Osborne's ligament
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| Osborne's ligament | |
|---|---|
 | |
| Details | |
| Synonym | Osborne's band, Osborne's fascia |
| Location | Dorsal medial of the elbow |
| Identifiers | |
| FMA | 85450 |
| Anatomical terminology | |
Osborne's ligament, also Osborne's band, Osborne's fascia, Osborne's arcade, arcuate ligament of Osborne, or the cubital tunnel retinaculum, refers to either the connective tissue which spans the humeral and ulnar heads of the flexor carpi ulnaris (FCU) or another distinct tissue located between the olecranon process of the ulna and the medial epicondyle of the humerus. It is named after Geoffrey Vaughan Osborne, a British orthopedic surgeon, who described the eponymous tissue in 1957.[1]
Due to inconsistent definitions in the literature, Osborne's ligament can be classified as the fibrous band bridging the two heads of the FCU as originally described by Osborne[2] or the ligamentous tissue connecting the olecranon and the medial epicondyle.[3] Different terminologies have also been used to describe the tissues, including ligamentum epitrochleo-anconeum[4] and epitrochleo-olecranal ligament,[5] further contributing to the problem of clarifying the definitions.
Structure
Under the first definition, Osborne's ligament is a band of fibrous tissue which connects the humeral and the ulnar heads of the FCU. It can be classified as being thin or thick and thought to be a separate structure from the aponeurosis of the FCU.[6]
Under the second definition, Osborne's ligament is a ligamentous tissue with one end attached to the olecranon and the other to the medial epicondyle. It is generally believed to be analogous to the anatomically variant epitrochleoanconeus muscle which is attached to the olecranon and the medial epicondyle in the same manner, meaning that people possessing Osborne's ligament do not have the epitrochleoanconeus and vice versa.[7][8] It can be categorized into two types:[9]
- Type Ia: thin; lax when the elbow is extended and becomes taut when the elbow is flexed.
- Type Ib: thick; taut even when the elbow is not fully flexed (90°–120°).
Under both definitions, Osborne's ligament forms the roof of the cubital tunnel, an opening between the muscles through which the ulnar nerve passes.[citation needed]