BRACHIAL PLEXUS

Prof.Dr. U.Murali.M.S;MBA

Dept.Of Surgery

D Y Patil Medical College

Mauritius.

Contents of Discussion

Spinal Nerves Nerve Plexus BP – Origin & Relations Formation Parts of BP Distribution - Nerve Supply – areas Anatomical Variations Applied Anatomy

Spinal Nerves Spinal nerves attach to the spinal cord via roots

Dorsal root Has only sensory neurons Attached to cord via rootlets Dorsal root ganglion

Ventral root Has only motor neurons No ganglion - all cell bodies

of motor neurons found in gray matter of spinal cord

Spinal Nerves

31 pair each contains thousands of nerve fibers All are mixed nerves have both sensory and motor

neurons

Connect to the spinal cord

Exit from SC – Supplying the muscles & structures of the body

8 pairs of cervical nerves from C1 to C812 pairs of thoracic nerves from T1-T125 pairs of lumbar nerves from L1 to L55 pairs of sacral nerves from S1 to S51 pair of coccygeal nerves located at C zero (Co)

Spinal Nerves

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Formation of Rami Rami are lateral branches of a

spinal nerve

Rami contain both sensory and motor neurons

Two major groups Dorsal ramus

Neurons innervate the dorsal regions of the body

Ventral ramus Larger Neurons innervate the

ventral regions of the body

Braid together to form plexuses (plexi)

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Nerve Plexuses

Nerve plexus A nerve plexus is nothing more than a

system or network of connected nerve fibers that link spinal nerves with specific areas of the body . A network of ventral rami.

Ventral rami (except T2-T12) Branch and join with one another Form nerve plexuses

In cervical, brachial, lumbar, and sacral regions No plexus formed in thoracic region of s.c.

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Branches of Spinal Nerves

Dorsal Ramus Neurons within muscles of trunk and back

Ventral Ramus (VR) Braid together to form plexuses

Cervical plexus - VR of C1-C4 Brachial plexus - VR of C5-T1 Lumbar plexus - VR of L1-L4 Sacral plexus - VR of L4-S4 Coccygeal plexus -VR of S4&S5

Communicating Rami: communicate with sympathetic chain of ganglia Covered in ANS unit

12-9

Brachial Plexus - Origin

Formed by ventral rami of spinal nerves C5-T1

Five ventral rami form Roots / Trunks that separate into Divisions that then form Cords that give rise to Branches

Major nerves Axillary Radial Musculocutaneous Ulnar Median

Brachial Plexus

15 cms long ,spinal column to

axilla.

Brachial plexus is responsible for

cutaneous (sensory) and muscular

(motor) innervation of the entire

upper limb & pectoral girdle.

It proceeds through the neck, the

axilla and into the arm.

In the neck, the brachial plexus lies in the posterior triangle, being covered by the skin, Platysma, and deep fascia; where it is crossed by the supraclavicular nerves, the inferior belly of the Omohyoid, the external jugular vein, and the transverse cervical artery.

Relations - BP

Relations - BP When it emerges

between the Scalene anterior and medius --* its upper part lies above the third part of the subclavian artery, * while the trunk formed by the union of C8 & T1 is placed behind the artery.

The plexus next passes behind the clavicle, the Subclavius, and the transverse scapular vessels, and lies upon the first digitation of the Serratus anterior, and the Subscapularis.

Relations - BP

Relations In the axilla it is placed

lateral to the first portion of the axillary artery; it surrounds the second part of the artery, one cord lying medial to it, one lateral to it, and one behind it; at the lower part of the axilla it gives off its terminal branches to the upper limb.

FORMATION OF THE BRACHIAL PLEXUS

PUT IT ALL TOGETHER…...

ROOTS

Originates froms C5-C8 and most of T1 Receives gray rami communicates from the

symphathetic trunk. Carry postganglionic symphathetic fibers

onto root for distribution of periphery. Root and trunk enter posterior triangle of

neck by passing between anterior scalene and middle scalene muscles and lies between superior and posterior to subclavian artery.

