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{{Short description|Nerve which runs near the ulna bone}}
{{Infobox Nerve |
{{redirect|Funny bone|the comedy-drama film|Funny Bones|the comedy club|The Funny Bone}}
Name = {{PAGENAME}} |
{{Infobox Nerve
Latin = Nervus ulnaris |
| Name = Ulnar nerve
GraySubject = 210 |
GrayPage = 943 |
| Latin = nervus ulnaris
Image = Brachial_plexus.JPG |
| Image = Brachial plexus 2.svg
Caption = Click image to enlarge - ulnar nerve is visible in lower left |
| Caption = Click image to enlarge - ulnar nerve is visible in lower left
Image2 = Gray816.png |
| Image2 = Nerves_of_the_left_upper_extremity.gif
Caption2 = Nerves of the left upper extremity. (Ulnar labeled at center left.) |
| 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]] |
| Innervates = [[Flexor carpi ulnaris]]<br />[[flexor digitorum profundus]]<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]] |
| BranchFrom = C8, T1 (branch from [[medial cord]])
BranchTo = |
| BranchTo =
MeshName = |
MeshNumber = |
DorlandsPre = n_05 |
DorlandsSuf = 12566994 |
}}
}}
In [[human anatomy]], the '''ulnar nerve''' is a nerve of that runs from the shoulder to the hand, at one part running near the [[ulna]] bone.


The '''ulnar nerve''' is a [[nerve]] that runs near the [[ulna]], one of the two long bones in the [[forearm]]. The [[ulnar collateral ligament of elbow joint]] is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is common.<ref>{{Cite journal|title=Risk of Ulnar Nerve Injury During Cross-Pinning in Supine and Prone Position for Supracondylar Humeral Fractures in Children: A Recent Literature Review|url=https://pubmed.ncbi.nlm.nih.gov/31037406/|last1=N|first1=Catena|last2=Mg|first2=Calevo|journal=European Journal of Orthopaedic Surgery & Traumatology: Orthopedie Traumatologie|language=en|pmid=31037406|access-date=2020-05-22|last3=D|first3=Fracassetti|last4=D|first4=Moharamzadeh|last5=C|first5=Origo|last6=M|first6=De Pellegrin|year=2019|volume=29|issue=6|pages=1169–1175|doi=10.1007/s00590-019-02444-0|s2cid=139108013}}</ref> This nerve is directly connected to the [[little finger]], and the adjacent half of the [[ring finger]], innervating the [[Hand|palmar aspect]] of these fingers, including both front and back of the [[Finger|tips]], perhaps as far back as the [[Nail (anatomy)|fingernail beds]].
===Course===


This nerve can cause an electric shock-like sensation by striking the [[medial epicondyle of the humerus]] posteriorly, or inferiorly with the elbow flexed. The ulnar nerve is trapped between the bone and the overlying skin at this point. This is commonly referred to as bumping one's "'''funny bone'''".<ref>{{cite web | url=https://www.atlanticortho.com/ulnar-nerve-entrapment/ | title=Ulnar Nerve Entrapment - Atlantic Orthopaedic Specialists | date=7 July 2019 }}</ref> This name is thought to be a [[pun]], based on the [[homophone|sound resemblance]] between the name of the bone of the upper arm, the [[humerus]], and the word "[[humour|humorous]]".<ref>{{cite book |author=Hendrickson, Robert A. |title=The Facts on File Encyclopedia of Word and Phrase Origins (Facts on File Writer's Library) |year=2004 |publisher=Checkmark Books |location=New York |page=281 |isbn=0-8160-5992-6}}</ref> Alternatively, according to the [[Oxford English Dictionary]], it may refer to "the peculiar sensation experienced when it is struck".<ref>{{cite web|url=http://dictionary.oed.com/cgi/entry/50091012/50091012se9?single=1&query_type=word&queryword=funny+bone&first=1&max_to_show=10&hilite=50091012se9 |title=Welcome to the new OED Online: Oxford English Dictionary |publisher=Dictionary.oed.com |access-date=2012-03-20}}</ref>
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]]. Because of the mild pain and tingling throughout the forearm associated with sudden compression of the nerve at this point, it is sometimes called the ''funny bone''. (It may also have to do with its location relative to the humerus, as well as the fact that "humerus" is homophonic to the word "humorous").


