The T6 vertebra is in the thoracic, or middle, part of your spine. Twelve vertebrae make up the thoracic spine; they are numbered from the top down. The muscles that connect to the T6 vertebra are the spinalis, a lower back muscle, and the trapezius, a muscle in your upper back.
T6 Vertebra Muscles
The spinalis muscle, which is part of the erector spinae muscle group, attaches to most of the thoracic vertebrae, including the T6. The spinalis muscle runs from just below your skull to the bottom of the thoracic spine. The lower fibers of the trapezius muscles also attach to several thoracic vertebrae. The lower trap runs from the T4 to the T12. From the spine, it runs diagonally across your upper back and attaches to your shoulder blade.
The spinalis, a muscle of the lower back, is involved in extension of the lumbar and thoracic spine. This movement is when you push the spine back, the opposite of a crunching motion. The lower fibers of the trapezius muscle are also involved in extension of the thoracic spine, but their involvement is minimal. They are primarily responsible for adduction and depression of the scapula, or shoulder blade. Adduction is pulling your shoulder blades together and depression is pulling your shoulder blades down.
To strengthen the lower portion of the trapezius muscle, perform exercises that pull the shoulder blades together and down. Rowing exercises, such as seated and bent-over rows, are shoulder blade adduction movements. Pulldown movements, such as lat pulldowns, involve shoulder blade depression. You cannot isolate the lower traps. These movements also involve other back muscles, such as the latissimus dorsi and rhomboids, so you also work these muscles when you do rows and pulldowns.
Low back hyperextension exercises work the spinalis muscle. Sit in a hyperextension machine with the pad against your upper back. Push back against the resistance. You also can perform this exercise on the floor. Lie on your stomach and lift your head and shoulders off the floor, keeping your hips in contact with the floor. Anchor your ankles on a body weight hyperextension machine to perform this exercise with a larger range of motion. Since the machine holds you off the floor, you can lower your torso past parallel.