A humeral fracture may cause uncompensated \x93wrist drop.\x94 Provide a developmental account for the anatomical location of muscles that extend the adult wrist. (6 pts)

Development

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Anatomy and Function

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Injury to the posterior cord of the brachial plexus may severely weaken extension at the elbow. Review the anatomy, relationships, and functions of the triceps brachii. (6 pts)

Anatomy

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Relationships

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Functions

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Venipuncture is the process of obtaining venous blood. Review the anatomy, relationships, and functions of the biceps brachii. (6 pts)

Anatomy

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Relationships

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Functions

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Pronator teres syndrome is a compression neuropathy. Review the anatomy, relationships, and functions of the pronator teres. (6 pts)

• The pronator teres muscle is the most lateral of the superficial group of muscles in the flexor forearm compartment. It has two heads of origin\x97humeral and ulnar. The humeral head is larger and more superficial and originates immediately above the medial epicondyle, from the common flexor tendon. The ulnar head is smaller and arises from the coronoid process of the ulna. Pronator teres passes obliquely (inferolaterally) across the forearm and inserts at the middle of the lateral surface of the radius. The median nerve enters the forearm between the two heads of the muscle (supplying it), and is separated from the ulnar artery by the ulnar head. The lateral border of pronator teres forms the medial boundary of the cubital fossa, containing the brachial artery, median nerve, and tendon of the biceps brachii. The actions of pronator teres are to pronate and weakly flex the arm. Pronation rotates the radius medially so that the palm of the hand faces posteriorly and the dorsum faces anteriorly. Blood supply to pronator teres is from branches of the anastamosis at the cubital fossa including ulnar artery, radial artery, inferior ulnar collateral artery, anterior ulnar collateral artery, and common interosseus artery.

(Median nerve entrapment between the two heads of pronator teres may lead to Pronator Syndrome. Symptoms include pain in the anterior forearm and wrist, loss of sensation of the palmar aspects of the radial 3.5 digits, adjacent palm and lateral 3.5 nail beds, as well as a weakened ability to pronate the arm.)

Scaphoid fractures only account for 2% of all fractures and often lead to avascular necrosis secondary to disruption of blood supply. Review the blood supply to the dorsum (posterior surface) of the wrist and hand. (6 pts)

Wrist

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Hand

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