The Musculus trapezius, also known as the hooded muscle, is a large flat shoulder muscle on the back of our body, named after its trapezoidal shape. It consists of two triangular parts, which together form a large square. It extends from the lower part of the back of the head, the so-called occipital bone, over the pointed ends of the cervical and thoracic vertebrae, also called spinous processes.
Towards the side, the musculus trapezius extends over the shoulder blades to the outer third of the clavicle. It thus covers the entire surface of the neck and shoulder area. The musculus trapezius is supplied by two nervous structures: On the one hand, by the eleventh cranial nerve, the so-called accessorius nerve. On the other hand, it is supplied by parts of a nerve plexus in the area of the neck, the so-called plexus cervicalis.
Function
The musculus trapezius consists of three parts, which have different functions:
- The descending part, also called pars descendens, forms the upper part of the musculus trapezius. Its origin is in the area of the neck, the occipital bone and the cervical spine. From there, the descending part of the Musculus trapezius moves to the outer shoulder blades and starts there.
Its function is to lift the shoulders and rotate the head.
- The transverse part of the trapezius muscle, the pars transversa, originates from the thoracic vertebrae and starts at a bony hump, the so-called acromion, the highest point of the shoulder blades. This part pulls the shoulder blades together.
- The lower ascending part of the musculus trapezius, the pars ascendens, originates from the lower thoracic vertebrae and attaches to the back surface of the shoulder blades. This part allows the shoulders to be pulled down. In short, the musculus trapezius is used to move the shoulder blades, thus enabling the shoulder blades to carry heavy loads, allowing the arms to be raised above 90°, the head to be turned and the neck to be stretched.
