Sensory information from the face and scalp is carried back to the trigeminal sensory nuclei (Section 4.4) in neurons with cell bodies in the trigeminal ganglion (except for proprioceptive neurons), and it is relayed to various centres within the brain. Examples of these central connections can be illustrated by what happens when we wash our face in the morning. Connections from the trigeminal nuclei include those to: 1 the sensory cortex and other cortical centres for perception:we know what we are doing;2 the limbic system: a habit like this pleases us because our mothers conditioned us to do it when we were children (quite wrongly as it happens since soap is bad for the skin); 3 the reticular formation: it wakes us up; 4 the hypothalamus: vasoconstriction or vasodilatation, according to the temperature of the water.
The second and third divisions of the trigeminal innervate the roof and floor of the mouth, so it will not surprise you to learn that they are involved not only with cutaneous sensation but also with sensation in the oral cavity and with movements of the mandible.
6.2 Motor aspects of ingestion and chewing The motor aspects of ingestion and chewing are:
- Depression of mandible: lateral pterygoid, mylohyoid, anterior
digastric (mandibular nerve (Vc)).
