Brachial plexus
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220794874
2008-06-21T16:44:04Z
Muro Bot
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robot Adding: [[nl:Plexus brachialis]]
{{Infobox Nerve |
Name = Brachial plexus |
Latin = plexus brachialis |
GraySubject = 210 |
GrayPage = 930 |
Image = Gray808.png |
Caption = The right brachial plexus with its short branches, viewed from in front. |
Image2 = |
Caption2 = |
Innervates = |
BranchFrom = [[cervical spinal nerve 5|C5]], [[cervical spinal nerve 6|C6]], [[cervical spinal nerve 7|C7]], [[cervical spinal nerve 8|C8]], [[thoracic spinal nerve 1|T1]] |
BranchTo = |
MeshName = Brachial+plexus |
MeshNumber = A08.800.800.720.050 |
DorlandsPre = p_24 |
DorlandsSuf = 12647576 |
}}
The '''brachial [[spine (anatomy)|plexus]]''' is an arrangement of nerve fibres, running from the spine, formed by the [[ventral rami]] of the lower cervical and upper thoracic nerve roots, specifically from above the fifth [[cervical vertebra]] to underneath the first [[thoracic vertebra]] ([[cervical spinal nerve 5|C5]]-[[thoracic spinal nerve 1|T1]]). It proceeds through the neck, the [[axilla]] (armpit region) and into the arm.
==Function==
The brachial plexus is responsible for cutaneous and muscular innervation of the entire upper limb, with two exceptions: the [[trapezius]] muscle innervated by the [[spinal accessory nerve]] and an area of skin near the axilla innervated by the [[intercostobrachialis nerve]].
Therefore, [[brachial plexus lesion]]s can lead to severe functional impairment.
==Anatomy==
===Path===
One can remember the order of brachial plexus elements by way of the mnemonic, "'''R'''ead '''T'''he '''D'''amn '''C'''adaver '''B'''ook" (Or, alternatively, [[Randy Travis|'''R'''andy '''T'''ravis]] '''D'''rinks '''C'''old '''B'''eer") - '''R'''oots, '''T'''runks, '''D'''ivisions, '''C'''ords, '''B'''ranches<ref>{{MedicalMnemonics|18|2741||}}</ref> or - Roots, Trunks, Divisions, Cords, Collateral/Pre-terminal Branches, and (Terminal) Branches.
* The five '''roots''' are the five [[anterior rami]] of the [[spinal nerve]]s, after they have given off their segmental supply to the muscles of the [[neck]].
* These roots merge to form three '''trunks''':
** "superior"<ref>{{Dorlands|t_20|12826113}}</ref> or "upper" ([[cervical spinal nerve 5|C5]]-[[cervical spinal nerve 6|C6]])
** "middle"<ref>{{Dorlands|t_20|12826075}}</ref> ([[cervical spinal nerve 7|C7]])
** "inferior"<ref>{{Dorlands|t_20|12826025}}</ref> or "lower" ([[cervical spinal nerve 8|C8]]-[[thoracic spinal nerve 1|T1]])
* Each trunk then splits in two, to form six '''divisions''':
** anterior division<ref>{{Dorlands|d_26|12310223}}</ref> of the upper, middle and lower trunks
** posterior division<ref>{{Dorlands|d_26|12310244}}</ref> of the upper, middle, and lower trunks
* These six divisions will regroup to become the three '''cords'''. The cords are named by their position in respect to the [[axillary artery]].
** The ''[[posterior cord]]'' is formed from the three posterior divisions of the trunks (C5-T1)
** The ''[[lateral cord]]'' is the anterior divisions from the upper and middle trunks (C5-C7)
** The ''[[medial cord]]'' is simply a continuation of the anterior division of the lower trunk (C8-T1)
* The '''branches''' are listed below. Most branch from the cords, but a few branch (indicated in italics) directly from earlier structures. The five in bold are considered "terminal branches".
