Week 4 Neuro Part 2

Front 1

Nerve tracts: purpose

Back 1

In the spinal cord together with the spinal nerves provide a two-way communication system between the brain and body parts outside the nervous system

composed of axons

Front 2

Ascending tracts: role

Back 2

Conduct sensory impulses to the brain

Front 3

Descending tracts: role

Back 3

Conduct motor impulses from the brain to motor neurons reaching mm. and glands

Front 4

Ascending tracts: names

Back 4

* fasciculus gracilis

*fasciculus cuneatus

*anterior spinothalamic

*lateral spinothalamic

*anterior spinocerebellar

*posterior spinocerebellar

Front 5

Ascending tracts: define

Back 5

Carry sensory impulses from pain, temp (thermal), touch (tactile), muscle and joint receptors (proprioception) to the brain.

Some of this info. eventually reaches a conscious level (cerebral cortex), while some is destined for subconscious centers (cerebellum)

Front 6

1st order neurons ( primary afferent): enters from->lye where?

Back 6

Enters the spinal cord through the dorsal root of the spinal nerve and its cell bodies lies in the dorsal root ganglion.

Front 7

1st order neurons (primary afferent): where are the main fibers and terminates?

Back 7

Main fibers remain on the ipsilateral side of the cord and terminates in synaptic contact w/ 2nd neuron either in the spinal gray matter or in the medulla oblongata of the brain stem

Front 8

DC-ML

Back 8

Divided into 2 regions:

* fasciculus gracilis: located more medially in the dorsal column & carries afferent info. from below T6

* fasciculus cuteaneous: located more laterally and carries info above T6

Front 9

2nd order neuron

Back 9

* cell body is in the spinal cord or medulla oblongata

* its axon crosses over (decussates) to the opposite side of the CNS & ascends to the thalamus, where it terminates upon the 3rd neuron

Front 10

3rd order neuron

Back 10

* cell body is in the thalamus

* its axon passes to the somatosensory cortex (post-central gyri) of the parietal lobe of the cerebral hemisphere

Front 11

2 main tract systems i the spinal cord of ascending tracts

Back 11

Dorsal columns: fasciculus gracilis/ cuneatus

Spinothalamic tracts: anterior/ lateral

Front 12

Fasciculus gracilis/ cuneatus: location

Back 12

Posterior funiculi (dorsal column) of spinal cord

Front 13

Fasciculus gracilis/ cuneatus: Action

Back 13

* conducts sensory impulses from skin, mm, tendons & joints to the brain

* closely associated c motor activity: motor control, manipulation of objects; stereognosis & graphesthesia

Front 14

Fasciculus gracilis/ cuneatus: Cross over (decussate)

Back 14

** From 1 side to the other at the level of the medulla**

those ascending on the L. side cross over to the R. * vice-versa.

EX>Impulses originating from sensory receptors on the L of the body reach the R. of the brain

Front 15

Fasciculus gracilis/ cuneatus: Results

Back 15

Interpreted as sensations of touch, pressure & body (vibration/proprioception)

Front 16

Lateral Spinothalamic: Location

Back 16

Lateral funiculi of the spinal cord

Front 17

Lateral Spinothalamic: action

Back 17

Conducts snesory impulses from various body regions to the brain (pain, temp & light touch)

Front 18

Lateral spinothalamic: cross over

Back 18

Impulses in these tracts cross over in the spinal cord

Front 19

Lateral spinothalamic: results

Back 19

Gives rise to sensations of pain and temp

Front 20

Anterior spinothalamic: location

Back 20

Anterior funiculi of the spinal cord

Front 21

Anterior spinothalamic: action

Back 21

Conducts sensory impulses from various body regions of the brain (pain, temp, & light tough)

Front 22

Anterior spinothalamic: cross over

Back 22

Impulses in these tracts cross over in the spinal cord

Front 23

Anterior spinothalamic: results

Back 23

Gives rise to sensation of touch and pressure

Front 24

Where do the spinocerebellar system 2nd order neuron cell body of origin lie?

