anterior

Anterior is an anatomical directional term used to describe a position toward the front of the body or toward the ventral surface in humans. It is the opposite of posterior (toward the back) and, in non-human animals, is often interpreted as toward the head end. In humans, the terms anterior and ventral are commonly used synonymously, but the mapping between terms shifts in quadrupedal anatomy, where anterior points toward the head and ventral toward the belly. The word comes from Latin anterior, meaning front or before.

Usage and examples include the naming of structures and approaches in medicine, such as the anterior chamber of the eye, the anterior horn of the spinal cord, and the anterior pituitary. An anterior approach to surgery or a procedure means access from the front. The anterior surface of an object is its front-facing surface; for example, the anterior surface of the tooth is the surface facing the lips.

Developmentally, the anterior-posterior axis describes the head-to-tail organization that guides tissue differentiation in embryos. Signaling pathways such as Sonic hedgehog, Wnt, and BMP establish regions along this axis, guiding regional identity and structure formation.

Other notes: In neuroscience, rostral is often used similarly to anterior for brain structures; however rostral and anterior are not always interchangeable in all contexts. Anterior remains a standard term in anatomy and clinical practice to describe location relative to the body's front.