Throughout the body, there are nerve structures called ganglia. They are generally found at the roots of nerves and protected by a layer of connective tissue. Some nerve ganglions are near organs; others located in the head and neck help to control various functions of muscles and glands in the face. The otic ganglion is a small oval structure that sits below the foramen ovale, a space in the sphenoid bone at the base of the skull. Filaments from the ganglion link to a muscle near the inner ear, and to nerves that go to the jaw and side of the head.
The otic ganglion is generally about 0.14 to 0.18 inches (about 3.5 to 4.5 mm) long and about 0.1 inches (about 3 mm) wide. It is one of four such structures in the neck and head, which also include the ciliary, peterygopalatine, and submandibular ganglia. With each, there is a network of motor roots that end within them, as well as sympathetic and sensor roots that organize the various nerve fibers that pass through. Some fibers for this ganglion are made of material that comes from tissue near the middle meningeal artery, a branch of an blood vessel that leads from the carotid artery.
Electrical signals from the otic ganglion are transmitted through a network of fibers. Some come from a structure called the glossopharyngeal nerve, while parts of the ganglion connect to neuron groups that lead to the parotid glands. These are large salivary glands inside the jaw and below each ear. Another fiber goes from the ganglion to a nerve called the pterygoid canal.
One of the main branches of this structure goes to the tensor tympani, a muscle that connects to the malleus bone in the middle ear. Sounds from chewing are dampened by this muscle. Another branch leads to a thin muscle called the tensor veli palatine, which controls the soft palate. The two parts that reach toward the middle ear and soft palate stretch in two different directions. Many of the extensions, however, reach other areas via different nerves.
Anatomic details about the otic ganglion have generally been determined by dissecting cadavers. There are several connections between it and other nerves and tissues, and variations from one person to another are sometimes seen. The location of the ganglion in relation to other nerves and anatomical structures is often important to know in surgical medicine as well as in dentistry.