==Structure==
===Arm===
The ulnar nerve originates from the [[cervical spinal nerve 8|C8]]-[[thoracic spinal nerve 1|T1]] nerve roots (and occasionally carries [[cervical spinal nerve 7|C7]] fibers which arise from the [[lateral cord]]),<ref name=":0">{{Citation|last1=Bonfiglioli|first1=Roberta|title=Chapter 22 - Occupational mononeuropathies in industry|date=2015-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780444626271000214|journal=Handbook of Clinical Neurology|volume=131|pages=411–426|editor-last=Lotti|editor-first=Marcello|series=Occupational Neurology|publisher=Elsevier|language=en|doi=10.1016/b978-0-444-62627-1.00021-4|access-date=2020-10-25|last2=Mattioli|first2=Stefano|last3=Violante|first3=Francesco S.|pmid=26563800|isbn=9780444626271|editor2-last=Bleecker|editor2-first=Margit L.}}</ref><ref name=":1">{{Citation|last=Rea|first=Paul|title=Chapter 3 - Neck|date=2016-01-01|url=http://www.sciencedirect.com/science/article/pii/B978012803633400003X|work=Essential Clinically Applied Anatomy of the Peripheral Nervous System in the Head and Neck|pages=131–183|editor-last=Rea|editor-first=Paul|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-803633-4.00003-x|isbn=978-0-12-803633-4|access-date=2020-10-25}}</ref> which then form part of the medial cord of the [[brachial plexus]], and descends medial to the [[brachial artery]], up until the insertion point of [[coracobrachialis muscle]] (middle 5&nbsp;cm over the medial border of the humerus). Then, it pierces the medial intermuscular septum and enters the posterior compartment of the arm, accompanied by superior ulnar collateral vessels. It runs at the posteromedial aspects of the humerus, passing behind the medial epicondyle (in the [[cubital tunnel]]) at the elbow, where it can be palpated by hand.<ref name="BD Chaurasia">{{cite book|last1=Krishna|first1=Garg|title=BD Chaurasia's Human Anatomy (Regional and Applied Dissection and Clinical) Volume 1 - Upper limb and thorax|date=2010|publisher=CBS Publishers and Distributors Pvt Ltd|location=India|isbn=978-81-239-1863-1|page=91,110,111|edition=Fifth|chapter=8 - Arm}}</ref>


===Forearm===
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.
The ulnar nerve is not a content of the [[cubital fossa]]. It enters the [[Anterior compartment of the forearm|anterior (flexor) compartment of the forearm]] between the two heads of [[flexor carpi ulnaris]],<ref name=":1" /> and lies along the lateral border of the flexor carpi ulnaris.<ref name=":1" /> The ulnar nerve runs between the [[Flexor digitorum superficialis muscle|flexor digitorum superficialis]] (laterally) and [[Flexor digitorum profundus muscle|flexor digitorum profundus]] [[Anatomical terms of location|medially]]. Near the wrist, it courses superficial to the [[Flexor retinaculum of the hand|flexor retinaculum of hand]], but covered by volar carpal ligament to enter the hand.<ref name="BD Chaurasia"/>


In the forearm it gives off the following branches:<ref name="isbn0-443-07168-3"/>{{rp|700}}
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]].
* [[Muscular branches of ulnar nerve]] - supplies one and a half muscles (flexor carpi ulnaris and the medial half of [[flexor digitorum profundus]])<ref name="BD Chaurasia"/>
* [[Palmar branch of ulnar nerve]] - arises from the middle part of the forearm and supplies the skin over the hypothenar eminence.<ref name="BD Chaurasia"/>
* [[Dorsal branch of ulnar nerve]] - arises from 7.5&nbsp;cm above the wrist, winds backwards to supply the skin of the proximal part of the ulnar one and half fingers and the adjoining area between the fingers.<ref name=":1" /><ref name="BD Chaurasia"/>
* Articular branches are given off to the elbow joint.<ref name="BD Chaurasia"/>


