In terms of embryological development, the hierarchical chain of events show the most important days of embryogenesis.
Day I. The fertilization of the egg and sperm cell signifies conception – the zygote
Day 16. The formation of the primitive streak – the future brain and spinal cord
Day 18. The formation of mesenchyme, the fascial formation – the ’Clingfilm’ that surrounds and encapsulates every aspect of the embryo.
Day 23. The formation from the pharyngeal arches of the four pairs of mixed cranial nerves. The trigeminal nerve (5), the facial nerve (7), the glossopharyngeal nerve (9) and the vagus nerve (10) make up the ‘survival kit’ of the final foetal performance at birth. The ability for the new born to suckle.
The trigeminal nerve, controls the jaws to find the nipple.
The facial nerve moves the facial muscles to latch onto the nipple
The glossopharyngeal nerve pushes the nipple against the roof of the mouth
The vagus nerve then sucks, swallows the milk, digests the milk and removes the waste from the nutrition, while maintaining the heart rate and the breathing, as well as all the other necessary activities of the body. This is the ‘survival kit’.
MESENCHYME – the fascial formation, is the precursor to the endoderm, the mesoderm and the ectoderm; a process known as gastrulation taking the single cellular structure to a multicellular structure, from a three vesicle formation to a five vesicle formation, as growth and embryological development takes place.
Ultimately, the fascial system envelopes and controls the entire central nervous system. The spinal cord and every pair of spinal nerve root are encapsulated by spinal dura which then becomes the cranial dura, supporting and maintaining the brain and all its components in a balanced configuration, this permits homeostasis within the cranium. Every nerve and circulatory vessel is surrounded and protected by the dural meningeal system which is a continuous fascial connector to all the aforementioned components. When this system is allowed to function normally then the body is maintained in a homeostatic environment.
The cranial dura consists of the meningeal dura covering the surface of the brain, and is made up of: the pia mater, arachnoid mater and the dura mater. The meningeal dura is continuous with the meningeal layer covering the spinal cord and is attached to the foramen magnum. The periosteum of the spinal column is a continuation of the dura mater and also anchors at the foramen magnum, then becomes part of the cranial dura mater. Within the cranium the dura mater is the periosteum and the endosteum, which in a ‘new born’ baby encapsulates islands of osseous bone which later become the cranial plates joined to their opposite number by the sutures of the cranium.
The dura mater in the brain forms the falx cerebri (which encapsulates the superior and inferior sagittal sinuses) and the falx cerebelli (which encapsulates the occipital sinus), the two vertical membranes that separate the left and right cerebral hemispheres and the left and right cerebellar hemispheres respectively. The third dividing membrane is the tentorium cerebellum (which encapsulates the transverse sinus, the sigmoid sinus posteriorly at the occiput, and the superior petrosal sinus laterally at the petrous portion of the temporal bone), a horizontal membrane, which separates the cerebral hemispheres from the cerebellum and the diaphragma sellae, which surrounds the hypophysial stalk of the pituitary. These are known as the reciprocal tension membranes (RTM) which support and separate the various brain components, effectively balancing the brain. These vertical and horizontal membranes form and encapsulate the straight sinus and the confluences of the sinuses. All these afore mentioned sinuses are responsible for draining the brain.