Brachial Plexus and Nerves MCQs

This nerve descends inferiorly through the posterior aspect of the forearm where it penetrates the supinator muscle and emerges as the posterior interosseous nerve. Its main function is to supply the muscles located in the posterior compartment of the forearm (the wrist extensors and the long muscles of the thumb). The median nerve also provides sensory innervation to the dorsal aspect (nail bed) of the distal first two digits of the hand, the palmar aspect of the thumb, index, middle, and half of the ring finger, the palm, as well as the medial aspect of the forearm. The adductor pollicis is innervated by the deep branch of the ulnar nerve(C8-1). Reference: Textbook of Gray's Anatomy for students, 3rd Edition, Upper Limb Page number - 816,818,763

The deep radial nerve emerges from the supinator muscle and runs in the deep layer of the posterior forearm. It runs next to the posterior interosseous artery, which, along with the anterior interosseous artery, is a branch of the common interosseous artery. The common interosseous artery comes off the ulnar artery to give these two branches that supply the deep arm on the anterior and posterior sides. The ulnar and radial arteries are branches of the brachial artery that run down the ulnar and radial sides of the anterior arm. Reference - Textbook of Gray's Anatomy for students, 3rd Edition, Upper Limb Page number - 818

The posterior interosseous nerve is the sensory continuation of the deep radial nerve, distal to its motor branches for the extensor muscles. It reaches the wrist joint and carpal bones for proprioceptive sense from these structures. Brachioradialis and extensor carpi radialis longus are innervated by the radial nerve, and extensor carpi radialis brevis is innervated by the deep radial nerve. Flexor digitorum superficialis is innervated by the median nerve. There are no parasympathetic nerves in the limbs or body wall. Reference: Textbook of Gray's Anatomy for students, 3rd Edition, Upper Limb Page number - 818

Finger drop - Posterior interosseous nerve Honeymoon palsy - Radial nerve Pointing index - Median nerve Book test - ulnar nerve Reference: Textbook of Gray's Anatomy for students, 3rd Edition, Upper Limb Page number - 816

The axilla is an anatomical region under the shoulder joint where the arm connects to the shoulder. It contains a variety of neurovascular structures, including the axillary artery, axillary vein, brachial plexus, and lymph nodes. Reference: Textbook of Gray's Anatomy for students, 3rd Edition, Upper Limb Page number - 737

Ans. is'c'i.e., Ulnar nerve and Median nerve (Rel BDC 5'h/e VoL I p. 108-111) On Palm side: Lateral 2/3 of the palm and lateral three and half fibers → Median nerve. Medial 1/3 of the palm and medial one and half fingers → Ulnar nerve.

This woman has experienced a lower brachial plexus injury due to forced abduction of the upper limb during the accident. This injury presents with numbness and paresthesia in the C8 and T1 dermatomes, which supply the axilla and medial aspect of her upper limb. These nerve roots primarily supply the medial cord of the brachial plexus, which creates the ulnar nerve. Due to damage to the ulnar nerve, she is experiencing weakness in the movement of her left hand. The abduction and adduction of the fingers are controlled by the deep branch of the ulnar nerve by supplying the dorsal interosseous and palmar interosseous muscles, respectively. Reference: Textbook of Gray's Anatomy for students, 3rd Edition, Upper Limb Page number - 747

Successful transposition of muscle flaps in reconstructive surgery hinges largely on maintaining the neurovascular pedicles that supply the muscle. The latissimus dorsi muscle is innervated by the thoracodorsal (middle subscapular) nerve, a branch of the posterior cord of the brachial plexus. Lesion of this nerve during dissection of the chest wall will cause loss of the muscle flap. Reference : Textbook of Gray's Anatomy for students, 3rd Edition, Upper Limb Page number - 747