Sneak Peek of the Sartorius Muscle Lesson: Anatomical Atlas of the Lower Limb

The Sartorius muscle is a long, thin, and uniquely complex structure within the anterior compartment of the thigh. As the longest muscle in the human body, often exceeding 50 cm, it presents both clinical significance and technical challenges during therapeutic neuromodulator injections, particularly for those managing spasticity in the lower limb.

In the Anatomical Atlas of the Lower Limb Related to Neuromodulator Injections and Management of Spasticity (available now through the Myoguide Academy) you’ll find a lesson on the Sartorius muscle that outlines its anatomy, functional role, and injection considerations. This article is a sneak peek into this lesson. 

 

Anatomy & Function

The Sartorius originates at the anterior superior iliac spine (ASIS) and inserts at the proximal medial surface of the tibia, forming part of the Pes Anserinus with the Gracilis and Semitendinosus tendons. It crosses both the hip and knee joints, allowing it to act on both.

Key actions include:

• Flexion, abduction, and lateral rotation of the thigh at the hip
  
• Flexion of the leg at the knee
  
• Assisting in internal rotation of the knee
  

Its role in these compound movements means the Sartorius does not function in isolation. It works synergistically with muscles like the Rectus Femoris, Tensor Fascia Latae, and Gluteal muscles, and opposes structures like the Quadriceps and Biceps Femoris, depending on the action involved.

Clinical Relevance in Neuromodulator Injection

The Sartorius muscle may require neuromodulator treatment in cases of spasticity involving the hip or knee. However, its slender shape, length, and superficial location make it a muscle that demands precision.

The Sartorius lesson guides users through:

• Patient Positioning: Supine, with slight hip flexion
  
• Muscle Activation: Engage the muscle via hip/knee flexion and rotation movements
  
• Needle Insertion: Needle is inserted 5–10 cm distal to the ASIS along a line toward the medial femoral epicondyle, lateral to the femoral artery
  
• Needle Length & Depth: 20–40 mm; typically 1–3 cm deep, depending on patient anatomy
  
• Number of Injections: 1–2
  

Injection Considerations

Due to its proximity to critical structures like the femoral artery, iliacus, Tensor Fasciae Latae, and femoral nerve, injections must be performed with anatomical awareness and safety precautions. Identification of the femoral artery and inguinal ligament prior to injection is essential.

As the lesson highlights, the Sartorius is difficult to inject due to its slender form and varied trajectory. The lesson provides both textual guidance and access to an interactive 3D-anatomical model to visualize and isolate the muscle before clinical practice.

Explore the Full Course

The Anatomical Atlas of the Lower Limb is designed to support therapeutic injectors, especially physiatrists and specialists treating spasticity, with evidence-informed guidance on lower limb muscles frequently targeted with neuromodulators.

Want more lessons like this?
Join the Myoguide Academy and explore the full Anatomical Atlas of the Lower Limb Related to Neuromodulator Injections and Management of Spasticity course.

Start learning today and deepen your confidence in anatomical injection planning. Courses are $225 CAD for three months of access and can be found in the Myoguide Academy Course Catalog.

Enroll in the course now: here.