• is a continuation of the brain and is located within the vertebral column (canal)

• it's about 40 cm long (depending on how tall the person is)

• the point up to where the SC extends down
• rear ending of the SC

• means horse tail or pony's tale
• they are pathways/nerves that are continued down from the point of the conus medulanis

• cervical
• thoracic
• lumbar
• sacral

• dura
• arachonoid
• pia
• just like the brain

• 8 cervical nerves
• 12 thoracic nerves
• 5 lumbar nerves
• 5 sacral nerves
• 1 coccyxgeal nerv
• total = 31 pairs of spinal nerves
• we refer to them by number - C1, L4, etc.

recieves somatosensory info from body

conveys info to SC and to brain (to the CNS) 

AKA - dorsal root (back/posterior)

controls the motor activity of different body segments

related ot motor act corresponding to the motor segment

AKA - front root (anterior)

• cervical - head, neck, diaphragm, deltoids, biceps, wrist extenders, triceps, hands
• thoracic - mostly abdomincal muscles also chest muscles
• lumbar - leg muscles
• sacral - bowel, bladder, and sexual function

for example:

• C1 - back of head
• C2 - various areas of the head
• C3 - side and front of the neck
• C4 - upper back of neck

medulla oblongata

where the brain ends the the SC continues

• body (towards the front)
• foramen - vertebral foremen
• vertebral canal - where the SC is located
• spinous processes - towards the back
• transverse process

the butterfly looking are in vertebra

contains cell bodies

surrounds grey matter (opposite of the brain)

contains pathways up and down (sensory and motor pathways)

pyrimidal tract

spinocerebellar tract

spinothalamic tract

they are named from where they begin and where they end  

EX: spinocerebellar tract begins at SC ends cerebellum

simplest motor response

sensory stimulation that goes to SC thru the dorsal root/sensory root, an interneuron is found and a motor neruon to muscle to representing a response

the motor activity of certian body segment is going to be impaired b/c motor pathways below that level can't connect/go to the cortex so the type of motor defect is going to depend upon the particular level of the SC that is impaired

each sensory root is innervating a particular motor segment by a SC

representation of body areas/segments innervating by different spinal nerves

primary somatosensory area

1.  posterior column medial luminiscus pathway - covers touch, 2 point discrimination 

     - info goes up ipsilateral and decussates at the

       level of the medulla

2.  spinothalamic pathway - conveys info about pain

and temperature

     - decussates as soon as it enters SC

upper motor neuron

lower motor neuron

they damage results in quite different manifestations

• decreased strength
• increased muscle tone
• increased stretch reflexes
• mild atrophy
• clonus - a rapid series of alternating muslce contractions in response to sudden stretch
• pathological reflexes - Babinski's sign

• decreased strength
• decreased muscle tone
• decreased stretch reflexes
• severe atrophy
• fasciculations - spontaneous contractions of groups of muscle fibers, visible thru the skin as twitches
• fibriluations - spontaneous contractions of individual muscle fibers, not visible but appear in electrical recording

subdivided into sympathetic and parasympathetic

usually sympathetic activates the particular organ and paraysympathetic decreases the activity of that particular organ

they are going to be changing activities of the internal organs that we do not have control over

EX: parasympathetic exhibits flow of saliva but sympathetic decreases it

Brown Seguard

Sringomyelia

• a hemisection of SC
• the spinothalamic tract decussates immediately entering SC, below this level we find disturbance in pain &temp contralateral