Final answer:
The posterior terminal branch's motor innervation involves axon terminals at the NMJ releasing ACh to stimulate muscle contraction. Sensory innervation refers to the transmission of sensory information towards the central nervous system through sensory neurons. Both processes are integral to the functioning of the peripheral nervous system, particularly the spinal nerves.
Step-by-step explanation:
The question pertains to the motor innervation and sensory innervation of a posterior terminal branch, which involves the functioning of the peripheral nervous system, specifically the spinal nerves. Spinal nerves transmit sensory and motor information between the spinal cord and the rest of the body. Each spinal nerve is composed of both sensory and motor axons. The sensory axons originate from cell bodies in the dorsal root ganglia and connect to sensory receptors in skin, muscle, or sensory organs. Meanwhile, motor axons, which originate in the motor neuron cell bodies located in the ventral gray matter of the spinal cord, innervate muscles through the ventral root.
In the context of a neuromuscular junction (NMJ), the axon terminal releases a neurotransmitter called acetylcholine (ACh). This occurs at the motor end-plate, where ACh receptors are located in the muscle fiber sarcolemma. During this motor innervation, the released ACh molecules diffuse across the synaptic cleft and bind to the receptors, leading to muscle contraction. Sensory innervation involves the transmission of sensory information from receptors to the central nervous system through sensory neurons.