Describe the structure of the spinal cord.

Where does it begin/end? 

What are the cervical and lumbar enlargements?

What are the conus medullaris, cauda equine, and filum terminale?

the spinal cord consists of the protective structures (vertebral column and meninges) as well as the roughly cylindrical cord

the cord extends from the medulla to the second lumbar

the cervical enlargement occurs from C4 to T1

the lumbar enlargement occurs from T9 to T12

conus medullaris is the tapered end of the spinal cord

cauda equine is the collective name for the spinal roots

filum terminale is a CT filament attached to coccyx and anchors cord

What functions are associated with the horns of gray matter?

dorsal gray horns: sensory

ventral gray horns:  motor

lateral gray horns:  ANS

What are the funiculi (columns)?

What are the three columns of white matter

in the spinal cord cross section?

funiculi = anterior, posterior, and lateral white columns

What are the major ascending tracts? 

What types of impuleses do they carry?

  Trace the pathway from origin to destination for each of the tracts. 

What type of information are they carrying?

ascending tracts are sensory

Fasciculus gracilis and cuneatus (skin and joint):

proprioception, stereognosis

Spinocerebellar (muscle):  subconscious proprioception

Spinothalamic (skin):  pain, temperature, touch

major descending tracts?

all motor

pyramidal

corticospinal to the skeletal muscles below head

corticobulbar to the head and neck muscles

extrapyramidal

reticulospinal for muscle tone

rubrospinal tracts for coordination and posture

vestibulospinal for posture

tectospinal for visual and auditory response

roots unite to form a spinal nerve

dorsal: sensory/inward

ventral: motor/outward

Describe the branches that are formed immediately

after the spinal nerve exits the vertebral column.

branches

meningeal:  supplies meninges, vertebrae & ligaments

dorsal: muscles and skin of back

ventral:  intercostal nerves and plexi

visceral:  ANS

Define plexus.  List the major plexi. 

What rami forms the plexi? 

Describe the composition of each plexus and the major nerves that emerge from each one. 

plexus: network of nerves from the ventral rami

cervical plexus:  C1 to C4;

skin and muscles of the neck, phrenic nerve

brachial plexus: C5 to T1

musculocutaneous (biceps), radial (triceps), median (forearm), ulnar (forearm), axillary (shoulder)

lumbar plexus:  L1 to L4

femoral nerve, obturator (adducts thigh)

sacral plexus:  L4 to S4

sciatic nerve (hamstrings)

Where do intercostal nerves originate?

T2-T12

intercostals directly connect to their destinations

What is a reflex? 

What are the componenets of a relflex arc?

an involuntary, automatic response to stimulus

reflex arc

receptor

sensory neuron transmits to CNS

interneuron/association in CNS

motor neuron to conduct to effector

effector --> response

What are the (4) different classifications of reflexes?

development:  innate vs acquired

processing site:  cranial vs spinal

motor response:  visceral vs somatic

complexity:  monosynaptic vs polysynaptic

Describe the stimulus, pathway, and response of a

stretch reflex,

golgi tendon reflex,

withdrawal/flexor reflex, and

crossed extensor reflex.

stretch:  muscle spindles detect stretch, send impulses to muscle that resist stretch

golgi:  stretched tendon sensed, causes muscle to relax

withdrawal/flexor:  pain receptor causes muscles to contract and withdraw limb

crossed extensor:  impulses from receptor cross over to integrate whole body movement

spinal meninges

epidural space

dura mater

subdural space

arachnoid

subarachnoid space

pia mater

functions of spinal cord and nerves?

conduct impulses to and from brain

integrate reflexes

organization of spinal nerves?

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccygeal

= 31 mixed nerves