Nerve anatomy

Nerve anatomy

1. NERVE Dr Ditesh Jain Dept of O rthopedics

2. Introduction Basic Nerve Anatomy Radial nerve U lnar nerve Median Nerve

3. Nerve anatomy A whitish fibre or bundle of fibres in the body that transmits impulses of sensation to the brain or spinal cord, and impulses from these to the muscles and organs.

4. Basic unit of any nerve is axon of neurons. Axons are arranged in bundles known as nerve fibre and is covered with endoneurium .. Group of nerve fibre form a fasciculi which is intern covered with perineurium . Group of these fasciculi form a nerve which is covered with areolar membrabe known as epineurium

5. The  epineurium is a loose connective tissue layer. The outer condensation of this layer comprises the  external epineurium . The portion of this tissue that extends into the substance of the nerve and defines fascicular groups is the  internal epineurium .

6. The peripheral nerve surgeon, Hanno Millesi , in the 1970’s described mesoneurium . This overlooked bit of connective tissue is what makes a nerve feel slippery or flick away when palpated. The nerve slides in this sheath during movement .

7. Vasa nervorum  are small arteries that provide blood supply to peripheral nerves. These vessels are tortuous to allow for considerable freedom of translational movement of peripheral nerves. More numerous near joints . These form anastomoses at intervals throughout the course of the nerve, reinforcing the blood supply within the epineurium . Where a considerable interval between the supplying nutrient vessels occurs, there will be a natural “watershed” area of a nerve that may experience stress from ischemia.

8. Radial Nerve Origin Course and relation Branches

9. Radial Nerve:- Origin Terminal Branch of posterior cord of Brachial plexus Contains C5, C6, C7, C8 & T1 roots. Its largest branch of brachial plexus

10. Course The nerve arises in the  axilla  region, where it is situated  posteriorly to the  axillary artery . It exits the axilla inferiorly (via the lower scapulartriangular interval), and supplies branches to the long and medial heads of the triceps brachii along with posterior cutaneous nerve of arm

11. The radial nerve then descends down the arm, travelling   along with deep brachial artery in the  radial groove/   musculospiral groove/   radial sulcus /  spiral groove . Branches to lateral head of triceps , anconeous and inferior lateral cutaneous nerve of arm

12. Through lateral inter-muscular septum 10-12 cm above lateral condyle and comes to anterior comprtment of arm Runs between brachialis and brachioradialis Gives accessory branch to brachialis , large branch to brachioradialis and ECRL just above the elbow

13. Radial nerve enters the forearm anterior to lateral epicondyle . At around 3 cm interval devides in to superficial radial and deep radial nerve with continues as posterior interosseous nerve after entering the supinator canal

14.      PIN Course : Arcade of Frosche at radial head dives under supinator at arcade of Frohse (thickened edge of between heads of supinator ) Forearm posterior compartment winds around radial neck within substance of muscle to posterior compartment of forearm Interosseous membrane reaches interosseous membrane of forearm

15. Branch Cutaneous Branches: Posterior cutanous n/v of arm Lower lateral cutanous n/v of arm Posterior cutanous n/v of forearm Superficial Radial sensory nerve

16. Branch Muscular branches above elbow: Triceps Anconeous Brachioradialis ECRL

17. Branch Muscular branches below elbow: ECRB Supinator Posterior interosseous nerve (PIN) Superficial PIN: EDC, EDQ, ECU Deep PIN: APL, EPL, EPB, EIP

18. Median Nerve Origin Course and relation Branches

19. Median Nerve (C 5,6,7,8 & T 1 ) Arise in axilla from 2 roots lateral and medial: Lateral root from lateral cord C567 Medial root from medial cord C8 T1

20. In a xilla Median nerve is formed by lateral root from lateral cord and medial root from medial cord of brachial plexus Median nerve runs lateral side of axillary artery

21. In arm M edian nerve continues to run on the lareral side of brachial artery till the middle of arm , where it crosses infront of the artery and passes anterrior to the elbow joint into forearm

