From the Guidelines
The gracilis muscle plays a crucial role in adduction of the thigh, flexion of the knee joint, and medial rotation of the leg at the knee. Its primary function is to pull the leg inward toward the midline of the body, and it is also involved in knee flexion and medial rotation. The gracilis muscle is a long, strap-like muscle located on the medial aspect of the thigh, originating from the pubic bone near the symphysis pubis and inserting on the medial surface of the tibia below the knee joint 1. As part of the adductor group of muscles, it works alongside the adductor magnus, adductor longus, and adductor brevis to control movement of the lower limb.
Some key points about the gracilis muscle include:
- It is a hip adductor and knee flexor, making it unique among the adductor group because it crosses two joints (the hip and knee)
- It is particularly important during activities like walking, running, and maintaining balance when standing on one leg
- The muscle receives its innervation from the anterior branch of the obturator nerve (L2-L4)
- In some surgical procedures, such as dynamic graciloplasty, the gracilis muscle is used to encircle the anus and form a new sphincter to treat fecal incontinence, as seen in studies like the one published in Clinical Gastroenterology and Hepatology 1.
The use of the gracilis muscle in surgical procedures highlights its importance and versatility in maintaining various bodily functions, including continence and lower limb movement.
From the Research
Action of Gracilis Muscle
The gracilis muscle is one of the hamstring muscles in the thigh, and its action is primarily related to knee flexion and tibial rotation. The following points summarize the action of the gracilis muscle based on available studies:
- The gracilis tendon is commonly used as an autograft to reconstruct torn tendons or ligaments in many parts of the body 2.
- Gracilis tendon harvesting results in a weakness of knee flexion but does not impair subjective knee function 2.
- Preserving the gracilis tendon in anterior cruciate ligament reconstruction (ACLR) surgery does not have a negative effect on knee flexion and tibial internal rotation strength 3.
- The gracilis tendon can be used as a graft for isolated MPFL reconstruction, but semitendinosus tendon grafts may perform better in selected patients suffering from recurrent patellofemoral instability 4.
- The addition of gracilis harvest to an isolated semitendinosus harvest for ACL reconstruction results in statistically significant, but likely not clinically relevant differences in isokinetic and isometric hamstring strength 5.
- A four-strand gracilis-only construct possesses biomechanical properties comparable to standard grafts, making it a potential option for ACL reconstruction, particularly in patients with partial ACL ruptures 6.
Key Findings
- Gracilis muscle plays a role in knee flexion and tibial rotation.
- Gracilis tendon harvesting can result in weakness of knee flexion.
- Preserving the gracilis tendon in ACLR surgery may not have a negative effect on knee function.
- The choice of graft for MPFL reconstruction may depend on individual patient factors.
- The biomechanical properties of a four-strand gracilis construct make it a potential option for ACL reconstruction.