Facial nerve paralysis can result from injecting into which structure during an infraorbital block?

Facial nerve paralysis can result from injecting into which structure during an infraorbital block?

• A. Parotid gland
• B. Submandibular gland
• C. Lacrimal gland
• D. Gingival tissue near canine

Answer: (A)

The key idea is that the facial nerve runs through the parotid gland and gives the facial muscles their motor control. If an injection for an infraorbital block is made deep enough or high enough to enter the parotid gland, the local anesthetic can spread to the facial nerve branches within the gland and temporarily block their function. That blockade produces facial paralysis on the same side because the nerve has not yet left the gland to supply those muscles. The lacrimal gland is primarily involved with tear production and receives parasympathetic fibers from the facial nerve, but injecting near it wouldn’t produce the motor facial paralysis seen with nerve branches in the parotid. The submandibular gland lies lower in the face and isn’t traversed by the infraorbital block pathway, so injecting there wouldn’t typically cause facial nerve paralysis. The gingival tissue near a canine is along the intended path of an infraorbital block to anesthetize the infraorbital nerve, and must be avoided deep into the gland to prevent diffusion to the facial nerve.

The key idea is that the facial nerve runs through the parotid gland and gives the facial muscles their motor control. If an injection for an infraorbital block is made deep enough or high enough to enter the parotid gland, the local anesthetic can spread to the facial nerve branches within the gland and temporarily block their function. That blockade produces facial paralysis on the same side because the nerve has not yet left the gland to supply those muscles.

The lacrimal gland is primarily involved with tear production and receives parasympathetic fibers from the facial nerve, but injecting near it wouldn’t produce the motor facial paralysis seen with nerve branches in the parotid. The submandibular gland lies lower in the face and isn’t traversed by the infraorbital block pathway, so injecting there wouldn’t typically cause facial nerve paralysis. The gingival tissue near a canine is along the intended path of an infraorbital block to anesthetize the infraorbital nerve, and must be avoided deep into the gland to prevent diffusion to the facial nerve.