The terms track and tract are commonly mixed up in radiology and medicine (and often English more generally).

Track

In medicine a track refers to a passage formed as something passes through tissue. For example a needle track, the narrow channel formed as a needle is inserted into and withdrawn from tissue, or the path created by an organism such as a parasitic worm. A track is also used when describing the route by which pus exits the body ¹.

Tract

A tract is usually used as an anatomical term referring to:

• a bundle of nerve fibers, e.g. corticonuclear tract

• a series of organs collectively providing a common function, e.g. digestive tract, respiratory tract

• others, e.g. portal tract

Although the meanings of track and tract are distinct, their similar spellings and the fact that they both refer to structurally similar entities means that they have often been confused and now there is a degree of blurring of their usage. So "surgical tract" is now more common than "surgical track", even though the latter is strictly more correct. And other usages such as needle tract are also now commonly seen ^3-6.

The water is also slightly muddied since "sinus tract" is the correct term for the pathologically formed path in some inflammatory conditions, which resembles a fistula but is open at one end only. This can result in the correct yet potentially confusing phrase that "the pus tracks along the sinus tract." The track formed by a fistula is also - correctly - called a fistulous tract.

History and etymology

Despite their superficial similarity in spelling, track and tract have different and unrelated etymologies ⁷. 

"Track" is first recorded in the late 15^th century as a mark left by something, from the Middle French "trac", itself of unclear origin, perhaps a Germanic source. It may be related to the Dutch term "trek" which ultimately gives us the modern English word of the same spelling ⁷.

Conversely, "tract" is derived from the Latin word "tractus" which means - somewhat ironically - track! Tractus comes from the verb "trahere" meaning to pull or draw ⁷.