Shoulder & Elbow. ISSN 1758-5732 E ORIGINAL ARTICLE Snapping triceps syndrome: a review of the literature Matthias K.D. Vanhees, Ghislain F.A.E. Geurts & Roger P. van Riet Department of Orthopedics and Traumatology, Monica Hospital, Deurne, Belgium Received Submitted 18 October 2009; accepted 22 October 2009 Keywords Elbow, ulnar nerve, triceps, snapping triceps, ulnar neuritis Conflicts of Interest None declared Correspondence Roger P. van Riet, Department of Orthopedics and Traumatology, Monica Hospital, Stevenslei 20, 2100 Deurne, Belgium. Tel: +32 (0)3 320 5800. Fax: +32 (0)3 320 5815. E-mail: rogervanriet@hotmail.com DOI:10.1111/j.1758-5740.2009.00033.x ABSTRACT Snapping triceps syndrome is a rare and therefore often unknown cause of medial elbow pain. It is a condition in which the distal portion of the triceps dislocates over the medial epicondyle during flexion and extension of the elbow. It can occur, with or without ulnar neuropathy symptoms. The available literature on this subject is scarce and consists mainly of case reports. This report reviews the current literature and will provide guidance in diagnosis and treatment of this uncommon condition. INTRODUCTION Snapping triceps is a relatively uncommon condition that is defined as a dynamic phenomenon in which the distal portion of the triceps dislocates over the medial or lateral epicondyle [1] of the elbow, during flexion or extension. Dislocation over the lateral epicondyle has been described only once, by Spinner and Goldner in 1999 [1], and, in this review, we focus on the medial snapping triceps. Patients usually complain of local tenderness and a snapping sensation around the medial side of the elbow. The condition usually coexists with ulnar nerve dislocation [2]. Although not all ulnar nerve subluxations present with an abnormality of the triceps, the clinician should consider the snapping triceps syndrome in the presence of ulnar nerve dislocation. Snapping triceps is more common in men, especially in manual workers, athletes, or those with varus deformity of the elbow as a result of previous trauma [3]. The first symptoms usually occur in adolescence or early adulthood [4]. Anatomy As the name suggests, proximally, the triceps muscle consists of three distinct parts: the lateral, long and medial heads. A fourth, medial head of the triceps muscle [5] has also been described in rare cases. The three heads combine to insert as a single tendon distally. The lateral head originates from three sites on the humerus. The long head originates from the infraglenoid tuberosity of the scapula, and the medial head originates from the posterior humerus distal to the spiral groove [6]. Distally, the triceps inserts with both tendon and muscle. The tendinous portion that inserts on the olecranon is referred to as the proper part. The second part, the expansion, inserts on four different areas: the posterior crest of the ulna medially, the fascia of the extensor carpi ulnaris origin laterally, the antebrachial fascia distally, and the anconeus insertion deeply [7]. In the snapping triceps, the position of the transition between the muscular and the tendinous insertion of the medial head is important, as the distance between the medial edge of the triceps muscle and the medial epicondyle becomes smaller with a more distal transition. A small interval between the medial edge of the triceps and medial epicondyle predisposes to snapping triceps. This is an important aspect to consider during clinical examination [4]. The fourth, medial head of the triceps muscle [5] and an abnormal musculotendinous portion of the triceps in the ulnar groove [8] have also been described as potential anatomical causes for snapping triceps syndrome. The ulnar nerve is formed from nerve roots C8–T1. From the middle of the humerus, the ulnar nerve runs posterior to the inter- muscular septum and anterior to the medial head of the triceps. At the elbow, the nerve enters the cubital tunnel formed by the medial epicondyle and the cubital tunnel retinaculum. The ulnar nerve runs between the medial edge of the triceps and the medial epicondyle. A shallow groove or insufficiency of the cubital tunnel retinaculum are potential anatomical causes of a dislocating ulnar nerve. Mechanism The triceps is thinner and wider at the level of the epicondyles, compared with at the insertion on the olecranon [7]. As the elbow is flexed, the triceps broadens because it is compressed against the  2009 The Author(s) 30 Journal Compilation  2009 British Elbow and Shoulder Society. Shoulder & Elbow 2010 2, pp 30–33