Anatomy and Examination of Ulnar & Sciatic Nerves

Brief description

1. ULNAR NERVE ROSSHINI JAGATHESWARAN

2. ULNAR NERVE

3. Palmar cutaneous branch Superficial branch Deep branch Sensation to skin of the palmar and distal dorsal aspects of digit 5 and medial side of digit 4 and proximal portion of palm Deep head of flexor pollicis brevis

4. ULNAR NERVE - Anatomy Origin Large terminal branch of the medial cord of the brachial plexus (C8-T1) Arises from the anterior division of the lower trunk

5. Course Passes distally from the axilla, medial to the axillary artery Middle of arm – it pierces the medial intermuscular septum with the superior ulnar collateral artery, descends between the septum and the medial head of triceps Passes posterior to the medial epicondyle & medial to the olecranon to enter the forearm

6. Descends forearm between two heads of proximal attachment of flexor carpi ulnaris In the forearm, it supplies only one and a half muscles – FCU and the ulnar part of the flexor digitorum profundus (sends tendons to 4 th & 5 th digits) Emerge from beneath the deep to the tendon of FCU & becomes superficial in distal forearm, just proximal to the wrist Passes superficial to flexor retinaculum(transverse carpal ligament) to enter hand through a groove between the pisiform and the hook of hamate Continues distally to the wrist via the ulnar canal A band of fibrous tissue from the flexor retinaculum bridges the groove to form the ulnar canal ( Guyon canal) .

7. Branches Articular branches – pass to the elbow joint while the nerve is between the olecranon and medial epicondyle Muscular branches – supply FCU and one half of FDP Palmar & dorsal cutaneous branches – arise from ulnar nerve in forearm, but their sensory fibres distributed to the skin of the hand

8. Ulnar nerve is bound by fascia to the anterior surface of the flexor retinaculum as it passes between the pisiform(medially) and the ulnar artery(laterally). Proximal to wrist, ulnar nerve gives off a palmar cutaneous branch which passes superficial to the flexor retinaculum & palmar aponeurosis, supplies skin on the medial side of the palm Dorsal cutaneous branch supplies medial half of the dorsum of the hand, 5 th finger and medial half of the 4 th finger

9. Ends at the distal border of flexor retinaculum by dividing into superficial and deep branches. Superficial branch supplies palmaris brevis and sensation to skin of the palmar and distal dorsal aspects of digit 5 and medial side of digit 4 and proximal portion of palm Deep branch supplies hypothenar muscles, lumbricals of digits 4 and 5, all interossei , adductor pollicis , deep head of flexor pollicis brevis

10. Ulnar nerve injured around elbow – elbow fractures or dislocations Wasting of hypothenar eminence & hollowing between metacarpals seen from dorsum of hand Paralysis of all muscles supplied Sensory deficit High Ulnar Nerve Palsy

11. Injury to the distal third of forearm Cuts on shattered glass C/F : Numbness, claw hand deformity, hypothenar & interosseous wasting, weak finger abduction, loss of thumb adduction Sensory loss Froment’s sign + ve Low Ulnar Nerve Palsy

12. Tardy Ulnar Nerve Palsy Slow in onset & progression Appears between age of 30-50 Preceding injury to the elbow in childhood Ischemic and fibrotic changes in nerve Seen most frequently in cubitus valgus deformity Treatment: Transposition of nerve from its normal position to the front of the joint

13. Ulnar Paradox The higher the lesion of the ulnar nerve injury, the less prominent is the deformity & vice versa (less clawing of fingers) Because in higher lesions the medial half of FDP is paralysed . The loss of finger flexion makes the deformity look less obvious the closer to the Paw, the worse the Claw

14. Froment’s sign Egawa’s test Card test

15. Ulnar Neuritis & Ulnar Tunnel Syndrome Ulnar neuritis – complication of local trauma at elbow or wrist Nerve is subjected to pressure Exposed to frictional damage Treatment : Reacnchorage or transposition, epicondylectomy

16. Combined Low Median & Ulnar Nerve Palsy Both ulnar & median nerve injured at wrist Hyperextension of the metacarpophalangeal joints and flexion of the Interphalangeal joints of the hand Referred to as “Intrinsic minus” hand Motor palsy : all intrinsic muscles of hand unopposed by long flexors of forearm Sensory loss : whole palm & fingers

17. SCIATIC NERVE ROSSHINI JAGATHESWARAN

18. Origin Sacral plexus (anterior & posterior divisions of anterior rami of L4-S3 spinal nerves) Course Enters gluteal region via greater sciatic foramen inferior to piriformis and deep to gluteus maximus ; descends in posterior thigh deep to biceps femoris ; bifurcates into tibial and common fibular nerves at apex of popliteal fossa Distribution Supplies no muscles in gluteal region; supplies all muscles of posterior compartment of thigh, part of adductor magnus that’s attached to ischium, all leg and foot muscles, skin of most of the leg and foot

19. Sciatic Nerve Palsy Traumatic hip dislocations + pelvic fractures, total hip replacement C/F: Complete lesion- hamstrings & all muscles below knee paralysed, absent ankle jerk, sensation loss(except medial side), drop foot, high stepping gait Trophic ulcers Treatment: Suture or nerve grafting