Now we’ll move on to look at the groups of muscles which produce adduction, and abduction at the hip. We’ll look at the five adductors first. There are three named adductors, adductors magnus, brevis, and longus; and there are two other muscles which adduct, pectineus and gracilis.
The adducting muscles all arise from this region on the ischium and pubis, and they’re all inserted along this line, the lowest, gracilis, right down here on the tibia. Let’s start with the named adductors.
Here’s the largest of the them, adductor magnus. Adductor magnus arises from the outer border of the ischio-pubic ramus. Its insertion is in two parts, with a gap in between. The upper part of adductor magnus inserts here, on the linea aspera. The lower part inserts here, on the adductor tubercle of the femur.
This gap is the adductor hiatus. The main blood vessels to the leg pass through here, from the front of the thigh, to the back.
The other two named adductors, brevis and longus, sit in front of adductor magnus. Here’s adductor brevis. Here’s adductor longus. Brevis arises here on the body of the pubis, longus arises here. They’re inserted on the femur right next to adductor magnus, brevis above, longus below. The insertion of adductor longus stops just short of the adductor hiatus.
The other two adducting muscles are a short muscle, pectineus, and a very long muscle, gracilis.
Pectineus is the shortest of the adductors. It arises from this line on the superior pubic ramus. It inserts here, just in front of adductor brevis.
Gracilis is the most medial of all the thigh muscles. It arises here on the pubis, and it’s inserted all the way down here, on the tibia.
The main effect of all these muscles, is to produce adduction at the hip joint.
Gracilis is the first muscle we’ve met which crosses both the hip joint, and the knee joint. We’ll be meeting more muscles like it quite soon. A muscle that crosses both the hip, and the knee can either act at the hip, at the knee, or at both joints at once. The movement that it does produce is determined by what other muscle groups are acting at the same time.
For now, when we look at a muscle that goes from above the hip to below the knee, we’ll just look at the way it acts at the hip. In the next section we’ll take a second look at each of these muscles, and see how it acts at the knee.