Orqa miyya balandligi odatda 40–45 sm, 31 segmentdan tashkil topgan: 8 bo'yin (C1–C8), 12 ko'krak (T1–T12), 5 bel (L1–L5), 5 tos (S1–S5) va 1 dumboq (Co1). Bo'yin va bel kengayishi nerv ildizlari uchun moslashgan