Musculus psoas minor is a special skeletal muscle. The muscle belongs to the internal musculature of the hip. What is special about the musculus psoas minor is that only some people have the muscle. It is therefore an inconstant muscle, which only about 50 percent of all people possess. In medical literature, the psoas minor muscle is also considered a component of the iliopsoas muscle in some cases.
What is the psoas minor muscle?
The medical name musculus psoas minor roughly means ‘small lumbar muscle’. The psoas minor muscle is a so-called skeletal muscle located in the lower extremity. Specifically, the psoas muscle is located in the anterior layer of the posterior muscles of the hip. Not everyone has the psoas minor muscle. Instead, it is present in only about half of all people. The psoas minor muscle forms a functional unit with the psoas major muscle. This is the large lumbar muscle. Also part of this functional unit is the iliopsoas muscle, the lumbar intestinal muscle. The psoas muscle originates from the twelfth thoracic vertebra as well as the first lumbar vertebra. In this, the psoas muscle has a long tendon that extends to a fascia on the psoas major muscle. In addition, the psoas minor muscle radiates to the arcus iliopectineus. The psoas minor muscle is innervated by the anterior branches of the so-called number one through three lumbar nerves.
Anatomy and structure
The beginning of the psoas minor muscle is located in the body of the twelfth thoracic vertebra and the first lumbar vertebra. The psoas minor muscle has a long tendon that extends into a special muscle band called the fascia iliaca. This muscle bandage surrounds the psoas minor muscle along with the iliac muscle and the large lumbar muscle. As a result, the psoas minor muscle fits into a curved band called the arcus iliopectineus. This ligament is located between the eminentia iliopubica on the pubic bone and the inguinal ligament (medical term ligamentum inguinale). Mammals with four legs also have a psoas minor muscle. This does not originate at the lumbar psoas muscle, but in a tiny bump in the region of the ilium called the tuberculum musculi psoas minoris. The musculus psoas minor is particularly long and narrow and is located near the hip joint. It has a ventral course, which is oriented towards the iliopsoas. Together, the two muscles form the subgroup known as the internal hip muscles. The long tendon of the muscle connects to the eminentia iliopubica as well as the pecten ossis pubis. In addition, there are several connections to the fascia iliaca. The psoas minor muscle is innervated directly by extensions of the lumbar plexus. In principle, the psoas minor muscle is located in the depths of the abdomen. For this reason, it can hardly be felt from the outside. In those people who do not have the psoas minor muscle, a tender ligament or extension of the iliopsoas is found in many cases.
Function and tasks
The tasks of the psoas minor muscle are rather limited. Because it is a very small lumbar muscle that is not present in all people, its importance is not great. On its own, the psoas minor muscle has virtually no effect. It only causes a tilt to the side when tightened on one side, and flexes the lumbar spine when tightened on both sides. However, it works in conjunction with other muscles in the area. Primarily, it supports the ilipsoas muscle. Since the psoas minor muscle is an internal hip muscle, it also stabilizes the pelvis as well as the hip joint. However, its overall contribution to various movements is rather small.
Diseases
Various diseases and disorders are possible in connection with the psoas minor muscle. These differ from person to person in their expression, the severity of symptoms and the individual clinical picture. Psoas minor syndrome, for example, is a condition in which the psoas minor muscle is very rigid and can hardly be moved. In healthy individuals, the origin of the muscle is in the pelvis. In diseased patients, the tendon in many cases extends to the so-called femur. For this reason, it is very susceptible to stronger loads on the part.Often, it is not only the hip that is restricted in terms of movement. The spine can also be affected by poor posture. In addition, the psoas minor muscle is in some cases associated with pain in the lower abdomen. Adolescent females are frequently affected by these complaints. The symptomatology is sometimes classified as appendicitis, when in fact it is psoas minor syndrome. In such a case, the discomfort is easily relieved by cutting the corresponding tendon. Any discomfort or pain originating in the area of the psoas minor muscle should be presented to an appropriate physician as soon as possible. The latter will then initiate appropriate therapeutic measures.