===Branches===
===Hand===
[[File:Guyon canal syndrome zones.svg|thumb|Branches of the ulnar nerve in hand]]
The ulnar nerve has the following named branches:
* '''Palmar cutaneous branch of the ulnar nerve''' - arises about the middle of the forearm, and descends on the ulnar artery, giving off some filaments to the vessel. It perforates the [[palmar carpal ligament]] and ends in the skin of the palm, communicating with the palmar branch of the [[median nerve]].
* '''Dorsal branch of the ulnar nerve''' - arises about 5 cm above the wrist; it passes posteriorly beneath the [[flexor carpi ulnaris]], perforates the deep fascia, and, running along the ulnar side of the back of the wrist and hand, divides into two dorsal digital branches; one supplies the ulnar side of the little finger; the other, the adjacent sides of the little and ring fingers. It also sends a twig to join that given by the superficial branch of the [[radial nerve]] for the adjoining sides of the middle and ring fingers, and assists in supplying them. A branch is distributed to the metacarpal region of the hand, communicating with a twig of the superficial branch of the [[radial nerve]].
* '''Palmar branch of the ulnar nerve''' - the continuation of the ulnar nerve as it crosses the [[flexor retinaculum of the hand]] on the lateral side of the [[pisiform]] bone, medial to and a little behind the [[ulnar artery]]. It ends by dividing into a superficial and a deep branch.
** '''Superficial branch of the ulnar nerve''' - supplies the [[palmaris brevis]] and the skin on the ulnar side of the hand, and divides into a '''proper palmar digital nerve''' for the ulnar side of the little finger, and a '''common palmar digital nerve''' which gives a communicating twig to the [[median nerve]] and divides into two proper digital nerves for the adjoining sides of the little and ring fingers. The proper digital branches are distributed to the fingers in the same manner as those of the [[median nerve]].
** '''Deep branch of the ulnar nerve''' - accompanied by the deep branch of the [[ulnar artery]], passes between the [[abductor digiti minimi]] and the [[flexor digiti minimi brevis]]. It then perforates the [[opponens digiti minimi]] and follows the course of the [[deep palmar arch]] beneath the flexor tendons. At its origin it supplies the [[hypothenar muscles]]. As it crosses the deep part of the hand, it supplies all the [[interosseous muscles]] and the third and fourth [[lumbricals of the hand|lumbricals]]. It ends by supplying the [[adductor pollicis]] and the medial head of the [[flexor pollicis brevis]]. It also sends articular filaments to the wrist-joint.


Ulnar nerve enters the palm of the hand via the [[ulnar canal|Guyon's canal]], superficial to the [[flexor retinaculum of the hand|flexor retinaculum]] and lateral to the [[pisiform bone]].<ref name="BD Chaurasia"/>


Here it gives off the following branches:<ref name="isbn0-443-07168-3">{{cite book |author1=Ellis, Harold |author2=Susan Standring |author3=Gray, Henry David |title=Gray's anatomy: the anatomical basis of clinical practice |publisher=Elsevier Churchill Livingstone |location=St. Louis, Mo |year=2005 |page=[https://archive.org/details/graysanatomyanat0000unse/page/726 726] |isbn=0-443-07168-3 |url=https://archive.org/details/graysanatomyanat0000unse/page/726 }}</ref>
===Innervation===
* [[Superficial branch of ulnar nerve]] - supplies the [[palmaris brevis]] and gives digital branches to the medial one and a half fingers.<ref name="BD Chaurasia"/>
* [[Deep branch of ulnar nerve]] - It accompanies the deep branch of the ulnar artery. It passes backwards between the abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi, supplying all the three muscles, and lying on the hook of [[hamate bone]]. It then turns laterally, supplying the 3rd and 4th lumbricals and all the [[palmar interossei muscles]] and [[dorsal interossei of the hand]]. It terminates by supplying the [[adductor pollicis]].<ref name="BD Chaurasia"/>
* Articular branches to the wrist.<ref name="BD Chaurasia"/>

==Function==
{{More citations needed section|date=June 2020}}
Ulnar nerve is also known as "musician's nerve" as it controls the fine movements of the fingers.<ref name="BD Chaurasia"/>

===Sensory===
[[File:Gray812and814.svg|thumb|Cutaneous innervation of the right upper extremity. Areas innervated by the ulnar nerve are the areas on the hand colored in light blue.]]

The ulnar nerve also provides [[sensory innervation]] to the fifth digit and the medial half of the fourth digit, and the corresponding part of the palm:
* [[Palmar branch of ulnar nerve]] - supplies cutaneous innervation to the anterior skin and nails
* [[Dorsal branch of ulnar nerve]] - supplies cutaneous innervation to the dorsal medial hand and the dorsum of the medial 1.5 fingers

