Identify the highlighted muscle. This muscle works synergistically with latissimus dorsi. Triceps brachii Pectoralis minor Coracobrachialis Rhomboid major Teres major Subscapularis Reset Zoom
The Correct Answer and Explanation is:
The correct answer is Teres major.
Explanation:
The muscle highlighted in the anatomical model is the teres major. This thick, flattened muscle is located in the posterior aspect of the shoulder, specifically along the inferior border of the scapula (shoulder blade). It originates from the posterior surface of the inferior angle of the scapula and courses superiorly and laterally to insert onto the medial lip of the intertubercular sulcus of the humerus (the upper arm bone). Due to its position and attachments, it is sometimes referred to as “lat’s little helper.”
The prompt provides a crucial clue by stating that this muscle acts synergistically with the latissimus dorsi. A synergist is a muscle that assists the primary mover (agonist) in performing a specific action. The teres major and the latissimus dorsi are powerful partners because they share the same three primary actions at the glenohumeral (shoulder) joint:
- Adduction: They pull the humerus toward the midline of the body, as in bringing your arm down to your side from an outstretched position.
- Medial (Internal) Rotation: They rotate the humerus inward, so the anterior surface of the arm faces the body.
- Extension: They move the humerus backward, behind the plane of the body.
This synergistic relationship is fundamental for powerful pulling movements. Activities such as rowing, climbing, swimming the freestyle or butterfly stroke, and performing pull-ups rely heavily on the combined force generated by both the teres major and the much larger latissimus dorsi. While the latissimus dorsi is the primary powerhouse for these actions, the teres major provides significant assistance, enhancing both the strength and stability of the movement.thumb_upthumb_down