TRUNKS

C5,C6 roots pass down wards between Scalenus medius and Scalenus anterior muscles and unite to form SUPERIOR TRUNK

C7 root pass between Scalenus muscles and at laeral border of scalenus anterior emreges as MIDDLE TRUNK

C8, T1 roots unite behind a fascial sheet (sibson”s fascia) and beneath the subclavian artery form LOWER TRUNK

DIVISION

Lateral to the 1st rib , where three trunks are located behind the axillary artery ,they separate into 3 anterior and 3 posterior divisions

The 3 anterior division form parts of brachial plexus that ultimately give rise to peripheral nerves associated with the anterior compartment of arm or forearm.

The 3 posterior division combine to form parts of the brachial plexus that give rise to nerves associated with the posterior compartments.

CORDS 3 posterior divisions unite to form posterior

cord Anterior divisions of upper and ,middle trunks

(C5-C7) unite to form lateral cord Anterior division of lower trunk forms medial

cord(C8-T1) Cords – named after their relation with AA &

passes through the thoracic outlet and give off major branches

BRANCHES - Roots

From the Roots

Dorsal Scapular nerve

Derived from C5 root

Motor nerve to the Rhomboideus major and minor muscles

Roots

Long Thoracic nerve

Derived from C 5,6,7Innervates the serratus anterior muscle

BRANCHES OF UPPER TRUNK

NERVE TO SUBCLAVIUS Root value – C5,C6SUPRASCAPULAR NERVERoot value – C5,C6

Branches – LC & MC

MEDIAL PECTORAL NERVE

Root value- C8,T1

LATERAL PECTORAL NERVE

Root value- C5,C6,C7

Lateral Cord

Direct branches:Lateral pectoral nerve: C5-7

To clavicular head of pectoralis major muscle

Terminal nerves:

Musculocutaneous: C5-7

Lateral root of median nerve: C5-7

Medial Cord: Direct Branches

Medial pectoral nerve:

C8-T1

To sternal head of pectoralis major muscle and pectoralis minor muscle.

Medial cutaneous nerve to

arm Medial cutaneous nerve to

forearm

MEDIAL CUTANEOUS

NERVE OF

ARM Root value- C8,T1

MEDIAL CUTANEOUS NERVE OF FOREARM

Root value – C8,T1

Medial Cord: Terminal Nerves

Ulnar C8-T1 Medial root of

median nerve C8-T1

ULNAR NERVE

Posterior Cord Direct Branches

Upper subscapular nerveC5-6To subscapularis muscle

Thoracodorsal nerve:C6-7To latissimus dorsi muscle

Lower subscapular nerve:C5-6To subscapularis and

teres major muscles

UPPER SUBSCAPULAR

Root value-C5,C6

LOWER SUBSCAPULAR

Root value- C5,C6

NERVE TO LATISSIMUS DORSI

Root value-C6,C7,C8

Posterior Cord Terminal Nerves

Axillary nerve: C5-6

Motor: To deltoid and teres minor muscles.

Sensory: Skin on arm over deltoid muscle:

AXILLARY NERVE

Posterior Cord Terminal Nerves

Radial nerve: C5-T1 Motor: Posterior compartments of

arm and forearm.Brachioradialis muscle

Sensory:Back of arm, forearm, hand

RADIAL NERVE

Cutaneous distribution

Anatomic Variations The plexus may include anterior rami from C4 or

T2 and these are designated as Pre fixed- C4 added Post fixed- T2 added. The connective tissue sheath that invests the

plexus especially in the axillary region has a convoluted and septated structure that can lead to non uniform distribution of local anaesthetics .

The musculocutaneous nerve may fuse to or have communications with the median nerve , which can result in its absence from within the coracobrachialis muscle.

Communication between median and ulnar nerves is common in the forearm with the median nerve replacing the innervations to various muscles normally supplied by the ulnar nerve.

Variations with respect to vessels within the arm may be present like double axillary veins , high origin of radial artery and double brachial arteries.

The interscalene groove may have variations in the relationship between the plexus roots and trunks and the muscles.

For eg.- the C5 or C6 roots may traverse through or anterior to the anterior scalene muscles.