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

*In the [[forearm]]:
*An articular branch that passes to the elbow joint while the ulnar nerve is passing between the olecranon and medial epicondyle of the humerus
**[[Flexor carpi ulnaris]]
*In the [[forearm]], via the [[muscular branches of ulnar nerve]]:
**[[Flexor digitorum profundus]] (medial half)
**[[Flexor carpi ulnaris]]<ref name=":0" />
*In the [[hand]] via the deep branch of the ulnar nerve:
**[[Flexor digitorum profundus]] (medial half)<ref name=":0" />
**[[Opponens digiti minimi]] - a hypothenar muscle
*In the [[hand]], via the [[deep branch of ulnar nerve]]:<ref name=":0" />
**[[Abductor digiti minimi]] - a hypothenar muscle
**[[Hypothenar]] muscles
**[[Flexor digiti minimi brevis]] - a hypothenar muscle
**[[Adductor pollicis]]
***[[Opponens digiti minimi]]
***[[Abductor minimi digiti muscle (hand)|Abductor digiti minimi]]
***[[Flexor digiti quinti brevis muscle (hand)|Flexor digiti minimi brevis]]
**The third and fourth [[Lumbricals of the hand|lumbrical muscles]]
**The third and fourth [[Lumbricals of the hand|lumbrical muscles]]
**[[Dorsal interossei of the hand|Dorsal interossei]]
**[[Dorsal interossei of the hand|Dorsal interossei]]
**[[Palmar interossei]]
**[[Palmar interossei]]
**[[Adductor pollicis muscle|Adductor pollicis]]
*In the hand via the superficial branch of the ulnar nerve:
**[[Flexor pollicis brevis muscle|Flexor pollicis brevis]] (deep head)
*In the hand, via the [[superficial branch of ulnar nerve]]:
**[[Palmaris brevis]]
**[[Palmaris brevis]]


==Clinical significance==
The ulnar nerve also provides sensory innervation to the part of the hand corresponding to the fourth and fifth digits, both anteriorly and posteriorly.

The ulnar nerve can suffer injury anywhere between its proximal origin of the brachial plexus all the way to its distal branches in the hand. It is the most commonly injured nerve around the elbow.<ref>{{Cite web|url = http://www.msdlatinamerica.com/ebooks/PracticalOrthopaedicSportsMedicineArthrocopy/sid328804.html|title = Practical Orthopaedic Sports Medicine & Arthroscopy, 1st edition: Elbow Injuries|date = 2007|website = msdlatinamerica.com|publisher = Lippincott Williams & Wilkins|last1 = Selby|first1 = Ronald|last2 = Safran|first2 = Marc|last3 = O'brien|first3 = Stephen|access-date = 2014-09-30|archive-date = 2014-10-06|archive-url = https://web.archive.org/web/20141006071910/http://www.msdlatinamerica.com/ebooks/PracticalOrthopaedicSportsMedicineArthrocopy/sid328804.html|url-status = dead}}</ref><ref>{{Citation|last1=Minieka|first1=Michael|title=Chapter 54 - Entrapment Neuropathies|date=2005-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780443066511500587|work=Essentials of Pain Medicine and Regional Anesthesia (Second Edition)|pages=426–432|editor-last=Benzon|editor-first=Honorio T.|place=Philadelphia|publisher=Churchill Livingstone|language=en|doi=10.1016/b978-0-443-06651-1.50058-7|isbn=978-0-443-06651-1|access-date=2020-10-25|last2=Nishida|first2=Takashi|editor2-last=Raja|editor2-first=Srinivasa N.|editor3-last=Molloy|editor3-first=Robert E.|editor4-last=Liu|editor4-first=Spencer S.}}</ref> Although it can be damaged under various circumstances, it is commonly injured by local trauma or [[Ulnar nerve entrapment|physical impingement]] ("pinched nerve"). Injury of the ulnar nerve at different levels causes specific motor and sensory deficits.

===At the elbow===
* ''Common mechanisms of injury'': [[Cubital tunnel syndrome]], fracture of the medial epicondyle of the humerus (causing direct ulnar nerve injury), fracture of the lateral epicondyle of the humerus (causing [[cubitus valgus]] with tardy ulnar nerve palsy), Driver's Elbow<ref>{{Citation|last=Waldman|first=Steven D.|title=Chapter 44 - Driver's Elbow|date=2014-01-01|url=http://www.sciencedirect.com/science/article/pii/B9781455709991000447|work=Atlas of Uncommon Pain Syndromes (Third Edition)|pages=126–129|editor-last=Waldman|editor-first=Steven D.|place=Philadelphia|publisher=W.B. Saunders|language=en|doi=10.1016/b978-1-4557-0999-1.00044-7|isbn=978-1-4557-0999-1|access-date=2020-10-25}}</ref>
* ''Motor deficit'':
** Weakness in flexion of the hand at the wrist, loss of flexion of ulnar half of digits, or the 4th and 5th digits, loss of ability to cross the digits of the hand. (Note: Motor deficit is absent or very minor in [[cubital tunnel syndrome]] as the ulnar nerve is [[Nerve compression syndrome|compressed]] in the cubital tunnel, rather than transected.)
** Presence of a [[Ulnar claw|claw hand]] deformity when the hand is at rest, due to hyperextension of the 4th and 5th digits at the [[metacarpophalangeal joint]]s, and flexion at the [[Interphalangeal articulations of hand|interphalangeal joints]].
** Weakness of adduction of the thumb, which may be assessed by the presence of [[Froment's sign]].
* ''Sensory deficit'': Loss of sensation or [[paresthesia]]e in ulnar half of the palm and dorsum of hand, and the medial 1½ digits on both palmar and dorsal aspects of the hand

