quadratus

Quadratus is a Latin term meaning square or four-sided. In anatomical naming, quadratus is used as an epithet for several muscles that are roughly quadrilateral in shape or have four-sided attachments. The name reflects form rather than a single shared function, and only a few muscles bear the title quadratus in common usage.

Notable examples

Musculus quadratus lumborum is a thick muscle of the posterior abdominal wall. It originates from the iliac crest and iliolumbar fascia, and inserts on the inferior border of the 12th rib and the transverse processes of L1–L4. Its actions include unilateral lateral flexion of the spine and stabilization of the pelvis; bilaterally, it assists in extending the lumbar spine and functions as an accessory muscle of respiration.

Musculus quadratus femoris is a small, flat muscle located in the gluteal region. It originates from the lateral border of the ischial tuberosity and inserts on the intertrochanteric crest of the femur. It serves to laterally rotate the thigh and helps stabilize the hip by gripping the femoral head in the acetabulum.

Musculus quadratus plantae is a muscle of the sole of the foot. It originates from the calcaneus and inserts into the tendons of flexor digitorum longus. By redirecting the pull of the FDL tendons, it assists in flexion of the toes.

Beyond muscles, quadratus appears in other scientific terms to denote square-shaped features in various organisms or structures, reflecting its Latin meaning. The exact usage depends on the anatomical or taxonomic context.