The back is subdivided into the upper, middle, and lower back. To build the back optimally, you should know the major muscles, their actions, and which exercises build muscles best. Fortunately, you don’t have to guess. Scientific studies using sophisticated tools such as electromyography (EMG) and magnetic resonance imaging (MRI) show us how these muscles work and which exercises work best for building them.
Back Muscles Anatomy
The surface muscles of the upper back include the trapezius muscles (traps) and posterior deltoids. These muscles give height and breadth to back development. The mid-back muscles include the latissimi dorsi (lats), rhomboids, and teres major. The low-back muscles are called collectively the erector spinae and include the longissimus, spinalis, and iliocostalis.
The lats are attached to the upper end of the arm bones (humeri) at one end and fan out down the length of the spine to the pelvis. The latissimus dorsi extends the shoulder, which means that it pulls the arm downward toward the hips. During pull-ups, the lats raise the body toward the arms when the arms are fixed. These muscles also stabilize the trunk during multiple-joint, large-muscle lifts, such as squats and bench presses. Good exercises for the lats include pull-ups, lat pulls, and pull-overs.
The rhomboids (major and minor) run from the spine to the scapulae (shoulder blades); the scapula is a large, flat bone that attaches to the upper-arm bone (humerus). When the rhomboids on both sides work together, the muscles squeeze the shoulder blades together. The rhomboids draw the scapulae toward the spinal column. The teres major muscle connects the scapula (shoulder blade) to the humerus. This muscle moves the humerus backward, meaning that it brings the arm toward the back. The rhomboids and teres major work together to move the arms backward during movements such as rowing. Exercises that build these muscles include rear deltoid raises, seated cable rows, wide-grip lat pulls, pull-ups, bent-over rows, and one-arm dumbbell rows.
The erector spinae muscles support and extend the spine. These muscles attach to the vertebrae, the ribs, and the pelvis. Good exercises for developing these muscles include back hyperextensions, bird dogs, dead lifts, and good mornings. Well-developed spinal muscles make you look as if you have two boa constrictors running up your back.
Strive to build all three parts of the back if you want to develop a superior physique and well-balanced muscles. Strong, symmetrical back muscles give balance to the shoulder joint by maintaining uniform tension on the front and back of the shoulder. This promotes joint health and prevents shoulder pain stemming from abnormal stresses on the joint.