Brachial Plexus Flashcards
What is the brachial plexus formed from?
The ventral rami of C5-T1
Which roots converge to form the superior trunk?
C5 + C6
Which roots form the middle trunk?
C7
Which roots converge to form the inferior trunk?
C8 + T1
Which divisions is the lateral cord formed from?
Anterior division of the superior and middle trunk
Which divisions is the posterior cord formed from?
The posterior divisions of the superior, middle and inferior trunk
Which divisions is the medial cord formed from?
The anterior division of the inferior trunk
What are the 5 terminal branches of the brachial plexus?
Remember MARMU
1. Musculocutaneous
2. Axillary
3. Radial
4. Median
5. Ulnar
What are nerves which branch off before the terminal branches called?
Preterminal (collateral) branches
Which cord and nerve roots does the median nerve arise from?
Arises from the lateral and medial cords
C5 - T1
Which muscles in the anterior forearm does the median nerve innervate?
- Flexor digitorum superficialis
- Pronator quadratus
- Flexor digitorum profundus (with ulnar nerve)
Which muscles in the hand does the median nerve innervate? - think LOAF
Lateral 2 lumbricals, opponens brevis, abductor pollicis brevis, flexor pollicis brevis
What is the sensory innervation of the median nerve?
- Palmar - lateral 3.5 digits and adjacent palm
- Dorsal - distal aspects of the lateral 3.5 digits (tips of these fingers)
Which cord and nerve roots does the musculocutaneous nerve arise from?
Arises from the lateral cord
C5 - C7
Which muscles does the musculocutaneous nerve innervate?
- Corabrachialis
- Biceps brachii
- Brachialis
Where is the sensory innervation of the musculocutaneous nerve located?
Lateral side of forearm
Which cord and nerve roots does the axillary nerve arise from?
Arises from the posterior cord of the brachial plexus
C5 - C6
Which muscles does the axillary nerve innervate?
- Deltoid
- Teres minor
What is the sensory innervation of the axillary nerve?
- glenohumeral joint
- skin covering the inferior portion of the deltoid (sergeants patch)
Which cord and nerve roots does the radial nerve arise from?
Arises from the posterior cord
C5 - T1
Which muscles does the radial nerve innervate?
All muscles of the posterior arm and forearm. This includes the tricpes brachii, anconeus, brachioradialis muscle and the wrist extensors and long muscles of the thumb
What is the sensory innervation of the radial nerve?
Skin of the posterior forearm
Dorsal hand (back of hand) - lateral hand, thumb and proximal 2nd-4th digits (not the tips of these fingers)
Which cord and nerve roots does the ulnar nerve arise from?
Arises from the medial cord
C8 - T1 (occasionally C7)
Which muscles does the ulnar nerve innervate?
- Flexor carpi ulnaris
- Ulnar half of the flexor digitorum profundus
- Most of the intrinsic muscles of the hand which aren’t innervated by the median nerve. This includes
- palmaris brevis
- lumbricals
- hypothenar
- interossei muscles
What is the sensory innervation of the ulnar nerve?
- Palmar - medial 1.5 digits and adjacent palm
- Dorsal - medial 1.5 digits and adjacent skin of the back of the hand
Nerve root at which level is responsible for shoulder abduction?
- movement = shoulder abduction
- muscle = deltoid
- nerve = axillary
- cord = posterior cord
- root = C5
Nerve root at which level is responsible for elbow flexion?
- movement = elbow flexion
- muscle = biceps brachii
- nerve = musculocutaneous
- cord = lateral cord
- root = C6
Nerve root at which level is responsible for elbow extension?
- movement = elbow extension
- muscle = triceps brachii
- nerve = radial
- cord = posterior cord
- root = C7
Nerve root at which level is responsible for wrist extension?
- movement = wrist extension
- muscle = extensor carpi radialis
- nerve = radial
- cord = posterior cord
- root = C7/8
Nerve root at which level is responsible for wrist flexion?
- movement = wrist flexion
- muscle = flexor carpi ulnaris
- nerve = ulnar
- cord = medial cord
- root = C7/8
Nerve root at which level is responsible for finger flexion?
- movement = finger flexion
- muscle = FDS/FDP
- nerve = median (+ ulnar)
- cord = lateral and medial cords
- root = C8
Nerve root at which level is responsible for finger extension?
- movement = finger extension
- muscle = extensor digitorum
- nerve = radial
- cord = posterior cord
- root = C8
Nerve root at which level is responsible for finger abduction?
- movement = finger abduction
- muscle = dorsal interossei
- nerve = ulnar
- cord = medial cord
- root = T1
Lesions in which nerves can cause scapular winging?
most common - long thoracic nerve
less common - accessory nerve
rare - dorsal scapular nerve
