The muscles surrounding the spine are positionally located on the dorsal and anterolateral sides of the spine, respectively. They can act on the spine directly or indirectly.
1. Dorsal group: mainly includes the superficial and deep muscles of the neck and back and the gluteus and posterior femoral muscles that act on the pelvis
(1) Superficial layer: all start from the spinous process and end at the upper humerus and ribs to move the upper limbs and ribs. There are rhomboid muscles in the collar and upper dorsal region, and latissimus dorsi in the lower dorsal region. In the anterior part, there are scapularis raphe, rhomboid muscle and upper posterior serratus. In the lumbar region there is the inferior posterior serratus.
(2) Deep: The deep muscles mainly maintain the extension of the spine and are divided into long and short muscles. The long muscles are the splinters and sacrospinous muscles (splinters include cervical splinters, etc.), the former running obliquely outward from the collar ligament and the superior thoracic spine processes. It stops at the occipital bone and the transverse process of the cervical spine. The sacrospinous muscle, also known as the erector spinae, starts from the sacrum and the iliac crest, and is divided into multiple muscle teeth, which can stop at the vertebrae and ribs, and the longest one can reach the occipital bone. The whole muscle can be divided into the lateral iliopsoas muscle, the middle longest muscle and the medial spine muscle. One side of the sacrospinous muscle contraction, so that the spine lateral flexion; bilateral contraction at the same time, so that: the spine posterior extension, head tilt. The short muscles are the transverse spine muscles, which are located deep in the sacral spine and start from the transverse process. It ends at the spinous process inward and upward. From superficial to deep are the semispinalis, multifidus, gyrus and transverse process muscles and interspinous muscles. They allow the spine to extend, rotate and flex laterally. In the deep occipital region, there are suboccipital muscles, including the superior oblique muscle, inferior oblique muscle, posterior major rectus muscle and posterior minor rectus muscle. They can make the head gyrate and tilt back.
(3) Gluteal and posterior femoral muscles: such as gluteus maximus, medius, minimus and semitendinosus, semimembranosus, biceps femoris, etc. They can maintain posterior pelvic tilt.
2.Anterolateral group
(1) Neck: The superficial sternocleidomastoid muscle can indirectly act on the spine. The head is tilted, flexed and turned to the opposite side. The deeper layers are located in the anterior and two lateral sides of the spine. The former are the longissimus dorsi and the longissimus cervicis. They are involved in forward head tilt and forward neck flexion. The latter includes three pairs of oblique muscles: anterior, middle and posterior. They originate from the transverse process of the cervical spine and end at the 1st and 2nd ribs. The anterior oblique muscles may originate from the anterior or posterior nodes of the 3rd-6th cervical vertebrae. Therefore, the 3-6th cervical nerve root travels outward through the beginning of the anterior oblique muscle. When this muscle is tense, it can pull the corresponding spinal nerve root. Conversely, lesions at the spinal nerve roots can also cause tension or even spasm in the anterior oblique muscles.
(2) abdomen: the anterolateral abdominal muscles such as the rectus abdominis, external oblique abdominis, internal oblique abdominis and transverse abdominis, in addition to housing the protection of organs and increasing abdominal pressure, can also make the spine forward flexion, lateral flexion and rotation. The lumbar square muscles of the posterior abdominal wall can also laterally flex the spine.
(3) The iliopsoas muscle, which starts from the lumbar vertebrae and transverse processes, travels outward and downward and ends at the lesser trochanter of the femur, which allows the spine and pelvis to flex forward.
3.Lumbar disorders
(1) Soft tissue strain of the lumbar region
Soft tissue strain of the lumbar region belongs to the category of “lumbago” and “lumbar spinal pain” in Chinese medicine. Common causes are: ① Long-term bending work or poor work posture. The lumbar muscle is stretched for a long time, forming an accumulative strain degeneration. ② Acute lumbar muscle injury is not treated timely or improperly. The injured tissue is not fully repaired and chronic lumbar pain is left behind. ③Lumbar spine congenital or acquired deformity, lumbar trauma, lumbar muscle overexertion or lower limb deformity are also prone to lumbar muscle strain. Under the action of all causes, it first causes traumatic soft tissue inflammatory reaction, and at a later stage, it leads to soft tissue adhesion, fibrosis or scarring depending on the degree of traumatic inflammatory reaction. The result can stimulate or compress the sensory nerve and nutrient blood vessel and lead to low back pain and radiating pain. Clinically, soft tissue strain in the lumbar region actually includes injuries to lumbar muscles, fascia, ligaments, hip joints and other complex tissues.
