Loss of the ability to adduct the thumb

[Oak]

A 26 year old construction worker has an isolated loss of the ability to adduct his thumb. The muscle that would normally accomplish this act is innervated by a nerve arising from which part of the brachial plexus?

A. Lateral cord only
B. Medial and lateral cords
C. Medial cord only
D. Posterior and medial cords
E. Posterior cord only

[bharat]

Originally Posted by Oak

A 26 year old construction worker has an isolated loss of the ability to adduct his thumb. The muscle that would normally accomplish this act is innervated by a nerve arising from which part of the brachial plexus?

A. Lateral cord only
B. Medial and lateral cords
C. Medial cord only
D. Posterior and medial cords
E. Posterior cord only

well i suppose he have the ulner nerve injury coz. it is the nerve supplying the Adductor pollicis muscle .and it's dysfunction causes loss of adduction.
ulner nerve arise from medial chord but it receives some fibers from C7 also (from laterl chord-through communicating branch from the lateral root of medain nerve) so due to this the root value of ulner nerve is C7,8 & T1 so i hope answer is B.

[Oak]

Explanation is somewhat reasonable your justmissed it, the correct answer is C. The muscle that adducts the thumb is the adductor pollicis, which is innervated by the ulnar nerve. The ulnar nerve is derived from the medial cord of the brachial plexus.

The lateral cord alone (choice A) gives rise to the musculocutaneous nerve.

The medial and lateral cords together (choice B) give rise to the median nerve.

No nerves arise from the combination of posterior and medial cords (choice D).

The posterior cord (choice E) gives rise to the axillary and radial nerves.

[bharat]

Originally Posted by Oak

Explanation is somewhat reasonable your justmissed it, the correct answer is C. The muscle that adducts the thumb is the adductor pollicis, which is innervated by the ulnar nerve. The ulnar nerve is derived from the medial cord of the brachial plexus.

The lateral cord alone (choice A) gives rise to the musculocutaneous nerve.

The medial and lateral cords together (choice B) give rise to the median nerve.

No nerves arise from the combination of posterior and medial cords (choice D).

The posterior cord (choice E) gives rise to the axillary and radial nerves.

well while answering the question i remebered the dermatome so replied so i missed.
well if you have asked me the same question with out any option i would have told u that answer is medial cord but i thought u were not serching such a simple answer so i made the mistake
well i resided book then i knew that adductor pollicis longus receives deep branch of ulner nerve and root value is C8-T1 so i knew where i was wrong
well hahaha...... this is my regular habbit that i miss most of time by slight mistake... well hope later i will develop confidence...
any way thanks..