Nerves of hand

Nerves of hand

1. NERVES OF UPPER LIMB Sourabh Chakraborty

2. Ulnar nerve Branch from medial cord of brachial plexus Conveys fibers from C8 & T1 Receives contribution from C7 through the median nerve for flexor carpi ulnaris

3. COURSE IN AXILLA Passes along medial side axillary artery third part Between axillary artery & vein

4. COURSE IN ARM Medial side of brachial artery Pierces medial IMS along superior ulnar collateral vs. Descends superficial to the medial head of the triceps Appears between medial epicondyle & olecranon process

5. COURSE IN FOREARM Enters between two heads FCU UPPER ONE- THIRD FOREARM Deeply placed Rests on FDP, covered by FCU Separated from ulnar artery LOWER ONE- THIRD FOREARM Superficial Along lateral side FCU Accompanied ulnar artery

6. AT LEVEL OF WRIST Passes superficial to flexor retinaculum Passes beneath palmaris brevis Divides into superficial & deep terminal branch

7. SUPERFICIAL TERMINAL BRANCH Supplies palmaris brevis Divides into a medial proper palmar digital branch a lateral common palmar digital branch

8. DEEP TERMINAL BRANCH Passes deeply between abductor, flexor digiti minimi Pierces opponens digiti minimi Passes deep to long flexor tendons Lies in concavity of deep palmar arch Supplies hypothenar muscles 3,4 lumbricals all interrosei adductor pollicis occasionally- FPB intercarpal, carpometacarpal, metacarpophalangeal joints

9. At the midforearm , the ulnar nerve is composed of three distinct fascicular grouP ’. a dorsal sensory group, a volar sensory group. and a motor group. the motor group is positioned between the ulnar dorsal sensory group and the radial volar sensory group The dorsal sensOry branch separates from the motor branch and the main sensory group8 to 10 cm proximal to the wrist . The motor branch remains ulnar to the sensory group until the Guyon canal, at which time it passes dorsally to the sensOry branches of the little and ring fingers to innervate the intrinsic muscles

10. Diagrammatic mappings of the fascicular groups of the left ulnar nerve at representative levels. The indicated level of the sections is in reference to the distance proximal to the radial styloid. Key: Red, motor fascicular group; Blue, sensory fascicular groups.

11. BRANCHES OF ULNAR NERVE Muscular branches forearm- FCU, medial half FDP hand- all intrinsic muscles except three thenar muscles, 1,2 lumbricals Articular branches to elbow, intercarpal, carpometacarpal joints Vascular branches axillary, brachial, ulnar, deep palmar arch

12. Cutaneous branches forearm- dorsal branch arises 5 cm proximal to the wrist -Supplies skin of the dorsal aspect of medial one and a half of the fingers, excluding terminal phalanges of ring & little fingers palmar cutaneous branch supplies skin of the medial side of the palm palm-digital branches- superficial terminal branch

13. Radial nerve largest branch of the posterior cord of brachial plexus with a root value of C5,6,7,8, T1

14. in axilla In axilla it passes behind the third part of axillary artery Anterior to subscapularis, latissimus dorsi & and teres major Medial to it is axillary vein Lateral to it are axillary nerve and coracobrachialis

15. Continues behind the brachial artery • Then passes posterolaterally with the profunda brachii vessels through the lower triangular space • Here it is anterior to teres major and passes between the long head of triceps and humerus

16. After this the nerve enters the radial groove with the profunda vessels In the radial groove nerve lies between the lateral and medial heads of triceps in contact with the humerus At the lower end of the groove, 5 cm below the deltoid tuberosity, the nerve pierces the lateral intermuscular septum and passes into anterior compartment of arm

17. In the anterior compartment nerve lies between brachialis (medially) and brachioradialis and extensor carpi radialis (laterally) • Here it is accompanied by radial collateral artery

18. Branches of radial nerve Muscular branches: • Before entering spiral groove- to long and medial heads of triceps • In the spiral groove lateral and medial heads of triceps and through nerve to medial head to anconeus • Below the radial groove, on the front of the arm, it supplies, the brachialis, brachioradialis and the extensor carpi radialis longus

19. Cutaneous branches: • Above the radial groove-posterior cutaneous nerve of the arm • In the radial groove-lower lateral cutaneous nerve of the arm and posterior cutaneous nerve of the forearm • Articular branches: to elbow

20. Superficial terminal branch In the forearm the superficial branch descend between brachioradialis anteriorly and supinator posteriorly lying lateral to radial artery • In the middle third it lies posterior to brachioradialis, lying successively on pronator teres, FDS (radial head) and FPL and lateral to radial artery

21. About 7 cm proximal to the wrist nerve leaves the artery • passes deep to the tendon of brachioradialis • Curves around the lateral side of radius • Pierces the deep fascia • Divides into 4 or 5 digital nerves on the dorsum of hand. it communicates with posterior & lateral cutaneous nerves of forearm • Supplies radial half of the dorsum of the hand, proximal part of the dorsal surface of thumb, index finger & the lateral half of the middle finger

22. Deep branch of radial nerve • Deep terminal branch reaches the back of forearm by passing between two heads of supinator • supplies ECRB and supinator

23. Posterior interosseous nerve of forearm • it is deep branch of radial nerve in forearm • Reaches the back of forearm by passing between the two heads of supinator • Descends between the superficial &and deep group of extensor muscles lying on the interosseous membrane

24. The upper part of nerve is accompanied by posterior interosseous artery but the lower part is accompanied by anterior interosseous artery • Terminates in to a pseudoganglion and ends by supplying the wrist and carpal joint Branches : • Muscular –supinator ED,EDM &ECU -Divides into lateral & medial branch

