do lower motor neurons make synaptic connections with all fibers in a skeletal muscle?
Lower motor neurons do not make synaptic connections with all fibers in a skeletal muscle. The organization of neuronal connections in a skeletal muscle involves a hierarchical system that allows for precise control and coordinated movement.
In the motor unit, a motor neuron connects to multiple muscle fibers. Motor units can vary in size, with smaller units having fewer muscle fibers and larger units having more. This organization allows for graded recruitment of muscle fibers, enabling fine control over muscle contractions.
At the neuromuscular junction, the synapse between a lower motor neuron and a muscle fiber, multiple muscle fibers receive input from a single motor neuron. However, each muscle fiber only receives input from a single motor neuron. This means that lower motor neurons typically do not innervate all the fibers within a muscle, but rather innervate a subset of fibers within a specific motor unit.
It's important to note that the number of motor neurons and their connections vary depending on the muscle and its function. Muscles that require more precise control, such as those involved in fine motor skills, will have smaller motor units with fewer muscle fibers per motor neuron compared to muscles involved in gross motor movements.