Muscle Action & Muscles of the Body Concepts

Question 1

Outline the basics of a muscle contraction, concentrating on the primary mover, fixators & synergists & Reverse Muscle Action (RMA)

Answer 1

Primary mover= agonist, the muscle that shortens to act as the primary mover
fixators= a muscle that stabilizes the origin of the prime mover to improve the efficiency of the prime mover
synergists= a muscle that contracts to stabilize an intermediate joint where you don’t want movement, when a biarticular muscle contracts
Reverse muscle action= when the origin moves towards the insertion

Question 2

Contrast the origin and insertion, in terms of which is the fixed point, and which is the “mobile” skeletal member

Answer 2

The origin is the fixed point, the bone which doesn’t move. The insertion is the mobile bone that moves toward the site of origin.

Question 3

Describe the relationship between the agonist and the antagonist, functionally, during muscle contraction. Contrast the two in terms of where they’ll be found.

Answer 3

During muscle contraction, the agonist is the muscular doing the primary contraction (flexion) and the antagonist is the muscle that’s being stretched (extended) due to the contraction of the agonist’s muscle. The agonist’s muscle is usually found anterior to the antagonist’s muscle.

Question 4

Contrast a uniarticular muscle with a biarticular muscle.

Answer 4

Uniarticular is a muscle that takes part in the movement of one joint. A biarticular muscle is one that takes part in the movement of two joints, like the hamstrings that cross both the knee and hip joint.

Question 5

Contrast 1st and 3rd-degree levers, pointing out pros and cons & highlighting which is more prevalent in the body.

Answer 5

1st-degree lever
Fulcrum in the middle, between load and resistance

3rd-degree lever
Most common and favors speed and range of motion over maximum force
Effort falls in between the fulcrum and load

Question 6

Determine the type of lever biceps brachii creates when flexing the forearm

Answer 6

The type of lever biceps brachii creates when flexing the forearm is a 3rd-degree lever. The fulcrum is at the elbow joint, the effort is at the forearm, and the load is in the hands

Question 7

Identify the types of fascicle arrangements in a skeletal muscle, and relate the arrangements to the strength of contraction and range of motion.

Answer 7

Parallel, Pusiform, Circular, Triangular, Pennate (Inipennate, Bipennate, Multipennate)
The thicker a muscle is, the stronger its strength of contraction. The longer a muscle is, the more range of motion it has.

Question 8

Define compartments when it comes to the musculature of the body, and identify the type of connective tissue surrounding a compartment.

Answer 8

Compartments are groups of muscles in the same region of the body that accomplish the same task. Fascia, made of dense irregular connective tissue, surrounds each muscle of a compartment.

Question 9

Understand how rectus, transverse (transverse), and oblique relate to one another in terms of muscle fibers and the midline of the body.

Answer 9

Rectus refers to the muscle fibers being parallel to the body’s midline.
Transverse refers to the muscle fibers being perpendicular to the body’s midline
Oblique refers to the muscle fibers being diagonal to the body’s midline.

Question 10

Contrast the structure of a tendon and an aponeurosis

Answer 10

A tendon connects muscle to a bone.
Aponeurosis connects muscles to adjacent muscles.