Or, at least, they drive eachother.
The accessory muscles of breathing in the upper body, quite specifically the SCM and Scalenes, help to pull open the chest on the inhale. For every action there is an equal and opposite reaction - the attachment points of these muscle/fascia patterns on the skull receive a reciprocal tug. The way that the muscles attach to the skull, the force vectors that would be exhibited during contraction of these muscles, seems to be reflected in the joints of the skull - especially in the temporal bone, which looks to be beveled to allow such movement. The movements would also largely coincide with the movement findings of craniosacral therapists and cranial osteopaths.
Within the skull, there is an increase in cerebrospinal fluid pressure caused by (and perhaps also the cause of) the inhale. The internal p
Deep breathing couples CSF and venous flow dynamics
Venous system pathologies have increasingly been linked to clinically relevant disorders of CSF circulation whereas the exact coupling mechanisms still remain unknown. In this work, flow dynamics of both systems were studied using real-time phase-contrast flow MRI in 16 healthy subjects during normal and forced breathing. Flow evaluations in the aqueduct, at cervical level C3 and lumbar level L3 for both the CSF and venous fluid systems reveal temporal modulations by forced respiration. During normal breathing cardiac-related flow modulations prevailed, while forced breathing shifted the dominant frequency of both CSF and venous flow spectra towards the respiratory component and prompted a correlation between CSF and venous flow in the large vessels. The average of flow magnitude of CSF was increased during forced breathing at all spinal and intracranial positions. Venous flow in the large vessels of the upper body decreased and in the lower body increased during forced breathing. Deep respiration couples interdependent venous and brain fluid flow—most likely mediated by intrathoracic and intraabdominal pressure changes. Further insights into the driving forces of CSF and venous circulation and their correlation will facilitate our understanding how the venous system links to intracranial pressure regulation and of related forms of hydrocephalus.
Kollmeier, J.M., Gürbüz-Reiss, L., Sahoo, P. et al. Deep breathing couples CSF and venous flow dynamics. Sci Rep 12, 2568 (2022). https://doi.org/10.1038/s41598-022-06361-x
Respiration: A New Mechanism for CSF Circulation?
In conclusion, Dreha-Kulaczewski et al. (2017) identify the negative venous pressure occurring during inspiration as the main force driving CSF movement from the spine into the head. This work is crucial for our understanding of human CSF dynamics and has important clinical implications. Future studies should aim to unravel the role of respiration and venous pressure in the pathogenesis of different types of hydrocephalus and other pathologies.
Delaidelli A, Moiraghi A. Respiration: A New Mechanism for CSF Circulation? J Neurosci. 2017 Jul 26;37(30):7076-7078. doi: 10.1523/JNEUROSCI.1155-17.2017. PMID: 28747391; PMCID: PMC6705733. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6705733/
Yogic Breathing Affects Cerebrospinal Fluid Dynamics During Breathing Practice
Findings from this study suggest that respiration can potentially be the primary driver of CSF dynamics, depending on the form of breathing an individual is practicing. The researchers noted that the next step is to see how long-term yogic breathing training could affect the CSF dynamics, and therefore, central nervous system health.
Yildiz S, Grinstead J, Hildebrand A, et al. Immediate impact of yogic breathing on pulsatile cerebrospinal fluid dynamics. Scientific Reports. 2022;12(1):10894. https://www.nccih.nih.gov/research/research-results/yogic-breathing-affects-cerebrospinal-fluid-dynamics-during-breathing-practice
Effect of Normal Breathing on the Movement of CSF in the Spinal Subarachnoid Space
At each level, CSF moved cephalad during inhalation and caudad during expiration. While the general pattern of fluid movement was the same in the 6 subjects, the flow rates, stroke volumes, and spine segment volume changes varied among subjects. Peak flow rates ranged from 0.60 to 1.59 mL/s in the cervical region, 0.46 to 3.17 mL/s in the thoracic region, and 0.75 to 3.64 mL/s in the lumbar region. The differences in flow rates along the canal yielded cyclic volume variations of spine segments that were largest in the lumbar spine, ranging from 0.76 to 3.07 mL among subjects. In the phantom study, flow velocities oscillated periodically during the respiratory cycle by up to 0.02 cm/s or 0.5%. CONCLUSIONS: Respiratory-gated measurements of the CSF motion in the spinal canal showed cyclic oscillatory movements of spinal fluid correlated to the breathing pattern.
C. Gutiérrez-Montes, W. Coenen, M. Vidorreta, S. Sincomb, C. Martínez-Bazán, A.L. Sánchez and V. Haughton American Journal of Neuroradiology September 2022, 43 (9) 1369-1374; DOI: https://doi.org/10.3174/ajnr.A7603