Left psoas major

Musculus psoas major sinister · Levý velký sval bederní

Muscles

Looks like

A long thick muscle beside the lower spine, running from the lumbar vertebrae through the pelvis to the inner top of the thigh bone.

The main hip flexor: lifts the thigh and bends the trunk forward, for example sitting up from lying.

Tight with long sitting; lunges help. Pain on lifting the right leg can signal appendicitis; back pain with fever needs a doctor.