Findings: A large osseous projection originates from the anterior cortex of the midhumerus and extends inferiorly into the arm.

Diagnosis: Supracondylar process of the humerus.

Discussion: This anatomic variant is present in 1% of the general population. It may represent a remnant structure from prehistoric humans and it is found in several mammals. The ligament of Struthers connects the process to the medial epicondyle of the humerus. Symptoms may be produced if the median nerve is compressed by the ligament leading to carpal tunnel like symptoms.

Reference:

1. Resnick D. Neuromuscular Disorders. In: Resnick D, ed. Diagnosis of
   Bone and Joint Disorders. 3rd ed. Philadelphia, PA: W.B. Saunders Co;1995:3365-3412.

2. Upper Arm. In: Schmidt H ed. Borderlands of Normal and Early Pathologic Findings
   in Skeletal Radiography. 4th ed. New York, NY, Thiem;1993:174-206.

3. Smith RV, Fisher RG. Struthers Ligament: Source of Median Nerve Compression
   Above Elbow: Case Report. J Neurosurg 1973;38:778.