MSK- Brachial Plexus Flashcards
Draw out the Brachial Plexus
What are the roots of each branch of the brachial plexus?
3 Musketeers assassinated 5 rats, 4 mice and 2 unicorns
Musculocutaneous- C5,6,7
Axillary- C5,6
Radial- C5,6,7,8,T1
Median-C6,7,8, T1
Ulnar- C8,T1
What are the motor functions of each of the nerves of the brachial plexus?
Musculocutaneous
BBC
- Brachialis
- Biceps brachii
- Coracobrachialis
Axillary
Regimental badge area
- Deltoid
- Teres minor
Radial
Extensors (posterior arm)
- Triceps
- Extensors in forearm
Median
Flexors (anterior arm)
- Flexors in forearm
- LOAF muscles
Ulnar
- Muscles of the hand except LOAF muscles
- Flexor carpi ulnaris
- Medial half of flexor digitorum profundus
Sensory function of the nerves of the brachial plexus
Musculocutaneous
- Lateral cutaneous branch innervates lateral half of anterior forearm
Axillary
- Superior lateral cutaneous branch-regimental badge area
Radial
- Posterior arm and forearm
- Posterolateral hand
Median
- Palmar cutaneous branch innervates lateral part of the palm
- Digital cutaneous branch, innervates lateral three and a half fingers on the palmar hand
Ulnar
- Anterior and posterior surfaces of the medial one and half fingers, and associated palm
What happens in Erb’s Palsy?
Roots Damaged
C5 and C6 damage due to stretching e.g. shoulder distocia during birth
Nerves Damaged
Affects musculocutaneous, axillary, suprascapular, and nerve to subclavius.
Waiters Tip
Muscles affected
Supraspinatus, infraspinatus, subclavius, biceps brachii, brachialis, coracobrachialis, deltoid and teres minor affected
Functions lost
Loss of abduction, lateral rotation, supination and flexion
Arm hangs limply, medially rotated by pectoralis major.
Pronated due to the loss of biceps brachii
Wrist is weakly flexed due to weakened extensors.
What happens in Klumpke’s Palsy?
Roots Damaged
C8-T1 Damaged
Sudden stretching of nerves, e.g. stopping yourself falling
Nerves affected
- Ulnar
- Median
Muscles affected
- Intrinsic hand muscles
Sensory effect
- Sensation along medial side of arm
Defining features
Clawed hand
Due to paralysis of the lumbrical muscles, which flex the metacarpophalangeal joints and extend interphalangeal joints
Extended MCPJs
Flexed IPJs
Identify the short and long heads of biceps brachii and biceps brachii tendon
Identify brachialis, coracobrachialis and the coracoid process of the scapula
Coracoid process= origin of short head of biceps brachii and coraccobrachialis, so look at where coracoobrachialis inserts to find short head insertion point
Long head of biceps brachii from the supraglenoid tubercle of the scapula
Identify the medial lateral and posterior cords
Identify:
- Musculocutaneous nerve
- Ulnar nerve
- Lateral head of the median nerve
- Medial head of the median nerve
- Median nerve
Identify the axillary and radial nerves
Where do the three heads of triceps brachii insert?
Long head
infraglenoid tubercle of the scapula.
Lateral head
Humerus (superior to the radial groove)
Medial head
Humerus (inferior to the radial groove).
Heads converge into one tendon, inserts on olecranon
