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unit 3 anatomy masterdeck > introduction to the spinal cord > Flashcards

introduction to the spinal cord Flashcards

1
Q

what is the spinal cord?

A

a part of the CNS. it runs down the spine and allows the body to feel

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2
Q

what are the functions of the spinal cord?

A
  • sensory and motor innervation of body
  • two-way conduction pathway for signals between body and brain
  • major center for reflexes
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3
Q

what is the position of the spinal cord against the spine?

A

extends from foramen magnum to level of L1 or L2 (lumbar vertebrae)

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4
Q

how many pairs of spinal nerves do humans have?

A

31 pairs
- 8 cervical
-12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal

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5
Q

what are cervical and lumbar enlargements for?

A

for nerves upplying the upper and lower limbs

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6
Q

do cervical spinal nerves appear superior or inferior to their respective vertebrae?

A

superior

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7
Q

which cervical spinal nerve appears inferior?

A

C8 (inferior to C7 vertebra)

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8
Q

how to the thoracic to coccygeal nerves appear?

A

inferior

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9
Q

what is the inferior end of the spinal cord called?

A

conus meduallaris

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10
Q

where does the spinal cord end in kids and adults?

A

kids - L4
adults - L1

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11
Q

what is the bundle of nerve roots at the end of the vertebral canal called?

A

cauda equina

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12
Q

what is the filum terminale?

A

a long filament that extends from the conus medullaris to the coccyx. it acts as a tether

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13
Q

how is the spinal cord protected?

A

protexted by bonne, meninges, and CSF

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14
Q

what is the epidural space?

A

a space in the spine that is filled with fat and veins. it is not in the CNS. this is also where the epidural during delivery is administered

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15
Q

what are the denticulate ligaments?

A

anchors for the spinal cord to the dura mater

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16
Q

what vertebrae is the epidural needle stuck into?

A

in between the L4 and L5. the needle pushes the cauda equina out of the way so the spinal cord has a lower chance of being pierced

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17
Q

describe the structure of the gray matter in the spine

A
  • forms a butterfly/H shape, surrounded by white matter
  • gray commisure: unmyelinated axons crossing from one side to another
  • dorsal (posterior) arms of butterfly are the doral horns
  • ventral (anterior) arms of butterfly are the ventral horns
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18
Q

how do the dorsal horns work?

A

dorsal horns receive information from sensory neurons (cell bodies located in the dorsal root ganglia). signals from sensory neurons reach spinal cord via the dorsal roots

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19
Q

how do ventral horns work?

A

ventral horns send out info to skeletal muscles. signals going out to motor neurons travel via ventral roots

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20
Q

what are spinal nerves?

A

dorsal and venrtral roots merge to form a spinal nerve

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21
Q

what kinds of axons does a spinal nerve have?

A

sensory and motor

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22
Q

where does the spinal nerve exit the vertebral column?

A

at the intervertebral foramina

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23
Q

what does the spinal nerve split into?

A

dorsal and ventral rami

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24
Q

how do rami work?

A
  • ventral and dorsal rami carry both sensory and motor fibers
  • ventral rami innervate most of the body, including trunk and limbs. dorsal rami innervate small portion of the back
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25
Q

what are reflexes?

A
  • very simple neuron chain
  • basic structural plan of nervous system
  • reflexes usually exclude brain; rapid, automatic, unlearned motor response to stimulus
  • can be somatic or visceral
  • signal comes in and synapses at spinal cord
  • motor neurons stimulate and inhibit as appropriate
26
Q

how are reflexes tested?

A
  • tapping at the patella
  • used in clinical setting to check muscle groups and spinal nerves, spinal cord
27
Q

what is a dermatome?

A

an area of skin supplied by a single spinal nerve

28
Q

which spinal nerve does not have a dermatome?

A

C1

29
Q

why are dermatomes important?

A
  • numbness can pinpoint spinal cord injuries
  • reffered pain: when pain from an organ is mistakenly referred to a dermatome
30
Q

what is a nerve plexus?

A

a network of nerves. formed only by the VENTRAL rami of spinal nerves. each muscle recieves nerve supply from more than one nerve

31
Q

which spinal nerves do not form a dermatome?

A

T2-T12

32
Q

how many nerve plexuses are there?

A

4:
- cervical (C1-C4)
- brachial (C5-T1)
- lumbar (L1-L4)
- sacral (L4-S4)

33
Q

describe the cervical plexus

A
  • ventral rami of the first 4 cervical nerves
  • most branches are cutaneous sensory
  • some motor to anterior neck
  • phrenic nerve receives fibers from C3, C4, and C5; innervates diaphragm for respiration
34
Q

describe the brachial plexus

A
  • partly in neck, partly in axilla
  • gives rise to most nerves of the upper limb
  • mixing of verntral rami of C5-C8 and most of the ventral ramus of T1
  • main components: ventral rami, trunks, divisions, cords
35
Q

describe how the brachial plexus splits?

