The greater petrosal nerve (or greater superficial petrosal nerve) is a
nerve
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...
of the head mainly containing pre-ganglionic parasympathetic fibres
which ultimately synapse in the
pterygopalatine ganglion.
It branches from the
facial nerve (CN VII) and is derived from the parasympathetic part of the
nervus intermedius component of CN VII, with its cell bodies located in the
superior salivary nucleus.
In the connective tissue substance of the
foramen lacerum, the greater petrosal nerve unites with the (
sympathetic)
deep petrosal nerve to form the
nerve of the pterygoid canal (vidian nerve) which proceeds to the pterygopalatine ganglion.
It forms part of a chain of nerves that provide secretomotor innervation to the
lacrimal gland
The lacrimal glands are paired exocrine glands, one for each eye, found in most terrestrial vertebrates and some marine mammals, that secrete the aqueous layer of the tear film. In humans, they are situated in the upper lateral region of each o ...
and mucosal glands of nasal cavity and palate.
Structure
Origin
Parasympathetic component
Preganglionic
parasympathetic fibres arise in the
superior salivary nucleus of the
pontine tegmentum. They join with general somatic sensory and special sensory fibres to form the
nervus intermedius. The nervus intermedius exits the cranial cavity at the
internal auditory meatus, and joins with the motor root of the facial nerve at the
geniculate ganglion. While preganglionic parasympathetic fibres pass through the geniculate ganglion, they neither synapse, nor have their cell bodies located there.
Preganglionic parasympathetic fibres exit the geniculate ganglion as the greater petrosal nerve.
Gustatory sensory component
The greater petrosal nerve also conveys some special sensory nerve fibres which carry gustatory (taste) sensory information from the
palate that are relayed to the pterygopalatine ganglion by the
lesser palatine nerves and are in turn conveyed to the geniculate ganglion by the greater petrosal nerve to synapse in the ganglion.
Course
The greater petrosal nerve enters the
petrous part of the temporal bone
The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three ...
and travels anteromedially through it at a 45° angle. It emerges into the
middle cranial fossa upon the anterosuperior surface of the bone
through the
hiatus for greater petrosal nerve alongside the
petrosal branch of the
middle meningeal artery
The middle meningeal artery (') is typically the third branch of the maxillary artery#First portion, first portion of the maxillary artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum t ...
.
In the middle cranial fossa, the nerve is situated between the two layers of the dura mater
and passes obliquely anterior-ward
along a groove upon the floor of the fossa
- the ''groove for the greater petrosal nerve'' - that is situated upon the anterosuperior aspect of the
petrous part of the temporal bone
The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three ...
and anteromedial to the
arcuate eminence, and adjacent and parallel to the
lesser petrosal nerve and its own groove.
The nerve passes deep to the
trigeminal ganglion to reach the
foramen lacerum.
At the foramen lacerum, it unites with the (sympathetic)
deep petrosal nerve, forming the
nerve of the pterygoid canal (which continues anterior-ward through the
pterygoid canal to reach the
pterygopalatine fossa and form the
pterygopalatine ganglion).
Clinical significance
During surgery of the middle cranial fossa, manipulation of the dura mater may damage the greater petrosal nerve,
causing bleeding
or swelling at the geniculate ganglion; this can compress the facial nerve and cause facial paralysis.
Additional images
File:Gray789.png, Course and connections of the facial nerve
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of ta ...
in the temporal bone
The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex.
The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bone ...
.
File:Gray841.png, Sympathetic connections of the sphenopalatine and superior cervical ganglia.
File:Head lateral gr petrosal nerve.jpg, Head lateral gr petrosal nerve
File:Autonomic Innervation to the Lacrimal Gland (and other glands of the deep face).svg, Depicts nerve branches that are involved in the autonomic innervation of the lacrimal gland
The lacrimal glands are paired exocrine glands, one for each eye, found in most terrestrial vertebrates and some marine mammals, that secrete the aqueous layer of the tear film. In humans, they are situated in the upper lateral region of each o ...
. The terminal parts of the pathway are variable between individuals and differ for the other glands of the deep face.
References
External links
* ()
University of Michigan Medical School "Dissector Answers - Ear and Nasal Cavity"
{{Authority control
Facial nerve
Cranial nerves
Otorhinolaryngology