The document provides information on the brachial plexus including its anatomy, variation, relations, and mechanisms of injury. It describes the formation of the brachial plexus from the ventral rami of cervical and thoracic spinal nerves. It details the trunks, divisions, cords and major branches of the brachial plexus. Common variations and mechanisms of injury including Erb's palsy, Klumpke's palsy, and brachial plexus injuries from shoulder dislocations are summarized. Clinical presentations of different brachial plexus injuries are also outlined.

1. TOPIC:- Brachial plexus- Anatomy, Variation, Relations, Mechanism of injury
CHAIRPERSON:- PROF. & HOD Dr. KIRAN KALAIAH
MODERATOR:- PROF. Dr. GOPALKRISHNA
SPEAKER:- Dr. Baibhav Kumar Agarwal

2.  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 ganglions, all cell bodies of motor
neurons found in gray matter of
spinal cord

3.  31 PAIRS
- 8 Pairs of cervical nerves ( C1- C8)
- 12 Pairs of thoracic nerves (T1- T12)
- 5 Pairs of lumbar nerves( L1-L5)
- 5 Pairs of sacral nerves( S1-S5)
- 1 Pair of coccygeal nerve
 Each contains thousands of nerve fibers
 All are mixed nerves , having both sensory and motor neurons
 Exit from the spinal cord supplying the muscles and structures of the
body

4.  Rami are lateral branches of a spinal nerve
 Rami contains both sensory and motor
neurons
 Two major group
1) Dorsal ramus:- neurons innervates the
dorsal regions of the body
2) Ventral Ramus:- neurons innervate the
ventral region of the body.
 Ventral ramus join together to form plexus

5.  The brachial plexus is an arrangement of nerve fibres, running from
the spine, formed by the ventral rami of the lower cervical and upper
thoracic nerve roots
 it includes –
from above the fifth cervical vertebra to underneath the first thoracic
vertebra(C5-T1).
 It proceeds through the neck, the axilla and into the arm. The brachial
plexus is responsible for cutaneous and muscular innervation of the
entire upper limb
 15 cms long ,spinal column to axilla.

6.  The trunks pass laterally and lies around the subclavian artery while
passing over the first rib to enter the axilla, between the clavicle and the
scapula.
 Behind the clavicle, each trunk splits into anterior and posterior
divisions. These recombine to form the posterior , lateral and medial
cords around the axillary artery.
 The upper roots (C5–7) tend to stay lateral, the lower roots (C8,T1)
tend to stay medial and All roots contribute to the posterior cord, and
therefore also to the radial nerve

7.  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

8.  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

9.  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.

10.  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.

12.  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.

13.  C5,C6 roots pass downwards 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

14.  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.

15.  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 2nd part of Axillary
Artery & passes through the thoracic outlet and give off
major branches

16.  Dorsal Scapular nerve
 Derived from C5 root
 Motor nerve to the
Rhomboideus major and
minor muscles( Christmas
tree muscle) and Levator
Scapulae.
 Function- Retraction of
Scapula.
 Branches to longus colli and
scalene muscle( C5- C8).

17.  Long Thoracic nerve
( nerve of bell )
 Derived from C 5,6,7
Innervates the serratus
anterior muscle (boxers
muscle).
 Causes protraction of scapula
 Accessory Phrenic Nerve
 Derived from C5

18.  NERVE TO SUBCLAVIUS
 Root value – C5,C6
 Supply Subclavius
 SUPRASCAPULAR NERVE
 Root value – C5,C6
 Supplies Supraspinatous and
Infraspinatous.

19. Lateral Cord Lateral Pectoral
nerve
C5, C6, C7
Pectoralis major
along with medial
pectoral nerve
Lateral Cord Musculocutaneous
nerve
C5, C6, C7
Coracobrachialis,
brachialis and
biceps brachii.
Becomes the lateral
cutaneous nerve of
the forearm
Lateral Cord Lateral root of
median nerve
C5, C6, C7
Fibers to the
median nerve

20. Medial cord Medial pectoral
nerve
C8, T1 Pectoralis major and
pectoralis minor
Medial cord
Medial root of the
Median nerve C8, T1 Fibers to the median
nerve
Portion of the hand
not served by the
ulnar and radial
nerve
Medial cord
Medial cutaneous
nerve of the Arm
C8, T1 Front and medial
skin of arm

21. Medial Cord Medial cutaneous
nerve of the
forearm
C8 , T1
Medial skin of the
forearm
Medial Cord Ulnar nerve C8 , T1
Flexor Carpi Ulnaris,
The Medial 2 Bellies Of
Flexor Digitorum
Profundus, The Intrinsic
Hand Muscles Except
The Thenar Muscles
And The Two Most
Lateral Lumbricals
The skin of the medial
side of the hand
medial one and a half
fingers on the palmar
side and medial one and
a half fingers on the
dorsal side

22. Posterior Cord Upper subscapular
nerve
C5 , C6 Subscapularis (upper part)
Posterior Cord Lower subscapular nerve C5, C6 Subscapularis (lower part) and teres major
Posterior Cord
Thoracodorsal nerve
(middle subscapular
nerve)
C6,C7,C8 Latissimus dorsi
(Climbers muscle)

23. Posterior cord Axillary nerve C5 , C6
Anterior Branch- Deltoid
and a small area of
overlying skin.
Posterior Branch- Teres
minor and Deltoid muscle
Posterior Branch
becomes the Upper
lateral cutaneous
nerve of the Arm.
Posterior cord Radial nerve C5,C6,C7,C8,
T1
Triceps Brachii, Supinator,
Anconeus, The Extensor
Muscles Of The Forearm,
And Brachioradialis
Posterior Cutaneous
nerve of the Arm,
Lower lateral
cutaneous nerve of
Arm and
Posterior cutaneous
nerve of Forearm.

