Foramen lacerum

The foramen lacerum (Latin for lacerated piercing) is a triangular hole in the base of the skull located at the base of the medial pterygoid plate.

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Transit through the foramen lacerum

Several anatomy texts incorrectly state that the internal carotid artery passes through the foramen lacerum. However, in vivo the foramen is actually occluded by cartilage, preventing the artery from passing through. Rather, the internal carotid artery enters the base of the skull through the carotid canal, and travels superiorly to the cartilage occluding the foramen lacerum.

However, some nerves, arteries, and veins do pass through the cartilage plug of the foramen lacerum: the artery of pterygoid canal, the nerve of pterygoid canal, and some venous drainage.

• The nerve of pterygoid canal comprises the deep petrosal nerve and the greater petrosal nerve the former carrying sympathetic fibres and the latter parasympathetic fibres of the autonomic nervous system to blood vessels, mucous membranes, salivary glands, and lacrimal glands.

• Furthermore, one of the terminal branches of the ascending pharyngeal artery (itself a branch of the external carotid artery) passes through the foramen lacerum. This is one of three possible "meningeal branches" of this vessel, the ascending pharyngeal artery.

• Lastly, some emissary veins pass through the foramen lacerum. These connect the extracranial pterygoid plexus with the intracranial cavernous sinus and present an unopposed route for infection.