The linea aspera (Latin: rough line) is a ridge of roughened surface on the posterior surface of the shaft of the femur.^[1] It is the site of attachments of muscles and the intermuscular septum.

Its margins diverge above and below.

The linea aspera is a prominent longitudinal ridge or crest, on the middle third of the bone, presenting a medial and a lateral lip, and a narrow rough, intermediate line. It is an important insertion point for the adductors and the lateral and medial intermuscular septa that divides the thigh into three compartments. The tension generated by muscle attached to the bones is responsible for the formation of the ridges.

A number of muscles attach to the linea aspera:

• From the medial lip of the linea aspera and its prolongations above and below, the vastus medialis muscle originates.
• From the lateral lip and its upward prolongation, the vastus lateralis muscle takes origin.
• The adductor magnus muscle is inserted into the linea aspera, and to its lateral prolongation above, and its medial prolongation below.
• Between the vastus lateralis and the adductor magnus two muscles are attached:
  • the gluteus maximus muscle inserted above,
  • and the short head of the biceps femoris muscle originating below.
• Between the adductor magnus and the vastus medialis four muscles are inserted:
  • the iliacus muscle and pectineus muscle above;
  • the adductor brevis muscle and adductor longus muscle below.

The linea aspera is perforated a little below its center by the nutrient canal, which is directed obliquely upward.^[1]

• Cross-section through the middle of the thigh.