What Are the Muscles Behind Your Back Called?

Your back muscles are made up of superficial, intermediate, and intrinsic layers that support the mobilization and stabilization of your trunk. Additionally, they join your pelvis and shoulders to the trunk, bridging the gap between your upper and lower body.

Superficial muscles

Superficial back muscles help you move your arms and shoulders and keep your spine straight:

• Trapezius: The upper, middle, and lower trapezius start at your neck and extend across your shoulders. The flat, triangular muscle attaches to your clavicle, acromion, and scapular spine at the rear of your shoulder blade. The spinal accessory nerve, or cranial nerve XI, innervates the trapezius.
• Major and minor rhomboids: Your rhomboids start from the spinous processes of cervical 7 to thoracic 5. After that, they join the medial scapular boundary and are innervated by way of the dorsal scapular nerve.
• Latissimus dorsi: Latissimus dorsi comes from the thoracolumbar fascia, the spinous processes of the thoracic 6 through 12, the iliac crest, and your lower three ribs. The muscle then joins to the upper arm bone and travels up to your shoulder. The thoracodorsal nerve supplies the latissimus with its innervation.

Intermediate muscles

The intermediate muscles are made up of the serratus posterior superior and inferior. These muscles run from your spinal column to your ribs and help your diaphragm and intercostal muscles move the ribs as you breathe.

• The serratus posterior superior starts from cervical 7 through thoracic 3 and extends to ribs 2-5.
• The inferior serratus posterior starts from thoracic 11 through lumbar level 3 and joins to ribs 9-12. 

Intrinsic muscles

Also referred to as the deep layer of the back muscles, the intrinsic muscles are located closest to the spine.

• Erector spinae: These are made up of the iliocostalis, spinalis, and longissimus muscles. The iliac crest, sacrum, lumbar vertebrae, sacroiliac, and supraspinous ligaments have a tendinous origin with these muscles. When they reach the top of your spine, they extend to your ribs, skull, and transverse processes of the vertebrae. The posterior rami of the spinal nerves are how the erector spinae are innervated.
• Multifidus: Your sacrum, iliac spine, lumbar vertebrae, and the transverse processes of your thoracic and cervical vertebrae are the sources of your multifidus muscles. Two to four vertebral levels up, each bundle of fiber ascends before joining to the spinous process. The posterior rami of spinal neurons supply the innervation for the multifidus muscles.
• Triple lumborum: The deepest back muscle, the quadratus lumborum (QL), starts from the iliac crest and goes to the transverse processes of lumbar vertebrae 1-5, as well as the bottom portion of rib 12. Thoracic nerve 12 and spinal rami of the lumbar nerves both innervate the QL.

Your back muscles each have different functions, and many of them work in sync with one another; one muscle may move a joint, whereas another muscle nearby offers support.

Each muscle group serves a specific purpose:

• Trapezius: Supports your shoulder blades and allows you to move your arms
• Rhomboids: Stabilize and retract your shoulder blades
• Latissimus dorsi: Medially rotates and lengthens your upper arm bone and maintains the stability of your lower back when your arm is fixed in a weight-bearing posture
• Erector spinae: Allows your spine to bend backward and cause your trunk to flex laterally when they only act on one side
• Multifidus: Stabilizes the spinal segment to which it is attached

When the facet joints or other bony regions of your spine are injured or inflamed, the strong muscles in your back may unintentionally tighten (spasm).

Chronic stress can cause your muscles to contract, depleting the energy required to maintain the spine's upright position. Tight muscles at the back of the thighs can also shift the pelvis, impairing the mobility of the spine.

Back pain can also occur if core muscles are weakened due to poor posture, lack of physical activity, and obesity.

Conditions that can lead to or aggravate back pain include:

• Overexertion
• Posture-related fatigue 
• Disk herniation
• Age-related disk degeneration
• Arthritic spine
• Spondylolisthesis
• Sciatica
• Being overweight

Many back muscle issues result in pain or spasms. In most cases, back pain can be relieved with rest, over-the-counter medication, and simple stretches.

Contact a doctor if you experience severe pain that keeps you from moving or if you feel weakness, numbness, or tingling in your legs.

In most cases, back pain can be treated conservatively with rest, over-the-counter medication, and simple stretches. Your therapist can evaluate the state of your back muscles and decide what treatments are required. Treatments may include:

• Stretching: The knees to chest stretch and prayer stretch can help lengthen and stretch your back muscles, improving the flexibility and mobility of your spine.
• Exercises: Strengthening your back muscles can speed up recovery from back injuries and prevent future back problems. 
• Massage: Deep tissue massage can promote tissue extensibility and increase local blood supply to damaged back muscles.
• Ice or heat: Back muscle strains are often treated with ice or heat application to increase blood flow and reduce pain.
• Taping: To offer biofeedback on the placement of your back muscles, your physical therapist may tape them with kinesiology tape. The tape can also support your spine, which will make it easier for your muscles to maintain proper posture.
• Electrical stimulation: After an injury, electrical stimulation, such as transcutaneous electrical neuromuscular stimulation, may be used to reduce pain and spasms.

If your muscular back pain persists for longer than 4 weeks, you may need to undergo more complex diagnostic procedures such as an X-ray or magnetic resonance imaging to identify the underlying source of your pain. 

More invasive procedures such as spinal surgery or steroid injections may be necessary for severe conditions such as sciatica or nerve root compression.

• Improve flexibility: Ask your doctor about stretches that can make your back muscles more flexible. Maintaining flexibility can help you loosen up tense muscles and prevent injuries.
• Use proper lifting techniques: Lift using your legs and hips and avoid twisting your trunk. While lifting heavy objects, keep them as close to your body as possible.
• Maintain a healthy weight: Back strains are more likely to occur if you are overweight. Talk to your doctor about the ideal weight for your body.
• Strengthen your core: Focus on developing your core muscles, since these support your spine. 
• Warm-up before exercising: Before working out, make sure to warm up properly. Muscles that are warm and flexible are less likely to get injured. When you are exercising, pay attention to your body and stop if you feel pain.