In anatomical position, the ulna lies:
(a) Medial to the radius
(b) Lateral to the radius
(c) Inferior to the radius
(d) Superior to the radius

Verified step by step guidance

1. Step 1: Understand the anatomical position, which is the standard reference position in anatomy where the body stands upright, facing forward, with arms at the sides and palms facing forward.
2. Step 2: Recall the bones of the forearm: the radius and the ulna. Both run parallel from the elbow to the wrist.
3. Step 3: Identify the relative positions of the radius and ulna in the anatomical position. The radius is located on the lateral (thumb) side of the forearm.
4. Step 4: Determine the position of the ulna relative to the radius. Since the ulna is on the side closer to the body’s midline (the pinky side), it is medial to the radius.
5. Step 5: Conclude that in anatomical position, the ulna lies medial to the radius, which corresponds to option (a).

Key Concepts

Anatomical Position

The anatomical position is a standard reference posture where the body stands upright, facing forward, arms at the sides with palms facing forward. This position is used to describe locations and relationships of body parts consistently.

Medial and Lateral Directions

Medial refers to a position closer to the midline of the body, while lateral means farther from the midline. These terms help describe the relative positions of structures, such as bones in the forearm.

Forearm Bones: Ulna and Radius

The forearm contains two long bones: the ulna and the radius. In anatomical position, the ulna is located on the medial side (toward the body’s midline), and the radius is on the lateral side (away from the midline).