Semimembranosus Muscle Anatomy & Function

The semimembranosus muscle, a critical component of the posterior compartment of the thigh, plays a pivotal role in the biomechanics of the lower extremity. This article provides an in-depth examination of its anatomy, function, and relevance in orthopedic practice, particularly emphasizing its significance for professionals in the field.

Introduction

The semimembranosus muscle is part of the hamstring group, which also includes the semitendinosus and biceps femoris muscles. Understanding its anatomy and function is crucial for orthopedic professionals in diagnosing and treating lower limb pathologies.

See Also: Biceps Femoris Muscle

Anatomy of the Semimembranosus Muscle

Origin and Insertion

• Origin: The semimembranosus originates from the superior lateral quadrant of the ischial tuberosity.
• Insertion: It inserts primarily onto the posterior surface of the medial condyle of the tibia.

Blood Supply and Innervation

• Blood Supply: It receives blood predominantly from the profunda femoris artery. It’s also supplied by the inferior gluteal artery and the superior muscular branches of popliteal artery
• Innervation: The muscle is innervated by the tibial component of the sciatic nerve.

Function of the Semimembranosus Muscle

The semimembranosus muscle has several key functions:

• Hip Extension: Assists in extending the thigh at the hip joint.
• Knee Flexion: Plays a major role in bending the knee.
• Medial Rotation: It helps in the medial rotation of the tibia on the femur when the knee is flexed.

Orthopedic Assessment and Pathologies

Common Injuries

• Hamstring Strains: Involving overstretching or tearing.
• Tendinopathy: Overuse can lead to inflammation of the tendon.
• Bursitis: Inflammation of the bursae near the semimembranosus insertion.

Diagnostic Tools

• MRI and Ultrasound: For detailed imaging of muscle and tendon structure.
• EMG: Electromyography for assessing muscle function and nerve condition.
• Gait Analysis: To observe biomechanical implications.

Treatment and Rehabilitation Strategies

Conservative Management

• RICE Protocol: Rest, Ice, Compression, Elevation for acute injuries.
• Physical Therapy: Strengthening and stretching exercises.
• Medication: NSAIDs for pain and inflammation management.

Surgical Interventions

• Tendon Repair: In cases of severe tears.
• Arthroscopic Procedures: For associated knee pathologies.
• Muscle Release: In select cases of chronic tightness or contracture.

Rehabilitation and Physical Therapy

• Phase I (Acute Phase): Focus on pain and inflammation reduction.
• Phase II (Recovery Phase): Gradual strengthening and flexibility exercises.
• Phase III (Maintenance Phase): Return to normal function and sports-specific training.

Conclusion

The semimembranosus muscle is an essential component of the hamstring group with significant implications in orthopedic practice. A thorough understanding of its anatomy, function, and pathologies is vital for effective diagnosis, treatment, and rehabilitation of related conditions. Orthopedic professionals must remain updated on the latest research and techniques to provide optimal care for patients with semimembranosus-related issues.

References & More

1. Clinically Oriented Anatomy – 8th Edition
2. Bejui J, Walch G, Gonon GP, Carret JP, Neidhardt JH, Fischer LP. Anatomical and functional study on the musculus semimembranosus. Anat Clin. 1984;6(3):215-23. doi: 10.1007/BF01784316. PMID: 6518115. Pubmed
3. Rodgers CD, Raja A. Anatomy, Bony Pelvis and Lower Limb, Hamstring Muscle. [Updated 2023 Apr 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK546688/