===At the wrist===
* ''Common mechanism'': penetrating wounds, Guyon canal cyst (and other lesions)<ref>{{Citation|last1=Fuller|first1=Geraint|title=Common peripheral nerve lesions|date=2010-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780702032240000549|work=Neurology (Third Edition)|pages=106–107|editor-last=Fuller|editor-first=Geraint|publisher=Churchill Livingstone|language=en|doi=10.1016/b978-0-7020-3224-0.00054-9|isbn=978-0-7020-3224-0|access-date=2020-10-25|last2=Manford|first2=Mark|s2cid=88836902 |editor2-last=Manford|editor2-first=Mark}}</ref>
* ''Motor deficit'':
** Loss of flexion of ulnar half of digits, or the 4th and 5th digits, loss of ability to cross the digits of the hand.
** Presence of a [[Ulnar claw|claw hand]] deformity when the hand is at rest, due to hyperextension of the 4th and 5th digits at the [[metacarpophalangeal joint]]s, and flexion at the [[Interphalangeal articulations of hand|interphalangeal joints]].
** The [[Ulnar claw|claw hand]] deformity is more prominent with injury at the wrist as opposed to a lesion higher up in the arm, for instance, at the elbow, as the ulnar half of the [[Flexor digitorum profundus muscle|flexor digitorum profundus]] is not affected. This pulls the distal interphalangeal joints of the 4th and 5th digit into a more flexed position, producing a more deformed 'claw'. This is known as the [[Ulnar claw#ulnar paradox|ulnar paradox]].
** Weakness of adduction of the thumb, which may be assessed by the presence of [[Froment's sign]].
* ''Sensory deficit'': Loss of sensation or [[paresthesia]]e in ulnar half of the palm, and the medial 1½ digits on the palmar aspect of the hand, with dorsal sparing. The dorsal aspect of the hand is unaffected as the posterior cutaneous branch of the ulnar nerve is given off higher up 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.

==Additional images==
<gallery>
Image:Brachial_plexus_color.svg|Brachial plexus with courses of spinal nerves shown
Image:Gray413.png|Cross-section through the middle of upper arm. <!-- this image is poor, there are better ones -->
Image:Gray417.png|Cross-section through the middle of the forearm.
Image:Gray421.png|Transverse section across distal ends of radius and ulna.
Image:Carpal-Tunnel.svg|Transverse section across the wrist and digits.
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: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.
File:Slide4t.JPG|Ulnar nerve
File:Slide4zzz.JPG|Brachial plexus with characteristic M, ulnar nerve labeled.
File:Slide3bbbb.JPG|Ulnar nerve
File:Slide2hhhh.JPG|Ulnar nerve
File:Slide10WWW.JPG|Ulnar nerve
File:Slide1ecc.JPG|Brachial plexus. Deep dissection. Anterolateral view
</gallery>


==See also==
==See also==
{{Anatomy-terms}}
* [[Radial artery]]
* [[Axillary nerve]]
* [[Axillary nerve]]
* [[Median nerve]]
* [[Median nerve]]
* [[Musculocutaneous nerve]]
* [[Radial nerve]]
* [[Brachial plexus]]
* [[Medial cord]]
* [[Palmar cutaneous branch of the ulnar nerve]]
* [[Dorsal branch of the ulnar nerve]]
* [[Deep branch of the ulnar nerve]]
* [[Superficial branch of ulnar nerve]]
* [[Muscular branches of the ulnar nerve]]
* [[Cubital tunnel]]
* [[Guyons canal|Guyon canal]]
* [[Struthers' ligament]]
* [[Cubital tunnel syndrome]]
* [[Ulnar nerve entrapment]]
* [[Nerve compression syndrome]]

