Diagnostic ultrasonography has, more recently, been applied to
the assessment of other less traditional musculoskeletal
problems such as evaluation of bone, joints, muscle and nerves.
The soft tissue structures of the head, neck, joints of the
forelimb and foot can be evaluated ultrasonographically;
yielding important diagnostic information that cannot be
obtained radiographically. Normal Sonographic Anatomy of the
Joints of the Forelimb The temporomandibular joint contains an
echogenic fibrocartilagenous disc that separates the larger
dorsal compartment from the smaller ventral compartment. No free
fluid is visible in the normal joint. The disc appears as a
homogeneously echogenic triangle with its base laterally. The
disc is attached to the thin echogenic joint capsule and
measures 2 cm in thickness caudally and caudolaterally, thinning
to 0.5 cm rostrolaterally. The hypoechoic layer of articular
cartilage adjacent to the disc measured up to 3 mm in foals but
was difficult to measure in adults. Ultrasonogra