The Social Nervous System
Feeling more connected in the body is at the core of Craniosacral Therapy. When we feel safe with the connections in our body, we have more choice in how we move and relate to other people. Important neurological relationships have been recognised by Prof Stephen Porges in how our bodies respond to stress. Porges’ ‘Polyvagal Theory & the Social Nervous System‘ is a model I work with on a daily basis in clinical practice so I would like to share a few highlights from his work here.
In Polyvagal Theory, Porges discusses some of the evolutionary differences between humans and other animals in adapting to our environment and coping with stressful and threatening situations. For humans, he suggests there is a three-tier hierarchy of responses to stress, I’d like to focus on the first response, Communication or the Social Nervous System:
Porges’ three-tier hierarchy of responses to stress
- Communication – using negotiation, social skills, vocalisation, listening and facial expression to resolve the stressful situation through social relationships (Social Nervous System)
- Mobilisation – fight/flight, energy is mobilised to defend or escape from the threat physically (Sympathetic Nervous System)
- Immobilisation – freeze response, body systems (digestion, respiration, movement) slow or shut down ie ‘playing dead’ (Parasympathetic Nervous System)
Mammals (especially humans) have developed the ability to use their social networks and skills to find safety from threats in their environment. In humans, this has deepened further with the complex social structures and behaviours that we use to ‘be’ safe and importantly, to ‘feel’ safe. In times of stress or threat, mammals will move to a mobilisation response to escape/fight if communication is ineffective. If this response is overwhelmed, the mammal will immobilise until the threat is gone (as in this freeze response video). Non-social animals like fish and repitles only have mobilisation and immobilisation responses.
In his model of the Social Nervous System, Porges describes the neurological features of humans that allow us to respond through social engagement. He highlights the relationships between the Cranial Nerves (CN) of the Autonomic Nervous System (ANS), and includes the CNs in the neck, the throat, the face and the middle ear.
How does the Social Nervous System enables us to respond to stress?
ANS – (CN X vagus nerve) heart and breathing rates are slowed down while we assess if a situation is threatening. If there is no threat, both rates return to ‘normal’. If there is a threat, the heart and breathing rates are fine-tuned to enable a social response (see throat, face, ears section), as we need different ways of breathing for speaking than for running, fighting or playing dead. Humans differ from other animals in that 80% of the nerves to our hearts are sensory with a high proportion of these covered in a protective myelin sheath meaning the nervous impulses are far more sensitive to give a more controlled response. Another difference is that some of the nerves feedback to the nucleus ambiguus, a cluster of nerve tissue found in the brain stem of humans but not found in non-social animals like fish and reptiles.
Neck – (CN XI accessory nerve) the trapezius and sternomastoid muscles are activated, enabling us to turn our heads to orient towards a potential threat and also to members of our group to engage socially (see below).
Throat, Face & Ears – (CN V trigeminal, VII facial & IX glossopharyngeal nerves) In the throat, swallowing and vocal prosodyare adjusted so that we can give a specific vocal response to stress, eg a rousing scream or a soothing whisper. Muscles of the face and jaw help with the articulation and pronunciation of words as well as facial expression, the movement of the muscles around the eyes are particularly important in social engagement and communication. One of the most interesting connections that Porges has made is the passage of the facial nerve through the muscles of the middle ear which enable us to attune to sounds so that we can distinguish the human voice from background noise. Facial expression is hard-wired into the recognition of the human voice.
The Social Nervous System can be affected by stress, dental work, surgery, shock & trauma, ear problems and developmental conditions such as Autism to name but a few. Mobilisation and immobilisation are vital responses for survival, however, our lives and relationships are much richer when we have the option to respond socially. As a Craniosacral Practitioner, the Social Nervous System plays an important role in deepening the health and wellness of clients on a regular basis, whether I’m working with the jaw and face, the temporal bones and structures around the ear, autonomic ganglions along the spine or facilitating relaxation in the body. Holding the intention that our face, ears and voice are intimately connected to our hearts can add deeper meaning and feeling to the interactions in our personal relationships.
