Brachial Plexus

brachial plexus

a network of spinal nerves that travel through scalenus medius and scalenus anterior: C5, C6 ,C7 C8 and T1

• runs with subclavian artery and once it exits the scalene muscles, they travel through the inlet of the axilla and underneath the clavicle

• then enter the main axillary area where they will innervate the muscles of the upper extremities

brachial plexus organization

divided into 5 sections:

• Roots

• Trunks

• Divisions

• Cords

• Branches

Roots

the anterior rami from the associated nerves of C5, C6, C7, C8 and T1

• nerves in the cervical spine exit above their corresponding vertebral body until T1 where they then exit under the body

trunks

3 trunks named for their anatomical position: superior, middle and inferior

• superior is uppermost

• inferior is lowermost

divisions

6 divisions named for the part of the upper limb their going to innervate

• allows for coordination of more complex limb movements, bc it’s getting more than 1 spinal nerve contribution

Anterior: supply the anterior compartments of the arm, forearm and hand

Posterior: supply the extensors and posterior compartments of the arm and forearm

nerves in anterior division

musculocutaneous and median nerve

nerves in posterior division

Axillary, radial and ulnar nerve

cords

3 cords named for their relativity to the axillary artery

• the 6 divisions combine to form these

• all cords found inferior and lateral to clavicle

Lateral

Posterior: behind the artery

Medial

terminal branches

5 branches: major nerves of upper extremity

• Musculocutaneous

• Median

• Axillary

• Radial

• Ulnar

Musculocutaneous nerve

has contributions from C5, C6, C7

Axillary nerve

receive innervation from C5 and C6

Median Nerve

come off of the the medial and lateral cord

• supply from all the spinal nerves (C5-T1)

• C5 and C6 travel the lateral cord

• C8 and T1 travel the medial cord

• C7 give contributions to lateral cord through anterior division

Radial nerve

receives contributions from all the brachial plexus: C5 to T1

• come off posterior cord

Ulnar nerve

come off medial cord, comprises of C8 and T1

Minor terminal branches

come off other parts of the brachial plexus: roots, trunks or cords

Roots:

• dorsal scapular nerve (C5): levator scapula and rhomboids

• Long thoracic nerve (C5-C7): serratus anterior

Trunks:

• Only superior trunk

• Suprascapular (C5-C6): supraspinatus, infraspinatus

• Subclavian (C5-C6): subclavian

Divisions: no minor branches

Cords: lots of minor branches

Minor terminal branches off cords

Lateral Cord

• lateral pectoral nerve (C5-C7): pectoralis major

Posterior Cord

• Upper subscapular (C5-C6): subscapularis

• Lower subscapular (C5-C6): teres major

• Thoracodorsal (C6-C8): latissimus dorsi

Medial Cord

• Medial pectoral (C8-T1): pec minor and minor

• Medial brachial cutaneous (C8-T1): sensory info to medial arm

• Medial antebrachial cutaneous (C8-T1): sensory info to forearm