Middle

In anatomy, "middle" is a directional (positional) term meaning situated between two other structures neither at one extreme nor the other, but in an intermediate position along a given axis.

It's typically used in two ways:

• As a relative positional descriptor between two named structures e.g., the middle cerebral artery lies between the anterior and posterior cerebral arteries; the middle phalanx sits between the proximal and distal phalanges.

• As part of a compound anatomical name identifying a structure's location within a three-part division of an organ or region e.g.:

  • Middle ear (between the outer and inner ear)

  • Middle lobe of the right lung (between the superior and inferior lobes)

  • Middle meningeal artery

  • Middle constrictor muscle (of the pharynx)

  • Middle cranial fossa (between the anterior and posterior cranial fossae)

It's distinct from other positional terms like medial (toward the midline of the body) "middle" refers to a position within a sequence or series of three, not necessarily to proximity to the body's midsagittal plane, though the two can sometimes coincide.