The diaphragm is the large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity and serves as the main muscle of respiration. On ultrasound, the diaphragm appears as a bright, echogenic, curved line that moves downward during inspiration and upward during expiration. It serves as an important anatomical landmark in abdominal ultrasound, marking the upper boundary of the liver and spleen. Ultrasound can assess diaphragm function by measuring its excursion during breathing, which is useful for evaluating patients with suspected diaphragm paralysis, and point-of-care diaphragm ultrasound has become increasingly important in critical care for assessing respiratory muscle function.
Sonography Term