Test your knowledge: anatomical variant in the shoulder.
During anatomical dissections, a lot of anatomical variations are observed throughout the body. One of the most interesting variations that is found is Langer’s arch. This arch is present in 7-13% of cadaver dissections and has been observed several times since 1864. Do you know which number(s) in the picture beneath represent this arch? And do you know its exact origin and attachment site? For the advanced among us: what is the clinical relevance of this arch during motion? (Please provide solid arguments!).
See the answer of this question below the image!
The right answer to the questions: Langer´s axillary arch.
A Langer's arch is an additional axillopectoral muscle bundle. It is described as an anomalous muscular slip of the latissimus dorsi muscle, and joins the pectoralis major muscle where it inserts onto the lateral border of the intertubercular sulcus of the biceps. During its course this slip will pass the biceps brachii and the axillary neurovascular bundle. Doing so, it is one of the potential causes of the thoracic outlet syndrome – especially during combined abduction and external rotation there is a possibility of compression of the axillary neurovascular bundle. The picture below demonstrates Langer’s axillary arch; its presence can be examined during elevation and external rotation of the arm.