==References==
{{Reflist}}


==External links==
==External links==
{{NIE Poster|Funny Bone}}
* {{eMedicineDictionary|Ulnar+nerve}}
* [http://www.cubital-tunnel.com Cubital Tunnel Support Forums] {{Webarchive|url=https://web.archive.org/web/20221004133404/http://www.cubital-tunnel.com/ |date=2022-10-04 }}
* {{SUNYAnatomyFigs|05|03|15}} - "The major subdivisions and terminal nerves of the [[brachial plexus]]."
* {{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|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."
* {{SUNYAnatomyFigs|08|03|07}} - "Transverse section through the [[carpal tunnel]] and distal row of the [[carpal]] bones."
* {{DukeOrtho|ulnar_nerve}}
* {{DukeOrtho|Ulnar_nerve}}
* {{KansasHandKinesiology|nerves/ulnar.htm}}
* [http://www.neuro.wustl.edu/neuromuscular/nanatomy/ulnar.htm Overview at neuro.wustl.edu]
* {{UMichAtlas|hand_plexus}} - "Axilla, dissection, anterior view"
* [http://www.med.mun.ca/anatomyts/nerve/ulnerv.htm Overview at med.mun.ca]
* [http://www.neuro.wustl.edu/neuromuscular/nanatomy/ulnar.htm Overview at neuro.wustl.edu]
* [https://lancashireshoulderclinic.co.uk/condition/ulnar-nerve-entrapment/ Shoulder Ulnar Nerve Entrapment]
* {{Webarchive|url=https://web.archive.org/web/20060906223857/http://www.neuro.wustl.edu/neuromuscular/nanatomy/ulnar.htm |date=2006-09-06 }}


{{Brachial plexus}}
{{Brachial plexus}}
{{Authority control}}
[[Category:Peripheral nervous system]]
[[Category:Upper limb anatomy]]


[[Category:Nerves of the upper limb]]
[[de:Nervus ulnaris]]
[[fr:Nerf ulnaire]]
[[pt:nervo ulnar]]
[[sv:Nervus ulnaris]]

Latest revision as of 15:00, 19 December 2024

"Funny bone" redirects here. For the comedy-drama film, see Funny Bones. For the comedy club, see The Funny Bone.
Ulnar nerve
Click image to enlarge - ulnar nerve is visible in lower left
Nerves of the left upper extremity. (Ulnar labeled at center left.)
Details
FromC8, T1 (branch from medial cord)
InnervatesFlexor carpi ulnaris
flexor digitorum profundus
lumbrical muscles
opponens digiti minimi
flexor digiti minimi
abductor digiti minimi
interossei
adductor pollicis
Identifiers
Latinnervus ulnaris
MeSHD014459
TA98A14.2.03.040
TA26449
FMA37319
Anatomical terms of neuroanatomy

The ulnar nerve is a nerve that runs near the ulna, one of the two long bones in the forearm. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is common.[1] This nerve is directly connected to the little finger, and the adjacent half of the ring finger, innervating the palmar aspect of these fingers, including both front and back of the tips, perhaps as far back as the fingernail beds.

This nerve can cause an electric shock-like sensation by striking the medial epicondyle of the humerus posteriorly, or inferiorly with the elbow flexed. The ulnar nerve is trapped between the bone and the overlying skin at this point. This is commonly referred to as bumping one's "funny bone".[2] This name is thought to be a pun, based on the sound resemblance between the name of the bone of the upper arm, the humerus, and the word "humorous".[3] Alternatively, according to the Oxford English Dictionary, it may refer to "the peculiar sensation experienced when it is struck".[4]

Structure

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Arm

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The ulnar nerve originates from the C8-T1 nerve roots (and occasionally carries C7 fibers which arise from the lateral cord),[5][6] which then form part of the medial cord of the brachial plexus, and descends medial to the brachial artery, up until the insertion point of coracobrachialis muscle (middle 5 cm over the medial border of the humerus). Then, it pierces the medial intermuscular septum and enters the posterior compartment of the arm, accompanied by superior ulnar collateral vessels. It runs at the posteromedial aspects of the humerus, passing behind the medial epicondyle (in the cubital tunnel) at the elbow, where it can be palpated by hand.[7]

Forearm

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The ulnar nerve is not a content of the cubital fossa. It enters the anterior (flexor) compartment of the forearm between the two heads of flexor carpi ulnaris,[6] and lies along the lateral border of the flexor carpi ulnaris.[6] The ulnar nerve runs between the flexor digitorum superficialis (laterally) and flexor digitorum profundus medially. Near the wrist, it courses superficial to the flexor retinaculum of hand, but covered by volar carpal ligament to enter the hand.[7]

In the forearm it gives off the following branches:[8]: 700 

Hand

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Branches of the ulnar nerve in hand

Ulnar nerve enters the palm of the hand via the Guyon's canal, superficial to the flexor retinaculum and lateral to the pisiform bone.[7]

Here it gives off the following branches:[8]

Function

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Ulnar nerve is also known as "musician's nerve" as it controls the fine movements of the fingers.[7]

Sensory

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Cutaneous innervation of the right upper extremity. Areas innervated by the ulnar nerve are the areas on the hand colored in light blue.

