Forearm

The forearm is a complex region of the upper limb that plays a crucial role in hand movement and function. It is composed of two long bones, the radius and ulna, along with a network of muscles, tendons, nerves, and blood vessels. The forearm muscles are divided into two compartments: the anterior (flexor) group, responsible for flexing the wrist and fingers, and the posterior (extensor) group, which extends them. Major nerves, such as the median, ulnar, and radial nerves, provide sensation and motor control to the forearm and hand. Blood supply to the forearm is maintained by the radial and ulnar arteries. Understanding the anatomy of the forearm is essential for assessing movement, diagnosing pathologies, and performing procedures, making it a key area of focus in musculoskeletal ultrasound.

The sonoanatomy of the forearm is essential for evaluating its muscles, tendons, nerves, and blood vessels through ultrasound. Using high-resolution imaging, the forearm’s muscles, such as the flexors and extensors, appear as hypoechoic (dark) tissue with bright, echogenic layers of fascia surrounding them. Tendons, which connect muscles to bones, show up as strong, linear, and bright structures, making ultrasound ideal for assessing tendon integrity during dynamic movement. Nerves like the median, ulnar, and radial nerves are easily distinguishable on ultrasound due to their unique “honeycomb” appearance, with small hypoechoic areas representing nerve fascicles surrounded by a brighter connective tissue layer. This pattern helps differentiate nerves from nearby tendons and muscles. Blood vessels, such as the radial and ulnar arteries, appear as anechoic (black) tubular structures, with arteries showing a pulsatile flow, while veins are compressible. Forearm ultrasound is a valuable tool for diagnosing injuries like muscle tears, tendonitis, nerve entrapments, and vascular issues, offering a real-time, non-invasive method to assess the structures and pathologies in this vital part of the upper limb.