Introduction• Ulnar nerve is on of the major terminal Branches of Brachial Plexus. It is the continuation of medial cord of brachial plexus which arises from the anterior Division of the lower Trunk.• Root Value:• The fibers of ulnar nerve arise from the eight cervical and first thorasic nerve, so the root value of ulnar nerve is C8 and T1. These (C8,T1) coordinate to form the lower trunk of brachial plexus.
Continuation of Ulnar Nerve• Course From Cord to Axilla.• The Ulnar nerve runs between the Axillary artery and vein in the axilla.• Course from Axilla to Arm• From the axilla it enters in the arm and stays between the brachial artery and vein.
• 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 and innervates no any muscle.
Cont’d Course from Elbow to Forearm• At the elbow the ulnar nerve lies in a groove (Retrocondylar groove) which is formed by medial epicondyle humerus and olecranon process of ulna, referred as "funny bone".• 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).
Supplies of Ulnar Nerve In ForearmThe 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 guyon canal.
Course from forearm to wristDorsal Cutaneous Innervations of the Ulnar NerveIn the forearm it runs distally on the ulnar artery, and aboutfive to eight centimeters proximal to the wrist , the dorsalulnar cutaneous sensory branch exits to supply sensation tothe dorsal medial hand and the dorsal little finger as fardistally 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.
At the wrist, the ulnar nerve and artery lie in acanal formed by the pisiform bone medially andthe 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
1. The superficial branch is generally considered a sensory branch which supplies to distal palm, fifth and half of the fourth digit.It also supplies palmaris brevis, a thin musclebeneath the skin which cannot be studiedelectromyographically.The deep branch gives off motor innervation to the hand muscles. .• After it travels down the ulna, the ulnar nerve enters the palm of the hand. The ulnar nerve and artery pass superficial to the flexor retinaculum via the ulnar canal.
Wrist to (Medial) Hand• http://www.acnr.co.uk/pdfs/volume3issue2/v 3i2anatomy.pdf• http://www.wheelessonline.com/ortho/ulnar _nerve
• Anatomy of the ulnar nerve at the elbow, the branches are the• dorsal ulnar cutaneous sensory (blue), the palmar cutaneous sensory• (yellow), hypothenar motor (green) and the digital sensory (red), the• trunk of the nerve in the hand continues as the deep palmar motor• branch.