Which muscle is used to reinforce mouth closure in embalming by cavity fluid injection?

• A. Pectoralis major
• B. Masseter
• C. Temporalis
• D. Orbicularis oris

Answer: (D)

The mouth is closed most reliably by a muscle that forms a ring around the lips. The orbicularis oris acts as a sphincter around the mouth, and when it contracts, the lips come together and seal the oral opening. In embalming with cavity fluid injection, this seal helps prevent leakage and produces a natural appearance after closure. The other muscles listed aren’t suited for this purpose: the masseter and temporalis are involved in chewing and jaw movement, which doesn’t provide controlled lip closure, and the pectoralis major is a chest muscle unrelated to the mouth. So, the orbicularis oris is the muscle best used to reinforce mouth closure.