Quadratus Femoris Muscle: Anatomy, Origin, Insertion, Nerve and Blood Supply, Function, MRI & CT Imaging

Topic

Rectus femoris tendon (Proximal tendon of rectus femoris)

The rectus femoris tendon is the proximal tendinous origin of the rectus femoris muscle, one of the four quadriceps muscles. The rectus femoris is unique among the quadriceps as it crosses both the hip and knee joints, making its tendon especially vulnerable to injury in athletes.

The proximal tendon has two distinct heads of origin: the straight head from the anterior inferior iliac spine (AIIS) and the reflected head from the superior rim of the acetabulum and hip joint capsule. These unite to form a strong tendon that transitions into the muscle belly in the proximal thigh. The rectus femoris tendon is clinically important because proximal avulsions and tendinopathies are common in kicking sports and sprinting.

Synonyms

Proximal rectus femoris tendon
Rectus femoris origin tendon
Straight and reflected head tendon of rectus femoris

Origin and Insertion

Origin:
- Straight head: Anterior inferior iliac spine (AIIS)
- Reflected head: Superior acetabular rim and hip joint capsule
Course:
- The two heads form a conjoined tendon, which continues distally into the muscular belly of the rectus femoris
Insertion:
- The tendon transitions into the rectus femoris muscle belly, which later contributes to the quadriceps tendon, inserting at the base of the patella

Nerve Supply

Femoral nerve (L2–L4)

Arterial Supply

Branches of the lateral circumflex femoral artery
Deep femoral (profunda femoris) artery

Venous Drainage

Femoral vein and profunda femoris vein

Function

Acts as the proximal anchor for the rectus femoris muscle
Contributes to hip flexion (via proximal attachment)
Participates in knee extension as part of quadriceps mechanism
Provides dynamic stability across both hip and knee joints

Clinical Significance

Tendinopathy: Chronic overuse in athletes leads to tendinosis and partial tearing
Avulsion injuries: Common in sprinting, soccer, and kicking sports, often involving the AIIS origin
Reflected head injuries: May mimic intra-articular hip pathology due to acetabular attachment
Surgical relevance: Important landmark during hip arthroscopy and tendon repair procedures

MRI Appearance

T1-weighted images:

Tendon appears as a low-signal (dark) structure at its origin on the AIIS and acetabular rim
Surrounding fat is bright, enhancing tendon visibility

T2-weighted images:

Normal tendon remains low signal
Partial tear, strain, or tendinopathy shows focal bright signal intensity within or around tendon fibers

STIR (Short Tau Inversion Recovery):

Normal tendon: low signal
Pathology (strain, tear, inflammation): bright hyperintense signal in and around tendon

Proton Density Fat-Saturated (PD FS):

Normal tendon: low signal
Pathologic tendon: bright hyperintensity in regions of edema, strain, or partial tear

T1 Fat-Sat Post-Contrast:

Normal tendon: minimal or no enhancement
Pathology: focal or rim enhancement (inflammation, enthesitis, or postoperative changes)

CT Appearance

Non-Contrast CT:

Tendon is not well visualized directly, but its bony origin at the AIIS and acetabulum is well seen
Avulsion injuries appear as bony fragments at the AIIS with surrounding soft tissue swelling

Post-Contrast CT: