Parasympathetic (Craniosacral) Division

Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system, blue fibers). Most are small terminal ganglia or intramural ganglia, so named because they lie near or within (respectively) the organs they innervate. 

The exceptions are the four paired parasympathetic ganglia of the head and neck. These paired ganglia supply all parasympathetic innervation to the head and neck: ciliary ganglion (spincter pupillae, ciliary muscle), pterygopalatine ganglion (lacrimal gland, glands of nasal cavity), submandibular ganglion (submandibular and sublingual glands), and otic ganglion (parotid gland).

Nerve innervation of the autonomic nervous system

The parasympathetic nervous system, shown in blue, is a division of the autonomic nervous system. 

This is a diagram that shows the nerve innervation of the autonomic nervous system. The sympathetic fibers are shown as red lines in their places on the spinal cord. The parasympathetic nervous system, a division of the autonomic nervous system, is shown as blue lines that connect a particular organ to the spinal cord.

Each has three roots entering the ganglion (motor, sympathetic, and sensory roots) and a variable number of exiting branches. 

1. The motor root carries presynaptic parasympathetic nerve fibers (general visceral efferent fibers) that terminate in the ganglion by creating a synapse for the postsynaptic fibers traveling to target organs. 
2. The sympathetic root carries postsynaptic sympathetic fibers (general visceral efferent fibers) that traverse the ganglion without creating a synapse. 
3. The sensory root carries general sensory fibers (general somatic afferent fibers) that also do not create a synapse in the ganglion. 

Some ganglia also carry special sensory fibers (special visceral afferent) for taste sensation.

The nerves that supply parasympathetic fibers to the parasympathetic ganglia of the head include the oculomotor nerve (ciliary ganglion), the facial nerve (pterygopalatine ganglion, submandibular ganglion), the glossopharyngeal nerve (otic ganglion), the vagus nerve, and the pelvic splanchnic nerves.

Because of its location, the parasympathetic system is commonly referred to as having craniosacral outflow, in contrast to the sympathetic nervous system, which is said to have thoracolumbar outflow.

Parasympathetic ganglia of the head

The parasympathetic division has craniosacral outflow, meaning that the neurons begin at the cranial nerves (CN3, CN7, CN9, CN10) and the sacral spinal cord (S2–S4). Pre- and post-ganglionic fibers and targets are depicted. 

This is a diagram of the parasympathetic ganglia of the head. It shows how the cranial and sacral nerves innervate the eyes, nose, and mouth.