A
  • 5 roots merge into 3 trunks which branch into 2 divisions each
  • anterior division: nerves that innervate anterior compartment muscles of upper limb and skin
  • posterior division: nerves that serve posterior compartment and skin
36
Q

name the terminal branches of the brachial plexus

A
  • axillary nerve
  • radial nerve
  • musculocueaneus nerve
  • median nerve
  • ulnar never
37
Q

musculocutaneous nerve

A
  • sensory innervation: skin sensation for lateral forearm
  • motor innervation: anterior compartment of arm
38
Q

ulnar nerve

A
  • sensory innervation: skin of medial hand, medial side of digit 4, all of digit 5
  • motor innervation: flexors and intrinsic hand muscles (interossei, hypothenar mm)
39
Q

median nerve

A
  • sensory innervation: skin of lateral palm and digits 1-3 and lateral side of digit 4
  • motor innervation: anterior compartment of forearm (with ulnar). thenar muscles of palm (muscles that opposee the thumb)
40
Q

what is carpal tunnel?

A
  • affects motor nerve to thenar muscles
  • pain/numbness in lateral palm
  • from compression of nerve near hand
  • median nerve lesion
41
Q

axillary muscles

A
  • sensory innervation: shoulder joint and skin overlying part of deltoid
  • motor innervation: teres minor and deltoid
42
Q

radial nerve

A
  • sensory innervation: skin over dorso-lateral arm, forearm, and hand
  • motor innervation: posterior compartment of arm and forearm (extensors)
43
Q

what nerves are in lumbar plexus?

A
  • iliohypogastric
  • ilioinguinal
  • genitofemoral
  • lateral femoral cutaneous
  • femoral
  • obturator
44
Q

femoral nerve

A
  • sensory innervation: skin of antero-medial thigh, skin of medial leg and foot
  • motor innervation: muscles of anterior thigh (thigh flexors, leg extensions)
45
Q

obturator nerve

A
  • sensory innervation: skin of medial thigh
  • motor innervation: muscles of medial thigh (adductors)
46
Q

sacral plexus

A
  • tibial nerve and common fibular nerve together in common sheath: sciatic nerve
  • longest and thickest nerve of the body. serves all of lower limb except anterior/medial thigh
47
Q

what nerves are in the sacral plexus?

A
  • tibial
  • pudendal
48
Q

tibial nerve

A
  • sensory innervation: skin of postero-lateral leg, skin of sole of foot (subdivides into plantar nerves)
  • motor innervation: muscles of posterior thigh, muscles of posterior leg (adductor magnus, biceps femoris)
49
Q

sacral plexus (posterior)

A
  • superior gluteal
  • lumbosacral trunk
  • inferior gluteal
  • common fibular
  • posterior femoral cutaneous
50
Q

common fibular nerve

A
  • sensory innervation: skin of antero-lateral leg, skin on dorsum of foot
  • motor innervation: muscles of anterior leg (deep fibular), muscles of lateral leg (superficial fibular)
  • common fibular nerve also innervates biceps femoris (with tibial nerve)
51
Q

what is foot drop?

A

a fibular nerve lesion (common peroneal nerve)

52
Q

phrenic

A
  • motor innervation: diaphragm
  • deficiet: inability/difficulty breathing
53
Q

axillary

A
  • motor innervation: deltoid
  • defiect: difficulty abducting arm to 90 degrees
54
Q

musculocutaneous

A
  • motor innervation: anterior arm
  • deficiet: weakness flexing elbow
55
Q

median

A
  • motor innervation: anterior arm and thumb
  • defiect: weakness flexing wrist, difficulty opposing thumb, carpal tunnel syndrome
56
Q

radial

A
  • motor innervation: posterior arm and forearm
  • defiect: difficulty extending elbow, wrist drop
57
Q

ulnar

A
  • motor innervation: deep hand muscles
  • defiect can’t adduct/abduct fingers, “funny bone”
58
Q

femoral

A
  • motor innervation: anterior thigh muscle
  • defeict: walking problema, knee buckles
59
Q

tibial

A
  • motor innervation: posterior thigh and leg
  • defiect: shuffling gait, difficulty with plantar flexing
60
Q

what endings does the sacral plexus have?

A
  • superior gluteal
  • lumbosacral trunk
  • inferior gluteal
  • common fibular
  • posterior femoral cutaneous
61
Q

common fibular nerve

A
  • sensory innervation: skin of the antero-lateral leg, skin on the dorsum of the foot
  • motor innervation: muscles of the anterior leg (deep fibular), muscles of the lateral leg (superficial fibular), biceps femoris (with tibial nerve)
62
Q

what is foot drop?

A

a condition in which the common peroneal nerve is damaged, causing the foot to drop from a natural resting position

unit 3 anatomy masterdeck (9 decks)

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