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Human back

life science Maturity 9-11 Next article →

The human back, or dorsum, is the large posterior area of the body. It extends from the top of the buttocks to the back of the neck. This area is the surface opposite the chest and abdomen. The back is essential for supporting the head and the trunk. It also provides strength and a great deal of flexibility.

Labled diagram of the muscles of the human back
Labled diagram of the muscles of the human back

The width of the back is defined by the shoulders and the pelvis. At the top, the scapula, or shoulder blades, create the breadth. The vertebral column runs the entire length of the back. This column creates a central area of recession in the body.

The central feature of the back is the vertebral column. This structure houses the spinal cord within a spinal canal. It consists of different types of vertebrae that give the back its shape. The thoracic vertebrae are located in the upper part of the spine. Below these are the lumbar vertebrae, which make up the lower back. The ribcage extends from the spine starting at the T1 vertebra. This ribcage covers more than halfway down the length of the back. This leaves a specific area with less protection between the ribs and the hips.

Muscles in the back are organized into three distinct groups. The superficial group is also called the appendicular group. These muscles, such as the trapezius and latissimus dorsi, move the appendicular skeleton. The intermediate group is known as the respiratory group. This group includes the serratus posterior superior and inferior muscles. They may serve a function related to breathing.

Labled diagram of the muscles of the human back
Labled diagram of the muscles of the human back

The third group is the deep group, or intrinsic group. These muscles originate within the back itself. They are divided into four subgroups: spinotransversales, erector spinae, transversospinales, and segmental muscles.

The deep muscles provide vital stability and movement. The spinotransversales include the splenius capitis and splenius cervicis. The erector spinae group consists of the iliocostalis, longissimus, and spinalis. The transversospinales group includes the semispinalis, multifidus, and rotatores. Finally, the segmental muscles include the levatores costarum, interspinales, and intertransversarii. These muscles are innervated by the posterior rami of spinal nerves. This differs from the superficial and intermediate groups, which use the anterior rami. This complex layering allows for both strength and intricate movement.

Movement in the back depends on the specific section of the spine. The upper back offers the most structural support. This is because the ribs are attached firmly to each level of the thoracic spine. Consequently, the upper back has very limited movement. In contrast, the lumbar vertebrae in the lower back allow for much more flexibility. This area permits extension, which is bending backward, and flexion, which is bending forward. However, the lower back does not permit twisting movements.

Edgar Germain Hilaire Degas 029
Edgar Germain Hilaire Degas 029

Several important organs are located near the back. The lungs sit inside the ribcage and extend toward the back. This allows doctors to listen to them through the back. The kidneys are situated beneath the muscles in the lower back area. They sit below the end of the ribcage and connect loosely to the peritoneum. Because of this position, a strike to the lower back can damage the kidneys.

Scourged back by McPherson & Oliver, 1863, retouched
Scourged back by McPherson & Oliver, 1863, retouched

The skin on the back is also unique. It is thicker and has fewer nerve endings than skin on the rest of the torso.

Back pain is a very common medical condition. It is the second most common type of pain in adults, following headaches. The most frequent cause of this pain is muscle strain. While intense, these muscle injuries can usually heal within a few weeks. Other causes include disc problems like a lumbar disc herniation. People may also experience degenerative disc disease or osteoarthritis. Other issues include fractures, such as spondylolisthesis or an osteoporotic fracture.

Thai tattoo Chiang Mai 2005 058
Thai tattoo Chiang Mai 2005 058

The back also holds significant cultural meaning. In art, the curvature of the back is a frequent theme. Artists like Edgar Degas have used the back in their paintings.

Edgar Germain Hilaire Degas 029
Edgar Germain Hilaire Degas 029

Because the back is large and has relatively little hair, it is a popular canvas for tattoos. Some people have tattoos that cover the entire back. Additionally, the back is used in many English idioms. Phrases like "watch one's back" or "having someone's back" highlight the area's perceived vulnerability or strength.

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🖼️ Images & Media (4)
File:Labled diagram of the muscles of the human back.svg
Labled diagram of the muscles of the...
File:Edgar Germain Hilaire Degas 029.jpg
Edgar Germain Hilaire Degas 029.jpg
File:Scourged back by McPherson & Oliver, 1863, retouched.jpg
Scourged back by McPherson & Oliver,...
File:Thai tattoo Chiang Mai 2005 058.jpg
Thai tattoo Chiang Mai 2005 058.jpg
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