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1.2.1 Introduction to the arm and forearm

TRANSCRIPT

(2.21)

In this section we’ll go from the shoulder to the wrist. We’ll look at the bones, joints and muscles that are involved in three different functions: elbow movement, forearm rotation, and wrist movement. We’ll also look at the vessels and nerves, from the shoulder to just below the elbow.

A good many of the muscles that are in the forearm are finger and thumb muscles. We’ll leave those out of the picture in this section, and see them when we do the hand.

We need to give a clear meaning to our usual anatomic terms, medial and lateral, anterior and posterior. When we use those terms in the upper extremity, we imagine the extremity to be fixed in this so-called anatomic position. That’s useful, but calling something medial or lateral can become pretty confusing below the elbow, because everything can rotate so much.

To get our bearings in the forearm and hand we'll often use the more convenient terms that are derived from the two functions, flexion and extension, and from the two bones of the forearm, the ulna and the radius. This is the flexor aspect of the forearm, and this is the extensor aspect. This is the ulnar side, and this side, with the thumb on it, is the radial side.

Let’s also understand the terms we use for movements. At the elbow, bending is flexion, straightening is extension. Rotation of the forearm is referred to as pronation and supination. Pronation puts the palm of the hand down, and supination brings it up. To remember which is which, remember supination has “up” in it.

At the wrist, this is flexion, this is extension. The two sideways movements of the wrist are ulnar abduction, and radial abduction. There’s one last term to define - the arm. In everyday ...

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(2.21)

In this section we’ll go from the shoulder to the wrist. We’ll look at the bones, joints and muscles that are involved in three different functions: elbow movement, forearm rotation, and wrist movement. We’ll also look at the vessels and nerves, from the shoulder to just below the elbow.

A good many of the muscles that are in the forearm are finger and thumb muscles. We’ll leave those out of the picture in this section, and see them when we do the hand.

We need to give a clear meaning to our usual anatomic terms, medial and lateral, anterior and posterior. When we use those terms in the upper extremity, we imagine the extremity to be fixed in this so-called anatomic position. That’s useful, but calling something medial or lateral can become pretty confusing below the elbow, because everything can rotate so much.

To get our bearings in the forearm and hand we'll often use the more convenient terms that are derived from the two functions, flexion and extension, and from the two bones of the forearm, the ulna and the radius. This is the flexor aspect of the forearm, and this is the extensor aspect. This is the ulnar side, and this side, with the thumb on it, is the radial side.

Let’s also understand the terms we use for movements. At the elbow, bending is flexion, straightening is extension. Rotation of the forearm is referred to as pronation and supination. Pronation puts the palm of the hand down, and supination brings it up. To remember which is which, remember supination has “up” in it.

At the wrist, this is flexion, this is extension. The two sideways movements of the wrist are ulnar abduction, and radial abduction. There’s one last term to define - the arm. In everyday conversation this whole thing is the arm, but in anatomy this is the arm, just this bit here, and this is the forearm.

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