25.  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.

26.  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.

27.  Leffert classification of brachial plexus injury
 Millesi classification of brachial plexus injury
 Classification on anatomical location of injury

28.  I Open (usually from stabbing)
 II Closed (usually from motorcycle accident)
IIa Supraclavicular
- preganglionic
- postganglionic
IIb Infraclavicular Lesion
 III Radiation induced
 IV Obstetric
IVa Erb's (upper root)
IVb Klumpke (lower root)

29.  I: Supraganglionic/preganglionic.
 II: Infraganglionic/postganglionic
 III: Trunk.
 IV: Cord.

31.  Injury to the Root - Winging of the Scapula
 Injury to the Trunk - Erbs Paralysis
- Extended upper Brachial plexus lesion
- Klumpke’s Paralysis
- Total Brachial Plexus Lesion
 Injury to the Cord - Injury to the Lateral cord
- Injury to the Medial cord

32.  Injury to the nerve of Serratus Anterior ( Nerve of bell)
 Mechanism of Injury:-
1. Sudden pressure on the shoulder from above
2. Carrying heavy load on the shoulder
 Deformity:-
Winging of scapula i.e excessive prominence of the
medial border of the scapula. Normally the pull of muscle
keeps the medial border against the thoracic wall.
 Disability :-
1. Loss of pushing and punching actions. During
attempts at pushing there occurs winging of scapula.
2. Arm cannot be raised beyond 90 degree ( overhead
abduction caused by serratus anterior is not possible).

33.  It involves C5 and C6 of the upper trunk.
 Mechanism of injury:-
1. Shoulder dystocia ( most common
cause)
2. Pressure on raised arms during a breech
delivery.
3. Clavicle fracture in neonates.
4. Traumatic fall onto the side of the head
and shoulder.

34.  Most commonly involved nerves are
suprascapular nerve,
musculocutaneous nerve and axillary
nerve.
 Characterised by-
 Loss of forearm supination and
flexion
 Weakness of shoulder abduction and
external rotation.
 Biceps and supinator jerks are lost.
 Paralysis and atrophy of the deltoid,
biceps and brachialis muscle.

35. •Arm hangs by the side adducted+
Rotate medially
•Forearm pronated + extended
•Flexed wrist + fingers.
 Sensory deficit is apparent in the
corresponding dermatome i.e on
the radial side of the forearm and
thumb.

36.  A C7 injury can accompany the erb’s paralysis.
 In addition paralysis of the elbow extensors, wrist extensors (extenser
carpi radialis brevis) and finger extensors ( extensor digitorum
communis and proprius) are also present.

37.  Named after augusta Dejerine
Klumpke’s.
 Involves C8 and T1, or the lower
trunk
 Mechanism of injury:-
1. Shoulder dystocia
2. Traction on the abducted arm.
3. When someone catching himself
by a branch as he falls from a tree.

38.  Affects, principally, the intrinsic
muscles of the hand and the flexors
of the wrist and fingers ( flexor
digitorum profundus and
superficialis).
 The classic presentation of
klumpke's palsy is the “claw hand”
where the forearm is supinated and
the wrist and fingers are
hyperextended with flexion at
interphalangeal.

39.  Sensory deficit is present over the
ulnar side of the forearm and hand.
 Vasomotor Changes:- The skin with
sensory loss is warmer due arteriolar
dilation. It is also dried due to the
absence of sweating as there is loss of
sympathetic activity.
 Trophic Changes:- Long standing case
of paralysis leads to dry and scaly skin.
 Involvement of T1 may also result in
Horner’s Syndrome with ptosis, miosis
and anhidrosis.

40.  The injury can involve the entire plexus (C5-T1) which causes a flail and
anaesthetic arm.
 Mechanism of injury:-
1. Injury by direct violence.
2. Gunshot wounds.
3. Violent traction on arm or by efforts at reducing a dislocated
shoulder.
 The amount of paralysis will depend on the amount of injury to the
constituent nerves.

41.  Cause:- Dislocation of humerus
 Nerves Involved:- Musculocutaneous and Lateral root of median.
 Muscle paralysed:- 1. Biceps and coracobrachialis.
2. All muscles supplied by the median nerve,
except those of the hand
 Deformity and Disablity:- 1. Midprone forearm.
2. Loss of flexion of wrist and forearm.
3. Sensory loss on the radial side of forearm.
4. Vasomotor and trophic changes.

42.  Cause:- Subcoracoid dislocation of humerus.
 Nerves involved:- Ulnar nerve and medial root of median.
 Muscle paralysed:- 1) Muscles supplied by ulnar nerve.
2) 5 muscles of hand supplied by the median nerve
 Deformity and Disablity:-
1) Claw hand.
2) Sensory loss on the ulnar side of the forearm.
3) Vasomotor and trophic changes.