Your back is made up of a complex set of bones, discs , nerves , joints, and muscles. The back muscles support the spine, connect the pelvis and shoulders to the trunk, and provide mobility and stability to the trunk and spine.
The anatomy of the back muscles can be challenging. The back is made up of several layers of muscles that are often stretched in different directions.
Understanding the anatomy and function of your back muscles can help you determine if (and when) you might need professional medical care if you have back problems.
Anatomy of the back muscles
Your back is made up of three different layers of muscles, namely the superficial layer, the middle layer, and the deep layer. These layers of back muscles help to mobilize and stabilize the trunk during daily activities. They also attach your shoulders and pelvis to your torso, creating a bridge between your upper and lower body.
The top layer of the back muscles is just under the skin and fascia . Many of these muscles are easy to identify and find just by looking at your body and touching it . The superficial muscles of the back include:
The trapezoid is divided into three different parts: the upper, middle, and lower trapezoid. This muscle originates from the cervical spine and skull, as well as the spinous processes of the cervical spine from the seventh to twelfth thoracic.
The triangular plane muscle then runs along the back of the scapula and attaches to the clavicle , acromion, and spine of the scapula. The innervation of the trapezius comes from the spinal accessory nerve, which is the 11th cranial nerve .
Rhomboid major and minor
Its diamond-shaped bones are formed from the spinous processes of the seventh to the fifth thoracic region. They then join the medial edge of the scapula. Innervation of the rhomboid bodies is through the dorsal scapular nerve.
The lats are the main muscle in the back and the driving force behind the shoulder joint. They originate from the thoracolumbar fascia , the sixth to twelfth spinous process of the thorax, the iliac crest , and the three lower ribs. The muscle is then raised up to the shoulder and attached to the shoulder bone. The latissimus dorsi muscle is innervated through the pectoral nerve.
The middle layer of the back muscles includes the upper and lower posterior dentate muscle. These muscles run from the spine to the ribs and help the diaphragm and intercostal muscles to move the ribs during breathing.
The superior posterior dentate muscle originates from the seventh cervical muscle to the third pectoral muscle and passes to the ribs from the second to the fifth. The serratus posterior inferior muscle originates from the pectoral 11 to the third lumbar level and joins ribs 9 to 12. Both posterior dentate muscles are innervated by intercostal nerves.
The deepest layer of the back muscles is also known as the inner layer and is closest to the spine. The deep layer consists of:
The muscles that erect the spine are long membranous muscles, consisting of the iliocostal, dorsal, and longus muscles. These muscles are derived from a common tendinous origin from the iliac crest, sacrum , lumbar vertebrae, and the sacroiliac and supraspinatal ligaments.
They then run along the spinal column and insert into the ribs, the transverse processes of the vertebrae, and the skull. Innervation of the muscles that straighten the spine is through the posterior branches of the spinal nerves.
Multiple muscles originate from the sacrum, iliac spine, lumbar vertebrae, and transverse processes of the thoracic and cervical vertebrae. Each fiber bundle rises from two to four vertebral levels, joining the superior spinous process. The multifid muscles are innervated by the posterior branches of the spinal nerves.
The quadratic muscle of the lower back, or QL, is the deepest muscle in the back and originates from the iliac crest and inserts into the transverse process of the lumbar spine from first to fifth and to the bottom of twelfth rib. The QL is innervated through the twelfth thoracic nerve and the spinal branches of the lumbar nerves.
Each muscle in the deep, intermediate, and superficial layers consists of pairs; one is on the left and the other is on the right of your body.
The function of the back muscles varies depending on the specific muscle and the stretching direction of each muscle. Many muscles work together; One muscle can provide movement to the joint, while the adjacent muscle provides stability.
For example, the function of the latissimus dorsi muscle is to stretch the shoulder and pull it back. In doing this, the middle and lower traps contract to stabilize the scapula.
Each muscle or group of muscles in the back has a specific function. These functions include:
- Trapeze : Your traps serve to lift your shoulders. The middle and lower trapezius muscles pull the shoulders back.
- Diamond -shaped elements: Diamond- shaped elements are used to retract and stabilize the blades.
- Latissimus dorsi : The latissimus dorsi muscle expands and medially rotates the shoulder bone. They also help stabilize the lower back when the arm is in a fixed loading position.
- Erector spinae muscles: The erector spinae muscles extend the spine by bending it backwards. Acting on one side only, they serve for lateral flexion of the trunk.
- Multifidus muscle: each level of the multifidus serves to stabilize the dorsal segment to which it attaches.
- Quadratus lumborum : QL flexes the spine laterally while contracting from the side. If both square muscles of the lower back are contracted, the spine is extended.
As mentioned earlier, the posterior serratus and inferior serratus muscles assist in the movement of the ribs during breathing.
The back muscles work by stabilizing and moving the spine, trunk, and shoulders. Common back muscle problems or conditions that can cause back pain can include:
Many back muscle problems cause pain or spasms, and most conditions resolve with rest, over-the-counter medications, and mild stretch marks.
If you experience severe pain that prevents you from moving, or if you feel weak, numb, or tingling in your leg or legs, it is recommended that you see a doctor. They can examine you and determine the best treatment for your back problem.
Most episodes of back pain or spasms are short-lived and can be treated conservatively. If you've injured your back muscles, it can help to work with a physical therapist to help you make a full recovery. Your therapist can evaluate your back muscles and determine what treatment is needed for your condition. Treatment may include:
- Stretching Exercises: Exercises to lengthen and stretch your back muscles may include stretching your knees toward your chest or stretching in prayer . These stretches can improve the flexibility and mobility of the spine, allowing for greater freedom of movement.
- Strengthening exercises : Maintaining the strength of your back muscles can help you recover from injuries and prevent future back problems. Exercises to strengthen your back may include a reverse disc, a prone superhuman position, or a prone hip extension .
- Massage – Massage has been shown to improve local blood flow to injured back muscles and can increase the elasticity of tissues, which improves back movement.
- Heat or ice : Heat or ice is often used to stretch the muscles in the back to improve blood flow and relieve pain.
- Bandage : Your physical therapist may apply kinesiology tape to your back muscles to provide biofeedback on the placement of your back muscles. The tape can also support your spine, helping your muscles stay upright.
- Electrical stimulation: Electrical stimulation , such as transcutaneous electrical neuromuscular stimulation (TENS), can be used to relieve pain and spasms in the back muscles after injury.
If your muscular back pain lasts for more than four weeks, you may need a more advanced diagnostic test, such as an X-ray or magnetic resonance imaging (MRI) , to determine the underlying cause of your pain. These diagnostic tests show the anatomy of the bone and soft tissues of the spine and surrounding tissues.
Serious problems, such as sciatica or nerve root compression, may require more invasive procedures, such as steroid injections or spinal surgery. The need for these procedures is rare; most episodes of back pain respond well to more conservative treatment.