Brachial Plexus Anatomy

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Author: Abdulaziz R. Alanzi

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<ul><li> 1. Brachial PlexusAnatomy Abdulaziz R. Alanzi Medical Student, Al-Imam University Riyadh, Saudi Arabia</li></ul> <p> 2. Bones of Upper Limb 3. Blood Supply of Upper Limb 4. Definition of Brachial PlexusThe brachial plexus (plexus brachialis) is a somaticnerve plexus formed by intercommunications among theventral rami (roots) of the lower 4 cervical nerves (C5-C8)and the first thoracic nerve (T1). The plexus, depicted inthe images below, is responsible for the motorinnervation of all of the muscles of theupper extremity, with the exceptionof the trapezius and levator scapula. 5. ContdThe brachial plexus is divided into 5 parts;Roots Trunks Divisions Cords Branches(a good mnemonic for this isRead That Damn Cadaver Book). 6. Parts of Brachial Plexus1- Roots:The ventral rami of spinal nerves C5 to T1 are referred to as the"roots" of the plexus. The roots emerge from the transverseprocesses of the cervical vertebrae immediately posterior tothe vertebral artery.2- Trunks: Superior trunk: A combination of C5 and C6 roots. Middle trunk: A continuation of C7. Inferior trunk: A combination of C8 and T1 roots. 7. Parts of Brachial Plexus3- Divisions: each trunk splits into an anterior division and aposterior division.4- Cords: The cords are formed by recombination of the sixdivisions to three nerve fibres. They are named by their positionrelative to the axillary artery.Lateral Cord:formed by anteriordivision of the superiortrunk &amp; anterior divisionof the middle trunkPosterior Cord:formed by posterior division ofthe superior trunk, posteriordivision of the middle trunk &amp;posterior division of the inferiortrunk.Medial Cord:formed by theanteriordivision of theinferior trunk 8. Minor branches of the brachial plexus 9. 1- Musculocutaneous Nerve Roots: C5, C6, C7 Motor Functions:Innervates the brachialis,biceps brachii andcorocobrachialismuscles. Sensory Functions: Givesoff the lateral cutaneousbranch of the forearm,which innervates thelateral half of the anteriorforearm, and a smalllateral portion of theposterior forearm 10. 2- Axillary Nerve Roots: C5 and C6 Motor Functions:Innervates the deltoid,teres minor and thelong head of thetriceps brachii Sensory Functions:Gives off the superiorlateral cutaneousnerve of arm, whichinnervates the inferiorregion of the deltoid(regimental badgearea) 11. 3- Median Nerve Roots: C6 C8 and T1 Motor Functions: Innervatesmost of the flexor muscles inthe forearm, the thenarmuscles, and the two laterallumbrical muscles that movethe index and middle fingers Sensory Functions: Gives offthe palmar cutaneous branch,which innervates the lateralpart of the palm, and thedigital cutaneous branch,which innervates the lateralthree and a half fingers on theanterior (palmar) surface ofthe hand. 12. 4- Radial Nerve Roots: C5-C8 and T1 Motor Functions:innervates the tricepsbrachii, and theextensor muscles in theposterior compartmentof the forearm. Sensory Functions:Innervates the posterioraspect of the arm andforearm, and theposterior, lateral aspectof the hand. 13. 5- Ulnar Nerve Roots: C8 and T1 Motor Functions:Innervates the musclesof the hand (apart fromthe thenar muscles andtwo lateral lumbricals),flexor carpi ulnaris andmedial half of flexordigitorum profundus Sensory Functions:Innervates the anteriorand posterior surfaces ofthe medial one and halffingers, and associatedpalm area 14. Blood Supply of the Brachial Plexus The blood supply of the brachial plexus is based largely on thesubclavian (which becomes the axillary) artery and its branches,and variations exist. Generally, the vessels involved are the vertebral, the ascendingand deep cervical, and the superior intercostal arteries.The cord and roots:supplied by the anteriorand posterior spinalbranches of thevertebral artery.The trunks of the plexus:supplied by muscular branchesof the ascending and deepcervical arteries and superiorintercostals, and occasionally bythe subclavian itself.[ 15. References Medscape Reference http://teachmeanatomy.info/ 16. Thank YouAbdulazizROA@gmail.com@Azizocyte </p>