Gross - Spring - Nerves Of The Thoracic Limb - Mt2

Front 1

What spinal nerves form the brachial plexus in the horse and ox?

What muscle does it come through?

What artery and vein is it close to?

Back 1

Ventral branches of C6 – T2 spinal nerves

The scalenus

The axillary artery and vein

Front 2

What spinal nerves form the brachial plexus in the sheep and goat?

Back 2

Ventral branches of C6 – T1 spinal nerves

(as opposed to Ventral branches of C6 - T2 spinal nerves in the ox and horse)

Front 3

Which pectoral mm do the cranial and caudal pectoral nn course to?

Back 3

Cranial pectoral n to superficial pectoral m.

Caudal pectoral n. to deep pectoral m. (and to subscapularis and brachiocephalicus in the horse)

Front 4

What muscles does the lateral thoracic n. innervate?

Back 4

Cutaneous trunci m. and preputial m in the the ruminants.

Front 5

What muscle does the long thoracic n. innervate?

Back 5

Serratus ventralis thoracis m.

Front 6

What muscles do suprascapular n. innervate?

What condition does paralysis of this nerve cause? How does it present?

Back 6

Supraspinatus and infraspinatus.

Suprascapular paralysis
AKA Sweeny
May cause lateral deviation of shoulder joint
Chronic – muscle atrophy resulting in
prominent spine of the scapula. (versus damage to the axillary nerve that might just show a prominent acromion - in the ruminant)

Front 7

What is the cutaneous area of the suprascapular n.?

Back 7

There is no cutaneous area

Front 8

What is the cutaneous area of the subscapular n.?

Back 8

There is no cutaneous area

Front 9

What is the definition of cutaneous area?

Back 9

The area of skin innervated to sensation by a nerve

Front 10

What nerves form a loop around the axillary a.?

Back 10

Median and musculocutaneous nn. join to form a loop (ansa axillaris) around the axillary a.

Front 11

What are the two branches of the musculocutaneous n.? What do they innervate?

Back 11

Proximal muscular br.: Coracobrachialis m. and biceps brachii.

Distal muscular br.: Brachialis m.

Front 12

What is the cutaneous innervation of musculocutaneous nerve? Where is the cutaneous branch palpable? What does it innervate?

Back 12

Cutaneous br:
Medial cutaneous antebrachial n.

Palpable as it crosses the lacertus fibrosus

Innervates the skin over the cranial and medial aspects of the antebrachium, carpus and part of metacarpus

Front 13

What muscles do axillary nerve innervate?

Back 13

Teres major, subscapularis, teres minor, deltoideus, cleidobrachialis

Front 14

What is the cutaneous innervation of axillary nerve? What does it innervate?

Back 14

Cutaneous brs:
Craniolateral cutaneous brachial n. and cranial cutaneous antebrachial n.

Innervates the skin over the lateral aspect of the brachium and cranial aspect of the antebrachium

Front 15

What muscles do radial nerve innervate?

Back 15

Triceps brachii, tensor fasciae antebrachii, anconeus

Front 16

What branches does radial nerve divide into? What do they innervate?

Back 16

Divides into deep and superficial brs.
Deep br. innervates: ext. carpii radialis, CDE, LDE, ext carpi ulnaris, ext carpii obliquus.

Superficial br. gives rise to:
Lateral cutaneous antebrachial n.
Innervates the skin over the craniolateral aspect of the distal third of the antebrachium to the level of the carpus

Front 17

Compare and contrast high radial nerve paralysis and low radial nerve paralysis in the horse.

Back 17

High radial nerve paralysis - damage occurs proximal to innervation of triceps brachii:
Horse is unable to support weight
“Dropped elbow”
Hoof rests on dorsum
Caused by damage to brachial plexus or injury to humerus

Low radial nerve paralysis - damage occurs distal to innervation of triceps brachii:
Horse is able to bear weight
Horse will likely have difficulty with uneven ground, but may compensate on even ground

Front 18

What is the median nerve motor to?

Back 18

Flexor carpii radialis, DDF – humeral and radial heads. In ruminant – also SDF, flex carp ulnaris, and pronator teres

Front 19

When does the median nerve become sensory?

Back 19

Becomes sensory after the flexors are innervated

Front 20

What does the median nerve branch into? Where? Where do these branches course and what do they give off?

(this is a lot, but you need to know this slide well)

Back 20

Proximal to the carpus, the median n. divides into medial and lateral palmar nn.
The medial and lateral palmar nerves course medial and lateral to the flexor tendons
The lateral palmar n. gives off a deep br. that gives rise to the palmar metacarpal nn. (medial and lateral) (important for blocking as they innervate deeply)
Communicating br. between medial and lateral palmar nn.
At the fetlock, the palmar nerves continue as palmar digital nn. (medial and lateral)

(this is a lot, but you need to know this slide well)

Front 21

Why is it important to know the difference between the palmar branch of digital n and the dorsal branch of digital n. in the horse?

