Question

Which of these muscles have motor units with the highest innervation ratio? a. Leg muscles b. Arm muscles c. Muscles that move the fingers d. Muscles of the trunk

Short answer

Among the given options, leg muscles (option a) and muscles of the trunk (option d) have the highest innervation ratio, as they require more force and less precision.

Step-by-step solution

Review the options

We have four options to analyze: a. Leg muscles b. Arm muscles c. Muscles that move the fingers d. Muscles of the trunk

Determine the muscle's function

For each option, we need to consider the primary function of the muscle and whether it requires more force and less precision or vice versa. a. Leg muscles: These muscles are primarily responsible for movements like walking, running, and jumping. They require a significant amount of force and less precision. b. Arm muscles: These muscles are responsible for lifting, pushing, and pulling actions. While they do require some level of precision, the force is relatively important. c. Muscles that move the fingers: Fingers are crucial for fine and precise motor control, such as writing, playing instruments, or manipulating objects. These muscles require a greater level of precision and less force. d. Muscles of the trunk: These muscles hold, stabilize and support our body during various movements and activities. They require a considerable amount of force and some level of precision but not as much as the muscles that move the fingers.

Compare innervation ratios

Now that we have analyzed the functions of the muscles in each option, we can conclude that: - Muscles that require more force and less precision, such as those found in the leg and trunk, will generally have a higher innervation ratio. - Muscles that require greater precision and fine motor control, such as those that move the fingers, will generally have a lower innervation ratio.

Identify the correct answer

Based on our understanding of the innervation ratio and the functions of each muscle group: a. Leg muscles: Higher force, lower precision – high innervation ratio b. Arm muscles: Moderate force, moderate precision – moderate innervation ratio c. Muscles that move the fingers: Lower force, higher precision – low innervation ratio d. Muscles of the trunk: Higher force, moderate precision – high innervation ratio Comparing the innervation ratios, the muscles with the highest innervation ratio are the leg muscles (option a) and the muscles of the trunk (option d).