Forelimb nerve supply Flashcards
What makes up the Brachial plexus?
The ventral branches of C6 C7 C8 T1 T2.
Some dogs = small contribution from the ventral branch of C5.
What does the Brachial plexus supply?
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
Where do the spinal nerves arise from?
Their spinal nerve lateral to their respective intervertebral foramen
What is the function of the extrinsic muscles?
Allows attachment of limb to trunk
What is the function of intrinsic muscles?
Movement of joints in limb
Why is T2 often not included in books as being part of the brachial plexus?
Only has minor contribution
What does the subscapular nerve innovate, what type and where found
- I - Subscapularis msucle
- Motor nerve
- Medial shoulder
What does the suprascapular nerve innovate, what type and where found
- I = cranial supraspinous muscle and caudal infraspinous muscle
- motor nerve
- Lateral aspect of shoulder
Where do the subscapular and suprascapular nerves travel?
Subscapular nerve twists around the scapula neck, from around the notch
Where is, what type of nerve is the musculocutaneous nerve, what does it innovate
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
If the musculocutaneous nerve is damaged when what would happen
- loss of elbow flexion
- no compensation as felxion of elbow is by BB muscles
What type, where locates, what does it innovate: Axillary nerve
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
If the axillary nerve is damaged is there any compensation?
YEs by the Lat dorsi, long head of the tricep (those that are responsible for shoulder flexion = innovated by different nerve)
What type of nerve and what do they innovate: median and ulna nerves
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
would there be any compensation if these nerves were damaged?
NO COMPENSATION: loss of distal limb flexion
What type, location, innovation does the radial nerve have?
- MIXED NERVE
- Sensory fibres:
- cutaneous sensation to:
- dorsal and cranial aspect limb
- Except dorsal aspect 5th digit - 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
If radial nerve is damaged what would happen?
No sensation on dorsal aspect (no pain), limb remains in flexion = can’t extend
What route does the radial nerve take?
FOLLOWS FLEXOR ASPECTS OF ALL JOINTS TO AVOID OVER STRETCHING
- starts medial
- passes caudal to shoulder
- passes through triceps: innovates triceps heads
- follows musculospiral groove (and brachialis muscle)
- Branches - lateral epicondyle: supplies distal limb extensors
- Branch - cranial/ dorsal aspect of the limb: runs along cephalic vein, supplies cutaneous sensation
What is the most common causes of radial nerve damage?
- Humeral fracture
How to know if radial nerve damage is at the proximal aspect
- 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
If damage of radial nerve occurs distally what does that mean?
- Nerve supply is still in tact to triceps = can extend elbow, can weight bear if limb extended, can learn to swing limb to compensate.
- the extensors of the carpus and digits affected: can’t extend carpus/ digits
If the radial nerve is damaged what are the sensory losses?
- cranial and dorsal aspect of antebrachail and manus region
- Trauma to dorsal aspect of paw drags
- self mutilation
If the brachial plexus is damaged what is the effect on the limb
- CAN protract/ abduct limb
- CAN’T Retract/ abduct limb
- CAN’T extend/ flex limb
- CAN’T weight bear
