Where is the psoas major muscle

Everyone has certain muscles in their body, but some people's muscles are very obvious, while most people's muscles are not particularly obvious. The main substance that allows the waist to move normally is muscle, and the psoas major is a particularly important muscle on the waist. At the same time, it is unimaginable if there is a problem with the psoas major muscle. The following article will explain to you where the psoas major muscle is mainly located in the human body.

The psoas major muscle is a long muscle located on both sides of the lumbar vertebrae. Most of it is located in the groove between the lumbar vertebral body and the transverse process. The muscle fibers are arranged in a feather-like manner and run outward and downward, forming a spindle-shaped strip of muscle that is thinner at the top and bottom and thicker in the middle.

Anatomy and Function

1. It originates from the sides of the 12th thoracic vertebra, the 1st to 5th lumbar vertebrae and intervertebral discs, and the front and lower edges of all lumbar transverse processes. The muscle bundle merges downward with the iliacus muscle to form a tendon, which passes through the muscle cavity of the inguinal ligament, descends along the front of the iliopectineal protuberance and the anteromedial surface of the hip joint capsule, and ends at the lesser trochanter of the femur.

2. Most of the psoas major muscle is located in the groove between the T12-L4 vertebral body and the transverse process, and its upper muscle fibers can extend to the lowest part of the posterior mediastinum and the back of the diaphragm. Most of the psoas major muscle is connected to the T12-L4 vertebral body and the edge of the intervertebral disc in the form of muscle teeth. The outer part is connected to the transverse process of the T12-L4 lumbar vertebrae, and together with the iliacus muscle, it forms the iliopsoas tendon, passes through the muscle cavity under the inguinal ligament, and ends at the lesser trochanter of the femur on the inner side of the thigh root. The distance between the outer edges of the psoas major muscle in the midsagittal plane is 40-63mm. The L3 transverse process is the longest, and the transverse diameter of the muscle belly here is the widest, which is the area where the psoas major muscle fibers are most concentrated. The T12-L4 intervertebral foramen is located behind the muscle attachment and in front of the lumbar transverse process, from which the lumbar spinal nerves emerge.

3. When nearly fixed, the contraction of this muscle can flex and externally rotate the thigh. When fixed at a distance, one side contracts to bend the trunk to the same side, and the muscles on both sides contract to flex the lumbar spine and bend the trunk forward.

4. Function and exercise: The psoas major and iliacus are collectively called the iliopsoas muscle. The iliopsoas muscle plays an important role in the forward swing of the thigh. Auxiliary exercises such as straight kicking, weighted high-leg running, hanging leg raises, and sit-ups are often used to develop the strength of the iliopsoas muscle. The psoas major is innervated by the muscular branches of the lumbar plexus (T12-L4).