Ciliary Ganglion

Ciliary Ganglion is a parasympathetic ganglion located in the orbit behind the eye. It is part of the autonomic nervous system and plays a crucial role in the innervation of the eye. The ganglion is associated with the control of the pupil and the focusing of the lens.

Structure

The Ciliary Ganglion is a small, triangular structure located in the posterior orbit, lateral to the optic nerve. It contains approximately 2,500 neurons and is connected by several nerves that facilitate its function. The ganglion receives inputs from the oculomotor nerve (specifically, its inferior division), and sends its postganglionic fibers through the short ciliary nerves to the sphincter pupillae and ciliary muscles.

Function

The primary function of the Ciliary Ganglion is to control the pupillary reflex and the accommodation reflex. The pupillary reflex involves the constriction of the pupil in response to light, while the accommodation reflex adjusts the shape of the lens to focus on near objects. These functions are vital for proper vision and eye protection.

Pupillary Reflex

The Ciliary Ganglion receives a preganglionic parasympathetic input from the Edinger-Westphal nucleus via the oculomotor nerve. This input stimulates the ganglion cells, which in turn send postganglionic fibers to the sphincter pupillae muscle of the iris, causing it to contract and the pupil to constrict in response to light.

Accommodation Reflex

For the accommodation reflex, the ganglion also receives signals from the Edinger-Westphal nucleus. The postganglionic fibers innervate the ciliary muscle, changing the shape of the lens to increase its refractive power for focusing on nearby objects.

Clinical Significance

Disorders associated with the Ciliary Ganglion can lead to various ocular symptoms, including abnormal pupillary responses and issues with focusing. Damage to the ganglion or its nerves can result in a condition known as Adie's pupil, where the pupil is dilated and reacts poorly to light. Additionally, an aneurysm or tumor in the orbit can affect the function of the Ciliary Ganglion, leading to ophthalmoplegia or double vision.

See Also

• Autonomic nervous system
• Oculomotor nerve
• Eye anatomy