The deltoid is innervated by the axillary nerve. Its function is to abduct, flex, and extend the humerus. The three major fibers have their origins on the lateral third of the clavicle, acromion, and the spine of the scapula. All three parts of the deltoid insert into the deltoid tuberosity on the lateral aspect of the humerus.

The supraspinatus and infraspinatus muscles are innervated by the suprascapular nerve. The triceps brachii are innervated by the radial nerve. The median nerve innervates various muscles of the forearm.

The correct answer is the 2nd metacarpal. We can come to this conclusion by looking at the name of the muscle. Because of the word radialis, we know that the muscle should should run along the radius and insert into one of the lateral metacarpals when in the anatomical position, leaving us with the answer choices: 1st and 2nd metacarpals. In addition, it is the 2nd over the 1st because any muscle dealing with the thumb will contain the word pollicus.

The humerus is located in the upper arm, meaning the muscle should also be located in the upper arm. This leaves us with the triceps brachii and biceps brachii as possible answer choices. The correct answer is the triceps brachii because it of its action as an extensor muscle.

If a muscle is split into multiple heads, there will usually be some indication in the name of the muscle. There are two answer choices which fit this category: biceps brachii and triceps brachii. "Bi" means two while "tri" means three, which means the correct answer is the biceps brachii. The triceps brachii has a long head, a lateral head, and a posterior head. 

A muscle that would only be responsible for the pinky finger would be a small one. In addition, extensor muscles of the hand are located in the posterior compartment, whereas flexors are located anteriorly. Of the following choices, the smallest muscle is the extensor digits minimi, which is also located posteriorly. It aids in abduction of the 5th digit as well.

The correct answer is the radial nerve. This is because the muscle is located in the posterior compartment of the arm, which means we are looking for a nerve that runs deep in the arm. For this reason, the only viable answer choice is the radial nerve.

The abductor digiti minimi is a muscle found in the pinky finger. It is innervated by the deep branch of the ulnar nerve. Its origin is the pisiform and the insertion is the base of the proximal phalanx of the 5th digit on the ulnar side. 

Three muscles attach to the coracoid process in the upper extremity. The pectoralis minor, coracobrachialis, and the short head of biceps brachii all attach to the coracoid process. The pectoralis major does not attach to the coracoid process, but it attaches to the humerus (deltoid also attaches to the humerus).

The musculocutaneous nerve (C5, C6, C7) runs the length of corachobrachialis and brachialis. 

Although all of the muscles listed above extend the wrist, as well as ulnarly or radially deviate the (depending on the muscle and the source being cited), on the extensor carpi radialis longus is able to flex the elbow. The extensor carpi radialis longus attaches more proximally on the humerus than the other wrist extensors, placing it further from the elbow's axis of rotation, which may explain why it can flex the elbow, but the other wrist extensors cannot.

The only muscle listed that receives its primary blood supply from the brachial artery is the biceps (more specifically known as the biceps brachii). 

The other muscles listed receive their blood supply as follows:

Deltoid: Thoracoacromial artery, and anterior and posterior circumflex humeral arteries

Subscapularis: Subscapular artery

Teres major: Subscapular and circumflex scapular arteries

Teres minor: Posterior circumflex humeral artery and circumflex scapular artery