Opistho-

Opistho- (from the Greek opisthen - “behind”, “back”) is a prefix used in anatomical and medical terminology to designate structures located behind or posterior to other structures.

For example:

1. Opisthocephalus is a congenital anomaly in which the child's head is turned backward.

2. Opisthotonus is a convulsive muscle tension in which the torso bends backward in the form of an arc.

3. Opisthorchiasis is a helminthiasis caused by parasitic trematodes of the genus Opisthorchis.

4. Opisthenar is one of three elevations on the palmar surface of the hand, located at the base of the little finger.

Thus, the prefix opistho- is used to designate structures located posterior or posterior to other anatomical structures.