Pectineus Muscle Anatomy

Location & Overview

The pectineus muscle is somewhat small, flat, and quadrangular-shaped. It is located in the medial (inner) portion of the superior (upper) thigh. This muscle belongs to the hip adductor group of muscles, which also includes the adductor brevis, adductor longus, adductor magnus, and gracilis. The pectineus muscle is unique because it is the most superior of the adductor muscles. It is also one of the few muscles in the body that can be innervated by two different nerves.^[1,2]

The pectineus muscle is located between the iliopsoas and adductor longus muscles anteriorly, and the obturator externus and adductor brevis muscles posteriorly. It is also deep and medial to the sartorius muscle. This location puts the pectineus muscle in a position to contribute to the complex functions of the hip joint.^[2]

Origin & Insertion

The pectineus muscle originates from the pectineal line of the pubic bone. The pectineal line of the pubic bone is a ridge located anteriorly on a section of the pubic bone called the superior ramus. The superior ramus is above the large O-shaped opening in the hip bone, called the obturator foramen. The picture below shows the origin on the pectineal line of the pubic bone.^[3,2,4]

From the pectineal line of the pubic bone, the muscle fibers of the pectineus travel diagonally and laterally, extending toward the femur. It then reaches its insertion on the pectineal line of the femur. The pectineal line of the femur is a bony ridge that runs obliquely along the upper part of the medial surface of the femur, just inferior to the lesser trochanter. The lesser trochanter is a small, bony prominence on the posterior aspect of the femur, specifically at the junction of the neck and the shaft of the femur. The picture below shows the insertion point on the pectineal line of the femur.^[3,2,4]

Action & Function

The pectineus muscle plays an important role in movements involving the hip joint. The pectineus muscle’s primary actions are to facilitate adduction and flexion of the hip joint.^[5,3,4]

To visualize these movements, consider the action of bringing your leg inward toward the center of your body; this is hip adduction. Now imagine the action of lifting your knee toward your chest while standing; this is hip flexion. Contraction of the pectineus muscle contributes to both of these actions.

In addition to hip adduction and flexion, there is ongoing research into the role of the pectineus in rotation of the femur.^[6,7] Studies suggest that the pectineus may provide a supportive role in maintaining dynamic stability during rotation. Furthermore, due to the muscle’s attachment on the medial side of the femur, it is hypothesized that the pectineus may provide a small degree of internal rotation when the femur is externally rotated, or provide a small degree of external rotation when the femur is internally rotated. However, more research is needed to determine conclusively whether the pectineus directly contributes to rotation of the femur. If it does contribute to rotation, its contribution would be minimal compared with other primary external and internal rotators of the hip joint. Presently, the consensus points more toward the pectineus acting as more of a stabilizer during rotational movements of the hip joint, rather than directly causing the rotation.

Innervation

The pectineus muscle is primarily innervated by the femoral nerve, with occasional contributions from the obturator nerve.^[1]

The femoral nerve, the largest branch of the lumbar plexus, originates from the dorsal divisions of the second, third, and fourth lumbar nerves (L2, L3, L4). It descends posterior to the psoas major, running between this muscle and the iliacus. It then passes beneath the inguinal ligament and enters the femoral triangle, an area in the upper thigh. Here, it divides into two main branches: anterior and posterior. The anterior division provides nerve supply to the pectineus and iliacus muscles, among others.^[2,3]

Occasionally, the obturator nerve also provides innervation to the pectineus. This nerve begins at the lumbar plexus and descends alongside the iliopectineal line, traversing the fibers of the psoas major muscle. Upon emerging from the medial border of the psoas major near the pelvic brim, it continues posterior to the common iliac arteries, descending toward the obturator canal. The obturator nerve then exits the pelvis through the obturator canal, making its way toward the medial thigh where it can innervate parts of the pectineus.^[2,3]

It is important to note that the pattern of innervation can vary among individuals, with some having slightly different configurations than the typical pattern described here.^[1]

Blood Supply

The pectineus muscle receives its blood supply primarily from the obturator artery and occasionally the medial circumflex femoral artery.^[8,2,3]

The obturator artery usually originates from the anterior division of the internal iliac artery. This origin is located in the lower pelvic region. The obturator artery then travels toward the obturator canal, an opening in the pelvic bone, to reach the inner thigh area. The obturator artery provides blood to a number of muscles in this region, including the pectineus.^[2,3]

Additionally, the pectineus muscle can receive blood supply from the medial circumflex femoral artery. This artery originates from the deep femoral artery (also known as the profunda femoris), which is a major branch of the femoral artery in the thigh. The medial circumflex femoral artery curves around the posterior aspect of the femur, where it supplies blood to various muscles of the hip and thigh, potentially including the pectineus muscle.^[2,3]

It is important to bear in mind that the exact pattern of blood supply can vary among individuals. Some people have slightly different vascular configurations than the pattern described above.