The cockroach body is elongated, bilaterally symmetrical and dorso-ventrally flattened, and is triploblastic, eucoelomate and truly segmented. Because its circulatory system is open, its body cavity is filled with blood and is called the haemocoel rather than a plain coelom. The body is glistening brown to reddish-brown and is covered by a hard, non-living, chitin-built exoskeleton that gives strength, elasticity and a surface for muscle attachment; each segment carries four chitinous sclerites — a dorsal tergum, a ventral sternum and two lateral pleura.
The body has three regions — head, thorax and abdomen — joined by a flexible neck (cervix) between head and thorax. The head, formed by the fusion of six segments, bears a pair of antennae (long, jointed, tactile and olfactory feelers seated in antennal sockets), a pair of fenestrae (ocellar spots) at the antennal base, a pair of compound eyes (built of many ommatidia, each forming a partial image that together give a mosaic view), and biting-and-chewing mouthparts around a pre-oral cavity: the labrum (upper lip), a pair of mandibles (true jaws with serrated edges, moved by adductor/abductor muscles), a pair of maxillae (accessory jaws with sensory maxillary palps, also used to groom the antennae/legs), the labium (lower lip with sensory labial palps) and the hypopharynx (tongue, where the salivary duct opens).
The thorax has three segments (prothorax, mesothorax, metathorax), each bearing one pair of walking legs (five podomeres: coxa, trochanter, femur, tibia, tarsus, the tarsus ending in claws plus a clinging arolium) and the meso-/metathorax additionally each bearing one pair of wings — the protective forewings (tegmina) and the true, flight-functional hindwings. Ten pairs of spiracles (two thoracic, eight abdominal) sit along the body sides. The abdomen has ten telescoping segments (terga/sterna), ending in a deeply notched tenth tergum bearing sensory anal cerci; males have a narrower abdomen and an additional pair of anal styles that females lack.