Scapular spinal part of deltoid muscle

The deltoid muscle (or musculus deltoideus) is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, the deltoid muscle is made up of three distinct sets of muscle fibers, namely the anterior deltoid or clavicular part (pars clavicularis) posterior or scapular part (pars scapularis) intermediate or acromial part (pars acromialis) The deltoid's fibres are pennate muscle. However, electromyography suggests that it consists of at least seven groups that can be independently coordinated by the nervous system. It was previously called the deltoideus (plural deltoidei) an (Wikipedia)