Forelimb nerve supply

Question 1

What makes up the Brachial plexus?

Answer 1

The ventral branches of C6 C7 C8 T1 T2.

Some dogs = small contribution from the ventral branch of C5.

Question 2

What does the Brachial plexus supply?

Answer 2

Extrinsic = 
Pectoral muscles:, Latissimus Dorsi: Thoracodorsal nerve (C7, C8, T1), 
Serratus Ventralis
Intrinsic:
ALLLLLLLL:
- Subscapular nerve
- Suprescapular nerve
- Axillary nerve
- Radial nerve
- Median adn ulnar nerve

Question 3

Where do the spinal nerves arise from?

Answer 3

Their spinal nerve lateral to their respective intervertebral foramen

Question 4

What is the function of the extrinsic muscles?

Answer 4

Allows attachment of limb to trunk

Question 5

What is the function of intrinsic muscles?

Answer 5

Movement of joints in limb

Question 6

Why is T2 often not included in books as being part of the brachial plexus?

Answer 6

Only has minor contribution

Question 7

What does the subscapular nerve innovate, what type and where found

Answer 7

1. I - Subscapularis msucle
2. Motor nerve
3. Medial shoulder

Question 8

What does the suprascapular nerve innovate, what type and where found

Answer 8

1. I = cranial supraspinous muscle and caudal infraspinous muscle
2. motor nerve
3. Lateral aspect of shoulder

Question 9

Where do the subscapular and suprascapular nerves travel?

Answer 9

Subscapular nerve twists around the scapula neck, from around the notch

Question 10

Where is, what type of nerve is the musculocutaneous nerve, what does it innovate

Answer 10

Medial aspect of antebrachial region
MIXED NERVE
1. Sensory:
cutaneous sensation to - cranial and medial aspects of the elbow 
- medial aspect of the antebrachium
2. Motor:
Elbow flexors:
- BBC
- Brachialis muscle
- Biceps brachii muscle
- Coracobrachialis muscle

Question 11

If the musculocutaneous nerve is damaged when what would happen

Answer 11

• loss of elbow flexion

- no compensation as felxion of elbow is by BB muscles

Question 12

What type, where locates, what does it innovate: Axillary nerve

Answer 12

MIXED NERVE
Axillary region: lateral aspect of brachial region
1. Motor supply:
- dedicated shoulder flexor:
- Deltoideus muscle 
- Teres major muscle
2. SENSORY 
- Cutaneous sensation to:
- lateral aspect shoulder and brachium

Question 13

If the axillary nerve is damaged is there any compensation?

Answer 13

YEs by the Lat dorsi, long head of the tricep (those that are responsible for shoulder flexion = innovated by different nerve)

Question 14

What type of nerve and what do they innovate: median and ulna nerves

Answer 14

MIXED:
Middle = median
outer = ulnar
Located= caudal lateral aspect and caudal medial aspect
Innovate all caudal muscle groups of the antebrachial region
1. Sensory fibres:
- cutaneous sensation to:
- caudal and palmer aspect limb
-dorsal aspect 5th digit
2. Motor supply:
- flexor carpi ulnaris muscle
- Flexor carpi radialis muscle
- superficial digital flexor muscle
- deep digital flexor muscle

Question 15

would there be any compensation if these nerves were damaged?

Answer 15

NO COMPENSATION: loss of distal limb flexion

Question 16

What type, location, innovation does the radial nerve have?

Answer 16

1. MIXED NERVE
2. Sensory fibres:
   - cutaneous sensation to:
   - dorsal and cranial aspect limb
   - Except dorsal aspect 5th digit
3. MOTOR supple:
   - extensors of elbow: triceps muscle
   - Extensors of carpus and digits:
   Extensor carpi radialis muscle
   Extensor carpi ulnaris/ ulnaris lateralis muscle
   - common digital extensor muscle
   - lateral digital extensor muscle

Question 17

If radial nerve is damaged what would happen?

Answer 17

No sensation on dorsal aspect (no pain), limb remains in flexion = can’t extend

Question 18

What route does the radial nerve take?

Answer 18

FOLLOWS FLEXOR ASPECTS OF ALL JOINTS TO AVOID OVER STRETCHING

1. starts medial
2. passes caudal to shoulder
3. passes through triceps: innovates triceps heads
4. follows musculospiral groove (and brachialis muscle)
5. Branches - lateral epicondyle: supplies distal limb extensors
6. Branch - cranial/ dorsal aspect of the limb: runs along cephalic vein, supplies cutaneous sensation

Question 19

What is the most common causes of radial nerve damage?

Answer 19

1. Humeral fracture

Question 20

How to know if radial nerve damage is at the proximal aspect

Answer 20

• supplying tricep:
  1. All extensor muscles affected (tricep)
  2. cannot extend elbow, carpus or digits
  3. cannor weight bear
  4. Limb appears longer than opposite one
  So everything distal - elbow flexed, non weight bearing

Question 21

If damage of radial nerve occurs distally what does that mean?

Answer 21

1. Nerve supply is still in tact to triceps = can extend elbow, can weight bear if limb extended, can learn to swing limb to compensate.
2. the extensors of the carpus and digits affected: can’t extend carpus/ digits

Question 22

If the radial nerve is damaged what are the sensory losses?

Answer 22

1. cranial and dorsal aspect of antebrachail and manus region
2. Trauma to dorsal aspect of paw drags
3. self mutilation

Question 23

If the brachial plexus is damaged what is the effect on the limb

Answer 23

1. CAN protract/ abduct limb
2. CAN’T Retract/ abduct limb
3. CAN’T extend/ flex limb
4. CAN’T weight bear