This motor reflex is carried out by motor neurons which are located in the Brain and spinal cord. They are of two types, the upper motor neuron and the lower motor neuron. They upper motor neuron connects with the lower motor neuron in the transmission of impulses. Their presynaptic tract is in the cerebral motor area via the corticospinal tract while their post synaptic tract is in muscle fibres. Thus when she hit her legs on the glass, afferent fires was sent to the brain which then sent efferent impulses to the muscle fibers to quickly withdraw the leg due to action of motor neurons.
For the Central Nervous system and different organs of the body to be in constant touch with the immediate environments,Sensory inputs must be sent from group of sensitive cells located under the skin in all mammals and special cells in other organism. These are called receptors. in this scenario they are exteroreceptos because the stimulus is the piece of glass .The changes/ stimulus detected by these receptors are carried as input by group of neurons called sensory or afferent Neurons, as action potential to the brain, via the spinal cord.
The cell body of sensory neuron is located in the spinal cord so that they can synapse with the interneurons, which send the input to the brain and the response from the brain ( outputs)return through another neuron type called motor neuron to the effectors (muscles in her legs ) for her to pull her leg away.This pathway which start with receptors ans ends with effectors is called Reflex arc.
