Deltoid and Latissimus Dorsi: Muscles of the Shoulder and Back
The deltoid muscle is located on the rounded corner of the shoulder. It has its origins from the lateral third of the clavicle and scapula spine, specifically the acromion process and the spi of the shoulder blade. Its primary function is to pull the humerus towards the acromion, allowing for movements such as extending the arm backward. This movement is commonly observed in athletes when throwing or executing underhand pitches.
On the other hand, the latissimus dorsi muscle has some fibers that originate from the scapula, but its main origin point is the T7 vertebrae, which coincides with the tip of the trapezius muscle. It extends downward and ends in the sacral region at the base of the spine. One of its key roles is to depress the scapula, particularly when providing support to the entire body during a pull-up exercise.
Understanding the Rhomboid Muscles
The rhomboid muscles are located in the upper torso of the back, specifically between each shoulder blade and the spine, underneath the trapezius muscle. There are two types of rhomboid muscles: the major and the minor.
The rhomboid minor is a triangular muscle that is thick and attached to the cervical and thoracic spinous processes at C7 and T1. On the other hand, the rhomboid major is a wider and thinner muscle that lies below the rhomboid minor. It is attached to the vertebrae T2 to T5.
These rhomboid muscles play an important role in the movement of the scapulae. They enable the individual to pull the scapulae together or rotate them downward.