An inertial measurement unit works by detecting the current rate of acceleration using one or more accelerometers, and detects changes in rotational attributes like pitch, roll and yaw using one or more gyroscopes. And some also include a magnetometer, mostly to assist calibration against orientation drift.
In the human there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine.
1 Cranial Nerves Cranial Nerves  Twelve pairs of cranial nerves arise from the brain  They have sensory, motor, or both sensory and motor functions  Each nerve is identified by a number (I through XII) and a name  Four cranial nerves carry parasympathetic fibers that serve muscles and glands. Cranial Nerves Cranial Nerves  Twelve pairs of cranial nerves arise from the brain  They have sensory, motor, or both sensory and motor functions  Each nerve is identified by a number (I through XII) and a name  Four cranial nerves carry parasympathetic fibers that serve muscles and glands.