In many specimens no inferior trunk exists , a single cord or a pair of cords may develop. In some cases no discrete posterior cord forms , with the posterior divisions diverging to form terminal branches.

APPLIED ANATOMY

Brachial Plexus Injury

Obstetric palsy - Injury to all or portion of a child

brachial plexus occurring at that time of the

delivery.

Excessive lateral traction on the head so that the

head is pulled away from the shoulder.

Divide into :

Erb’s Duchenne Palsy

Klumpkee’s Palsy

Erb’sparalysis•C5 -C6

•Birth injury / Trauma

•Arm hangs by the side + Rotate medially

•Forearm pronated + extended

•Flexed wrist + fingers

•Deltoid/supraspinatus/ infraspinatus/biceps/

brachialis

. LOS – in arm

Erb’s Palsy – Nerves Affected

LEFT SIDE PARALYSIS

Klumpke’sparalysis

•C8 –T1•Traction injuries / Fall* Intrinsic muscles of the hand + long flexors of the wrist & hand paralysed• Claw hand = extension at MPJ + flexion at IPJ ( wrist & hand )* Forearm – supinated* LOS – medial side - am•Cervical rib can cause paralysis similar to Klumpke’sparalysis with post-fixed T2 contribution

BRACHIAL PLEXUS BLOCK

Supraclavicular approach Axillary approach

Begin with a letter “Y”, an “I” and a “Y”.

Add a “strike” and a “spare”

Draw “arches”.

Draw horizontal lines to separate the parts.

Roots

Trunks

Divisions

Cords

Branches

Roots

Trunks

Divisions

Cords

Branches

Begin labeling.C5 C6 C7 C8 T1

Upper Middle Lower

Musculocutaneous Axillary Median Radial Ulnar

Lat

eral

Pos

teri

or M

edia

l

SLOW

Add details . . .Branches off the posterior cord spell “ULTRA”

Axillary Radial

C5 C6 C7 C8 T1Roots

Trunks

Divisions

Cords

Branches

Upper Middle Lower

Musculocutaneous Median Ulnar

Lat

era

l Pos

teri

or M

edia

l

Upper subscapularLower subscapularThoracodorsal

SLOWSLOW

“3M” comes off the medial cord.

Axillary Radial

Roots

Trunks

Divisions

Cords

Branches

C5 C6 C7 C8 T1

Upper Middle Lower

Musculocutaneous Median Ulnar

Lat

era

l Pos

teri

or M

edia

l

Upper subscapularLower subscapularThoracodorsal

Medial pectoral n.Medial cutan. n. of armMedial cutan. n. forearm

SLOWSLOW

The lateral pectoral n. comes off the lateral cord.

Axillary Radial

Roots

Trunks

Divisions

Cords

Branches

C5 C6 C7 C8 T1

Upper Middle Lower

Musculocutaneous Median Ulnar

Lat

era

l Pos

teri

or M

edia

l

Upper subscapularLower subscapularThoracodorsal

Medial pectoral n.Medial cutan. n. of armMedial cutan. n. forearm

Lateral pectoral n.

There are 4 supraclavicular branches.

Axillary Radial

Roots

Trunks

Divisions

Cords

Branches

C5 C6 C7 C8 T1

Upper Middle Lower

Musculocutaneous Median Ulnar

Lat

era

l Pos

teri

or M

edia

l

Upper subscapularLower subscapularThoracodorsal

Medial pectoral n.Medial cutan. n. of armMedial cutan. n. forearm

Lateral pectoral n.

Dorsal Scapular n.

N. to subclaviusSuprascapular n.

LongThoracic n.

SLOW

That’s it! The Brachial Plexus

Axillary Radial

Roots

Trunks

Divisions

Cords

Branches

C5 C6 C7 C8 T1

Upper Middle Lower

Musculocutaneous Median Ulnar

Lat

era

l Pos

teri

or M

edia

l

Upper subscapularLower subscapularThoracodorsal

Medial pectoral n.Medial cutan. n. of armMedial cutan. n. forearm

Lateral pectoral n.

Dorsal Scapular n.

N. to subclaviusSuprascapular n.

LongThoracic n.