出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/12/22 15:35:11」(JST)
| Psoas major muscle | |
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| Position of psoas major (shown in red) | |
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| The psoas major and nearby muscles | |
| Latin | Musculus psoas major |
| Gray's | subject #127 467 |
| Origin | Transverse processes of T12-L5 and the lateral aspects of the discs between them |
| Insertion | In the lesser trochanter of the femur |
| Artery | lumbar branch of iliolumbar artery |
| Nerve | Lumbar plexus via anterior branches of L1-L3 nerves |
| Actions | Flexes and rotates laterally thigh |
| Antagonist | Gluteus maximus |
| MeSH | Psoas+Muscles |
The psoas major (/ˈsoʊ.əs/ or /ˈsoʊ.æs/) is a long fusiform muscle located on the side of the lumbar region of the vertebral column and brim of the lesser pelvis. It joins the iliacus muscle to form the iliopsoas. In less than 50 percent of human subjects,[1] the psoas major is accompanied by the psoas minor. In mice, it is mostly a fast-twitching, type II muscle,[2] while in human it combines slow and fast-twitching fibers.[3]
The psoas major is divided into a superficial and deep part. The deep part originates from the transverse processes of lumbar vertebrae I-V. The superficial part originates from the lateral surfaces of the last thoracic vertebra, lumbar vertebrae I-IV, and from neighboring invertebral discs. The lumbar plexus lies between the two layers.[1]
Joined by the iliacus, psoas major forms the iliopsoas which is surrounded by the iliac fascia. The iliopsoas runs across the iliopubic eminence through the muscular lacuna to its insertion on the lesser trochanter of the femur. The iliopectineal bursa separates the tendon from the iliopsoas muscle from the external surface of the hip joint capsule at the level of the iliopubic eminence.[4] The iliac subtendinous bursa lies between the lesser trochanter and the attachment of the iliopsoas.[1]
Innervation of the psoas major is through the anterior rami of L1 to L4.
As part of the iliopsoas, psoas major contributes to flexion and external rotation in the hip joint. On the lumbar spine, unilateral contraction bends the trunk laterally, while bilateral contraction raises the trunk from its supine position.[5]
It forms part of a group of muscles called the hip flexors, whose action is primarily to lift the upper leg towards the body when the body is fixed or to pull the body towards the leg when the leg is fixed.
For example, when doing a situp that brings the torso (including the lower back) away from the ground and towards the front of the leg, the hip flexors (including the iliopsoas) will flex the spine upon the pelvis.
Owing to the frontal attachment on the vertebrae, rotation of the spine will stretch the psoas.
Tightness of the psoas can result in lower back pain by compressing the lumbar discs.[6]
|accessdate= requires |url= (help)| This section contains a gallery of images. Galleries containing indiscriminate images of the article subject are discouraged; please improve or remove the section accordingly, moving freely licensed images to Wikimedia Commons if not already hosted there. |
Position of psoas major muscle. Animation.
Close up. Hip bones are shown in semi-transparent.
Anterior view. Still image.
Posterior view. Still image.
Horizontal disposition of the peritoneum in the lower part of the abdomen. (Psoas major labeled at bottom left.)
Right femur. Anterior surface.
Diagram of a transverse section of the posterior abdominal wall, to show the disposition of the lumbodorsal fascia.
The diaphragm. Under surface.
Muscles of the iliac and anterior femoral regions.
The arteries of the pelvis.
The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side.
The thoracic and right lymphatic ducts.
The lumbar plexus and its branches.
Nerves of the right lower extremity. Front view.
Sacral plexus of the right side.
Transverse section, showing the relations of the capsule of the kidney.
Psoas major muscle
Psoas major muscle
Psoas major muscle
| Wikimedia Commons has media related to Psoas major muscles. |
This article incorporates text from a public domain edition of Gray's Anatomy.
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| リンク元 | 「大腰筋」 |
| 関連記事 | 「major」「psoas」「muscle」 |
下肢帯の筋＞:下肢帯の筋
Henry Gray (1825-1861). Anatomy of the Human Body. 1918.