View source for Ulnar nerve

{{Infobox Nerve |
  Name         = Ulnar nerve |
  Latin        = nervus ulnaris |
  GraySubject  = 210 |
  GrayPage     = 943 | 
  Image        = Brachial_plexus.jpg |
  Caption      = Click image to enlarge - ulnar nerve is visible in lower left |
  Image2       = Nerves_of_the_left_upper_extremity.gif |
  Caption2     = Nerves of the left upper extremity. (Ulnar labeled at center left.) |
  Innervates   = [[flexor carpi ulnaris]]<BR>[[flexor digitorum profundis]]<BR>[[lumbrical muscle]]s<BR>[[opponens digiti minimi]]<BR>[[Flexor digiti minimi brevis (hand)|flexor digiti minimi]]<BR>[[Abductor minimi digiti muscle (hand)|abductor digiti minimi]]<BR>[[interossei]]<BR>[[adductor pollicis]] |
  BranchFrom   = [[Medial cord]] |
  BranchTo     = |
  MeshName     = Ulnar+nerve |
  MeshNumber   = A08.800.800.720.050.850 |
  DorlandsPre  = n_05 |
  DorlandsSuf  = 12566994  |
}}
{{SI}}
{{CMG}}



In [[human anatomy]], the '''ulnar nerve''' is a nerve which runs from the shoulder to the hand, at one part running near the [[ulna]] bone. It is the only exposed nerve in the human body (it is unprotected for a few centimeters at the elbow). When someone says "hitting their funny bone" it is the aggravation of this nerve that is being referred to. 

==Course==

The ulnar nerve comes from the medial cord of the [[brachial plexus]], and runs inferior on the medial/posterior aspect of the [[humerus]] down the arm, going behind the [[medial epicondyle]] at the [[Elbow-joint|elbow]]. Because of the mild pain and tingling throughout the forearm associated with an inadvertent impact of the nerve at this point, it is usually called the '''funny bone'''.  (It may also have to do with its location relative to the humerus, as the name "humerus" is a homonym to the word "humorous").

It enters the anterior (front) side of the forearm and runs alongside the [[ulna]]. There it supplies one and a half muscles (flexor carpi ulnaris & medial half of flexor digiti profundus).  It soon joins with the [[ulnar artery]], and the two travel inferiorly together, deep to the [[flexor carpi ulnaris]] muscle.

After its journey down the ulna, the ulnar nerve enters the palm of the hand.  Unlike the [[median nerve]] which travels below the [[flexor retinaculum of the hand]] and through the [[carpal tunnel]], the ulnar nerve and artery pass superficial to the [[flexor retinaculum of the hand|flexor retinaculum]] via the [[ulnar canal]].

==Branches and innervation==

===Muscular===
The ulnar nerve and its branches innervate the following muscles in the forearm and hand:

An Articular branch that passes to the elbow joint while the ulnar nerve is passing between the olecranon and medial epicondyle of the femur.

*In the [[forearm]], via the [[muscular branches of ulnar nerve]]:
**[[Flexor carpi ulnaris]]
**[[Flexor digitorum profundus]] (medial half)

*In the [[hand]], via the [[deep branch of ulnar nerve]]:
**[[hypothenar]] muscles
***[[Opponens digiti minimi]]
***[[Abductor minimi digiti muscle (hand)|Abductor digiti minimi]] 
***[[Flexor digiti minimi brevis (hand)|Flexor digiti minimi brevis]] 
**[[Adductor pollicis]]
**The third and fourth [[Lumbricals of the hand|lumbrical muscles]]
**[[Dorsal interossei of the hand|Dorsal interossei]]
**[[Palmar interossei]]

*In the hand, via the [[superficial branch of ulnar nerve]]:
**[[Palmaris brevis]]

===Cutaneous===
The ulnar nerve also provides [[sensory innervation]] to the part of the hand corresponding to the fourth and fifth digits:
* [[Palmar branch of ulnar nerve]] - anterior
* [[Dorsal branch of ulnar nerve]] - posterior

==Ulnar nerve entrapment==

{{main|Ulnar nerve entrapment}}
The Ulnar nerve can be trapped or pinched in various ways as it proceeds down the arm from the Brachial plexus to the ring and middle fingers.  One common cause is [[cubital tunnel]] syndrome, where the tunnel runs the inner outside side of the elbow.  Pinching of the nerve often causes tingling symptoms in the little and ring fingers.  In some cases moderate to severe pain is experienced from pinching this nerve.  Often such [[Paresthesia|pins and needles]] sensations can be caused by sleeping wrongly on your arm, but sometimes the problems last for days.  In severe cases, surgery is performed.

==See also==
* [[Radial artery]]
* [[Axillary nerve]]
* [[Median nerve]]

==Additional images==
<gallery>
 Image:Brachial plexus_svg.png|Brachial plexus
 Image:Gray413.png|Cross-section through the middle of upper arm. 
 Image:Gray417.png|Cross-section through the middle of the forearm. 
 Image:Gray421.png|Transverse section across distal ends of radius and ulna.
 Image:Gray422.png|Transverse section across the wrist and digits.
 Image:Gray425.png|The palmar aponeurosis.
 Image:Gray523.png|The axillary artery and its branches.
 Image:Gray525.png|The brachial artery.
 Image:Gray528.png|Ulnar and radial arteries. Deep view.
 Image:Gray809.png|The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front. 
 Image:Gray811.png|Cutaneous nerves of right upper extremity. Anterior view.
 Image:Gray812_svg.png|Diagram of segmental distribution of the cutaneous nerves of the right upper extremity. Anterior view.
 Image:Gray813.png|Cutaneous nerves of right upper extremity. Posterior view.
 Image:Gray814.png|Diagram of segmental distribution of the cutaneous nerves of the right upper extremity. Posterior view.
 Image:Gray815.png|Superficial palmar nerves. 
 Image:Gray817.png|Deep palmar nerves.
 Image:Gray1235.png|Front of right upper extremity, showing surface markings for bones, arteries, and nerves.
 Image:Gray1236.png|Back of right upper extremity, showing surface markings for bones and nerves.
</gallery>

==External links==
* {{eMedicineDictionary|Ulnar+nerve}}
* {{SUNYAnatomyFigs|05|03|15}} - "The major subdivisions and terminal nerves of the [[brachial plexus]]."
* {{SUNYAnatomyFigs|07|04|04}} - "Anterior view of the nerves, vessels, and superficial tendons that cross the left [[wrist]]."
* {{SUNYAnatomyFigs|08|03|07}} - "Transverse section through the [[carpal tunnel]] and distal row of the [[carpal]] bones."
* {{DukeOrtho|ulnar_nerve}}
* {{MUNAnatomy|nerve/ulnerv}}
* {{KansasHandKinesiology|nerves/ulnar.htm}}
* {{UMichAtlas|hand_plexus}} - "Axilla, dissection, anterior view"
* [http://www.neuro.wustl.edu/neuromuscular/nanatomy/ulnar.htm Overview at neuro.wustl.edu]

{{Brachial plexus}}

[[Category:Peripheral nervous system]]
[[Category:Upper limb anatomy]]
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[[de:Nervus ulnaris]]
[[fr:Nerf ulnaire]]
[[he:עצב הגומד]]
[[nl:Telefoonbotje]]
[[pt:nervo ulnar]]
[[sv:Nervus ulnaris]]