Which combining form is used to represent the ulna in anatomical terms?

The combining form that represents the ulna in anatomical terms is "uln/o." This specific form is derived from the Latin word for ulna, which refers to the bone located in the forearm on the side opposite to the thumb, running parallel to the radius. In medical terminology, combining forms typically consist of a root word plus a vowel, making it easier to connect it to other terms when constructing medical language.

For instance, in terms like "ulnorrhaphy" (surgical repair of the ulna), the "uln/o" component clearly indicates the focus on the ulna bone. This form is essential for clarity and precision in anatomical descriptions and procedures involving the arm.

The other options represent different anatomical or physiological concepts: "trich/o" pertains to hair, "ur/o" relates to urine or the urinary system, and "tympan/o" refers to the eardrum (tympanic membrane). Each of these forms serves its specific context, but they do not pertain to the ulna, highlighting why "uln/o" is the correct choice.