Let us begin with some basic anatomy of the ribcage. In order to allow oxygen into the body, the ribs have to expand on the inhalation and then relax on the exhalation. However not all ribs move in the same way. The most well-known analogy to describe this mechanism is that the upper ribs move in a similar way to a ‘pump handle’ and the lower ribs like a ‘bucket handle’. This means that the upper ribs elevate themselves in a vertical plane and the lower ribs expand in a slightly more horizontal plane. All joints require a degree of muscular involvement to move and this is where posture and breathing are interrelated. Breathing muscles can be put into two categories – primary and accessory. In a nutshell, an over activation and dependence on the accessory muscles of breathing is what can lead to poor posture.
The accessory muscles are called the sternocleidomastoid, scalenus anterior, medius, and posterior, pectoralis major and minor, the inferior fibres of serratus anterior and latissimus dorsi, the serratus posterior anterior and iliocostalis cervicis. To put it more simply the muscles around the front and side of your neck, the upper chest and beneath the shoulder blade are where to find the accessory muscles of breathing. It is important to note that the main function of these muscles is not to allow you to breathe, rather it is to create movement in the neck and shoulders. The only time that these muscles should be activated to take a breathe is when you are sprinting down the road and need to urgently get the extra bit of air into your lungs.
The sternocleidomastoid and scalenus anterior, medius and posterior muscles are of particular importance. The function of these muscles is to allow us to bring our chin towards our chest i.e cervical spine flexion & bring our ears towards our shoulders i.e cervical spine side bending/lateral flexion. In order to achieve this the muscle needs to contract or shorten.
To help better explain this, imagine there is a miniature rope tied from the tip of your chin to the middle point of your chest. Now imagine a group of little creatures sat on your chest pulling on that rope, in theory it would pull your chin down towards the chest in a nodding motion. This is essentially what occurs when you activate these muscles. However when you take a short and shallow breath you inadvertently activate these little creatures with their rope. The force is not enough to bring your chin down towards your chest but it is enough to mimic that movement on a minute scale due to the activation of the muscles.
We take approximately 23000 breathes a day which amounts to 8400000 a year. You may recall our discussion in the previous article about how the human body is like a sculpture that is in a constant state of reshaping and remoulding. With every single breathe you create micro-tension in these ‘accessory muscles of breathing’, this in turn creates what we might call the 21st century posture. The neck slowly gets drawn forward, the shoulders gradually begin to round and the lower back in turn begins to slump.