Forelimb Nerve Supply

What extrinsic muscles are supplied by the brachial plexus?

pectoral muscles, latissimus dorsi and the serrates ventralis

Which nerves make up the brachial plexus?

subscapular, suprascapular, musculocutaneus, axillary, radial, median, unlar

What type of nerve are the subscapular and supra scapular nerves?

- Motor nerves only, no cutaneous sensation

What muscles do the subscapular and supra scapular nerves supply?

- Subscapular supplies subscapularis muscle

- Suprascauplar supplies supraspinatous and infraspinatous muscles

What kind of nerve is the musculocutaneous nerve?

Mixed nerve

Where does the musculocutaneous nerve supple cutaneous sensation to?

- Cranial and medial aspect of elbow

- medial aspect of antebrachium

Which muscles does the musculocutaneous nerve supply motor function to?

Elbow Flexors:

- biceps brachii

- brachialis

- coracobrachialis

What are potential consequences of damage to the musculocutaneous nerve?

loss of elbow flexion, no compensation.

What type of nerve is the axillary nerve?

mixed nerve

Which muscles does the axillary nerve supply?

Dedicated shoulder flexors:

- Deltoideus

- Teres major

What area does the sensory fibres of the axillary nerve supply?

Lateral aspect of shoulder and brachium

If the axillary nerve becomes damaged which muscles can compensate?

Latissimus dorsi and long head of triceps as these are also shoulder flexors

What type pf nerves are the median and ulnar nerves?

Mixed

Which area do the sensory fibres of the median and ulnar nerves supply?

- Caudal and palmar aspects of the limb

- Dorsal aspect of the 5th digit

Which muscles do the median and ulnar nerves supply?

Carpal and digital flexors

- Flexor carpi ulnaris

-Flexor carpis radialis

- Superficial digital flexor

- Deep digital flexor

What would happen if the median and ulnar nerves become damaged?

there is no compensation so there would be a loss of distal limb flexion

What type of nerve is the radial nerve?

Mixed

Which area of the forelimb do the sensory fibres of the radial nerve supply?

Dorsal and cranial aspect of the limb (except the dorsal aspect of the 5th digit )

Which muscles do the radial nerve supply?

Elbow extensors:

- Triceps

Carpus and digit extensors:

- Extensor carpus radialis

- Extensor carpus ulnaris/ unlarıs lateralis

- Common digit extensor

- Lateral digital extensor

Describe the route of the radial nerve

- Starts medial

- passes caudal to the shoulder

- passes though triceps (supplies them)

- follows musculospiral groove (and briachialis muscle)

- branch at lateral epicondyle supplies distal limb extensors

- branch at cranial/ dorsal aspect of limb runs alongside cephalic vein, supples cutaneous sensation

What motor losses occur if there was damage to the proximal end radial nerve?

- all extensor muscles effected

- can't extend elbow, carpus or digits

- can't weight bear

- limb appears longer than the opposite one

What motor losses would occur if there was damage to the distal end of the radial nerve?

- extensors of carpus and digits affected

- can't extend carpus or digits

- triceps remain intact so elbow extension not affected and can still weight bear if limb extended

How does the nerve supply of a dog's forelimb compare to that of the horse?

Brachial plexus:

-same branches, same motor function

- horses have different sensory areas

- nerve damage is uncommon in horses

What are the two major branches of the median and ulnar nerves is the horse's distal forelimb?

1. Palmar metacarpal nerves

2. Palmar nerves

What is the route and function of the palmar metacarpal nerves?

- Paired medial and lateral nerves

- run between MC3 and the splint bones

- emerge at distal end of splint bones

- supply dorsal aspect of digit

What is the route and function of the palmar nerves?

- Paired medial and lateral nerves

- runs between suspensory ligament and and SDFT

- cross abaxial aspect of the proximal sesamoids

- become the palmar digital nerves, which have dorsal and palmar branches and supply the hoof contents