Which structures are typically injured with a deep laceration just anterior to the masseter muscle?

When a deep laceration occurs just anterior to the masseter muscle, the structures most likely to be injured include the facial nerve, the parotid duct, and the transverse facial artery.

The facial nerve runs close to the masseter muscle as it emerges from the stylomastoid foramen and travels through the parotid gland, giving off various branches that can be affected by trauma in this area. Injury to the facial nerve can result in significant functional impairment of the muscles of facial expression.

The parotid duct, which carries saliva from the parotid gland to the oral cavity, crosses the lateral aspect of the masseter muscle. A deep laceration in this region can easily damage the duct, leading to complications such as salivary fistula or sialocele.

Additionally, the transverse facial artery, a branch of the superficial temporal artery, runs horizontally across the face at the level of the zygomatic bone and can also be at risk during such lacerations.

These anatomical relationships make option B the most appropriate answer, as the injury to these specific structures reflects a common outcome of penetrating trauma in that particular region.