The origin of the long head of the triceps: a cadaveric study.

Hypothesis: There is a paucity of literature examining the origin, size, and capsular contribution of the long head of the triceps brachii muscle. We hypothesize that there is a more extensive origin and capsular contribution than previously described.

Materials And Methods: Twenty fresh, frozen cadaveric specimens were dissected from a posterior and anterior approach exposing the long head of the triceps and the inferior capsule. The origin and size of the long head of the triceps and contribution to the capsule was documented.

Results: The average age of the specimens was 65.8. At the scapula, the tendon width averaged 2.69cm at the insertion and the thickness averaged 0.47cm laterally and 0.29cm medially. The bony origin extended on the lateral border dorsal surface of the scapula in addition to the infraglenoid tubercle. The long head of the triceps gave a capsular contribution in each specimen. This contribution measured 1.43cm from superior to inferior and 1.01cm from anterior to posterior after dissecting the capsule off the glenoid.

Discussion: We found the origin of the long head of the triceps had a more extensive bony attachment on the scapula then previously described. In addition, the long head of the triceps has a consistent contribution to the inferior shoulder capsule.

Conclusion: The anatomic origin of the long head of the triceps gives a capsular contribution to the inferior glenohumeral capsule. The triceps may be affected by open and arthroscopic procedures that release or shift the posterior inferior glenohumeral capsule.

Level Of Evidence: Cadaveric study.