Exploring The Adductor Muscles
The adductors are a group of five muscles that are important for stabilizing and balancing our pelvis when we’re standing, walking, and running. We previously covered the largest muscle in this group: adductor magnus. In this article, we’ll take a look at the four other adductor muscles.
What are the adductor muscles?
This is a large group of muscles in our thigh. If we include adductor magnus, this group covers about a quarter of the volume of space taken up by muscles in our thigh (Watanabe et al., 2009). The five muscles of the adductor group are: pectineus, adductor brevis, adductor longus, gracilis, and as I mentioned above, adductor magnus.
Where are the adductor muscles?
Muscle attachments
As a group, the adductors weave together to form a fan of muscles on the medial part of the thigh between the quadriceps on the front and the hamstrings on the back. They attach at their superior end to various places along the medial, and posterior aspects of the pubic bone. With the exception of gracilis, each of these muscles attaches at their inferior end to a different point along a bony ridge on the back of the femur called the linea aspera. As you’ll see below, gracilis is the longest in this muscle group. It goes all the way to the tibia before it attaches at its inferior end.
Let’s look at each of these muscle's attachments more specifically. Pectineus attaches superiorly to the superior pubic ramus and inferiorly to the pectineal line. The pectineal line is a bony ridge that extends along the femur from the lesser trochanter to the linea aspera. Adductor brevis attaches superiorly to the inferior pubic ramus and inferiorly to the upper third of the linea aspera. Adductor longus attaches superiorly to the pubic ramus, just laterally to the pubic symphysis. Inferiorly, it attaches to the middle third of the linea aspera of the femur.
Finally, gracilis attaches superiorly to the inferior pubic ramus. It’s unique among the adductors in that it is the only one of the group to cross two joints: the hip joint and the knee joint. This is because its inferior attachment is at the pes anserine of the tibia.
Muscle actions
As a group, all of the adductor muscles contribute to adduction of the thigh at the hip. Additionally, adductor longus, adductor brevis, and pectineus also assist with flexion of the thigh at the hip. Adductor longus and Adductor brevis can assist with medial rotation of the thigh at the hip as well, depending on the position that we’re in. Finally, gracilis, as I said, is the only one of this muscle group to cross the knee joint and the hip joint. So, it can also assist with flexing the knee when the knee is straight and with medial rotation of the lower leg at the knee joint.
It may not be obvious when we do adduction of the thigh at the hip in everyday movements. It’s important to remember that muscles don’t just function to create movement, they also function to control movement. Walking is an example where adduction is a necessary part of a chain of actions to control our movement. While we might not think of adduction right away as part of how we walk, it is part of the connected series of actions in walking. During walking, the adductors’ main action is to work in relation to their antagonists (the abductors) to help stabilize each side of the pelvis as we take a step. The adductors also work in relation to the abductors of each hip to help stabilize our pelvis when we are in a simple standing position.
Conclusion
Although they sometimes get overlooked when we give our attention to our more dynamic thigh muscles like the quadriceps or hamstrings, the adductor muscles are an important group to know. They have a key role in assisting those more dynamic muscles in their actions. They are also critical to maintaining a balanced posture in our lower body in stillness and in movement.
References
Chaitow, L. and J. Delany. 2011. Chapter 11: The Pelvis. In: Clinical Application of Neuromuscular Techniques. Volume 2 - The Lower Body. (Second Edition). Churchill Livingstone Elsevier. New York, NY.
Travell, J.G and D.G. Simons, 1993. Chapter 13: Pectineus Muscle and Chapter 15: Adductor Muscles of the Hip. In: Myofascial Pain and Dysfunction- The Trigger Point Manual. Vol. 2 - The Lower Extremities. Lippincott, Williams, and Wilkins Philadelphia, PA.
