Special functional abilities of muscle that are the basis for muscle response.

Full Answer Section

Here's a helpful analogy: Imagine a baby bird just hatched from its egg. Its head is much larger in proportion to its body compared to a fully grown bird. Similarly, a fetus's cranium dominates its overall head structure, much like the baby bird's head compared to its body.

Four Special Functional Abilities of Muscle

Muscles possess unique properties that enable them to generate force and cause movement. Here are four key functional abilities:

1. Contractility: This is the ability of a muscle to shorten actively and generate force. It's the fundamental property that allows muscles to produce movement.

2. Excitability: Muscles can respond to stimuli, whether it's from the nervous system (nerve impulses) or external factors like electrical stimulation. This responsiveness allows muscles to be activated and contract.

3. Extensibility: Muscles can be stretched beyond their resting length without damage. This property is important for allowing flexibility and a range of motion.

4. Elasticity: Muscles have the ability to return to their original length after being stretched. This elasticity helps muscles function efficiently and prevents them from becoming permanently elongated.

These four functional abilities work in a coordinated manner to enable the wide range of movements and functions that muscles perform in the body.

Sample Answer

Cranium vs. Face in Fetus and Adult

The proportions of the cranium (skull) and face are dramatically different in a fetus compared to an adult. Here's a breakdown:

• Fetus:
  • The cranium is disproportionately large compared to the face. This is because the brain develops very rapidly during fetal development.
  • The face is relatively small and underdeveloped, with features that are not yet fully formed.
• Adult:
  • The cranium and face are more balanced in size.
  • The facial features are fully developed and more prominent.