Spinal Nerves

Question 1

how many pairs of spinal nerves are there?

Answer 1

30+ pairs

Question 2

how many cranial nerves are there?

Answer 2

12 pairs

Question 3

interoception

Question 4

exteroception

Answer 4

sensory nerves of the somatic nervous system responsible for skin sensation

Question 5

proprioception

Answer 5

sensory nerves of the somatic nervous system which detect limb positions in order to know how and where to move

Question 6

where do neurons with cell bodies inside the CNS develop from? give examples of these neurons

Answer 6

• neural tube
• motor, preganglionic autonomic neurons

Question 7

where do neurons with cell bodies in ganglia outside the CNS develop from? give examples of these neurons

Answer 7

• neural crest
• sensory, postganglionic autonomic

Question 8

what induces spinal nerves to grow?

Answer 8

embryonic somite

Question 9

what is the skin innervated by?

Answer 9

overlapping dermatome stripes

Question 10

why do adjacent spinal nerves often tangle after leaving the vertebral column?

Answer 10

the nerves travel to their myotomes of origin but many muscles are derived from more than one myotome

Question 10

what are muscles innervated by?

Answer 10

nerves to their myotomes of origin (many muscles derive from more than one myotome)

Question 11

plexi

Answer 11

tangles of nerves

Question 12

where in the spinal cord do spinal nerves end?

Answer 12

no more spinal nerves after Cd 4, 5, 6, 7 (but nerves still travel past these points?)

Question 13

what is different about the nerves in C1?

Answer 13

only a motor nerve exists (from the lateral foramen of atlas)

Question 14

where do spinal nerves emerge from the spinal cord?

Answer 14

generally, one nerve emerges from each intervertebral notch (caudal end of the vertebra)

Question 15

how are spinal nerves numbered?

Question 16

what do nerves C1-5 innervate? what do they join?

Answer 16

innervate:
- segmental skin
- spinal muscles

join:
- cranial nerve XI to innervate the cranial muscles of the trunchobrachial junction

Question 17

what types of nerves does C1 and C2 contain? what does the C2 nerve innervate?

Answer 17

C1 - motor only
C2 - sensory innervates skin of caudal head and medial ear

Question 18

what do nerves C5, 6, 7 join to form? what does this innervate?

Answer 18

• phrenic nerve
• to the diaphragm

Question 19

which nerves are included in the cervical nerves?

Answer 19

C1-C7

Question 20

which nerves are included in the brachial plexus?

Answer 20

C6-T2

Question 21

what forms the brachial plexus?

Answer 21

• hypaxial rami of C6-T2 mingle
• gives rise to the dozen nerves of the forelimb

Question 22

where does the brachial plexus lie?

Answer 22

deep to the scapula

Question 23

where do limb muscles derive from? what do they subdivide into?

Answer 23

• hypomere part of myotome
• subdivide into dorsal and ventral groups within the limb

Question 24

what nerve could horses striking their scapulae on gate posts or wearing ill-fitting draught collars damage? what would you see?

Answer 24

- suprascapular nerve - supra and infraspinatus atrophy (more prominent scapula spine)

Question 25

what nerve could be damaged by the lateral elbow being struck, a humeral fracture or prolonged recumbency in horses?

Answer 25

radial nerve

Question 26

when can animals still stand after radial nerve damage?

Answer 26

if damage is distal to the innervation of triceps

Question 27

what do T3-T12 innervate? where do they run in relation to ribs?

Answer 27

- spinal segments - intercostal spaces - run caudal to each rib

Question 28

what does T13-L3 innervate? why is this important?

Answer 28

- flank - important in paravertebral analgesia in ruminants

Question 29

what forms the lumbosacral plexus? where do these nerves go?

Answer 29

- hypaxial rami of L4-S2 mingle - gives rise to four main nerves of the hindlimb

Question 30

what forms the sciatic "trunk"?

Answer 30

the fibular and tibial nerves running together proximally in the limb

Question 31

what nerve can a calf rub against during birth? what could paralysis of this nerve cause? what else can cause this syndrome?

Answer 31

- obturator nerve - downer cow syndrome - can also be caused by hypocalcemia

Question 32

what do S3-Cd4-7 innervate?

Answer 32

segmental muscles of the tail

Question 33

six extrinsic muscles of the tail

Answer 33

- extrinsic sagittal flexor (with long tendons) - extrinsic sagittal extensor (with long tendons) - medial, lateral, dorsal, ventral sacrocaudalis

Question 34

what are the intrinsic muscles of the tail?

Answer 34

continuation of transversospinales

Question 35

sensory and motor neurons of the somatic nervous system

Answer 35

sensory: - exteroception - proprioception motor: - to skeletal muscles

Question 36

sensory and motor subdivisions of the visceral nervous system

Answer 36

sensory: - interoception (internal organs and receptors) motor: - autonomic (internal organs and receptors)

Question 37

how many cervical nerves are there? why?

Answer 37

- 7+1 - C1-C7 nerves leaves cranial to the vertebra (with one leaving caudal to C7)

Question 38

what does the femoral nerve innervate?

Answer 38

stifle flexors

Question 39

what innervates the stifle flexors?

Answer 39

femoral nerve

Question 40

six nerves of the lumbosacral plexus

Answer 40

- gluteal (fibular) - obturator - hamstrings (tibial) - femoral - tibial - radial???

Question 41

nerves of the brachioplexus

Question 42

what does L4-L6 innervate?

Answer 42

femoral nerve: - hip flexors - stifle flexors

Question 43

what does the obturator innervate?

Answer 43

medial thigh muscles

Question 44

what doesq the L6-S2 innervate?

Answer 44

sciatic nerve: - gluteals - hamstrings

Question 45

what does the pudendal nerve innervate?

Answer 45

- pelvic diaphragm - anus - urethra

Question 46

what is the dorsal/cranial nerve of the lumbosacral plexus? what does it innervate?

Answer 46

- fibular ("peroneal") nerve - hock flexors - digital extensors

Question 47

what is the ventral/caudal nerve of the lumbosacral plexus? what does it innervate?

Answer 47

- tibial nerve -

Question 48

what is ataxia? what are its symptoms?

Answer 48

- injury to proprioception nerves - wide stance, crossed legs, stumble, floating gait