Foramen lacerum

Foramen lacerum is an irregular opening in the middle cranial fossa. It is bordered by the apex of the petrous temporal bone laterally, and the body of sphenoid bone and the basilar part of occipital bone medially.

During a person’s lifetime, the foramen lacerum is closed by a cartilaginous plug, and no structures completely pass through it to enter or exit the cranial cavity. However, several important structures pass above the foramen lacerum, including the internal carotid artery, the deep petrosal nerve, and the greater petrosal nerve.

The foramen lacerum is located immediately medial to the carotid canal. This allows the internal carotid artery, after entering the cranial cavity through the carotid canal, to pass over the foramen lacerum before it enters the cavernous sinus on both sides of the sphenoid bone.

Within its anterior bony wall, the foramen lacerum contains an opening. This opening is for the pterygoid canal, which connects to the pterygopalatine fossa in the front. It is important to know this because two significant nerves, the deep petrosal nerve (carrying sympathetic neurons from the plexus around the internal carotid artery) and the greater petrosal nerve (carrying parasympathetic fibers), merge in the foramen lacerum to form the nerve of the pterygoid canal, also known as the vidian nerve. The vidian nerve then travels through the pterygoid canal to reach the pterygopalatine fossa.