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

Motor

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

Clinical significance

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The ulnar nerve can suffer injury anywhere between its proximal origin of the brachial plexus all the way to its distal branches in the hand. It is the most commonly injured nerve around the elbow.[9][10] Although it can be damaged under various circumstances, it is commonly injured by local trauma or physical impingement ("pinched nerve"). Injury of the ulnar nerve at different levels causes specific motor and sensory deficits.

At the elbow

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  • Common mechanisms of injury: Cubital tunnel syndrome, fracture of the medial epicondyle of the humerus (causing direct ulnar nerve injury), fracture of the lateral epicondyle of the humerus (causing cubitus valgus with tardy ulnar nerve palsy), Driver's Elbow[11]
  • Motor deficit:
    • Weakness in flexion of the hand at the wrist, loss of flexion of ulnar half of digits, or the 4th and 5th digits, loss of ability to cross the digits of the hand. (Note: Motor deficit is absent or very minor in cubital tunnel syndrome as the ulnar nerve is compressed in the cubital tunnel, rather than transected.)
    • Presence of a claw hand deformity when the hand is at rest, due to hyperextension of the 4th and 5th digits at the metacarpophalangeal joints, and flexion at the interphalangeal joints.
    • Weakness of adduction of the thumb, which may be assessed by the presence of Froment's sign.
  • Sensory deficit: Loss of sensation or paresthesiae in ulnar half of the palm and dorsum of hand, and the medial 1½ digits on both palmar and dorsal aspects of the hand

At the wrist

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  • Common mechanism: penetrating wounds, Guyon canal cyst (and other lesions)[12]
  • Motor deficit:
    • Loss of flexion of ulnar half of digits, or the 4th and 5th digits, loss of ability to cross the digits of the hand.
    • Presence of a claw hand deformity when the hand is at rest, due to hyperextension of the 4th and 5th digits at the metacarpophalangeal joints, and flexion at the interphalangeal joints.
    • The claw hand deformity is more prominent with injury at the wrist as opposed to a lesion higher up in the arm, for instance, at the elbow, as the ulnar half of the flexor digitorum profundus is not affected. This pulls the distal interphalangeal joints of the 4th and 5th digit into a more flexed position, producing a more deformed 'claw'. This is known as the ulnar paradox.
    • Weakness of adduction of the thumb, which may be assessed by the presence of Froment's sign.
  • Sensory deficit: Loss of sensation or paresthesiae in ulnar half of the palm, and the medial 1½ digits on the palmar aspect of the hand, with dorsal sparing. The dorsal aspect of the hand is unaffected as the posterior cutaneous branch of the ulnar nerve is given off higher up 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.

Additional images

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  • Brachial plexus with courses of spinal nerves shown
    Brachial plexus with courses of spinal nerves shown
  • Cross-section through the middle of upper arm.
    Cross-section through the middle of upper arm.
  • Cross-section through the middle of the forearm.
    Cross-section through the middle of the forearm.
  • Transverse section across distal ends of radius and ulna.
    Transverse section across distal ends of radius and ulna.
  • Transverse section across the wrist and digits.
    Transverse section across the wrist and digits.
  • Ulnar and radial arteries. Deep view.
    Ulnar and radial arteries. Deep view.
  • The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front.
    The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front.
  • Front of right upper extremity, showing surface markings for bones, arteries, and nerves.
    Front of right upper extremity, showing surface markings for bones, arteries, and nerves.
  • Back of right upper extremity, showing surface markings for bones and nerves.
    Back of right upper extremity, showing surface markings for bones and nerves.
  • Ulnar nerve
    Ulnar nerve
  • Brachial plexus with characteristic M, ulnar nerve labeled.
    Brachial plexus with characteristic M, ulnar nerve labeled.
  • Ulnar nerve
    Ulnar nerve
  • Ulnar nerve
    Ulnar nerve
  • Ulnar nerve
    Ulnar nerve
  • Brachial plexus. Deep dissection. Anterolateral view
    Brachial plexus. Deep dissection. Anterolateral view

See also

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This article uses anatomical terminology.

