Muscle Group: Back

About the back muscles

Latissimus Dorsi

The latissimus dorsi (/ləˈtɪsɪməs ˈdɔːrsaɪ/) is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: latissimi dorsi) comes from Latin and means "broadest [muscle] of the back", from "latissimus" (Latin: broadest)' and "dorsum" (Latin: back). The pair of muscles are commonly known as "lats", especially among bodybuilders. The latissimus dorsi is the largest muscle in the upper body.

The latissimus dorsi is responsible for extension, adduction, transverse extension also known as horizontal abduction, flexion from an extended position, and (medial) internal rotation of the shoulder joint. It also has a synergistic role in extension and lateral flexion of the lumbar spine.

Due to bypassing the scapulothoracic joints and attaching directly to the spine, the actions the latissimi dorsi have on moving the arms can also influence the movement of the scapulae, such as their downward rotation during a pull up.

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Trapezius

The trapezius[4] is a large paired surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports the arm.

The trapezius has three functional parts: an upper (descending) part which supports the weight of the arm; a middle region (transverse), which retracts the scapula; and a lower (ascending) part which medially rotates and depresses the scapula.

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Levator Scapulae

The levator scapulae is a skeletal muscle situated at the back and side of the neck. As the Latin name suggests, its main function is to lift the scapula.

When the spine is fixed, levator scapulae elevates the scapula and rotates its inferior angle medially.[1] It often works in combination with other muscles like the rhomboids and pectoralis minor to produce downward rotation of the scapula.

Elevating or rotating one shoulder at a time would require muscles to stabilize the cervical spine and keep it immobile so it does not flex or rotate. Elevating both at once with equal amounts of pull on both side of cervical spinal origins would counteract these forces. Downward rotation would be prevented by co-contraction of other muscles that elevate the spine, the upper fibers of the trapezius, which is an upward rotator.

When the shoulder is fixed, levator scapulae rotates to the same side and flexes the cervical spine laterally. When both shoulders are fixed, a simultaneous co-contraction of both levator scapulae muscles in equal amounts would not produce lateral flexion or rotation, and may produce straight flexion or extension of the cervical spine.

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Rhomboid Major & Minor

The rhomboid major is a skeletal muscle on the back that connects the scapula with the vertebrae of the spinal column. In human anatomy, it acts together with the rhomboid minor to keep the scapula pressed against thoracic wall and to retract the scapula toward the vertebral column.

The rhomboid major helps to hold the scapula (and thus the upper limb) onto the ribcage. Other muscles that perform this function include the serratus anterior and pectoralis minor.

Both rhomboids (major and minor) also act to retract the scapula, pulling it towards the vertebral column.

The rhomboids work collectively with the levator scapulae muscles to elevate the medial border of the scapula, downwardly rotating the scapula with respect to the glenohumeral joint. Antagonists to this function (upward rotators of the scapulae) are the serratus anterior and lower fibers of the trapezius. If the lower fibers are inactive, the serratus anterior and upper trapezius work in tandem with rhomboids and levators to elevate the entire scapula.

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Stretches

1. Cat-Cow Stretch
• Begin in quadruped (hands and knees) with knees under hips and hands under shoulders.
• Inhale as you move your sit bones up towards the ceiling, arching the back and pressing the chest towards the floor as you lift the head up. Relaxing the shoulder blades behind you.
• From there, inhale as you move from this “cow” position to an angry “cat” position, rounding out your back and pushing shoulder blades away from you as your spine forms a “C” curve in the opposite direction.


2. Side-Lying Thoracic Rotation
• Begin by lying on your left side with knees bent and arms straight out in front of you, palms touching.
• Gently lift your right hand straight up off of the left hand, opening up the arm like it’s a book or door while following the top hand with your head and eyes until your right hand is on the other side of your body, palm up, with your head and eyes turned towards the right.
• Hold this stretch for a few breaths before returning to the starting position with palms facing each other.


3. Child’s Pose with Rotation
• Begin on your hands and knees.
• Spread your knees apart while keeping your toes touching, then gently lower your hips forward towards the ground with arms outstretched in front of you.
• Keep your arms extended forward with palms down on the floor, lengthening the lower back. Hold this pose for several breaths.
• For an added stretch, bring both hands to one side in front of you, lengthening the lats and muscles of the opposite side of your body.
• Repeat by reaching to the other side after a good stretch is felt.


4. Thoracic Extension Over Foam Roller/Chair
• Sit in front of the foam roller, and gently hammock the head with your hands, interlocking the fingers and supporting the weight of your head without pulling it.
• Lean backwards so that your upper back is reaching backwards over the foam roller.
• Gently allow your shoulders to reach towards the floor while the foam roller supports your upper back.
• Carefully lift the hips to roll up and down the muscles of the upper back or move the foam roller up and inch after each stretch, leaning backwards over the roller until a gentle stretch is felt.
• Repeat several times, without forcing your body into discomfort.


5. Sphinx Pose
• Open up the chest and back by lying on the floor and propping yourself up on your forearms.
• As you inhale, gently press your forearms into the floor and lift the head and chest up.
• Draw your shoulders blades down and back and lengthen your tailbone.
• Hold for 30 seconds.

Injuries

Injuries to the latissimus dorsi are rare. They occur disproportionately in baseball pitchers. Diagnosis can be achieved by visualization of the muscle and movement testing. MRI of the shoulder girdle will confirm the diagnosis. Muscle belly injuries are treated with rehabilitation while tendon avulsion injuries can be treated surgically, or with rehab. Regardless of treatment, patients tend to return to play without any functional losses.

Although rare, underdevelopment or absence of the trapezius has been reported to correlate to neck pain and poor scapular control that are not responsive to physical therapy.[9] Absence of the trapezius has been reported in association with Poland syndrome.

If the rhomboid major is torn, wasted, or unable to contract, scapular instability may result. The implications of scapular instability caused by the rhomboid major include scapular winging during scapular protraction, excessive lateral rotation and depression of the scapula, as the antagonistic action by the rhomboid major is absent. With scapular instability, movement in the upper extremity is limited as the scapula cannot guide the desired movement of the arm and shoulders. Pain, discomfort, and limited range of motion of the shoulder are possible implications of scapular instability.

Treatment for scapular instability may include surgery followed by physical therapy or occupational therapy. Physical therapy may consist of stretching and endurance exercises of the shoulder. Pilates and yoga have been also suggested as potential treatment and prevention of scapular instability.