Topic: blood and nerve supply of upper and lower limbs
Question: . A 35-year-old rowdy sheeter involved in a fight received a deep cut in the middle of the back of his right arm. He was bleeding profusely and was rushed to the hospital. a) Which nerve and artery at this site are in danger of injury. b) What is the origin and termination of this artery. c) How will you assess the functional integrity of the nerve in this case. d) Which part of the brachial plexus gives origin to this nerve and which other nerves arise from this part. e) Give the motor distribution and cutaneous branches of this nerve.
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a) The nerve and artery at risk of injury are the radial nerve and the profunda brachii artery.
b) The profunda brachii artery is a branch of the brachial artery. It originates in the middle third of the arm and terminates by splitting into the radial collateral artery and middle collateral artery.
c) To assess the functional integrity of the radial nerve, I would test:
– Wrist drop – inability to extend the wrist and fingers indicates radial nerve injury.
– Finger and thumb extension – inability to extend the thumb and fingers also indicates radial nerve damage.
– Sensation in the radial nerve dermatome – loss of sensation over the back of the hand and thumb side of the index and middle fingers points to radial nerve injury.
d) The radial nerve arises from the posterior cord of the brachial plexus. The other major branch from the posterior cord is the axillary nerve.
e) Motor distribution: Extends wrist, supinates forearm, extends elbow. Also supplies extensor muscles in the posterior compartment of the forearm and intrinsic muscles of the hand.
Cutaneous branches: Posterior cutaneous nerve of arm, lower lateral cutaneous nerve of arm, posterior cutaneous nerve of forearm.
