The muscles of the shoulder
© Mark Mobley, West Midlands Surgical Training Centre, UHCW Trust, 2013
There is no space in the body: the bones, muscles, nerves, tendons, vessels, fat and connective tissue are all crammed together, and the appearance of much of the soft tissue is remarkably similar. Anatomical illustrations thus tend to separate out the structures, introducing space between the muscles and making the paths of the vessels and nerves more regular and comprehensible. The modern technique of plastination allows a similar approach to the actual tissues of a dissected subject, by teasing them apart and then impregnating them with a setting polymer.
Above is a 3D film of a dissected and plastinated shoulder. The chest muscles (pectoralis major and minor) have been removed to reveal the structures deep below the collarbone (clavicle), including the axillary artery and the network of nerves to the upper limb (brachial plexus) leaving the spinal column.
This presentation of the anatomy is remarkably similar to several of Leonardo’s depictions of the shoulder, as shown left.
All the drawings on this sheet deal with the muscles of the right shoulder, with the chest muscle, pectoralis major, split into four separate muscle bodies. At top right is one of Leonardo’s ‘thread diagrams’, in which the muscles are reduced to threads along their lines of force, conveying the complex three-dimensional structure of the shoulder in a single depiction.
