The skull is classically separated into two parts:

• The cranial, membrane vault, which contains the brain (including the brain and its glands, pituitary gland, epiphysis, hypothalamus, and thalamus. The latter acts as a "telephone standard" receiving all calls containing information from the spinal cord via the brainstem to dispatch it to the different gray nuclei.

It will reach 80% of its final volume around the age of 3 years, hence the importance of consulting quarterly from birth until 3 years. It is a period during which the skull is easily manipulated by its plasticity that allowed it by deforming to pass through the small pelvis of the mother during childbirth.

Uterine contractions will press on the skull, especially when the presentation is made by the top (about 2 out of 3 deliveries) during delivery.

• The cranial base, which connects it with the neck, at the level of the 1s^{t c}ervical, called Atlas, and from which emerge the 12 pairs of cranial nerves (for 11 holes) that convey in particular our 5 senses.

• The face, which contains 6 fixed bones on each side, the maxilla, the malaire, the clean bone of the nose, the lower cone, the palatin, the vomer and the unguis. They say these bones are the soldiers of ^the first line, because they face ^the first external aggressions. It is composed of cavities, nasal pits, sinuses, maxilla, frontals, etmoïdaux and sphenoids, which are cavities in which mucus circulates. They must be clear, ventilated, because stagnant mucus is the door open to viral or bacterial infections. The Osteopath can provide you with care to clear these cavities.

At the ENT level, permanent pressure on these bones can accumulate and create inflammations, this time of mechanical origin, at the cavities that are the orbits (creating conjunctivitis) or the ears (otitis).

In adults, the skull consists of 22 bones, which have ossified during growth, the border areas between these bones are called sutures, which are the remnants of infant fontanelles. They are cut into bevels, i.e. a cranial bone will fit with another bone, either by being covered by it or by covering it. This will be of considerable importance in the manipulations of Osteopathy.

The Osteopath will systematically work the sphenoid bone because it is the keystone of the skull, that is to say that it is the only bone on which all the bones of the skull rest and articulate, it is palpable at the temples, at the large wings of the sphenoid, (the small wings are not palpable because they are part of the orbit, the space between the large and small wings delineate what is called the sphenoidal cleft , also called the upper orbital crack where the nerves PASs III IV V1 AND VI). Finally, the sphenoid bone is palpable in the mouth, behind the last molars at the level of the pterygoid apophyses. (Adult mouth contains 32 teeth counting 4 wisdom teeth)

In infants, the fontanelles are 6, the posterior, or lambdatic, triangle-shaped closes around 3 months, and the anterior, called bregmatic, at the level of the vault, closes between 18 and 36 months (area where one feels the beat of the blood circulation)

At the base of the skull, the phphenoidal fontanelle will close in adulthood around 20 years of age!

During infant consultations, they are very important areas in Osteopathy because they are subjected to pressure forces that will condition the good brain expansion, but also the proper vascularization of the 3 meninges, and a homogeneous circulation of cerebrospinal fluid (CSF).

They give us indications on the future good development of the infant, in order to prevent possible deformities (craniosenosis, microcephaly), dehydration (hollow fontanelles), or even, in rare cases, meningitis or cranial hypertension (bulging fontanelles).

• The jaw, composed of the 2 Temporo-Mandibular Articulations (ATM) right and left, is a joint connecting the mandible that is suspended from the temporal bone to which it is suspended.

Between the two bones is a meniscus, or disc that ensures joint congruence between a convex round surface, and a concave hollow surface.

Meniscus can cushion shocks during bruxisms in people who grind their teeth especially at night or when clenching in people who snap their teeth. They thus avoid friction, but eventually wear out with age. They can be luxurious when opening the mouth non-physiologically, during an extended yawning for example, the osteopath can reduce the urgent luxuration in the office.

ATMs are diarthritis-type joints with a capsule and cartilage bathed in a synovia. They are maintained by ligaments and their mobility is ensured by the chewing muscles, numbering 6 on each side, the external massageters and temporals, the pterygoidians, medial and lateral internally, and the above and sub-hyoid muscles. They allow movements:

1) backwards (deformation when it is too retropulsed is called retrognathism) and forward propulsion (deformation when it is too propelled is called prognathism)

2) lowering (opening) and elevation (closing)

3) diduction (right and left laterality)

They can suffer when wearing too heavy implants, for example, and generate over time a malocclusion that can create the famous SADAM syndrome.

It combines a muscular melting of the massageters and temporal, irritation of the tri-twin (V) and facial (VII) nerves that can cause face burns, permanent cracking, hearing problems, tinnitus with a type of buzzing or high-pitched hiss, and bouts of benign paroxytic positional vertigo (BPV), since the mandible is in contact with the middle ear through its rising branch. , and thus being able to compress it. Not to be confused with the dizziness associated with calcium crystals, or otoliths that bathe in the endolymph, and which can clog one of the 3 semi-circular channels in the vestibule of the inner ear.

In Osteopathy, tensions are very frequently found in this area, often of anxiety origin, but also consequent to heavy dental treatment (prostheses, implants, inlay, onlay, bridges, crowns, extractions…)

There are manual techniques to decompress the ATM, especially intra-oral, very effective also to declutter the sinuses, during ENT disorders (sinusitis, otitis, conjunctivitis …)