Somatic Nervous System & Cranial Nerves
We take a lot of our body’s functions for granted, but the simple, profound ability for us to move and sense our surroundings relies on a network of nerves: the somatic nervous system and cranial nerves. Both allow us to move, sense and connect to the world around us. These systems make everyday experiences—like walking, typing, or feeling a gentle breeze—not just possible, but “no brainers.”
In this post, we’ll explore what these systems are, how they work together, and how you can support their health.
Image edit from this NEJM article. No affiliation.
WHAT ARE CRANIAL NERVES?
Cranial nerves are not a distinct system, but a specialized subset of the peripheral nervous system. There are 12 pairs of cranial nerves that connect the brain directly to parts of the head, neck, and torso. Unlike spinal nerves, which branch off from the spinal cord, cranial nerves originate in the brainstem or cerebrum.
These nerves control highly specialized functions, including sight, smell, facial expressions, balance, and digestion. Some cranial nerves even serve dual roles, contributing to both the somatic nervous system (SNS) and the autonomic nervous system (ANS), that is to say voluntary or involuntary actions.
The Cranial Nerves and Their Functions:
Olfactory nerve (CN I): Sense of smell
Optic nerve (CN II): Vision
Oculomotor nerve (CN III): Controls eye movement and blinking
Trochlear nerve (CN IV): Controls eye movement up and down or back and forth
Trigeminal nerve (CN V): Controls facial sensations and jaw movements
Abducens nerves (CN VI): Controls moving your eyes from left to right
Facial nerve (CN VII): Controls facial expressions and taste perception
Vestibulocochlear nerve (CN VIII): Controls hearing and balance
Glossopharyngeal nerve (CN IX): Controls throat sensations and taste perception
Vagus nerve (CN X): Yup, the main nerve of the parasympathetic nervous system. Controls many internal organs, including the heart, lungs, and digestive system, as well as mood and more.
Accessory nerve (CN XI): Controls neck and shoulder movements
Hypoglossal nerve (CN XII): Controls tongue movements, which are important for speaking, swallowing, and breathing
WHAT IS THE SOMATIC NERVOUS SYSTEM?
The somatic nervous system (SNS) is a key part of the peripheral nervous system (PNS), which connects the brain and spinal cord (central nervous system) to the rest of the body. The SNS is responsible for voluntary movement and sensory perception, making it essential for how we interact with the world.
Key Functions of the SNS:
Voluntary Muscle Control: Enables intentional movements, like sipping your morning cuppa or dancing like nobody’s watching.
Sensory Input: Processes information from your skin, muscles, and joints, including touch, pain, and proprioception (your sense of body position).
Fun fact: All senses except vision are processed through the SNS.
Reflex Actions: Manages protective reflexes, like pulling your hand away from something hot (or from your bestie’s hand swatting you away from her last piece of chocolate)!
HOW DO THE SOMATIC NERVOUS SYSTEM AND CRANIAL NERVES WORK TOGETHER?
The SNS and cranial nerves collaborate to allow for movement, sensory perception, and communication between the brain and body. Together, they create a seamless experience of the world around us. Like having great Wi-Fi, a 4K picture, and surround sound makes for a better movie watching experience.
Movement and Motor Coordination
The SNS directs voluntary movements through spinal nerves, while cranial nerves specialize in localized actions like turning your head (accessory nerve, CN XI) or speaking (hypoglossal nerve, CN XII).
Sensory Integration
Sensory neurons in the SNS relay information from your skin, muscles and joints, while cranial nerves transmit input from specialized sensory organs like the eyes (optic nerve, CN II) and nose (olfactory nerve, CN I).
This collaboration allows you to feel your kitten’s soft fur while admiring the colors of her coat.
Reflexive Protection
Reflexes involving cranial nerves, such as blinking (oculomotor nerve, CN III) or wincing in pain or sympathy (trigeminal nerve, CN V), work with the SNS to protect your body from harm.
Touching a hot surface activates an SNS reflex, while cranial nerve reflexes might produce tears to protect your eyes.
Body Awareness and Balance
Proprioception is managed by the SNS, while the vestibulocochlear nerve (CN VIII) handles balance. Together, they help you stay upright or explain why you feel off-balance on a rocking boat.
ACTIONABLE TIPS TO SUPPORT YOUR SNS & CNs
Caring for your nervous system is essential for maintaining movement, sensation, and overall health. Here are actionable tips:
Move: The old adage “move it or lose it” holds true. Regular physical activity stimulates your nervous system to maintain health and create new neural connections. Go for walks, have a morning dance party, engage in Tai Chi, or lift weights—any movement counts!
Sense: Engaging your senses invigorates your body, mind, and spirit. Visit new places, taste new foods, or listen to live or new music. Bonus: noticing and savoring these experiences can trigger a dopamine hit, enhancing your mood with gratitude and joy.
Connect: Hug your friends, pet your fur babies, sing, smile at your barista, or even make silly faces at yourself in the mirror. These activities activate the SNS, engage your cranial nerves, and foster deeper connection with yourself and the world around you.
Notice: Pay attention to your posture, ergonomics, and even your resting expressions. Supporting your nervous system starts with aligning your body and reducing strain from unsupportive habits.
A personal example of this was when I noticed I was scowling and leaning forward while I was driving. Realizing this gave me the awareness to relax, sit back and let the road come to me, rather than trying to be somewhere before I was. Noticing is another way to be aware, and be present.
Nourish: Eat well to live well. Incorporate foods rich in B vitamins, magnesium, and omega-3s to support nerve health and optimal function. If you want to evaluate your nutrition status, book an appointment: we can review your lifestyle & order some labs.
Heal: Therapeutic practices can promote balance and recovery:
Craniosacral therapy (CST): Supports nerve health and encourages overall balance.
Physical therapy: Retrains muscles and neural pathways after injury.
Acupuncture: Balances the body and chi, promoting nervous system harmony.
Massage: Provides a safe, therapeutic way to relax and engage in healthy, boundaried touch.
The somatic nervous system and cranial nerves work in harmony to help you move, sense, and connect to the world. From protecting you with reflexes to enabling joyful experiences like dancing or hugging a friend, these systems are integral to your well-being.
Take a moment to marvel at how seamlessly your nervous system connects you to the world around you. By supporting its health, you nurture your ability to move, sense, and thrive. Next time, we’ll journey deeper into the brain, exploring its remarkable regions and uncovering how they shape our thoughts, moods, and movements.
What's coming:
The Somatic Nervous System & Cranial Nerves
Brain Regions and Their Roles in Thought, Mood, and Movement
How the Nervous System Impacts Mental Health & Trauma Recovery
Craniosacral Therapy - Enhancing Nervous System Balance
Are there specific areas of the nervous system you're curious about? Drop a comment below, and I'll be sure to cover them as we journey through this incredible body-wide network!
