Flashcards in Innervation of the Upper Limb Deck (36):
Which ventral rami form the brachial plexus?
What type of fibres are contained within the brachial plexus?
Sympathetic postganglionic, sensory and somatic.
Name the separate parts of the brachial plexus.
Roots --> trunks --> divisions --> cords --> branches.
What are the roots of the brachial plexus?
What are the trunks of the brachial plexus, and what roots form them?
Superior (C5+C6), Middle (C7) and Inferior (C8+T1)
What are the divisions of the brachial plexus?
Anterior and posterior from each cord. Nerves from anterior division innervate flexors + overlying skin. Nerves from posterior division innervate extensors + overlying skin.
Why are the cords named how they are?
Due to their relative position to the axillary artery
What are the cords of the brachial plexus, and what do they consists of?
Lateral (anterior divisions of superior and middle trunk), posterior (posterior divisions of all trunk) and medial (anterior divisions of inferior trunk).
What are the branches of the brachial plexus that innervate the upper limb?
Axillary and radial nerves (from posterior cord), musculocutaneous (from lateral cord), ulnar nerve (from medial cord) and median nerve (from both lateral and medial cords).
What part of the nervous system does NOT innervate the limbs?
What sympathetic nerves travel in the brachial plexus?
What do post-ganglionic sympathetic fibres innervate?
Arrector Pili muscles, sweat glands and blood vessels.
What 2 parts of the upper limb does the SNS NOT innervate
Cartilage and Nail.
What are the scores of the MRC grading scale?
0 - no movement
1 - belly of muscle moves
2 - moves without gravity
3- moves against gravity
4- against gravity + resistance
5 - full strength.
Identify myotome and reflexes fro C5, C6, C7, C8 and T1.
C5 - Deltoid - Biceps Reflex.
C6 - Wrist Extensors - brachioradialis reflex
C7 - Triceps - Triceps reflex
C8 - Finger flexors - finger flexor reflex
T1 - Finger abductors/adductors - no reflex.
When considering single spinal nerve injury, what should be assessed?
Dermatome, myotome and reflex.
What are the root values of the axillary nerves, and what does it innervate?
C5C6. Innervates deltoid and teres minor, the shoulder joint and skin over deltoid.
What are the root values of the radial nerve, and what does it innervate?
C5-T1. Innervates muscles in the posterior arm and forearm and skin overlying it. (+skin on dorsum of hand)
When the radial nerve splits, which nerves are formed and what do they innervate?
Posterior interosseous nerve (deep) supplies extensor muscles of forearm.
Superficial branch of radial nerve - innervates skin on dorsum of hand.
What are the root values of the musculocutaneous nerve, and what does it innervate?
C5-C7. innervates muscles in the anterior compartment of the arm.
how does the musculocutaneous nerve terminate?
As the lateral cutaneous nerve of the forearm.
Name the 6 additional nerves from the brachial plexus
Dorsal Scapular (C5), long thoracic (c567), suprascapular (sup. trunk), subscapular (post. cord), thoracodorsal (post cord), Medial/lateral pectoral nerves (med/lat cords)
What does the following nerve innervate. Dorsal scapular
Rhomboid major + minor, Levator scapulae.
What does the following nerve innervate. Long thoracic.
What does the following nerve innervate. Suprascapular.
Supraspinatus + infraspinatus
What does the following nerve innervate. Subscapular.
Subscapularis + teres major
What does the following nerve innervate. Thoracodorsal
What does the following nerve innervate. Pectoral nerves
Pectoralis Major + Minor.
What are the root values of the ulnar nerve?
C8-T1 (can be worked out from plexus). Comes from the medial cord of the brachial plexus.
Where does the ulnar nerve run?
Medial to brachial artery, behind medial epicondyle of humerus, into medial side of forearm. Lies with ulnar artery at the wrist and passes over flexor retinaculum to enter the hand.
Where it the ulnar nerve most vulnerable to damage?
Behind medial epicondyle and wrist.
Which structures does the ulnar nerve innervate?
Flexor carpi ulnaris, medial 1/2 of flexor digitorum profundus, hypothenar, interossei and medial lumbrical muscles. Skin over medial aspect of hand and medial 1.5 fingers.
What are the root values of the median nerve?
C5-T1. (remember, the only root values that cannot be worked out from the brachial plexus is axillary nerve C5-C6.)
Where in the brachial plexus does the median nerve arise?
Medial and lateral cords
Where does the median nerve run?
Medial to brachial artery at cubital fossa, deep into the forearm before it becomes superficial to pass through the carpal tunnel. Vulnerable to injury at the wrist.