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Pectineus muscle

The pectineus is a flat, quadrangular muscle located at the anterior part of the upper medial thigh. It is one of the primary muscles of the adductor group and also acts as a hip flexor. Due to its dual innervation, it is considered a transitional muscle between the anterior and medial compartments of the thigh. The pectineus is clinically significant because of its involvement in hip flexion, adduction, and as an anatomical landmark for femoral neurovascular structures.

It is situated immediately below the inguinal ligament, forming part of the floor of the femoral triangle, making it important in surgical and radiological anatomy.

Synonyms

  • Hip pectineal muscle

  • Pectineal adductor

  • Medial thigh flexor (pectineus)

Origin, Course, and Insertion

  • Origin:

    • Pecten pubis (pectineal line of the pubis)

    • Superior pubic ramus

  • Course:

    • Fibers run downward, backward, and laterally from the pubis

    • Positioned at the uppermost medial thigh, it lies close to the femoral neurovascular bundle

    • Forms part of the floor of the femoral triangle beneath the femoral vessels

  • Insertion:

    • Attaches into the pectineal line of the femur, extending from the lesser trochanter to the linea aspera

Relations

  • Anteriorly: Femoral artery, femoral vein, femoral sheath

  • Posteriorly: Adductor brevis and obturator externus

  • Medially: Adductor longus

  • Laterally: Iliopsoas tendon and femoral nerve branches

Nerve Supply

  • Primarily by the femoral nerve (L2–L3)

  • May also receive accessory innervation from the obturator nerve (dual innervation is common)

Arterial Supply

  • Medial circumflex femoral artery

  • Obturator artery

  • Femoral artery (contributing branches)

Venous Drainage

  • Venous drainage into the femoral vein and obturator vein

Function

  • Flexion of the thigh at the hip joint

  • Adduction of the thigh

  • Assists in medial rotation of the hip

  • Stabilizes pelvis during standing and locomotion

Clinical Significance

  • Important in groin pain syndromes and sports-related injuries

  • Involved in hip impingement syndromes

  • Serves as a surgical and imaging landmark for femoral triangle approaches

  • May be used as a reference point in femoral nerve blocks

MRI Appearance

T1-weighted images:

  • Muscle shows low-to-intermediate signal intensity

  • Chronic fatty infiltration may appear as bright signal

T2-weighted images:

  • Muscle shows low-to-intermediate baseline signal

  • Acute strain or edema appears as bright signal

STIR (Short Tau Inversion Recovery):

  • Normal muscle low-to-intermediate

  • Inflammation or strain appears as bright hyperintensity

Proton Density Fat-Sat (PD FS):

  • Normal muscle low-to-intermediate

  • Pathological changes appear with bright signal

T1 Fat-Sat Post-Contrast:

  • Normal muscle enhances mildly and uniformly

  • Pathological muscle shows heterogeneous or rim enhancement depending on lesion type

CT Appearance

Non-Contrast CT:

  • Appears as homogeneous soft tissue density

  • Hematomas appear as focal hyperdense areas

  • Chronic fatty changes appear as low-attenuation regions

Post-Contrast CT:

  • Normal muscle enhances mildly and evenly

  • Inflammatory or neoplastic lesions enhance more intensely and heterogeneously

  • Abscess appears as central low density with peripheral rim enhancement

MRI image

Pectineus muscle MRI axial anatomy image-img-00000-00000

CT image

Pectineus muscle ct axial image

CT image

Pectineus muscle

MRI image

Pectineus muscle MRI coronal anatomy image-img-00000-00000