37

-gives rise to the phrenic nerve
-innervates the diaphragm (breathing)

Back 37

cervical plexus

Front 38

-innvervates the muscles and skin of upper limbs
-musculocutaneous nerve
-axillary nerve
-radial nerve
-median nerve
-ulnar nerve

Back 38

Brachial Plexus

Front 39

-innervates muscles and skin of thighs
-gives rise to femoral nerve

Back 39

lumbar plexus

Front 40

-muscle and skin of lower limbs
-gives rise to sciatic nerve

Back 40

sacral plexus

Front 41

-each spinal nerve except C1 receives sensory input from a specific area of skin
-area of skin
-large overlap up to 50%
-usually 3 spots to anesthetize to get whole region

Back 41

Dermatomes

Front 42

-quick, automatic response to a stimulus
-to maintain homeostasis (visceral; involves glands/organs) and prevent injury (somatic)

Back 42

reflex

Front 43

-requires stimulation
-involuntary
-quick
-stereotyped (predictable)

Back 43

properties of reflexes

Front 44

components of a reflex arc (somatic reflexes)

Back 44

sensory receptors --> afferent nerve fibers --> integrating center (SC/brainstem) --> efferent fibers --> skeletal muscles

Front 45

-only 1 synapse between afferent and efferenct neuron so little synaptic delay and a prompt response
-between sensory nerves and motor nerves
sensory--> motor

Back 45

monosynaptic

Front 46

-multiple synapses
-interneurons
-pathway in which signals travel over many synapses on their way back to the muscle

Back 46

polysynaptic

Front 47

-specialized stretch receptors embedded in muscles
-involved with many somatic reflexes
-concentrated at ends of muscles near tendons
-provide info about length and movement --> sensitive to small and sudden changes--> tells brain to initiate reflex to adjust tension to keep balance
-muscles involved in fine motor control have more

Back 47

muscle spindles

Front 48

-to maintain equilibrium and posture
-involved for coordinated movement
-monosynaptic
-sudden change in tendon length relfexively causes muscle contraction
-ex: knee jerk/patellar relfex, calcaneal tendon --> plantar flexion, triceps-brachii tendon--> forearm ext.

Back 48

stretch/tendon reflex

Front 49

-stretch reflexes and other muscle contractions often depend on this
-a reflex phenomenon that prevents muscles from working against eachother by inhibiting antagonists
-anatagonist muscles are inhibited so dont work against other (polysynaptic)
ex: knee jerk (patellar) reflex

Back 49

Reciprocal Inihbition

Front 50

-quick contraction of flexor muscles to withdraw from injurious stimulus
-flex ipsilateral leg
-polysynaptic
-employs ipsilateral reflex arc
-requires reciprocal inhibition

Back 50

Flexor Reflex

Front 51

-contraction of contralateral extensor muscles to shift center of gravity and maintain balance
-polysynaptic
-employs contralateral reflex arc
-requires reciprocal inhibition

Back 51

crossed extension reflex

Front 52

flexor/withdrawal reflex pathway

Back 52

pain receptor --> sensory neuron --> dorsal root ganglion --> dorsal root --> interneurons --> motor neurons ---> ventral root --> flexor or extensor muscle --> contraction/relaxation