Nerve Palsies in the Limbs Flashcards
What is the anatomy of the Axillary nerve?
Axillary Nerve (C5, C6)
- Exits axillary fossa posteriorly, passing through quadrangular space with posterior circumflex humeral artery
- Gives rise to superior lateral brachial cutaneous nerve
- Winds around surgical neck of humerus deep to deltoid
Where is the axillary nerve most at risk?
Surgical neck of humerus
What are the causes of damage to the axillary nerve?
- Fractural humeral neck
- Shoulder dislocation
- Saturday night palsy - pressure on post. cord of brachial plexus
How does someone with axillary nerve palsy present?
- Appearence - Can be normal
- Motor Deficit - Loss of shoulder abduction (deltoid C5)
- Atrophy - Deltoid
- Sensory deficit - badge area
What is the anatomy of the radial nerve?
Radial Nerve (C5 - T1)
- Passes posterior to humerus in radial groove with profunda brachii artery between lateral and medial heads of triceps
- Perforates lateral intermuscular septum
- Enters cubital fossa, dividing into superficial (cutaneous) and deep (motor) branches
Where is the radial nerve most at risk?
- Spiral groove of humerus
- Lateral intermuscular septum
- Posterior interosseous branch at radial neck
What is the aetiology of radial nerve palsy?
- Fractured humeral shaft
- Saturday night palsy - pressure on post. cord of brachial plexus
- Exposure of proximal radius
What are the clinical features of Radial nerve palsy?
- Appearence - Wrist Drop - Classic deformity
- Motor deficit - Dependent upon site of injury - extensors of arm and forearm
- Atrophy - extensor muscles
- Sensory deficit - 1st web space dorsally - over anatomical snuff box is most reliable
What is the anatomy of the Median Nerve?
Median Nerve (C5, C6, C8, T1)
- Descends along the lateral side of the axillary artery and upper part of the brachial artery
- Crosses to the medial side of the brachial artery and enters the cubital fossa
- Enters forearm between two heads of pronator teres
Where is the median nerve most commonly affected?
- Volar aspect of the wrist
- Cubital fossa
What are the most common ways for the median nerve to be affected?
Inflammation
- Carpal tunnel syndrome
Trauma
- Wrist lacerations
- Supracondylar fractures
- Struther’s ligament - palmar weakness
What are the clinical features of Median Nerve Palsy?
- Appearence - Ape hand - cannot move the thumb away from the rest of the hand
- Motor deficit - Loss of pronation of forearm, weakness in flexion of the hand at the wrist, loss of flexion of radial half of digits and thumb, loss of abduction and opposition of thumb.
- Atrophy - Thenar wasting
- Sensory Deficit - Volar aspect of the thumb
What is the anatomy of the ulnar nerve?
Ulnar Nerve (C8, T1, occasionally C7)
- Descends along the medial side of the brachial artery
- Enters the posterior compartment of the arm through the medial intermuscular septum
- Runs along the medial head of triceps and to the back of the medial epicondyle
- Passes between two head of flexor carpi ulnaris to enter forearm
Where is the ulnar nerve most at risk to damage?
Trauma
- Humeral condyle fractures
- Arcade of Struthers - musculofascial band 8cm proximal to medial epicondyle
- Epicondylar groove
- Point where nerve passes between the 2 heads of FCU
What are the clinical features of Ulnar Nerve Damage?
- Appearence - Ulnar Claw - classic deformity
- Motor Deficit - Weakness in flexion of the hand at the wrist, loss of flexion of ulnar half of digits, or the 4th and 5th digits, loss of ability to cross the digits of the hand, weakness of adduciton of the thumb
- Atrophy - Hypothenar wasting
- Sensory Deficit - Little finger
What is the anatomy of the Lateral Cutaneous nerve of the thigh?
Lateral Cutaneous Nerve (L2,3)
- Lies on surface of iliacus muscle; usually exits pelvis under lateral end of inguinal ligament, but variable
- Purely sensory to lateral aspect thigh
What is the anatomy of the sciatic nerve?
Sciatic Nerve (L4-S3)
- Exits pelvis through sciatic foramen below piriformis muscle
- Runs deep to gluteus maximus muscle
What is the anatomy of the common fibular nerve?
Common Fibular Nerve (L4-S1/S2)
- Passes around lateral aspect of neck of fibula
- Communicating branch to sural nerve
- Divides into superficial and deep fibular nerves
What is the clinical presentation of someone with Common fibular nerve damage?
- Appearence - Foot drop
- Motor deficit - Weak ankle dorsiflexion/eversion
- Atrophy - externsor compartment/everters
- Sensory Deficit - Sensory loss over dorsum of foot
What are the clinical features of Tibial nerve damage?
- Appearance - Calcaneovalgus deformity
- Motor - Inability to stand on tiptoes (plantar flexion), Inability in invert foot, Inability to flex toes
- Atrophy - muscles in distribution
- Sensory - loss over sole, absent ankle jerk
What is the classic deformity of Erb’s Palsy?
Porter’s tip
What does the median nerve supply?
Supplies - LOAF and Flexors
- Lumbricals - 1+2
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis
- All flexors of the forearm, except FCU and the medial part of FDP (supplies 4th and 5th digits))
What does the ulnar nerve supply?
Supplies
- Flexor carpi ulnaris
- Ulnar half of flexor digitorum profundus (forearm)
- Most intrinsic muscles of hand
- Skin of hand medial to axial line of digit 4
What does the sciatic nerve supply?
Supplies
- Hamstring muscles
- Part of adductor magnus
- All lower leg and foot muscles
- Tibial nerve
- Common fibular nerve
What does the tibial nerve supply?
Supplies - posterior compartment of leg
- Gastrocnemius
- Popliteus
- Soleus
- Plantaris
- Tibialis posterior
- Flexor digitorum longus
- Flexor hallucis longus
What does the common fibular nerve supply?
Superficial fibular nerve
- Fibularis longus
- Fibularis Brevis
Deep fibular nerve
- Tibilais anterior
- Extensor digitorum longus
- Extensor hallucis
- Fibularis tertius
