Battle sign is positive if bruise is present in
**Core Concept**
Battle sign is a clinical sign that indicates the presence of a posterior cranial fossa fracture, specifically involving the mastoid process. It is characterized by bruising behind the ear, in the mastoid region.
**Why the Correct Answer is Right**
The mechanism behind Battle sign involves the extravasation of blood into the soft tissues of the mastoid region due to a fracture of the posterior cranial fossa. This typically occurs when a blow to the back of the head causes a fracture of the temporal bone, leading to bleeding into the subperiosteal space. The blood then tracks down to the mastoid region, causing ecchymosis (bruising). The presence of Battle sign is a reliable indicator of a posterior cranial fossa fracture.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the definition of Battle sign.
* **Option B:** This option is incorrect because Battle sign is not a sign of a fracture of the anterior cranial fossa.
* **Option C:** This option is incorrect because Battle sign is not a sign of a fracture of the frontal bone.
* **Option D:** This option is incorrect because Battle sign is not a sign of a fracture of the zygomatic bone.
**Clinical Pearl / High-Yield Fact**
Remember that Battle sign is a valuable clinical indicator of a posterior cranial fossa fracture, which can be a life-threatening injury. Always examine the mastoid region for signs of bruising or swelling in patients with a history of trauma to the back of the head.
**Correct Answer:** C.