A therapist assesses a patient's pulse by palpating along the medial aspect of the arm midway between the shoulder and elbow. This location would be used to assess the:

The correct answer is the brachial artery, which is located along the medial aspect of the arm. When assessing the pulse in this area, therapists can feel the pulsation of the brachial artery, which runs from the shoulder to the elbow. This location is particularly significant for checking circulation in the upper limb and is often used in cases where blood pressure is being measured or when assessing arterial flow.

The other choices represent different arterial sites. The carotid artery is found in the neck, the radial artery is located in the wrist, and the ulnar artery runs along the inner side of the forearm. Each of these arteries has specific palpation sites that are distinct from the medial aspect of the arm. Therefore, for a therapist palpating midway between the shoulder and elbow on the medial side, the appropriate artery to assess is indeed the brachial artery.