SURGICAL ANATOMY OF BRACHIAL PLEXUS

Sudhir suggala

ANATOMY

A network of nerves starting from 5 nerve roots in upper spine & ending in nerves that control movement & sensation in the upper limb.

ANATOMY contd…

Located where neck joins shoulder behind clavicle & between spine & upper arm just distal to axilla.

5 roots ant.primary rami after giving segmental supply to prevertebral muscles &scalene muscles.

Levels

Roots

Trunks

Divisions

Cords

Branches

ROOTS

THE ORIGIN NERVES ARE THE ANT. PRIMARY RAMI OF5th TO 8th CERVICAL VERTEBRAE AND T1.

ROOTS EMERGE FROM THE TRANSVERSE PROCESSES OF CERVICAL VERTEBRAE IMMED. POST. TO VERTEBRAL ARTERY

T1:VULNERABLE IN FRACTURE AND DISLOCATION OF FIRST RIB

NERVES FROM ROOTS .

DORSAL SCAPULAR N. C5

ARISES FROM C5 JUST LAT. TO LONG THORACIC

TRAV. POST TO Plx

INNERVATES LEV.SCAPULAE, RHOMBOIDES

Brachial Plexus

Netter 2nd ed

ROOTS contd…

LONG THORACIC N. OF BELL C567

IMMED. AFTER THEY ORIG. FROM INTERVERTEBRAL FORAMEN

ALSO PIERCES S.MED. AS IT PASSES POST TO Plx

TRUNKS

IN THE POST. TRIANGLE OF NECK C56: UPPER/SUPERIOR TRUNK C7; MIDDLE TRUNK C8 T1: LOWER/INFERIOR TRUNK TRUNKS LIE IN FRONT OF ONE ANOTHER RELATION b/w C5 AND PHRENIC NERVE

NERVES FROM TRUNKS

SUPRASCAPULAR N. C5,6 SENSORY TO SHOULDER JT. MOTOR TO SUPRASPINATUS AND

INFRASPINATUS

N.TO SUBCLAVIUS C5,6

DIVISONS

LIE DEEP TO CLAVICLE POSTERIOR DIV. OF UPPER AND MIDDLE

TRUNK LARGER 10% OF CASES NO POST. DIVISON OF

LOWER TRUNK

CORDS

NAMED LAT. ,POST. AND MEDIAL ACC. TO RELATION WITH AXILLARY ARTERY

LATERAL CORD: ANT. DIV OF UPPER & MIDDLE TRUNK

MEDIAL CORD: ANT. DIV. OF LOWER TRUNK

POSTERIOR CORD:POST./DORSAL DIVISONS OF ALL 3 TRUNKS

FROM LAT.CORD

Lateral pectoral nerve- c5,c6,c7 Pierce clavipectoral fascia. Communicate with medial pectoral across front

of 1st part of axillary art. Br. To P.major & P.minor No cut. Br.

FROM LAT. CORD contd…

Musculocutaneous nr.-c5,c6,c7 To biceps & brachialis. Becomes lateral cut. Nr. Of forearm. Lateral root of median nr.-c5,c6,c7 Continuation of lat.cord

FROM MEDIAL CORD

Medial pectoral nr.- behind 1st part of ax.art

Perforates p.minor

No cut.br.

Medial root of median nr-. Crosses ax. Art to join lat root.

Medial cut.nr. Of arm – smallest & most medial.

Medial cut. Nr. Of forearm –

Large nr.

Runs down bet ax.art & ax. Vein in front of ulnar nr.

Ulnar nr.- largest br. C7 C8 T1

To most of the hand muscles.

FROM POST CORD contd…

Radial nr. – c5,c6,c7,c8,T1 Cont.of post cord Largest in the whole plexus Gives post cut nr. Of forearm.

FROM POST.CORD

Upper subscapular- c5,c6 Small nr. Enters upper part of subscapularis. Thoracodorsal – c6,c7,c8 nr.to lat. Dorsi. A large nerve. Runs down post.ax. Wall.

FROM POST CORD contd…

Lower subscapular –c5,c6 To lower part of subscapularis Ends in teres major. Axillary nr. – c5,c6 Circumflex nr. A large terminal br. No supply in axilla. Br.to shoulder jt. Ant. & post div.

FROM POST CORD contd…

Radial nr. – c5,c6,c7,c8,T1 Cont.of post cord Largest in the whole plexus Gives post cut nr. Of forearm.