Back 24

In the base of the dorsal horn

Front 25

How do the spinocerebellar system differ?

Back 25

They only have 2 neurons - 1st and 2nd neurons

Front 26

Where do the spinocereellar system tract neurons terminate?

Back 26

Cerebellar cortex

Front 27

What are the two Spinocerebellar system names?

Back 27

Anterior spinocerebellar

Posterior spinocerebellar

Front 28

Anterior spinocerebellar: location

Back 28

Near the surface in the lateral funiculi of the spinal cord

Front 29

Anterior spinocerebellar: action

Back 29

Conducts sensory impulses that originate in the mm. of the lower limbs and trunk and travel to the cerebellum

Front 30

Anterior spinocerebellar: cross over

Back 30

Some fibers stay on the ipsilateral side some fibers cross over contralateral and ascend, however they cross back over to the same side they originated from before entering the cerebellar cortex

Front 31

Anterior spinocerebellar: results

Back 31

Impulses coordinated muscular movement

Front 32

posterior spinocerebellar: location

Back 32

Near the surface in the lateral funiculi of the spinal cord

Front 33

Posterior spinocerebellar: action

Back 33

conducts sensory impulses that originate in mm of the UE/head and then travel to the cerebellum

Front 34

Posterior spinocerebellar: cross over

Back 34

FIBERS REAMAIN UNCROSSED

Front 35

Posterior spinocerebellar: results

Back 35

Impulses coordinate muscular movements

Front 36

Pathways: pain and temp- extremities/trunk

Back 36

lateral spinothalamic tract

Front 37

Pathways: pressure & simpule (crude) touch- extremeties/trunk

Back 37

Anterior spinothalamic tract

Front 38

Pathways: proprioception, fine (discriminatory) touch and vibratory sense- extremities/trunk

Back 38

Fasciculus gracilis/fasciculus cuneatus

Front 39

Pathway for pain & temp from extremities & trunk

Back 39

pain- Sensory receptors in dermis or epidermis -> impulse travels towards spinal cord -> cell bodies in dorsal root ganglion -> dorsal root to spinal nerve -> Dorsal horn of gray matter -> 1st neuron synapses c 2nd neuron -> axon cross over other (contralateralO side of cord via ventral white commissure ->lateral spinothalamic tract -> impulse ascends to the thalamus -> synapse c 3rd neuron ->axons travels thru internal capsule-> postcentral gyrus (parietal lobe)-> interpreted as pain

Front 40

-Algia

Back 40

Pain

ex. Neuralgia=nerve pain

analgesic= "absence of/w/o pain" substance the deadens or dulls pain (morphine, aspirin or alcohol)

Front 41

-Esthesia

Back 41

Sensation/feeling

ex. Anesthesia- absense of/without sensation or feeling

substance the deadens or dulls all pain

Front 42

Common cause of neuralgia

Back 42

Pressure from a herniated intervertebral disc on the spinal cord or spinal nerve, can produce great pain

ex. sciatica

Front 43

Referred pain

Back 43

Pathway from viscera is poorly understood

*visceral pain is not well localized in the brain & cortex often "interprets" such impulses as coming from adjacent skin areas whose afferent fibers reach the same area of the cortex

* certain cases: such pain is exprerienced at the surface of the body some distance from the affected organ

Front 44

Examples of Referred pain

Back 44

Heart attack= gnawing pain that radiates along inner aspect of L. arm

Ureter paion- felt in the flank & inguinal area

gallbladder- felt in shoulder area (sometimes btw shoulder blades)

Lungs & diaphragm= shoulder near root of the neck

Front 45

Phantom limb

Back 45

Cases after amputation, pt, c/o excruciated pain from finger, toes etc., that no longer excist

* stimulus applied anywhere after the nerve fiber is experienced by the sensory cortex as coming, not from the site of stimulation but rather, from the skin area supplied by the nerves being stimulated

* nerve fibers at the "stump" are frequently squeezed by the scar tissue, and is pain stimulus passes to the sensory cortex, which interprets it as coming, from the stump area but, from the skin area of the missing limb