References

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  1. ^ N, Catena; Mg, Calevo; D, Fracassetti; D, Moharamzadeh; C, Origo; M, De Pellegrin (2019). "Risk of Ulnar Nerve Injury During Cross-Pinning in Supine and Prone Position for Supracondylar Humeral Fractures in Children: A Recent Literature Review". European Journal of Orthopaedic Surgery & Traumatology: Orthopedie Traumatologie. 29 (6): 1169–1175. doi:10.1007/s00590-019-02444-0. PMID 31037406. S2CID 139108013. Retrieved 2020-05-22.
  2. ^ "Ulnar Nerve Entrapment - Atlantic Orthopaedic Specialists". 7 July 2019.
  3. ^ Hendrickson, Robert A. (2004). The Facts on File Encyclopedia of Word and Phrase Origins (Facts on File Writer's Library). New York: Checkmark Books. p. 281. ISBN 0-8160-5992-6.
  4. ^ "Welcome to the new OED Online: Oxford English Dictionary". Dictionary.oed.com. Retrieved 2012-03-20.
  5. ^ a b c d Bonfiglioli, Roberta; Mattioli, Stefano; Violante, Francesco S. (2015-01-01), Lotti, Marcello; Bleecker, Margit L. (eds.), "Chapter 22 - Occupational mononeuropathies in industry", Handbook of Clinical Neurology, Occupational Neurology, 131, Elsevier: 411–426, doi:10.1016/b978-0-444-62627-1.00021-4, ISBN 9780444626271, PMID 26563800, retrieved 2020-10-25
  6. ^ a b c d Rea, Paul (2016-01-01), Rea, Paul (ed.), "Chapter 3 - Neck", Essential Clinically Applied Anatomy of the Peripheral Nervous System in the Head and Neck, Academic Press, pp. 131–183, doi:10.1016/b978-0-12-803633-4.00003-x, ISBN 978-0-12-803633-4, retrieved 2020-10-25
  7. ^ a b c d e f g h i j k Krishna, Garg (2010). "8 - Arm". BD Chaurasia's Human Anatomy (Regional and Applied Dissection and Clinical) Volume 1 - Upper limb and thorax (Fifth ed.). India: CBS Publishers and Distributors Pvt Ltd. p. 91,110,111. ISBN 978-81-239-1863-1.
  8. ^ a b Ellis, Harold; Susan Standring; Gray, Henry David (2005). Gray's anatomy: the anatomical basis of clinical practice. St. Louis, Mo: Elsevier Churchill Livingstone. p. 726. ISBN 0-443-07168-3.
  9. ^ Selby, Ronald; Safran, Marc; O'brien, Stephen (2007). "Practical Orthopaedic Sports Medicine & Arthroscopy, 1st edition: Elbow Injuries". msdlatinamerica.com. Lippincott Williams & Wilkins. Archived from the original on 2014-10-06. Retrieved 2014-09-30.
  10. ^ Minieka, Michael; Nishida, Takashi (2005-01-01), Benzon, Honorio T.; Raja, Srinivasa N.; Molloy, Robert E.; Liu, Spencer S. (eds.), "Chapter 54 - Entrapment Neuropathies", Essentials of Pain Medicine and Regional Anesthesia (Second Edition), Philadelphia: Churchill Livingstone, pp. 426–432, doi:10.1016/b978-0-443-06651-1.50058-7, ISBN 978-0-443-06651-1, retrieved 2020-10-25
  11. ^ Waldman, Steven D. (2014-01-01), Waldman, Steven D. (ed.), "Chapter 44 - Driver's Elbow", Atlas of Uncommon Pain Syndromes (Third Edition), Philadelphia: W.B. Saunders, pp. 126–129, doi:10.1016/b978-1-4557-0999-1.00044-7, ISBN 978-1-4557-0999-1, retrieved 2020-10-25
  12. ^ Fuller, Geraint; Manford, Mark (2010-01-01), Fuller, Geraint; Manford, Mark (eds.), "Common peripheral nerve lesions", Neurology (Third Edition), Churchill Livingstone, pp. 106–107, doi:10.1016/b978-0-7020-3224-0.00054-9, ISBN 978-0-7020-3224-0, S2CID 88836902, retrieved 2020-10-25
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Wikisource has the text of the 1905 New International Encyclopedia article "Funny Bone".
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