(2) Myofasciitis of the lumbar region Myofasciitis is also known as fibrofibrillitis
The body is rich in white fibrous tissue such as fascia, tendons, tendon sheaths, muscle membranes, ligaments, periosteum and subcutaneous tissue for a non-specific inflammatory disease. It is mostly caused by wind, cold and dampness, but can also occur due to injury, infection, rheumatic fever or parasitic infection, the former being called primary and the latter secondary. The former is called primary, and the latter is called secondary. The low back and sacroiliac region are the preferred sites.
(3) Injury to the supraspinous and interspinous ligaments
The supraspinous, interspinous and ligamentum flavum are all composed of dense collagenous connective tissue and are important structures of the fibrocartilage. They connect the adjacent bony bodies together. It carries flexibility and flexion to facilitate joint movement. On the other hand, it is strong and firm enough. It can withstand strong tensile forces but cannot be elongated. Therefore, the ligament is susceptible to rupture in acute sprains; it will relax during continuous or intermittent strains. Once the ligament loses its elasticity, it is not easy to restore the original strength.
Supraspinous ligament injury: supraspinous ligament injury is a common and frequent disease among manual workers. If the injury is not treated in a timely and appropriate manner, it often leads to chronic ligament strain and inability to perform heavy work. The supraspinous ligament is a cord-like fibrous tissue on the top of the spinous process of each vertebra. According to statistics, 73% stop at the 4th lumbar vertebra, 22% at the 3rd lumbar vertebra, and only 5% at the 5th lumbar vertebra. Because of this anatomical feature, the lower back is weaker and the most active area. It is reported that 75% of middle-aged people have degeneration of the interspinous ligaments, and because of local trauma, the ligaments are very prone to tear at this location. Under normal conditions. These ligaments are protected from injury by the sacrospinous muscle. When the body is fully bent over to move heavy objects, the sacrospinous muscle is in a relaxed state and the gluteal muscles and posterior thigh muscles are contracted. The lumbar spine is used as a lever to lift heavy objects. The fulcrum is often located in the lumbosacral region, at this time, because there is no sacrospinous muscle protection, so the gravity falls on the ligaments. When the spine is suddenly flexed, it is easy to cause the supraspinous ligaments to tear off from the individual spinous processes. This is particularly common in the lower back and lumbosacral region.
The supraspinous and interspinous ligaments are distributed by the nerve endings of the posterior branch of the spinal nerve and are extremely sensitive tissues. Once injured, they can be transmitted to the center through the posterior branch of the spinal nerve, causing severe low back pain or leg pain although the extent is small.
② Interspinous ligament injury: interspinous ligament both helps the movement between the spine. However, it also gives it some limitation. It is between the adjacent spinous processes and is rectangular in shape, its ventral side is connected to the ligamentum flavum and its dorsal side is fused to the fascia of the dorsal muscles and the supraspinous ligament. These 3 ligaments form a unified body. In daily life, the flexion and extension movements of the back often cause the spinous processes to separate and squeeze and rub against each other. This causes stretching and squeezing of the interspinous ligaments. Daily mechanical friction can cause degeneration.
The interspinous ligament can only undergo different types of rupture and relaxation by external forces based on degeneration. The ligaments contain nerve fibers. It is most sensitive to pain, so ligament rupture or laxity is one of the main causes of lower back pain.
(4) Third lumbar transverse process syndrome
The posterior thickness of the 1st and 2nd lumbar vertebrae is greater than the anterior; the 4th and 5th lumbar vertebrae are the opposite, while the anterior and posterior thicknesses of the 3rd lumbar vertebrae are equal. The transverse processes of the 3rd lumbar vertebra are longer than those of the other 4 lumbar vertebrae, so the pulling leverage of the back muscles is strongest, especially when the transverse processes are asymmetrical from side to side or when the transverse processes are deflected backward. The pull is even stronger when the lumbar vertebrae are bent sideways and twisted. Attached to the transverse process are the deep lumbodorsal fascia and the lumbar square muscles. When these muscles contract unilaterally. The lumbar region can be bent to the ipsilateral front. The transverse process and the musculofascial attachments are injured, resulting in multiple small muscle hernias. It can also cause pain due to muscle contraction and stretching of the sensory branch of the lumbar nerve. This disease is especially common in young adults, and most patients have a history of injury, which is related to the wide range of lumbar activities and weight bearing. This is especially likely to occur when there is frequent bending or sudden twisting and uncoordinated movements.