## Core Concept
The adductor canal, also known as Hunter's canal, is an aponeurotic tunnel in the middle third of the thigh, extending from the apex of the femoral triangle to the opening in the adductor magnus, the adductor hiatus. It contains vital structures that pass from the anterior compartment of the thigh to the posterior compartment.

## Why the Correct Answer is Right
The adductor canal contains several important structures including the femoral artery and vein, and the saphenous nerve. The **saphenous nerve** is a branch of the femoral nerve and provides sensory innervation to the medial aspect of the leg. The femoral vessels (artery and vein) pass through the canal.

## Why Each Wrong Option is Incorrect
* **Option A:** The femoral artery is indeed a content of the adductor canal, making it an incorrect choice for the exception.
* **Option B:** The femoral vein also passes through the adductor canal alongside the femoral artery, which rules it out as the correct exception.
* **Option C:** The saphenous nerve, a terminal branch of the femoral nerve, traverses the adductor canal, providing it as an incorrect option for the exception.

## Why Option D is Correct
* **Option D:** The **obturator nerve** primarily runs through the obturator canal, not the adductor canal. It provides motor innervation to the medial thigh muscles (adductor longus, brevis, and magnus, and obturator externus) and sensory innervation to the medial thigh.

## Clinical Pearl / High-Yield Fact
A key clinical correlation is that the adductor canal can be a site for femoral vessel injury, particularly in cases of penetrating trauma or iatrogenic injury during procedures like femoral line placement.

## Correct Answer: D. obturator nerve