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Functions and anatomy of the pectineus muscle shown with 3D model animation.
Hello everyone! This is Joao from Kenhub, and on this tutorial, we will be looking at the anatomy and functions of the pectineus muscle – the muscle which you can now see isolated on the screen. Before we’ll look at the functions and movements of the pectineus muscle, let’s first look at its anatomy.
As you can see here on the image, the pectineus muscle is a flat, quadrilateral-shaped muscle which extends from the anterior aspect of the pelvis to the posteromedial aspect of your thigh bone or femur. Although sometimes considered to lie within the anterior compartment of the thigh, the pectineus muscle is functionally considered to be one of the adductor muscles of the thigh, which are also known as the hip adductors.
The adductors of the thigh are a group of six muscles which are located in the medial compartment of the thigh along with the obturator externus muscle. The adductor muscles of the thigh are arranged in three layers. The pectineus muscle along with the neighboring adductor longus muscle are the most anterior. Unlike the other adductors of the thigh, the pectineus muscle is innervated by the femoral nerve seen here highlighted in green on this image – the femoral nerve which originates in the lumbar plexus; in this case, specifically, the anterior rami of the second and third lumbar nerves.
I would like to add that the pectineus muscle can also occasionally be innervated by a branch of the obturator nerve. When we isolate the pectineus muscle, we see that it originates from the anterior aspect of the superior ramus of the pubis specifically at the site known as the pecten ossis pubis or pectineal line of the pubis.
The pectineus muscle continues posterolaterally from its origin into a flat long belly before inserting into the femur at the pectineal line of the femur or linea pectinea which runs from the lesser trochanter to the linea aspera.
Now if we look at the attachment sites of the pectineus muscle, we can then now guess the joint is going to be moving while the pectineus muscle is then contracting, and it is, of course, the hip joint which is formed by the head of the femur and the acetabulum.
Now let’s turn our focus to the functions of the pectineus muscle, and as I mentioned before, it is considered to be one of the adductors of the thigh so it’s no surprise that the pectineus muscle is primarily involved in the adduction of the thigh at the hip joint, meaning that it acts on the hip joint to move the thigh medially or towards the midline as you can see now on the screen. An example of this type of movement would be crossing your legs at the knee or ankle.
The pectineus muscle also plays a role producing flexion of the thigh at the hip joint bringing it forward or to the front of your body. And finally, the pectineus muscle is also said to assist in both internal and external rotation of the thigh, which is when you rotate the thigh medially and laterally as shown on the screen now.
I should mention here that the involvement of the pectineus muscle in internal and external rotation of the thigh is not always included by all anatomical sources.
Now, to summarize, the pectineus muscle has two primary functions which happen at the hip joint – that is adduction of the thigh and flexion of the thigh. And then we mentioned that it may assist in internal and external rotation of the thigh as well.
So that’s it for our video of the function of the pectineus muscle. Thanks for using Kenhub today and I will see you next time.