Sartorius muscle The Sartorius muscle is a long, slender, and superficial muscle in the anterior compartment of the thigh. It is the longest muscle in the human body. Name origin: Sartorius originated from the Latin word ‘Sartor’, meaning tailor. It got its name because of its function and position, as its action produces the cross-legged sitting posture traditionally used by tailors when sewing. Therefore, it is referred to as the tailor’s muscle. ANATOMY: Image Created By: Malathi Proximal Attachment: Sartorius proximally attaches to the anterior superior iliac spine (ASIS) of the pelvis and then runs obliquely across the length of the anterior thigh. Distal attachment: Distally, it attaches to the anteromedial aspect of the proximal tibia as a part of the pes anserine tendon along with the gracilis and sartorius. Nerve innervation: The sartorius gets its innervation from the Femoral nerve(L2, L3, L4). Blood supply: Arterial supply for the sartorius is through the branches of the femoral artery, such as the deep femoral artery, the lateral circumflex artery and muscular branches. The venous drainage is through the femoral vein, which drains into the external iliac vein. Function Sartorius is a two-joint muscle that crosses both the hip and knee joints, so it has a function in both. Concentric (shortening) action: Standard mover action (distal attachment moving towards proximal) 1. At the Hip joint: Sartorius produces flexion, abduction and lateral rotation of the femur at the hip joint, as if crossing one leg over the other. 2. At the Knee joint: Sartorius crosses the knee joint posteromedially, so it flexes and medially rotates the leg at the knee joint. The combined action of the sartorius at the hip and knee joints will produce a crossed-leg sitting posture (sewing posture). Thus, the name “Tailor’s muscle”. Since it is a slender muscle with a small cross-sectional area, it is not a prime mover in hip and knee movements. However, due to its multijoint attachment, it facilitates smooth, multiplanar movements with control and precision. Reverse mover action (proximal attachment moving towards distal) When the femur is fixed, the sartorius pulls the ASIS inferiorly, causing anterior pelvic tilt. It also causes contralateral rotation of the pelvis. At the knee joint, it causes flexion and lateral rotation of the thigh. Eccentric (lengthening) action: When the sartorius contracts eccentrically, it controls and slows down hip extension, adduction and medial rotation. Also, it controls posterior pelvic tilt. In the knee joint, it restrains the extension and lateral rotation of the tibia. Isometric function: Sartorius helps stabilise the pelvis and hip when it contracts isometrically. The distal attachment of sartorius, along with gracilis and semitendinosus (Pes Anserine tendon), provides medial stability to the knee joint, preventing against valgus stress. Axis and plane: The sartorius is oriented in the oblique plane and has one line of pull, producing a combination of movements in the hip and knee joints. What is the purpose of your sartorius muscle? The primary purpose of the sartorius is to facilitate a smooth gait, control multi-directional movement, provide medial knee joint stability, and coordinate complex, multijoint movements, such as cross-leg sitting. Common injuries: The sartorius is a slender yet versatile muscle that contributes to many of the everyday lower limb activities, such as walking, running, and crossing one's legs. However, being versatile also makes it vulnerable to injuries. As it crosses two major joints, the hip and knee, and coordinates multiplanar movements, it is prone to getting overloaded or injured, which may lead to significant functional limitations. Sartorius strain or intramuscular rupture Overstretching or tearing of the sartorius muscle fibres is referred to as Sartorius strain, and an intramuscular rupture is a more severe form involving partial or complete disruption of the muscle belly. Causes: It occurs when the muscle eccentrically controls a forceful hip extension and knee flexion during sprinting or kicking. However, it is uncommon for sartorius muscle strain to occur in isolation, as it is often associated with ASIS avulsion, rectus femoris strain, or pes anserine overload.Symptoms: Sudden, sharp, pulling pain in the front and inner thigh, which worsens with hip flexion, abduction, or knee flexion. Tenderness, swelling or bruising along with a painful gait. Pes anserine tendinopathy: Pes anserine tendinopathy is the tendinopathy of the conjoined tendons of sartorius, gracilis and semitendinosus that results from overuse-related inflammation or degeneration. Causes: Repetitive knee flexion or overuse (such as running, cycling, or stair climbing), dynamic knee valgus, being overweight or obese, diabetes or metabolic changes that affect tendon quality, and poor lower-limb biomechanics. Symptoms: It presents as medial knee pain commonly in runners, cyclists, obese individuals, and those with diabetes. ASIS avultion: ASIS avulsion occurs when the sartorius contracts suddenly, pulling off a part of the bone. Causes: Sudden, forceful contraction of the sartorius during explosive hip flexion, e.g. sprint starts, kicking, or jumping. It usually occurs in adolescent athletes whose growth plates have not yet fused. It is common in sports like football, running, and gymnastics Symptoms: Sudden sharp pain over the front of the hip or pelvis, swelling and tenderness at the ASIS, pain on hip flexion or abduction and difficulty in walking