==Diagram==
[[Image:Brachial plexus.png|thumb|center|750px]]
===Specific branches===
{| class="wikitable"
|-
| '''From''' || '''Nerve''' || '''Roots''' || '''Muscles''' || '''[[Cutaneous innervation|Cutaneous]]'''
|-
| roots || ''[[dorsal scapular nerve]]'' || [[cervical spinal nerve 5|C5]] || [[rhomboid muscle]]s and [[levator scapulae]] || -
|-
| roots || ''[[long thoracic nerve]]'' || C5, [[cervical spinal nerve 6|C6]], [[cervical spinal nerve 7|C7]] || [[serratus anterior]] || -
|-
| superior trunk || ''[[nerve to the subclavius]]'' || C5, C6 || [[subclavius muscle]] || -
|-
| superior trunk || ''[[suprascapular nerve]]'' || C5, C6 || [[supraspinatus]] and [[infraspinatus]] || -
|-
| lateral cord || [[lateral pectoral nerve]] || C5, C6, C7 || [[pectoralis major]] (by communicating with the [[medial pectoral nerve]]) || -
|-
| lateral cord || '''[[musculocutaneous nerve]]''' || C5, C6, C7 || [[coracobrachialis]], [[brachialis]] and [[biceps brachii]] || becomes the [[lateral cutaneous nerve of the forearm]]
|-
| lateral cord || '''lateral root of the [[median nerve]]''' || C5, C6, C7 || fibres to the median nerve || -
|-
| posterior cord || [[upper subscapular nerve]] || C5, C6 || [[subscapularis]] (upper part) || -
|-
| posterior cord || [[thoracodorsal nerve]] (middle subscapular nerve) || C6, C7, C8 || [[latissimus dorsi]] || -
|-
| posterior cord || [[lower subscapular nerve]] || C5, C6 || subscapularis (lower part ) and [[teres major]] || -
|-
| posterior cord || '''[[axillary nerve]]''' || C5, C6 || ''anterior branch:'' [[deltoid]] and a small area of overlying skin<BR> ''posterior branch:'' [[teres minor]] and deltoid muscles || posterior branch becomes [[upper lateral cutaneous nerve of the arm]]
|-
| posterior cord || '''[[radial nerve]]''' || C5, C6, C7, C8, T1 || [[triceps]] brachii, [[supinator]], [[anconeus]], the [[extensor muscle]]s of the [[forearm]], and [[brachioradialis]] || skin of the posterior arm as the [[posterior cutaneous nerve of the arm]]
|-
| medial cord || [[medial pectoral nerve]] || C8, T1 || [[pectoralis major]] and [[pectoralis minor]] || -
|-
| medial cord || '''medial root of the [[median nerve]]''' || C8, T1 || fibres to the median nerve || portions of hand not served by ulnar or radial
|-
| medial cord || [[medial cutaneous nerve of the arm]] || C8, T1 || - || front and medial skin of the [[arm]]
|-
| medial cord || [[medial cutaneous nerve of the forearm]] || C8, T1 || - || medial skin of the forearm
|-
| medial cord || '''[[ulnar nerve]]''' || C8, T1 || [[flexor carpi ulnaris]], the medial 2 bellies of [[flexor digitorum profundus]], most of the small muscles of the [[hand]] || the skin of the medial side of the hand and medial one and a half fingers on the palmar side and medial two and a half fingers on the dorsal side
|}
==Additional images==
[[Image:Brachial plexus.JPG|thumb|center|750px|Brachial plexus with areas of roots, trunks, divisions and cords marked.]]
<center><gallery>
Image:Gray507.png|Superficial dissection of the right side of the neck, showing the carotid and subclavian arteries.
Image:Gray523.png|The axillary artery and its branches.
Image:Gray811and813.PNG|Cutaneous nerves of right upper extremity.
Image:Gray812and814.PNG|Diagram of segmental distribution of the cutaneous nerves of the right upper extremity.
Image:Gray838.png|The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.
Image:Gray1210.png|Side of neck, showing chief surface markings.
</gallery></center>
==See also==
* [[Brachial plexus lesion]]
* [[Anesthesia of the brachial plexus]]
==References==
<references/>
==External links==
* {{NormanAnatomy|lesson3brachialplexus}}
* [http://anatome.ncl.ac.uk/tutorials/brachial1/text/index.html Tutorial] at [[Newcastle University]]
{{Spinal nerves}}
{{Brachial plexus}}
[[Category:Peripheral nervous system]]
[[Category:upper limb anatomy]]
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