The pulldown exercise is a strength training exercise designed to develop the latissimus dorsi muscle. It performs the functions of downward rotation and depression of the scapulae combined with adduction and extension of the shoulder joint.
The cable lat pulldown is done where the handle is moved via a cable pulley, as opposed to doing pulldowns on a leverage machine.
The standard pulldown motion pulldown is a compound movement that requires dynamic work by muscles surrounding the three joints which move during the exercise. These are the elbow in conjunction with the glenohumeral and scapulothoracic joints in the shoulder girdle.
The latissimus dorsi performs extension and adduction of the arm directly to the spinal fascia. It bypasses the scapulae unlike other muscles which perform this function, so work performed by this muscle will not contribute to muscles that affect the scapulae. The lower sternal fibers of the pectoralis major also perform this role of extension and adduction to a lesser degree.
The contraction of these adductor/extensor muscles can indirectly depress and downwardly rotate the scapulae; this is only required when they are pulled into elevation and upward rotation by the contraction of muscles that attach to the scapulae. If the weight were being pulled solely by the lats, for example, the scapulae would simply be pulled down by gravity, along for the ride.
Muscles that attach to and depress the scapulae include the lower trapezius muscle and the pectoralis minor. The pec minor also works in conjunction with the rhomboid muscle and levator scapulae to perform downward rotation of the scapulae.
Muscles which attach to the scapulae that adduct and extend the arm include the posterior deltoid muscles, the teres major, and minor stabilizing contribution from some rotator cuff muscles (infraspinatus and teres minor as lateral rotators, subscapularis as medial rotators).