Ulnar nerve

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In human anatomy,

the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of the elbow joint is associated with the ulnar nerve. Nerves are the largest unprotected nerves in the human body (meaning they are not protected by muscles or bones), so injuries are common. This nerve is directly connected to the little finger, and half the adjacent adjacent finger, innervates this palmar aspect of the radius, including the front and back edges, possibly as far as the nail bed.

This nerve can cause electrical shock sensation by attacking the medullary epicondyle of the humerus from the posterior, or inferior with the flexed elbow. The ulnar nerve is trapped between the bone and the skin above it. This is usually referred to as bumping into someone " funny bone ". This name is considered a pun, based on the sound similarity between the name of the upper arm bone, the "humerus" and the word "funny". Alternatively, according to the Oxford English Dictionary, this may refer to "the strange sensation experienced when beaten".




Video Ulnar nerve





Struktur

Arm

The ulnar nerve originates from the C8-T1 nerve roots (and occasionally carries C7 fibers) which are part of the medial cord of the brachial plexus, and descends medial to the brachial artery, to the point of insertion of the coracobrachial muscle (center 5 cm beyond the medial border of the humerus). Then, it penetrates the medial intermuscular septum and enters the posterior compartment of the arm, accompanied by superior ulnar collateral vessels. It runs on the posteromedial aspect of the humerus, passing the back of the medial epicondyle (in the cubital tunnel) at the elbow where it can be palpated by hand.

Lower Arms

The ulnar nerves are not the contents of the cuboid fosa. Entered the anterior anterior (flex) compartment between the two head of the ulnaris karpi flexor, located along the lateral boundary of the ulnaris karpi flexor. The ulnar nerves lie between flexor digitorum superficialis (lateral) and meditated digitorum profundus flexors. Near the wrist, it occurs superficial to the retinakulum of the flexor of the hand, but is covered by a voluntary carpal ligament to get into hands.

In the forearm it outlines the following branches:

• The ulnar nerve branch - supplying one half of the muscle (flexor carpi ulnaris and half medial of flexor digitorum profundus)
• The branch of the ulnar nerve palmar - emerging from the middle of the forearm and supplying the skin above the hypothenar superiority.
• The dorsal branch of the ulnar nerve - emerging from 7.5 cm above the wrist, moves backwards to supply the proximal skin of the ulnar one and half fingers and the adjacent area between the fingers.
• The Articular Branch is given to the elbow joint.

Hands

The ulnar nerve enters the palm through the Guyon canal, superficial to the flexor and lateral retinaculum of the bone of pisiform.

Here he issued the following branches:

• The superficial branch of the ulnar nerve - supplying the brevis palmaris and giving the digital branch to the medial one and a half fingers.
• Branch in the ulnar nerve - This accompanies the inner branch of the ulnar artery. It passes backwards between the abductor digiti minimi, the flexi digiti minimi, and the opponent digiti minimi, supplies all three muscles, and lies on a bent bone hook. These then change laterally, supplying lumbricals 3 and 4 and all palmar muscle interossei and dorsal interossei from the hand. This ends by providing adductor pollicis.
• Articular Branch to wrist.



Maps Ulnar nerve





Function

The ulnar nerve is also known as the "nerve musician" because it controls the movement of the fine fingers.

Sensoric

The ulnar nerve also provides the sensory innervation to the fifth and medial digits of the fourth digit, and the corresponding portion of the palm:

• Palmar from the ulnar nerve - supplying skin innervation to the skin and anterior nails
• The dorsal cutaneous branch of the ulnar nerve - supplying skin innervation to the medial dorsal of the hand and the medial dorsum 1.5 fingers

Motor

The ulnar nerve and its branches conserve the following muscles in the forearm and hand:

Articular branches passing through the elbow joint while the ulnar nerves pass between olecranon and the medial humorous epicondilus.

