Functional Anatomy Lecture

10 Questions

Muscles act as the motors that drive movement in humans and other animals. Which statement best explains the unique arrangement of myosin molecules?

Tails together and heads at the ends

Shortening and lengthening of sarcomeres affect the force generated by muscles during contraction.

True

What is the main purpose of human functional anatomy?

To better understand factors that influence both injury risk and human physical performance

In muscles, the parallel elastic component (PEC) includes membranes surrounding fibers, fascicles, and the whole muscle, contributing to preventing muscle from overstretching. Another component that decreases as fibers shorten during contraction is the _______.

Passive elastic component (PEC)

In movements that require work to be performed, work (W) is calculated by multiplying ______ by distance (d).

force (F)

What type of muscle fibers/fascicles allow for a larger range of motion?

Long fibers/fascicles

What type of muscles have a lower metabolic cost due to less ATP use?

Short-fibred muscles

Longer fibers in muscles can generate good force at higher shortening speeds.

True

Match the following muscle type with their property:

Pennate muscles = Higher physiological cross-sectional area (PCSA) Short-fibred muscles = Optimum for low metabolic cost Long-fibred muscles = High shortening speeds

What is the fundamental component of tendons?

Collagen

Study Notes

Introduction to Functional Anatomy

Functional anatomy is an area of science that examines the functional role of musculoskeletal and neurological structures in human movement.
It aims to better understand the factors that influence injury risk and human physical performance.

Muscle Structure

Muscles are the motors that drive human movement.
Myosin has a heavy chain (head, neck, and tail) and light chains that influence function.
The head/neck (motor) domain bends to pull on actin, causing muscle contraction.
Myosin molecules arrange themselves in a unique way, with tails together and heads at the ends, to cause muscle contraction.

Muscle Properties

Muscle contraction is based on the cross-bridge model, where myosin heads rotate, detach, recover, and reattach to actin.
The faster the cycle rate, the less time myosins are in contact with actin, resulting in less force produced.
There is a force-velocity relation, where maximum force decreases as muscle shortening speed increases.
Muscle force also changes with length, with fewer bound cross-bridges and actin-myosin collision at shorter lengths.
Within a muscle, sarcomeres can be at different lengths, affecting muscle force.

Muscle Architecture

Muscles have different designs, such as strap, unipennate, multipennate, and pennate, which affect muscle function.
Pennate muscles have a greater physiological cross-sectional area (PCSA) for a given anatomical cross-section (ACSA).
Fibres also rotate as they shorten, allowing for more force production in dynamic contractions.

Tendon

Tendons transfer muscle forces to bones and have a hierarchical structure, with collagen as the fundamental component.
Tendons are elastic due to covalent bonds between amino acids and exhibit load sharing and shear between fibrils and fascicles.
Tendons can dissipate energy through shear during relaxation, which helps prevent injury and aids in braking.

Tendon Force-Length Relation

Tendons stretch when loaded, with varying properties, and exhibit a force-length relation.
The force-length relation can be normalised by stress and strain, allowing for comparison between tendons.

Tendon Stress-Strain Relation

The stress-strain relation shows the relationship between stress and strain in tendons.
Tendons can dissipate energy through hysteresis, which is good for injury prevention and braking.

Viscoelasticity

Biological tissues, including tendons, are viscoelastic, exhibiting both viscous and elastic behaviors.
Viscoelasticity is caused by fibril sliding and provides protection from injury and over-elongation.

Importance of Tendon and Muscle Function

Understanding tendon and muscle function is crucial for understanding functional movement and preventing injury.
Tendon and muscle function are influenced by various factors, including stiffness, hysteresis, and viscoelasticity.