Pectineus
| |
| Pectineus | |
|---|---|
| Muscle Type | |
| Origin | pecten pubis and adjacent superior pubic ramus |
| Insertion | pectineal line of the femur |
| Action | adduct the thigh at the hip |
| Synergists | |
| Antagonists | |
| Spinal innervation | |
| Peripheral Innervation | Femoral Nerve |
| Vasculature | |
The pectineus is a flat muscle of the upper inner thigh that adducts the hip, functioning as a transitional muscle between the anterior and medial thigh
Muscle Type
Pectineus is a short, quadrangular muscle located in the anterior part of the medial thigh. It lies just below the hip crease, forming part of the floor of the femoral triangle. Anatomically, it is often considered a transitional muscle because it shares characteristics of both the anterior compartment (hip flexors) and medial compartment (adductors) of the thigh
Origin
It takes origin from the pecten pubis and adjacent superior pubic ramus (the pectineal line of the pubis) on the anterior pelvis. This bony ridge on the superior ramus gives the muscle its name.
Insertion
Pectineus inserts onto the pectineal line of the femur (a vertical line on the posterior proximal femur just below the lesser trochanter). The insertion spans to the upper linea aspera region of the femur, meaning the muscle attaches between the lesser trochanter and the proximal part of the linea aspera.
Action
Pectineus acts to adduct the thigh at the hip and assists in hip flexion. Due to its position, it can also contribute slightly to medial rotation of the thigh when the hip is flexed. Overall, it helps stabilize the pelvis during gait by steadying the femur.
Synergists
As an adductor, pectineus works with the other medial thigh muscles, including adductor longus, adductor brevis, and adductor magnus, as well as gracilis, to produce thigh adduction. In hip flexion, it functions alongside the iliopsoas and rectus femoris (and to a lesser degree sartorius) to lift the thigh.
Antagonists
The primary antagonists to pectineus are the hip abductors and extensors. Gluteus medius and gluteus minimus (and tensor fasciae latae) oppose thigh adduction by abducting the hip. The gluteus maximus and hamstrings (which extend the hip) counteract the flexion component of pectineus. Spinal Innervation
The spinal segments contributing to pectineus innervation are typically L2 and L3 (and sometimes L4). These fibers originate from the lumbar plexus and provide the muscle’s motor supply.
Peripheral Innervation
The pectineus is usually innervated by the femoral nerve (a branch to pectineus from the femoral nerve’s posterior division). Notably, in some individuals, pectineus receives dual innervation: a portion of the muscle may get a branch from the obturator nerve (anterior division) in addition to the femoral nerve. This dual innervation reflects the muscle’s hybrid function (between anterior and medial compartment).
Vasculature
The blood supply to pectineus comes from the medial circumflex femoral artery and obturator artery. These arteries provide branches that penetrate the muscle. Venous return flows into the femoral vein via corresponding veins.
Clinical Application
Because of its dual innervation in some cases, an isolated pectineus injury or nerve lesion might not completely abolish its function. A femoral nerve injury can weaken hip flexion and adduction, but if the obturator nerve innervates part of pectineus, some adduction strength may persist. The pectineus can be strained in activities requiring quick adduction or flexion (such as sprinting or kicking). Palpation of the muscle (just lateral to the pubic tubercle) can elicit tenderness in groin strains. Strengthening or stretching of pectineus is often addressed in groin rehabilitation protocols to improve stability of the pelvis and coordination of hip flexor-adductor movements.
