Chapter 2: Introduction to Human Movement Science

Question 1

What does the HMS (human movement system) consist of?

Answer 1

The HMS consists of the muscular system (functional anatomy), the skeletal system (functional biomechanics), and the nervous system (motor behavior) ( 1 – 3 ).

Question 2

What is the term for the motions the HMS produces?

Answer 2

Kinematics

Question 3

What is the term for the forces the HMS produces?

Answer 3

Kinetics

Question 4

What are the three planes of movement?

Answer 4

sagittal, frontal, and transverse planes

Question 5

In what plane of motion does most flexion/extension occur?

Answer 5

Sagittal

Question 6

In what plane of motion does most adduction/abduction occur?

Answer 6

Frontal

Question 7

In what plane of motion does lateral flexion occur?

Answer 7

Frontal

Question 8

In what plane of motion does eversion/inversion occur?

Answer 8

frontal

Question 9

In what plane of motion do internal/external rotation occur?

Answer 9

Transverse

Question 10

In what plane of motion does left/right spinal rotation occur?

Answer 10

Transverse

Question 11

In what plane of motion does horizontal add/abduction occur?

Answer 11

transverse

Question 12

What is the axis for the sagittal plane?

Answer 12

Coronal

Question 13

What is the axis for the frontal plane?

Answer 13

Anterior-Posterior

Question 14

What is the axis for the transverse plane?

Answer 14

Longitudinal

Question 15

Describe pronation

Answer 15

internal rotation

Question 16

Describe supination

Answer 16

external rotation

Question 17

During which part of the gait does pronation occur?

Answer 17

Contact

Question 18

During which part of the gait does supination occur?

Answer 18

midstance

Question 19

what are the three different muscle actions?

Answer 19

eccentric, isometric, and concentric

Question 20

What is eccentric muscle action?

Answer 20

An eccentric action occurs when a muscle develops tension while lengthening; the muscle lengthens because the contractile force is less than the resistive force. The overall tension within the muscle is less than the external forces trying to lengthen the muscle. During resistance training, an eccentric muscle action is also known as “a negative.” This occurs during the lowering phase of any resistance exercise.

Question 21

What is concentric muscle action?

Answer 21

A concentric muscle action occurs when the contractile force is greater than the resistive force, resulting in shortening of the muscle and visible joint movement. This is referred to as the “positive” during integrated resistance training (5,11). All movements require concentric muscle actions.

Question 22

What is isometric muscle action?

Answer 22

An isometric muscle action occurs when the contractile force is equal to the resistive force, leading to no visible change in the muscle length (5 , 9). As the muscle shortens, elastic components of the muscle lengthen. The muscle is shortening; however, there is no movement of the joint.

Question 23

Define a muscular force

Answer 23

A force is defined as the interaction between two entities or bodies that result in either the acceleration or deceleration of an object (1,4,5,7). Forces are characterized by both magnitude (how strong) and direction (which way they are moving) (1,5).

Question 24

Define a length-tension relationship

Answer 24

Length-tension relationship refers to the resting length of a muscle and the tension the muscle can produce at this resting length (1,6,16,17). There is an optimal muscle length at which the actin and myosin filaments in the sarcomere have the greatest degree of overlap [Figure 2.10]. The thick myosin filament is able to make the maximal amount of connections with active sites on the thin actin filament, leading to maximal tension development of that muscle. When the muscle is stimulated at lengths greater than or
less than this optimal length, the resulting tension is less because there are fewer interactions of the myosin cross-bridges and actin active sites (1.5.6.16–18).

Question 25

Define a force couple

Answer 25

Because muscles are recruited as groups, many muscles will transmit force onto their respective bones, creating movement at the joints . Th is synergistic action of muscles to produce movement around a joint is also known as a force-couple. Muscles in a force-couple provide divergent tension to the bone or bones to which they attach. Because each muscle has different attachment sites and lever systems, the tension at different angles creates a different force on that joint. Th e motion that results from these forces depends on the structure of the joint, the intrinsic properties of each fiber, and the collective pull of each muscle involved Figure 2. 12

Question 26

Define the classes of levers

Answer 26

Three classes of levers are present in the body [Figure 2. 14]. A first class lever has the fulcrum between the force and the load. A second class lever has the load between the force and the fulcrum. Third class levers, the most common in the body, have the pull between the load and the fulcrum.

Question 27

List and define the different muscle roles/functions

Answer 27

Agonists are muscles that act as prime movers. For example, the gluteus maximus is the prime mover for hip extension. Antagonists are muscles that act in direct opposition to prime movers. For example, the psoas (hip flexor) is antagonistic to the gluteus maximus. Synergists are muscles that assist prime movers during functional movement patterns. For example, the hamstring complex and the erector spinae are synergists to the gluteus maximus during hip extension. Stabilizer muscles support or stabilize the body while the prime movers and the synergists perform the movement patterns. For example, the transversus abdominis, internal oblique, multifi dus, and deep erector spinae muscles stabilize the lumbo-pelvic-hip complex (LPHC) during functional movements while the prime movers and synergists perform functional activities. `

Question 28

What is the local muscular system?

Answer 28

Th e local musculature system consists of muscles that are predominantly involved in joint support or stabilization Figure 2.16 . It is important to note, however, that joint support systems are not confined to the spine and are evident in peripheral joints as well. Joint support systems consist of muscles that are not movement specific, rather they provide stability to allow movement of a joint. They usually are located in close proximity to the joint with a broad spectrum of attachments to the joint’s passive elements that make them ideal for increasing joint stiffness and stability.

Question 29

What is the global muscular system?

Answer 29

The global muscular systems are responsible predominantly for movement and consist of more superficial musculature that originate from the pelvis to the rib cage, the lower extremities, or both Figure 2.17. Some of these major muscles include the rectus abdominis, external obliques, erector spinae, hamstring complex, gluteus maximus, latissimus dorsi, adductors, quadriceps, and gastrocnemius. The movement system muscles are predominantly larger and associated with movements of the trunk and limbs that equalize external loads placed on the body. These muscles also are important in transferring and absorbing forces from the upper and lower extremities to the pelvis.

Question 30

What are the global musculature subsystems?

Answer 30

the deep longitudinal, posterior oblique, anterior oblique, and lateral subsystems

Question 31

Define the Deep Longitudinal Subsystem (DLS)

Answer 31

The major soft tissue contributors to the deep longitudinal subsystem are the erector spinae, thoracolumbar fascia, sacrotuberous ligament biceps femoris, and peroneus longus Figure 2. 18 .