Ultrasonographic morphology of the bicipital tendon and bursa in clinically normal quarter horses.

The bicipital tendons and bursae of 25 healthy adult Quarter Horses were ultrasonographically examined. Cross-sectional images of the right and left bicipital tendons were obtained from each horse, using a 7.5-MHz transducer held in the frontal plane at the point of the shoulder. The bicipital tendon at the point of the shoulder appeared as a bilobate structure overlying the echogenic surface of the humerus. Median distance from the skin surface to the cranial surface of the tendon on the medial sagittal plane of the tendon was 23 mm (range, 16.5 to 30 mm); median distance on the lateral sagittal plane was 14 mm (range, 8.5 to 19 mm). Median distance from the skin surface to the tendon on the midsagittal plane of the tendon was 17 mm (range, 10.5 to 22 mm). Median cranial-to-caudal widths of the lateral and medial lobes of the tendon at their greatest dimensions were 20.5 mm (range, 18 to 27.5 mm) and 16 mm (range, 13 to 20.5 mm), respectively. The median cranial-to-caudal width of the central (midsagittal) portion of the tendon was 10 mm (range, 7 to 13.5 mm). The bicipital bursa was < or = 3 mm wide at all locations at which it was measured. Ultrasonographic imaging was easily performed and allowed evaluation of the bicipital tendon, bursa, and surface of the underlying humerus.