VARIATIONS

GREATEST VARIATION IN FORMATION OCCURS IN LATERAL CORD

10% OF CASES MUSCULOCUT. N. MAY ARISE AS 2-3 BRANCHES

LATERAL ROOT OF MEDIAN N. MAY ARISE AS 2-3 BRANCHES

BLOOD SUPPLY

From subclavian & vertebral art. Vertebral art.- c5, c6. & more proximal

cervical nerves C8, T1,- br. From costocervical trunk.

MICRO ANATOMY

120,000-150,000 Myelinated fibres C5 &T1-least no. of myelin.fibres C8 –largest no. of myelin.fibres. Proportion of motor fibres highest in c5, then

c8 & least in c7 & t1. Sensory greatest in c7, then c6, then c8. Segregation of nr fibres well established

proximally.

PREFIXATION & POSTFIXATION

PREFIXED: CONTRIBUTION FROM C4 IS LARGE ,T2 IS OFTEN ABSENT

POSTFIXED: CONTRIBUTION FROM T1 IS LARGE, T2 IS ALWAYS PRESENT,C4 IS ABSENT,C5 IS REDUCED IN SIZE

Anatomy

BRACHIAL PLEXUS SHEATH

C.t. of prevertebral fascia Blends with fascia of biceps & brachialis. C.t. septae compartmentalize components of

the sheath. Controversies – septae may limit spread of

solutions during BP block.

Brachial Plexus Branches & Muscular Innervations

Dorsal Scapular N. Levator Scapulae Rhomboid Major/Minor

Lateral Pectoral N. Pectoralis Major/Minor

Suprascapular N. Infraspinatus Supraspinatus

Musculocutaneous N. Biceps Brachii Brachialis Coracobrachialis

Brachial Plexus Branches & Muscular Innervations

Axillary N. Deltoid Teres Minor

Upper Subscapular N. Subscapularis

Middle Subscapular or Thoracodorsal N.

Latissimus Dorsi

Lower Subscapular N. Subscapularis Teres Major

Brachial Plexus Branches & Muscular Innervations

Median N. Abductor Pollicis

Brevis/Longus Flexor Carpi Radialis Flexor Digitorum Superficialis Flexor Digitorum Profundus

(Lat. 2) Flexor Pollicis Brevis (Lat.) &

Longus Lumbricales (Lat. 2) Opponens Pollicis Palmaris Longus Pronator Quadratus Pronator Teres *

Radial N. Abductor Pollicis Brevis Anconeus Brachioradialis Extensor Carpi Radialis

Brevis/Longus Extensor Carpi Ulnaris Extensor Digiti Minimi Extensor Digitorum Communis Extensor Indicis Extensor Pollicis

Brevis/Longus Supinator Triceps Brachii

Brachial Plexus Branches & Muscular Innervations

Ulnar N. Abductor Digiti Minimi Adductor Pollicis Dorsal Interossei Flexor Carpi Ulnaris Flexor Digiti Minimi Flexor Digitorum Profundus

(Med. 2) Flexor Pollicis Brevis (Med.) Lumbricals (Med. 2) Opponens Digiti Minimi Palmar Interossei

Long Thoracic N. Serratus Anterior

Medial Pectoral N. Pectoralis Major

Medial Brachial Cutaneous N. (sensory)

Medial Antebrachial Cutaneous N. (sensory)

FUNCTIONAL DISTRIBUTION MOTOR

C5-SHOULDER ABDUCTION C6-WRIST EXTENSION C7-WRIST FLEXION AND FINGER

EXTENSION C8-FINGER FLEXION T1-FINGER ABDUCTION AND ADDUCTION

SENSATION

C5-LATERAL ARM C6-LAT.FOREARM ,THUMB,INDEX FINGER C7-MIDDLE FINGER C8-MEDIAL FOREARM,RING,SMALL

FINGER T1-MEDIAL ARM T2-AXILLA

TRANSITIONAL ZONE

BERTHOLD (1993):JUNC. b/w ROOTS AND SPINAL CORD

A CENTRAL-PERIPHERAL TRANSITIONAL ZONE

2 TYPES OF INTRADURAL INJURY-RUPTURE AND AVULSION

RUPTURE & AVULSION

INTRADURAL RUPTURE IS TEARING OF ROOTLETS AT OR PERIPHERAL TO T.Z

AVULSION IS ROOTLETS ARE TORN FROM SPINAL CORD ITSELF AND INJURY IS CENTRAL TO TRANSITIONAL ZONE .

UPPER PLEXUS INJURY (ERB’S PARALYSIS)

LOWER PLEXUS INJURY(KLUMPKE’S PARALYSIS)

INJURY AT LEVEL OF ROOTS

CORDS INJURY

LATERAL POSTERIOR MEDIAL

NEOPLASTIC RADIATION

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