Latin: Musculus semimembranosus
Definition
The semimembranous muscle is located on the back of the thigh and belongs to the “ischiocrural musculature” located there. It extends from approximately the lower edge of the pelvis to just below the inside of the knee joint, where it attaches to the upper inner shin bone. If the muscle contracts, it bends in the knee joint.
However, it can also be used to stretch the leg in the hip, for example, when the thigh is bent. The semi-membranous muscle bears its unusual name because of its long, broad original tendon. Only well below its origin at the pelvis does the muscle form a strong muscle belly; before that, the muscle with its thin, broad course resembles a “membrane”. The insertion tendon of the muscle at the tibia represents an anatomically famous structure: The appearance of the broad attachment at the upper inner shinbone reminds of a goosefoot, which is why this structure was anatomically named like this, namely as deep-set goosefoot (“Pes anserinus profundus”). On the surface of this foot, tendons of three other muscles form the superficial goosefoot.
History
Embouchure: Inner upper tibia, deep-set goosefoot (Pes anserinus profundus) Origin: cusp of the ischium (Tuber ischiadicum) Innervation: N. tibialis (L5-S2)
Function
Due to its course, the muscle supports movement in both the hip joint and the knee joint. In the hip joint it has the function of an extensor and adductor. An extension in the hip joint occurs, for example, when extending the bent thigh, but also when standing upright.
Adduction is the Latin word for advancement, i.e. the semimembranous muscle can bring the splayed leg back to the body. In the knee joint, the muscle supports flexion (flexion) and inward rotation (internal rotation). In other words, movements in which the lower leg is guided towards the thigh, such as when standing on one leg, or the lower leg is rotated inwards.