22. In forearm Enters to the forearm b/w two heads of pronator teres . Then deep to fibrous arch of flexor digitorum superficialis , in proximal third In mid forearm descends b/w flexor digitorum superficialis and flexor digitorum profundus . About 5 cm above wrist , it comes to lie on the lateral side of the flexor digitorum superficialis , becomes superficial just above wrist

23. In hand Nerve passes deep to the flexor retinaculum and enters the palm Muscular braches supply muscles of thenar eminence ( abductor pollicis brevis , opponens pollicis and flexor pollicis brevis )

24. Finally divides into 4 to 5 palmar digital branches supplying lateral three and half digit and their nail beds Also , motor braches are given to the first and second lumbrical muscles

25. B r a n c h e s In arm : vascular branches to the brachial In the forearm : muscular branches to all superficial flexor muscles ( pronator teres , flexor carpi radialis , palmaris longus and flexor digitorum superficialis ) Anterior interosseous , lateral half of flexor digitorum profundus , flexor pollicis longus and pronator quadratus Articular branches supply the elbow joint and proximal ulnar joint Palmar cutaneous branch supply skin over thenar eminence and central part of palm

26. Ulnar nerve Origin Course and relation Branches

27. Origin Ulnar nerve is the continuation of medial cord of brachial plexus which arises from the anterior Division of the lower Trunk. Root Value : C8 & T1

28. Co urse of Ulnar Nerve Course From Cord to Axilla. The Ulnar nerve runs between the Axillary artery and vein in the axilla .

29. Course from Axilla to Arm From the axilla it enters in the arm and stays between the brachial artery and vein

30. Course from Arm to Elbow The nerve runs inferior and posterior medial aspect of humerus bone till it enters the cubital tunnel. In the arm throughout the course the nerve runs superficially gives medial cutaneous n/v of arm and innervates no any muscle.

31. C o n t ’ d Course from Elbow to Forearm At the elbow the ulnar nerve lies in Retrocondylar groove which is formed by medial epicondyle humerus and olecranon process of ulna . The ulnar nerve is trapped between the bone and the overlying skin at this point. It enters the forearm through the aponeurotic arcade (Cubital Tunnel).

32. Ulnar Nerve In Forearm The ulnar nerve enters the anterior (flexor) compartment of the forearm through the two heads of flexor Carpi ulnaris and runs alongside the ulna bone. There it innervates the Flexor Carpi Ulnaris (FCU) muscle & medial half of Flexor Digitorum Profundus III & IV (FDP) muscle. No further muscle is supplied by the ulnar nerve in the medial forearm until it enters the wrist through G uyon canal.

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34. Course from forearm to wrist Dorsal Cutaneous Innervations of the Ulnar Nerve In the forearm it runs distally on the ulnar artery, and about five to eight centimeters proximal to the wrist , the dorsal ulnar cutaneous sensory branch exits to supply sensation to the dorsal medial hand and the dorsal little finger as far distally as the nail & the 4 digit. Palmar Cutaneous Innervations of the Ulnar Nerve At that level of the ulnar styloid the Palmer Cutaneous sensory branch originates to supply sensation to the proximal medial palm.

35. Dorsal cutaneous branch

36. Palmar cutaneous branch

37. At the wrist, the ulnar nerve and artery lie in a canal formed by the pisiform bone medially and the hook of hamate laterally (Guyon’s canal) . In this region the nerve divides into two superficial and deep branches. The Superficial Branch The Deep Motor Branch

38. The superficial branch , sensory suppl y to distal palm, fifth and half of the fourth digit. Motor suppl y palmaris brevis . The deep branch gives off motor innervation to the hand muscles. ..

39. Ulnar Innervated Muscles Forearm: Flexor Carpi Ulnaris (C7, C8, T1) Flexor Digitorum Profundus III & IV (C7, C8) Thenar: Hypothenar Muscles (C8, T1) Adductor Pollicis (C8, T1) Flexor Pollicis Brevis (C8, T1) Fingers: Palmer Interosseous (C8, T1) Dorsal Interosseous (C8, T1) III & IV Lumbricles (C8, T1) Digiti Minimi: Abductor Digiti Minimi (Quinti) (C8, T1) Opponens Dgiti Minimi (C8-T1) Flexor Digiti Minimi. : ( C8-T1)

40. Thank you