Emily is examining a bone that is 3 inches long and 1 inch wide. Choose the correct classification.

Choice A reason: Circumduction is a circular movement that combines flexion, extension, abduction, and adduction. It is typically seen in ball-and-socket joints like the shoulder or hip, not in the neck. It does not describe the backward bending of the head.

Choice B reason: Rotation refers to the movement of a bone around its longitudinal axis, such as turning the head side to side. It does not involve bending the head backward.

Choice C reason: Hyperextension occurs when a joint is extended beyond its normal anatomical position. In the case of the head, bending it backward past the neutral anatomical position is a classic example of hyperextension.

Choice D reason: Flexion is the movement that decreases the angle between two body parts, such as bending the head forward toward the chest. It is the opposite of the movement described in the question.

Choice A reason: The central canal, also known as the Haversian canal, is located at the center of each osteon in compact bone. It contains blood vessels and nerve fibers that supply nutrients and signals to the bone cells.

Choice B reason: Adipose tissue is found in yellow marrow, primarily in the medullary cavity of long bones, not in the central canal of osteons.

Choice C reason: Yellow marrow and spicules are found in the medullary cavity and spongy bone, respectively. They are not components of the central canal.

Choice D reason: Cartilage is not present in the central canal. Interstitial lamellae are layers of bone matrix found between osteons, not within the canal.

Choice E reason: Red marrow is found in spongy bone and certain flat bones, not in the central canal. While nerves are present, the absence of blood vessels in this choice makes it incomplete.