Brachial Plexus Ch 10

Median Nerve

Also a terminal branch of the brachial plexus (C6-T1; appearance of C5 is inconsistent); innervates most ventral antebrachial muscles as well as the thenar muscles of the hand. -Goes down to forearm and hand.

Radial nerve

The other terminal branch of the posterior cord (C5 - T1). Innervates all muscles of the dorsal surface of the upper limb. -*HAS POTENTIAL* to get all nerves C5 to T1, but rarely does.

Lateral cord

-Lateral pectoral nerve innervates the *pectoralis major* -Contribution to the median nerve - carries fibers of C6 and C7, rarely C5.

Supraclavicular branches

Contains Dorsal scauplar nerve Suprascapular nerve Nerve to subclavius Long thoracic nerve

Median Cord

Contains Medial pectoral nerve Medial brachial cutaneous nerve Medial antebrachial cutaneous nerve Ulnar Nerve Its contribution to the median nerve contains fibers C8 and T1.

Note about brachial plexus

Each ventral ramus that participates in the formatoin of the brachial plexus receives a gray ramus communicans (postganglionic sympathetic fiber) distributed via the nearly adjacent cervical sympathetic trunk.

Musculocutaneous nerve

terminal branch of the lateral cord (C5,6,7). Innervates the anterior compartment of the arm

Posterior cord

contains: Upper subscapular nerve Thoracodorsal nerve (middle subscapular nerve) Lower subscapular nerve Axillary nerve Radial nerve

Dorsal scapular nerve

direct from C5 Innervates levator scauplae, rhomboideus major and minor

Upper subscapular nerve

innervates subscapularis

Lower subscapular nerve

innervates subscapularis and teres major

Thoracodorsal nerve

-(middle subscapular nerve) innervates latissimus dorsi

General info of brachial plexus

-Provides motor, sensory and sympathetic innervation to the upper limb -Composed of *ventral rami* of *spinal nerves C5-T1* -Passes from the neck and upper thorax to the upper limb via the *cervicoaxillary canal* (ch. 9) its covered in a certain sheath. what is it?

Long thoracic nerve

From ventral rami C5, C6, C7. Innervates the serratus anterior

Divisions

*Anterior:* extension of "trunks" that contribute to the lateral and medial cords. *Posterior:* extensions of all 3 trunks to form the posterior cord.

Trunks

*Upper:* union of C5 and C6 ventral rami *Middle:* continuation of C7 ventral ramus *Lower:* union of C8 and T1 ventral rami

Roots

*Ventral primary rami of C5, C6, C7, C8, and T1* as they exit their respective intervertebral foramina in the neck and upper thorax.

Cords

Are the first portion of the brachial plexus located in the axilla -Named for their relationship to the axillary artery, viz. lateral, medial and posterior *Lateral cord:* formed by the union of 2 anterior divisions: one from the upper trunk (a direct continuation) and one from the middle trunk supplying cord level C7 to the lateral cord. *Medial cord:* the direct continuation of the anterior portion of the lower trunk (C8 & T1) *Posterior cord:* union of the 3 posterior divisions; contains fibers from all spinal nerve "Roots" participating in the formation of the brachial plexus, viz. C5 - T1

Nerve to subclavius

Arises from the upper trunk (C5,6). Innervates the subclavius muscle

Suprascapular nerve

Formed at the junction of C5 and C6. Getc C5, C6 Innervates the supra and infraspinatus muscles

Dermatomal innervation of the upper limb

Includes innervation from spinal cord levels C4-T3 -Reflects the segmental innervation of the rest of the mody -Provided mostly by branches of the brachial plexus (C5-T1) -Shoulder area innervated by C4 from supraclavicular nerves of the cervical plexus -Anterior medial and posteromedial portion of brachium innervated by the *intercostobrachial cutaneous nerve(s)* (T1, T2 and sometimes T3)

Axillary nerve

One of 2 terminal branches of the posterior cord (C5,6). Innervates the deltoid and teres minor. *DOES NOT* have the potential to get all nerves C5 to T1 which is illogical, but the truth

Medial brachial cutaneous nerve

Provides cutaneous innervation to the medial portion of the arm.

Medial antebrachial cutaneous nerve

Provides cutaneous innervation to the medial portion of the forearm.

Ulnar Nerve

Terminal branch of the medial cord (C8, T1) Innervates the majority of intrinsic hand muscles

Medial pectoral nerve

provides innervation to the pectoralis major and minor.