Which is the longest muscle in the human body?

• A. Biceps Brachii
• B. Rectus Femoris
• C. Gastrocnemius
• D. Sartorius

Answer: (D)

Muscle length is determined by the distance between its origin and insertion, and the Sartorius has the greatest span across the body. It begins at the anterior superior iliac spine of the pelvis and travels diagonally down the front of the thigh to the medial surface of the tibia, crossing two joints along a long, slender path. That extensive origin-to-insertion distance makes it—the longest muscle in the human body. It’s a strap-like muscle, so its long course is visually evident on the front of the thigh, and its length is roughly around 40 cm (about 16 inches) in many adults. Other muscles may be long in their fibers or span, but their overall distance from start to end is shorter, which is why they don’t reach the length of the Sartorius.