25. lateral branch supplies APL &EPB Medial branch supplies EPL& EI • Articular branch: to wrist joint, distal radioulnar joint, some intercarpal & intermetacarpal joint • Sensory branches :to interosseous membrane, radius & ulna

26. In the radial nerve, the motor and sensory components are separated into discrete fascicles. Awake stimulation can be used to identify the motor and & senSory components of the proximal nerve, whereas anatomic: dissection is used to identify them distally Several histochemical techniques have been described that allow motor (acetylcholinesterase and choline acetyltransferase) or sensory (carbonic anhydrase) discrimination

27. MEDIAN NERVE Formation: from two roots from lateral cord [C(5),6,7]& from medial cord(C8,T1) of brachial plexus • These two roots embrace the third part of axillary artery uniting anterior or lateral to it

28. In the arm • Closely related to the brachial artery through out the course in arm • In the upper part it is lateral to artey • In the middle part it crosses the artery from lateral to medial side • Remains on the medial side up to elbow

29. Branches in arm • Branch to Pronator Teres just above elbow • Branch to brachial artery • Branch to elbow joint at or just below the elbow

30. In the cubital fossa • Descends medial to brachial artery • Posterior to bicipital aponeurosis • Anterior to brachialis, seperated by the muscle from the elbow Leaves the cubital fossa by passing between two heads of pronator teres

31. In the forearm • Enters the forearm between the heads of pronator teres • Crosses the lateral side of ulnar artery from which it is seperated by the deep head of pronator teres • Gives branch to pronator teres while passing between the two heads Proceeds behind a tendinous ridge between the two heads of Flexor digitorum superficialis and anterior to Flexor digitorum profundus • Here it is accompanied by median artery, a branch of anterior interosseous artery

32. About 5 cm proximal to flexor retinaculum it becomes superficial • Here it lies between the tendon of palmaris longus and the flexor carpi radialis muscle Leaves the forearm and enters the palm of the hand by passing through the carpal tunnel deep to flexor retinaculum

33. Branches in the forearm • Muscular branches to all the muscles in the superficial and intermediate layer of forearm except one (FCU) originate Anterior interosseous nerve: originate between two heads of pronator teres • passes distally down the forearm with the anterior interosseous artery. • Innervates the muscles of deep layer (FPL, lateral half of FDP and pronator quadratus) • Terminates as articular branch to wrist

34. •Palmar cutaneous branch: starts just proximal to flexor retinaculum •Lateral branches - thenar skin and connecting branch to the lateral cutaneous nerve of fore arm •Medial branches - central palmer skin and connecting branch to the palmar cutaneous branch of the ulnar nerve • Communicating branch: multiple –Arise in the proximal forearm – Pass medialy between FDP & FDS and behind the ulnar artery to join the ulnar nerve

35. Lateral branch: gives Recurrent branch- short and stout, curls upwards over the distal border of flexor retinaculum and FPL to supply three thenar muscles APB, FPB &OP Three palmer digital branches- First two supply the skin of the sides of the thumb ,its web and distal part of its dorsal surface. • Third supplies the skin of the radial side of index finger and the first lumbrical muscle through its superficial surface

36. Medial branch: gives – Two common palmar digital branches- lateral and medial which descend to the interdigital clefts between the index, middle and ring finger – Each nerve divides again into two to supply adjacent sides of the fingers – So in total it supplies skin of lateral three and half fingers including the skin on the dorsal aspect of terminal phalanges

37. • The lateral common palmar digital supplies the second lumbrical • the median common palmar digital gives a communicating branch to common palmar digital branch of ulnar nerve • Articular branches: to wrist ,metacarpophalangeal & interphalangeal joint

38. Pattern of topographic distribution of median nerve motor fascicles. The median nerve was sectioned in 2 palmar (radial and ulnar) and 2 dorsal (radial and ulnar) quadrants each, according to black lines in the oval. The motor fascicles were assigned to the quadrants. The size of the squares represents the frequency of the observed fascicles’ locations and their ratios are given [%]. d, dorsal; n, sample size; p, palmar; r, radial; u, ulnar

39. Pattern of topographic distribution of median nerve sensory fascicles. The median nerve was sectioned in 2 palmar (radial and ulnar) and 2 dorsal (radial and ulnar) quadrants each, according to black lines in the oval. The sensory fascicles were assigned to the quadrants. The size of the squares represents the frequency of the observed fascicles’ locations and their ratios are given [%]. The numeric values are rounded to one decimal with the result that the numeric values partially vary from 100. (a) Palmar cutaneous branch (PCB) and thumb, (b) index finger, (c) middle finger, (d) ring finger and communicating branch of median nerve with ulnar nerve. d, dorsal; n, sample size; p, palmar; r, radial; u, ulnar; asterisk, the missing sample was supplied by the ulnar nerve

40. In the ulnar and median nerves, the fascicle count was higher in the forearm in comparison to the upper arm whereas in the radial, the number of fascicles decreases along forearm. The radial nerve near its termination in the forearm had the smallest fascicle count of 2. The highest fascicle count in all nerves was found in the median nerve with a value of 42 fascicles.

41. Fascicular diameters were found to be larger in the upper arm region than they were in the forearm region in the ulnar, median, and radial nerves. The maximum fascicular diameters from each cross section in the upper arm were also larger than the forearm maximum fascicular diameters Fascicular diameter was not correlated with location or nerve size, but was inversely correlated with the fascicle count. Similarly, other groups have shown cross sectional images at the elbow in the ulnar nerve consisting of a low fascicle count and a very large fascicle