Semimembranosus – Attachments, Actions & Innervation

Author: Scott A. Sheffield MS

Last update:

The semimembranosus is the largest of the hamstring muscles and is located on the posterior thigh region.

image descriptionSemimembranosus

Posterior view of the thigh and gluteal region with semimembranosus highlighted. Labelled muscles: gluteus medius, tensor fasciae latae, gluteus maximus, gracilis, iliotibial tract (band), semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Posterior view of the thigh and gluteal region with semimembranosus highlighted. Labelled muscles: adductor magnus, gracilis, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Posterior view of the thigh and gluteal region with semimembranosus highlighted. Labelled muscles: semimembranosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Posterior view of the thigh and gluteal region. Labelled muscles: semimembranosus.
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image descriptionAttachments of Semimembranosus: Origin & Insertion

Origin: (proximal attachments)
a.Ischial tuberosity of os coxa.

Insertion: (distal attachments)
a.Posterior medial condyle of tibia.

Posterior view of the thigh and gluteal region with semimembranosus highlighted. Labelled muscles: gluteus medius, tensor fasciae latae, gluteus maximus, gracilis, iliotibial tract (band), semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Posterior view of the thigh and gluteal region with semimembranosus highlighted. Labelled muscles: semimembranosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Posterior view of the thigh and gluteal region. Labelled muscles: semimembranosus.
Posterior view of the thigh and gluteal region. Origin and insertion of semimembranosus labelled.
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Actions of Semimembranosus on the leg (tibia & fibula):

a. image descriptionFlexes leg at knee.

b. Medially rotates leg at knee when knee is flexed.

Retain your knowledge on semimembranosus anatomy with this handy lower limb muscle anatomy reference chart.

c. It also extends thigh at hip.

Nerve to Muscle and its Spinal Segment:

a.Tibial (nerve) portion of sciatic nerve (L5, S1, S2).

An Overview of the Posterior Muscles of the Thigh:

Test yourself image 1, posterior view of thigh and gluteal region showing all superficial muscles with no labels.
Test yourself image 2, posterior view of thigh and gluteal region, all superficial muscles and structures labelled- gluteus medius, tensor fasciae latae, gluteus maximus, gracilis, iliotibial tract (band), semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 3, posterior view of thigh and gluteal region. Muscles and structures labelled- gluteus medius, tensor fasciae latae, quadratus femoris, adductor magnus, gracilis, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 4, posterior view of thigh and gluteal region. Muscles and structures labelled- gluteus medius, piriformis, quadratus femoris, adductor magnus, gracilis, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 5, posterior view of thigh and gluteal region. Muscles and structures labelled- gluteus minimus, piriformis, quadratus femoris, adductor magnus, gracilis, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 6, posterior view of thigh and gluteal region. Muscles and structures labelled- piriformis, quadratus femoris, adductor magnus, gracilis, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 7, posterior view of thigh and gluteal region. Muscles and structures labelled- piriformis, adductor magnus, gracilis, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 8, posterior view of thigh and gluteal region. Muscles and structures labelled- adductor magnus, gracilis, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 9, posterior view of thigh and gluteal region. Muscles and structures labelled- adductor magnus, semimembranosus, semitendinosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 10, posterior view of thigh and gluteal region. Muscles and structures labelled- adductor magnus, semimembranosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 11, posterior view of thigh and gluteal region. Muscles and structures labelled- semimembranosus, biceps femoris: short head, biceps femoris: long head, gastrocnemius.
Test yourself image 12, posterior view of thigh and gluteal region. Muscles and structures labelled- semimembranosus, biceps femoris: short head, biceps femoris: long head.
Test yourself image 13, posterior view of thigh and gluteal region. Muscles and structures labelled- semimembranosus, biceps femoris: long head.
Test yourself image 14, posterior view of thigh and gluteal region. Muscles and structures labelled- semimembranosus.
Test yourself image 15, posterior view of thigh and gluteal region. Origin and insertion of semimembranosus labelled.
Test yourself image 16, posterior view of skeleton of thigh and gluteal region.
Test yourself while observing the Semimembranosus muscle
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