2. Brachial plexus
1.Formed by the ventral ramii of cervical spinal nerves
c5 to c8 and the thoracic spinal nerve T1
2.Prefix- includes the ramii of C4
3.Postfix- includes the ramii of T2
4.Consists of ROOTS, TRUNKS , DIVISIONS , CORDS and
BRANCHES
5.Responsible for sensory and motor innervation
of entire limb
3. ROOTS- consists of ventral ramii of spinal nerves C5 to T1
TRUNKS- roots c5 and c6 join to form the upper trunk
root c7 forms the middle trunk
roots c8 and T1 forms the lower trunk
CORDS- lateral cord- ventral division of upper and
middle trunk
medial cord-ventral division of lower trunk
posterior cord- dorsal division of all 3 trunks.
5. Radial nerve
Arises from posterior cord of brachial plexus
Root value- c5 to T1
Enters the arm behind the axillary artery in the post. Compartment of arm
Enters the radial groove to emerge on the lateral aspect of arm in the
anterior compartment
Reaches the distal part of humerus and passes anterior to the lateral
epicondyle to enter forearm
6. Branches in arm-
Before entering spiral groove- motor br. To long and medial head of
triceps and the posterior cutaneous nerve of arm
In the spiral groove- motor br. To lateral and medial head of triceps and
the post cutaneous nerve of forearm and the lower lateral cut. Nerve of
arm
Between the spiral groove and elbow-brachioradialis and ECRL
After crossing elbow before piercing supinator-supinator and ECRB
After piercing the supinator-continues as the post interroseous nerve and
supplies the post. Compartment of forearm
ECRL- last muscle supplied by radial nerve
24. Median nerve
Also called labourer’s nerve
derived from both the medial and lateral cords of
the brachial plexus
Lateral root of median nerve- c6 c7
Medial root of median nerve- c8 t1
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26. In the arm proximally the median nerve is lateral to the axillary artery
Midway through the arm it crosses the artery from lateral to medial
anteriorly and lies medial to the brachial artery in the cubital fossa
Gives an articular branch to the elbow and a branch to pronater teres just
before the joint
In the cubital fossa gives branches to palmaris longus, FCR and FDS
27. Enters the forearm between the two heads of pronater teres and supplies
the deep muscles of flexor compartment as the Ant. Interroseous nerve
Gives no branches in the ARM
In the hand- supplies the thenar muscles except adductor policis and the
lateral 2 lumbricals
Sensory distribution-lateral two third of palm
lateral three and half fingers on palmar side
distal phalanx of lat. Three and half fingers on dorsal
side.
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39. Aetiology of median nerve injury
At the elbow- supracondylar humerus fractures; elbow dislocations
At the wrist- sharp cuts ; lunate dislocation ; carpel tunnel syndrome
Features-
Pointing index-paralysis of FDS and FDP of index finger leads to failure of
its flexion
Pen test- APB paralysis
Ape thumb-thumb lies in the same plane as rest of the fingers in adducted
and laterally rotated position( due to overactivity of adductor policis)
Wasting of thenar muscles
40. Ulnar nerve
Originates from the medial cord ; c8 T1
Descend medial to the brachial artery and enters the posterior
compartment of the arm
Not a content of the cubital fossa as it passes behind the
medial epicondyle at elbow.
Enters the anterior compartment of forearm between the two
heads of FCU.
41. Does not give branch in arm
In the forearm- FCU and medial third of FDP
In the hand- superficial branch- hypothenar muscles
deep branch- adductor pollicis, interrossie,
medial two lumbricals
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52. Called the muscians nerve as it controls the finer movements
of hand
Claw hand- hyperextension at MCP and flexion at IP joints. (
due to paralysis of intrinsic musces)
Ulnar paradox- clawing seen in low ulnar palsies and not in
high palsy
In high palsy there is paralysis of FDP hence flexion at IP joint
does not occur.
