BRACHIAL PLEXUS• By: Syed Irshad Murtaza

• Technologist CNPS AKUH Karachi• Date: 13-05-2014

What is the Brachial Plexus?• Introduction• A network of spinal nerves that originates in the

back of the neck, extends through the axilla (armpit) and gives rise to nerves to the upper limb.

• The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral (Anterior) rami of the lower four cervical and first thoracic nerve roots (C5-C8, T1).

Anatomy

• Brachial Plexus proceeds through the neck, the axilla (armpit region), and into the arm. It is a network of nerves passing through the cervico-axillary canal to reach axilla and innervates brachium (upper arm), antebrachium (forearm) and hand.

Horns in the spinal Cord• In the spinal cord the gray matter is present inside

and white matter I towards outside while in the brain this distribution is vice versa.

• On cross section of the spinal cord gray matter in spinal cord presents butterfly like structure from which some projections like “Horns” are seen, termed as

• Ventral/Anterior Horn (ventral/anterior/motor root centre (Efferent Nerve)

• Lateral Horn (Preganglionic sympathetic neurons, • Dorsal/posterior Horn (dorsal/posterior/sensory

root centre (Afferent Nerve)

Terms to define• Ganglion: collection of the nerve cell bodies is called

ganglion. E.g Dorsal root ganglion (DRG)• Ramu (Pl: Rami) Spinal nerve when exits from the

vertebrae , it divides into two branches termed as,• 1. ventral/anterior primary ramus• 2. dorsal/posterior primary ramus• Ventral/anterior ramus: it is the ventral division of

spinal nerve outside the vertebrae, which supplies to the skin, muscles on anterior body.

• Dorsal division supplies to the skin and muscles of the back.

RTDCB• Brachial plexus comprises of Root, Trunk,

Division, Cord and peripheral Branches.

• A mnemonic for remember the region of the brachial plexus is:

• Real - Roots• Teenagers - Trunks• Drink - Divisions• Cold - Cords• Beer – Branches

Brachial Plexus

Anatomy of RTDCB

• Roots: (lying between the anterior and middle scalene muscles),

• Trunks: (found in the posterior triangle of the neck),

• Divisions: (lay posterior/behind the clavicle), Cords: (found in axilla & named according to their relationship with axillary/brachial artery ) &

• Branches: (the five main nerve fibers in the arm).

Formation of Roots & Trunk of the Brachial Plexus

The roots of the brachial plexus come from branches of the spinal vertebrae C5-8 and T1.

The cervical roots, C5 and C6, fuse together to

form the Upper (Superior) trunkThe cervical root C7 goes on to become

the Middle trunkThe cervical roots, C8 and T1, fuse together to

form the Lower (Inferior) trunk

The Trunks & Divisions of the Brachial Plexus• There are three trunks of the brachial plexus that

lie in the posterior neck triangle. • Each of the Trunks has its two divisions• Anterior Division• Posterior Division • (Anterior divisions of the upper, middle, and

lower trunks• Posterior divisions of the upper, middle, and

lower trunks)

• These six Divisions further unite to form the Cords.

The Divisions & Cords of the Brachial Plexus• There are two divisions of the brachial plexus that

lie posterior to the clavicle. These divisions go on to form the cords of the brachial plexus.

• Anterior divisions of Upper and Middle Trunks go on to form the Lateral cord

• All Posterior divisions go on to form the Posterior cord

• The Anterior division of the Lower Trunk goes on to form the Medial Cord

The Cords and main Terminal (Peripheral) branches of Brachial Plexus

• The cords of the brachial plexus divide and join together to form the five main nerve branches of the arm.

• The Lateral cord divides to become the Musculocutaneous and Median Nerve Branches.

• The Medial cord divides to become the Median and Ulnar Nerve Branches

• The Posterior cord divides to become the Radial and Axillary Nerve Branches

Branches from direct roots• Dorsal scapular nerve-(c4-c5)- (levator

scapulae, rhomboids)• Subclavian nerve(c5-c6)- (subclavian muscle• Long thoracic nerve(c5-c7)- serratus anterior

muscle• Branch from trunk• Supra scapular nerve(c5-c6)- branch from

upper trunk.• Supplies infra/supraspinatus

Branches and their Roots• There are five "terminal" branches and numerous other "pre-

terminal" or "collateral" branches that leave the plexus at various points along its length.

• Lateral cord-1) musculocutaneous nerve(c5-c7) 2) lateral head of median nerve(c5-c7)• Medial cord-1) med.ant.thoracic nerve(c8-T1) 2) med. Cut. Nerve of arm(c8-T1) 3) med.cut. Nerve of forearm(c8-T1) 4) ulnar nerve(c7-T1) 5) med. Head of median nerve(c8-T1)• Posterior cord- 1) subscapular nerve(upper, lower)(c5-c7) 2) thoraco dorsal nerve(c5-c7) 3) axillary nerve(c5-c6) 4) radial nerve(c5-c8)

THANKSTHANKS