Final answer:
The latissimus Doris is a large, triangular muscle located on the lower back and is responsible for various arm movements and acts as an accessory muscle in respiration. The erector spine group, including the iliocostal is, longissimus, and spinalis, supports diverse spinal motions.
Step-by-step explanation:
The latissimus dorsi is a broad, triangular axial muscle located on the inferior part of the back. Its primary functions include the movement of the arm, such as extension, adduction, transverse extension also known as horizontal abduction, and internal rotation of the shoulder joint. Additionally, it plays a role in respiration; when the arms are fixed, it helps with the deep inspiration by elevating the thoracic cage, thus acting as an accessory muscle of respiration.
The muscles of the erector spinal group, including the iliocostalis, longissimus, and spinal groups, form the majority of muscle mass of the back and control movements like flexion, lateral flexion, and rotation of the vertebral column. Among them, the longissimus thoracic is associated with the thoracic region and part of the longissimus group that is situated intermediately and has functions aligned with extending, flexing laterally, and rotating the spine.