Back 21

Because you can actually only block the palmar branch of digital n. for a lameness block in horses and not the dorsal branch of digital n. if you want to.

Front 22

What is the ulnar nerve motor to? What is it cutaneous to? Through what cutaneous branch?

Back 22

Flex carp ulnaris (ulnar head), SDF, interosseus

Cutaneous br:
Caudal cutaneous antebrachial n.
Innervates the skin over the caudal aspect of the antebrachium

Front 23

Where does the ulnar n. branch? What does it branch into? Where do the branches emerge and innervate?

(Another one that is a lot, but that we need to know well.)

Back 23

Proximal to the carpus, the ulnar n. divides into dorsal and palmar brs.
Dorsal br. emerges between tendons of insertion of flexor carpi ulnaris and ulnaris lateralis mm.
Innervates skin of dorsolateral aspect of carpus and metacarpus to the fetlock
Palmar br.
Joins lateral palmar n. of median n.

Front 24

Which nerves of the horse course all the way to the fetlock?

Back 24

Ulnar n and medial cutaneous antebrachial n from musculocutaneous n.

Lateral cutaneous antebrachial n from radial n. and cranial cutaneous antebrachial n. from axillary n. only go to the carpus.

Front 25

What are the fours thoracic limb nerve blocks in the horse? What is a good anesthetizing philosophy?

Back 25

Palmar digital nerve block (heel block)
Abaxial sesamoidean nerve block
Low palmar block (4 point block)
High palmar block (high 4 point block)

Start low, limit the area to determine soundness to as small a one as possible.

These are stepwise blocks to localize the cause of lameness.

Front 26

Where do you conduct the palmar digital nerve block (heel block)? What nerve does it anesthetize? What part of the foot does it block?

Back 26

On the palmar aspect of the pastern medially or laterally midway between the fetlock and the coronet, just palmar to the palmar digital v. and a. Typically done with two injections one medially and one laterally.

Anesthetizes the palmar digital nerves, not including dorsal brs.

Blocks palmar one-third of the foot (including the navicular bone and navicular bursa)

Front 27

Where do you conduct an abaxial sesamoidean nerve block in a horse? What nerve does it anesthetize? What does it block on the foot?

Back 27

At the abaxial surface of the proximal sesamoids
Anesthetizes palmar digital nerves including dorsal brs.
Blocks everything distal to fetlock (but not fetlock, if successful)

Front 28

Where do you conduct a low palmar block (4 point block)? What will it block on the foot?

Back 28

Between the interosseus and deep digital flexor tendon to anesthetize the palmar nerves
Between the interosseus and splint bone to anesthetize the palmar metacarpal nerves

Though it's called 4 point, you can usually get both palmar metacarpal nn. with one injection and the others with just one as well.

Blocks fetlock and everything distal to the fetlock

Front 29

Where do you conduct a high palmar block (high 4 point block)? What nerves does that anesthetize? What structures do you block?

Back 29

Between the interosseus and the deep digital flexor tendon medially and laterally approximately 5 cm distal to the carpometacarpal joint
Anesthetizes the palmar nerves and the palmar metacarpal nerves
Blocks metacarpal region, fetlock and everything distal to fetlock

Front 30

What is the sensory nerve supply to the dorsal aspect of the manus of the ruminant?

Back 30

Superficial br. of radial n.
Dorsal br. of ulnar n.

Front 31

What is the sensory nerve supply to the palmar aspect of the manus of the ruminant?

Back 31

Median n.
Palmar br. of ulnar n. (palmar common digital n. IV)

Front 32

Name these nerves of the manus of the ruminant?

Back 32

See key

Front 33

What are the palpable structures of the metacarpal region of the distal equine limb?

Back 33

Metacarpal region
MC III
MC II, MC IV
Interosseous
Palmar nerves and vessels
Communicating br. between medial and lateral palmar nn.
Deep digital flexor tendon
Superficial digital flexor tendon

Front 34

What are the palpable vascular structures in the fetlock region of the horse?

Back 34

Fetlock region
Palmar digital v. (dorsal)
Palmar digital a.
Palmar digital n. (palmar)

Front 35

What is good to keep in mind regarding the palmar digital vessels and nerves of the horse?

Back 35

Digital nerves are just the continuation of the palmar nerves whereas the vessels are new branches.

Front 36

What forms the carpal canal in the horse and ruminant? What structures course through them?

Back 36

The carpal canal is formed by the palmar carpal ligament and flexor retinaculum
Structures coursing through the carpal canal:
Horse
Superficial digital flexor tendon
Deep digital flexor tendon
Medial palmar artery
Medial palmar nerve

Ruminant
Deep part of superficial digital flexor tendon
Deep digital flexor tendon
Median artery
Median vein
Median nerve
Palmar branch of ulnar nerve

Front 37

Where are the autonomous zones of the equine forelimb?

Back 37

Medial cutaneous antebrachial-Musculocutaneous-(MCA-MU)

Median (Me)

Ulnar (U)