Page 5 - MSK assignment

5 F. Elahi

Triceps Brachii - Medial Head -Humerus (Posteromedial, -Olecranon process of ulna
lower one-half)

Anconeus -Lateral epicondyle of -Lateral aspect of olecranon
humerus (Posterior) -Ulna (Upper ¼)

(O’Neill, 2008)
Nerves
Sonographically the ulnar, median, and radial nerves can be assessed. The ulnar nerve
is at the level of the medial epicondyle and travels with a groove on the posteromedial aspect of
the humerus. The sonographic appearance of the ulnar nerve is oval shaped with many
echogenic foci within it (O’Neill, 2008). At the level of the olecranon fossa, the ulnar nerve is
about 2-3mm. In the longitudinal plane, the fascicles again give a hyperechoic appearance to
the ulnar nerve. Image 10 of the protocol shows the normal ulnar nerve. Median nerve is found
at the antecubital fossa anteriorly. It lies medial to the brachial artery and is positioned posterior
to the bicipital aponeurosis. Median nerve can be seen in the first image of the elbow protocol.
The radial nerve at the elbow lies in a groove between the brachialis and brachioradialis muscle
(O’Neill, 2008). Radial nerve is shown in image 4 of the elbow protocol.

Bursae
The subcutaneous olecranon or olecranon bursa is found between the olecranon
process and subcutaneous tissue as a flattened potential space. Often this bursa appears as a
very slim hypoechoic area with a subtle hyperechoic outline. Subtendinous olecranon bursa is
found proximal to the tendon insertion. It lies deep to the triceps muscle and aids in helping slide
over the olecranon process (O’Neill, 2008). The bicipitoradial bursa or cubital bursa is a
subtendinous bursa. It lies between the distal biceps insertion and radius deep to it, providing
cushioning to reduce friction. Finally, the radioulnar bursa is found between the extensor
digitorum, radiohumeral joint, an supinator muscle (O’Neill., 2008).

Ligaments
The medial and lateral collateral ligaments provide stability to the elbow joint. The ulnar
or medial collateral ligament is made up of anterior, posterior, and transverse bundles. This
ligament is usually 4mm in transverse thickness taken in long axis. A normal medial collateral
ligament is seen in image 7 of the elbow protocol. The radial collateral ligament complex has
four parts. These include the radial collateral ligament, lateral ulnar collateral ligament,
accessory collateral ligament, and annular ligament. A normal sonographic image of the radial
collateral ligament (O’Neill., 2008).

Chapter 2: Pathologies
Osteoarthritis
Osteoarthritis is seen in the elbow due to overuse or fracture malalignment. Most often
the external radio-capitellar compartment is affected. The patient’s clinical findings include