下鼻甲有二块，呈卷曲样，形成鼻腔外侧壁的一部份。他们与上鼻甲及中鼻甲担任相同的功能，允许空气进入肺以前的循环及过滤作用。然而下鼻甲是独立的骨而非筛骨的一部份。

In anatomy, a nasal concha (/ˈkɒnkə/), plural conchae (/ˈkɒnki/), also called a turbinate or turbinal, is a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various animals.The conchae are shaped like an elongated seashell, which gave them their name (Latin concha from Greek κόγχη). A turbinate bone is any of the scrolled spongy bones of the nasal passages in vertebrates.