Canine Cranial Nerves
- Everwell Pets
- Dec 3, 2024
- 4 min read
Updated: Jun 27
Cranial nerves are actually part of the peripheral nervous system (PNS), not the central nervous system (CNS), though they are closely connected to the brain, which is definitely CNS territory.
These nerves pop out from the brainstem and travel to several areas including the dog’s head, neck, and even down into the abdomen. They’re responsible for everything from sensory input (smell, sight, taste, etc.) to motor control (muscles in action) and even regulating things like heart rate.
Cranial nerve function is pretty varied. Some nerves send sensory info—like letting your dog smell that tasty treat or hear a squirrel rustling. Others control motor functions—like moving their ears to track a sound or lifting their muzzle to give a growl. Some are a mix of both. These nerves are essential to your dog’s nervous system and keep everything running smoothly.
The Names and Functions of Cranial Nerves
CN I = Olfactory: Associated with smelling.
Fun fact: ⅓ of a dog’s brain is dedicated to their olfactory sense. This cranial nerve is ground zero for transporting significant information.
CN II = Optic: Associated with seeing.
Your dog’s retinas take in visual information and convey it to the optic nerves. The optic nerve from each eye passes signals to opposite sides of the brain through the Optic Chiasm.
CN III = Oculomotor: Associated with seeing.
This nerve allows for motor function in many of the muscles surrounding the eyes, as they move and focus. The oculomotor nerve also controls the dilation and constriction of dogs' pupils as they respond to light.
CN IV = Trochlear: Associated with muscle or motor movement .
The trochlear nerve operates the muscles that coordinate many eye movements (inward, outward, and downward).
CN V = Trigeminal: Associated with collecting information
The trigeminal nerve is composed of three branches (ophthalmic, maxillary, and mandibular) that make up what is commonly referred to as the Trigeminal System. This system carries both motor and sensory information and is integral when using the muscles of mastication (chewing).
CN VI = Abducens: Associated with eye muscle movement
The abducens nerve controls the lateral rectus and retractor bulbi muscles which is responsible for retraction of the globe which keeps the eyeball in the socket.
CN VII = Facial : Associated with muscle movement and collecting information
This is another nerve that has both motor and sensory nerve fibers. The facial nerve takes information from your taste buds, innervates facial expression muscles, and supplies the glands that make saliva and produce tears.
CN VIII = Vestibulocochlear: Associated with hearing
The vestibulocochlear nerve is composed of two divisions (cochlear and vestibular), which collect information about balance and head orientation, detect vibrations from sounds, and receive hearing signals.
CN IX = Glossopharyngeal: Associated with sensory & motor control of vocal cords
The glossopharyngeal nerve shares information from your external and middle ear, the back area of your tongue, and your sinuses at the back of your throat. Is involved with vocalization and swallowing. This nerve is involved if your dog “gags” after eating or drinking.
CN X = Vagus: Associated with sensory & motor control of major internal organs
The vagus nerve is the longest cranial nerve. It serves both sensory and motor purposes and has a lot of functions, including transmitting information about parts of your dog’s throat (as in laryngeal paralysis), organs in your dog’s chest and trunk, and tastes on their tongue.
CN XI = Accessory: Associated with sensory & motor information of the upper neck
This nerve is also known as the spinal accessory nerve, it allows for movement of a dog’s shoulders, neck, and head, and innervates muscles that help a dog swallow. Along with the vagus nerve, the accessory nerve is involved when a dog is struggling with laryngeal paralysis.
CN XII = Hypoglossal: Associated with motor control of the tongue
This nerve carries only motor information. The hypoglossal nerve makes it possible for your dog to move their tongue around and lap up water.
In Summary
The cranial nerves are an important part of the PNS and these nerves are responsible for controlling various functions, including sensory perception, motor control, and autonomic functions.
Given that chiropractic care is all about functional neurology, if your dog is dealing with any issues related to cranial nerves—or really, any nerve in the body—an adjustment could be a game-changer. Chiropractic care isn’t just about bones being out of place; it’s a specific, specialized way to tap into the nervous system, helping the body do what it does best—heal itself!
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Citations
Dr. Carl DeStefano, Health Pioneers Institute, Module 3 (Cranial-Cervical). 2023