Origin and Insertion
- Origin (O): Arises from the pectineal crest of the pubic bone, also known as the pectineal line of the pubis (pecten ossis pubis).
- Insertion (I): Inserts into the pectineal line of the femur (linea pectinea). This line is located on the posterior aspect of the proximal femur, extending from the lesser trochanter (trochanter minor) to the linea aspera (linea aspera).
Function
- Adduction: Adducts the thigh at the hip joint.
- Flexion: Assists in flexion of the thigh.
- Rotation: Weakly contributes to medial rotation of the thigh.
Blood Supply and Innervation
- Blood supply: Supplied by the obturator artery (a. obturatoria), deep artery of the thigh (a. profunda femoris), and the femoral artery (a. femoralis).
- Innervation: Shows anatomical variability. Most commonly, the muscle receives dual innervation from branches of the femoral nerve (n. femoralis) and the obturator nerve (n. obturatorius).
Topography and Neighboring Structures
- Floor of the femoral triangle: M. pectineus forms part of the floor of the femoral triangle. It lies medially, while the iliopsoas muscle (m. iliopsoas) lies laterally to it. Together, they form the iliopectineal fossa (fossa iliopectinea), situated deep to the fascia lata.
- Relationship to vessels: Within the femoral triangle, the femoral artery (a. femoralis) lies anterior to the pectineus and long adductor muscles, covered anteriorly by fascia and the sartorius muscle.
- Deep relations: Deep to the pectineus muscle lie the adductor brevis muscle (m. adductor brevis) and the obturator externus muscle (m. obturatorius externus).
- Vascular pathways: The deep branch of the medial femoral circumflex artery (r. profundus a. circumflexae femoris medialis) passes through the gap between m. pectineus and m. obturatorius externus, subsequently dividing into ascending and descending branches.
- Obturator canal: The pectineus muscle covers the external opening of the obturator canal (canalis obturatorius), located at the upper border of the obturator externus muscle. Surgical exposure of the canal requires retraction or incision of the pectineus.
Clinical Significance
- Muscle strength testing: In neurological examinations, the strength of the pectineus muscle, along with the iliopsoas, sartorius, and quadriceps femoris, is graded using the MRC (Medical Research Council) scale to detect paresis in mononeuropathies.
- Spread of infection: In the formation of deep abscesses originating from the anterior 'weak spot' of the hip joint (located between the iliofemoral and pubofemoral ligaments), pus may spread via a medial pathway. It extends from beneath the medial margin of m. iliopsoas between the pubic bone and the pectineus muscle into the medial fascial compartment of the thigh.