• On the forearm, through the ulnar nerve muscle branch:
  • Flexor carpi ulnaris
  • Flexor digitorum profundus (half medial)
• At hand, through deep ulnar nerve branches:
  • Hypotension muscle
    • Against minimi digits
    • Abductor digin minimi
    • Flexor digiti minimi brevis
  • Third and fourth lumbar muscles
  • Dorsal interossei
  • Palmar interossei
  • Adductor Pollicis
  • Flexor pollicis brevis (inner head)
• In hand, through a shallow ulnar nerve branch:
  • Palmaris brevis



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Clinical importance

The ulnar nerve can get injured anywhere between the proximal origin of the brachial plexus to the distal branch in the hand. This is the most commonly injured nerve around the elbow. Although it can be damaged under various circumstances, it is usually injured by local trauma or physical impingement ("pinched nerve"). Ulnar nerve injury at different levels causes specific motor and sensory deficits:

On the elbow

• General Mechanism of Injury : Cubital Tunnel Syndrome, Medullary Fluid Epicondyle Fracture (causing direct ulnar nerve injury), lateral humerus epicondyle fracture (causing cubitus valgus) with ulnar nerve palsy)
• Motor deficit :
  • Weakness in hand flexion at the wrist, loss of ulnar half digit flexion, or 4th and 5th digit, loss of ability to cross the fingers. (Note: The motor deficit is absent or very small in cubital tunnel syndrome because the ulnar nerve is compressed in the cubital tunnel, rather than transmitted.)
  • The presence of hand deformities of the claws during resting hands, due to hyperextension of the 4th and 5th digits of the metacarpophalangeal joint, and flexion of the interphalangeal joint.
  • Weakness of adduction of the thumb, which can be judged by the Froment sign.
• sensory deficit : Loss of sensation or paresthesia in the ulnar half of the palms and hand dorsum, and medial 1½ digits on both palmar and back aspect of the hand

On the wrist

• Common mechanisms : through wounds, Guyon canal cyst
• Motor deficit :
  • Loss of ulnar flexibility is half the digits, or the 4th and 5th digit, the loss of the ability to cross the digit of the hand.
  • The presence of hand deformities of the claws during resting hands, due to hyperextension of the 4th and 5th digits of the metacarpophalangeal joint, and flexion of the interphalangeal joint.
  • The deformity of the hand claw is more prominent with an injury to the wrist than a higher lesion in the arm, for example, on the elbow, since the ulnar half of the flexor digitorum profundus is unaffected. This pulls the distal interphalangeal joint from the 4th and 5th digit to a more flexible position, producing a more defective 'claw'. This is known as the ulnar paradox.
  • Weakness of adduction of the thumb, which can be judged by the Froment sign.
• Sensory deficit : Loss of sensation or paresthesias on the ulnar of the palm, and medial 1½ digits on the palm aspect, with prolonged back. The dorsal aspect of the hand is unaffected because the posterior cutaneous branch of the ulnar nerve is released higher in the forearm and does not reach the wrist.

In severe cases, surgery may be performed to relocate or "release" the nerve to prevent further injury.



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See also

• Axillary nerve
• The median nerve
• Muskulokutaneus nerve
• Radial nerve



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Additional images




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References




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External links

• The Tunnel Tunnel Support Forum
• Anatomical figure: 05: 03-15 at Human Anatomy Online, SUNY Downstate Medical Center - "Main subdivision and terminal brachial plexus nerve."
• Anatomical figure: 07: 04-04 at Human Anatomy Online, SUNY Downstate Medical Center - "An anterior view of the nerves, vessels, and superficial tendons that cross the left wrist."
• Anatomical figure: 08: 03-07 in Human Anatomy Online, SUNY Downstate Medical Center - "Cross section through carpal tunnel and distal row of carpal bone."
• Ulnar_nerve in the Duke University Health Systems Orthopedic program
• Hand kinesiology at the University of Kansas Medical Center
• Atlas Image: hand_plexus in Michigan University Healthcare System - "Axilla, dissection, anterior display"
• Overview in neuro.wustl.edu

Source of the article : Wikipedia