Nerves of upper limb Flashcards
What are the nerves of the upper limb?
- Musculocutaneous nerve
- Axillary nerve
- Radial nerve
- Median nerve
- Ulnar nerve
Dermatome map for upper limb?
Very important! learn this!
NOTE: https://www.notion.so/Nerves-of-upper-limb-8216d9e1c8624bfe95137c7a27cbb265
Mytome map for upper limb?
Very important! learn this!
NOTE: https://www.notion.so/Nerves-of-upper-limb-8216d9e1c8624bfe95137c7a27cbb265
What is the origin of the musculocutaneous nerve?
C5/ C6/ C7
Anterior division of superior & middle trunks > lateral cord
What is the course of the musculocutenous nerve?
Pierces coracobrachialis & passed down anterior compartment of arm beneath biceps muscle
then becomes lateral cutaneous nerve of forearm
NOTE: https://www.notion.so/PBL-week-11-92f7a1365c35422b8d2810696c535658
What is the sensory and motor function of muscolcutaneous nerve?
Sensory function (skin- touch):
- supplies skin oflateral forearm.
Motor function (movement):
- Biceps brachii -flexes elbow, supinates forearm.
- Brachialis -flexes elbow.
- Coracobrachialis - flexes & adducts the arm at the glenohumeral joint.
What are common injuries to the musculocutaneous nerve?
Injuries rare as protected by bulk of bicep muscle
Stab wounds to upper arms
What are the results of the injury to the musculocutaneous nerve?
Sensory loss:
- numb lateral forearm
Motor deficit:
- weak elbow flexion
- wear forearm supination
- absent biceps reflex
Deformity:
- wasting of biceps
What is the origin of the axillary nerve?
C5/ C6
posterior division of superior trunk > posterior cord
What is the course of the axillary nerve?
Passes beneath shoulder joint into posterior compartment of arm
then wraps around surgical neck of humerus
NOTE: know the difference between surgical & actual neck of humerus
NOTE: https://www.notion.so/PBL-week-11-92f7a1365c35422b8d2810696c535658
What is the sensory and motor function of the axillary nerve?
Sensory function:
- sergeants patch over lover deltoid
Motor function:
- deltoid
- teres minor
What are the common injuries of the axillary nerve?
fracture of the surgical neck of humerus
stab wounds to posterior shoulder
compression by shoulder dislocation or pressure of crutches on armpits
What are the results of the injury to the axillary nerve?
Sensory loss:
- numb seargents patch
Motor deficit:
- weak shoulder abduction from 15-90
- weak shoulder flexion
- weak shoulder extension
- weak shoulder external rotation
Deformity:
- wasting of deltoid
What is the origin of the radial nerve?
C5/ C6/ C7/ C8/ T1
posterior division of superior, middle & inferior trunks > posterior cord
What is the course of the radial nerve?
winds around spinal groove of humerus, passes through ACF into forearm then divides into 2 terminal branches; superficial & deep/ posterior interosseous
What is the sensory and motor function of the radial nerve?
Sensory:
- lower posterior arm
- posterior forearm
- lateral 2/3 dorsal of hands
- proximal dorsal aspect of lateral 3 1/2 fingers
Motor function:
- Posterior compartment of arm- tricep brachii
- posterior compartment of forearm- wrist extensors, finger extensors, brachioradialis & supinator
What are the common injuries of the radial nerve?
fracture of proximal humerus, humeral shaft or proximal radius
stab wound to ACF/ forearm/ wrist
compression by pressure of crutches on armpits, falling asleep on arm, tight pressure cast or prolonged torquiest use
What are the results of injury to the radial nerve?
Sensory loss:
- numb posterior arm & forearm
- numb radial distribution of hand
Motor deficit:
- weak elbow extension
- absent triceps reflex
- weak wrist extension
- weak finger MCP joint extension
- absent supinator reflex
Deformity:
- wrist drop on attempted wrist extension
- wasting of triceps & posterior compartment of forearm
What is the origin of the median nerve?
C5/ C6/ C7/ C8/ T1
lateral root from anterior divisions of superior & middle trunks to lateral cord
Medial root from anterior division of inferior trunk to medial cord
What is the course of the median nerve?
runs down arm w. brachial arm, passed through ACF into forearm & divides into 3 terminal branches; anterior interosseous, deep & superficial/ palmar cutaneous
What is the sensory and motor function of the median nerve?
Sensory:
- Thenar eminence
- Lateral ⅔ palm of hand
- Palmar aspect lateral 3½ fingers
- Digital dorsal aspect of lateral 3½ fingers
NOTE: view image on notes
Motor function- supplies all muscles ofanterior compartment of forearmexcept flexor carpi ulnaris & medial part of flexor digitorum profundus:
- Flexor carpi radialis
- Palmaris longus
- Pronator teres
- Flexor digitorum superficialis
- Flexor pollicis longus
- Pronator quadratus
- Lateral half of flexor digitorum profundus
LOAF muscles of hand:
- Lateral two lumbricals
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis
What are common injuries of the median nerve?
supracondylar fracture of humerus
stab wound to ACF/ forearm/ wrist
Wrist lacerations in deliberate self arm
compression at carpal tunnel in wrist
What are the results of injury to the median nerve?
Sensory loss:
- numb thenar eminence
- numb median distribution of hand
Motore deficit:
- wrist forearm pronation
- weak wrist flexion
- weak wrist abduction
- weak finger flexion- ring & little finger DIP joints preserved
- weak grip strength & opsonisation
Deformity:
- hand of benediction on attempted finger flexion - i.e.cant flex 1st 3 fingers
- wasting of anterior forearm & thenar eminence
NOTE: view image on hand of benediction & claw hand
What is the origin of the ulnar nerve?
C8/ T1
anterior division of inferior trunk > medial cord
What is the course of the ulnar nerve?
runs down arm w/ brachial artery, passes behind medial epicondyle into forearm, then travels down anterior compartment w/ ulnar artery to enter palm of hand via guyon’s canal
What is the sensory and motor function fo the ulnar nerve?
Sensory function:
- Hypothenar eminence
- Medial ⅓ palm of hand
- Palmar aspect medial 1 ½ fingers
- Dorsal aspect of medial 1 ½ fingers
- Medial ⅓ dorsum of hand
NOTE: view image on notes
Motor function:
2 muscles in anterior compartment of forearm
- Flexor carpi ulnaris
- Medial part of flexor digitorum profundus
HILA muscles of hand
- Hypothenar eminence - abductor digiti mini, opponens digiti minimi, flexor digiti minimi brevis and palmaris brevis.
-Interossei
- Lumbricals (medial two)
- Adductor pollicis**
What are common injuries of the ulnar nerve?
Supracondylar fracture of humerus
medial epicondylar fracture or injury
stab wound to forearm/ wrist
compression at cubital tunnel in elbow
What is the result of injury to the ulnar nerve?
Sensory loss:
- numb hypothenar eminence
- numb ulnar distribution of hand
Motor deficit:
- weak wrist flexion
- weak wrist adduction
- weak flexion of ring & little finger MCP & DIP joints & weak extension at their IP joints
- weak finger abduction, adduction & opposition
Deformity:
- claw hand- cannot extend 4th & 5th finger
- wasting of hypothenar eminence & intrinsic muscles of hands
