Nerve injuries and consequences in the upper limb Flashcards
Which nerves supply the shoulder muscles and elbow joint flexors?
C5+C6
Which nerves supply the elbow extensors?
C7+C8
Which nerves are responsible for coarse wrist and hand movements?
C6-C8
Which nerves supply small muscles of the hand (fine movements)?
C8+T1
Which rami for superior trunk
C5-6
Which rami form middle trunk
C7
Which rami form inferior trunk
C8 T1
How does each trunk divide
Into a posterior and anterior division
What forms lateral chord
Anterior branches of superior and middle trunks
What forms posterior chord
All 3 posterior divisions of chord
What forms medial chord
Anterior branch of inferior trunk
How are chords named
On position to axillary artery
Why is dermatome vs cutaneous nerve pattern so different
The recombination of fibres in the plexus
What does axillary nerve come off
Posterior chord
Route of axillary nerve
Passes posterior to axillary artery then becomes lateral before going behind shoulder joint
How is axillary nerve commonly damaged
Dislocation of shoulder and fracture of surgical neck of humerus
Supply of axillary nerve
Deltoid
Teres minor
Effects of axillary nerve damage
Atrophy of deltoid
Branch of axillary nerve
Superior lateral cutaneous nerve of arm
Useful in axillary nerve assessment
Where does superior lateral cutaneous nerve of arm supply
Superior lateral humerus area of skin
How to assess axillary nerve damage
Wasting of deltoid
Sensory innervation of superior lateral arm
Path of radial nerve
Passes into posterior compartments of arm and forearm
How can radial nerve be easily damaged
Fracture of humerus as runs very close to it in radial groove
Effects of radial nerve damage
Wrist drop off as lose extension ability in forearm
Anaesthesia of lateral dorsal hand
Wasting of posterior forearm muscles
Loss of power grip
How do you lose power grip in radial nerve damage
You need extensors to exert maximal grip as if not flexors have to do too much work
Where does musculocutaneous nerve branch off
Lateral chord
Route of musculocutaneous nerve
Goes through coracobrachioradialis muscle to supply anterior arm muscles with a cutaneous branch supplying the lateral side of the forearm and lower arm
How is musculocutaneous nerve damaged
Not damaged in trauma as well protected by muscle but is easily damaged in breast cancer surgery due to its proximity to lymph nodes
Path of ulnar nerve
Comes off medial chord in the axilla and continues down the medial side of the arm behind medial humeral epicondyle then down the medial forearm to muscles of hand
Common sites of injury to ulnar nerve
Behind medial epicondyle
Ulnar side of wrist in a lot of cases due to self harm
Muscles supplied by ulnar nerve in forearm
Flexor carpi ulnaris
Medial half to digits 4,5 of flexor digitorum profundus
Muscles supplied by ulnar nerve in hand
Palmaris brevis Hypothenar muscles All interossei Adductor pollicis Lumbricals 4 and 5
Signs of injury to ulnar nerve
Claw deformity as lumbrical muscles for digits 4 and 5
What is the ulnar paradox
Clawing deformity is much worse in injury to ulnar nerve at elbow as ulnar nerve also innervates medial half of FDP which if injured at wrist isn’t affected
Route of median nerve
Comes from lateral and medial chords and passes medially down anterior portion of arm over elbow joint to medial aspect of forearm through carpal tunnel
Branches of median nerve after coming out of carpal tunnel
One to hypothenar muscles
Then sensory ones to all digits except medial half of ring finger and little finger
Signs of carpal tunnel syndrome
Wasting of hypothenar muscles so loss of hypothenar muscle
Loss of sensation and fine movement in lateral digits
Supply of long thoracic nerve
Serratus anterior
How is long thoracic nerve easily damaged
Very superficial so any trauma will damage it
Signs of damage to long thoracic nerve
When you press against a wall the scapula will move up in a movement called winging as serratus anterior has role in holding scapula in place
Name of injury to upper root
Erb duchenne palsy
How are upper roots damaged
Over stretching of neck in fall and also in child birth
Sign of upper root injury
“Waiters tip” position where forearm pronated and unopposed flexion as lack of biceps innervation
Lower root nerve injury name
Klumpkes palsy
In particular T1 but also C8
Cause of klumpkes palsy
Over abduction due to for example gripping overhead to break a fall
Childbirth
Lower root injury signs
T1 mainly supplies small muscles of hand via ulnar and median nerve so hand becomes very clawed
Hierarchal order to brachial plexus anatomically
Rami
Tunks
Divisions
Cords
Which rami form long thoracic nerve
C5-7
Nerves which make up brachial plexus
C5-T1
