L3 - Muscular Considerations

Muscles can exert force by pulling or pushing

False, only pulling

Skeletal muscle

internal motors that contribute to movement in the human body

What allows us to achieve the general joint movements at each articulation in the body

the location of skeletal muscle relative to the skeletal system

What are the 4 tissue properties of skeletal muscle

• irritability

• contractility

• extensibility

• elasticity

Irritability

• permits muscles the ability to respond to stimulation

• enables the proper fibers of skeletal muscle to utilize stimulation of the neurological system to produce movement

Contractility

permits muscles the ability to shorten and produce the necessary tension to move the skeletal system

Muscles can shorten 50-70% of their normal resting length

True

Extensibility

permits muscle the ability to lengthen or stretch past its normal resting length

Muscles can produce elongation on their own

False, another muscle/external force is required

Elasticity

allows the muscle to return to its resting length after the stretch is removed

Extensibility is a critical component in facilitating output in a shortening muscle action that is proceeded by a stretch

False, elasticity

Functions of muscle

• produce movement

• maintain postures and positions

• stabilize joints

Muscles must interact with the skeletal system in order to cause movement

True

How can muscles attach directly to bone

by attaching to the periosteum of bone

Periosteum

a thin covering on outside of bone

How do muscles attach to bone via tendon

tendon is fused with muscle fascia

Aponeurosis

a fibrous connective sheath that permits muscles to increase attachment to bon bey widening the area of attachment

Muscles can only contribute to movement if it crosses a joint

True

Uniarticular muscles

muscles that cross only one joint

Advantage of uniarticular muscles

the muscle can contribute every part of it to the intended joint actions without becoming an opponent to itself

Majority of the muscles in the human body are multiarticular

False, uniarticular

Multiarticular muscles

muscles that cross multiple joints in human body

Disadvantage of multiarticular muscles

• passive insufficiency

• active insufficiency

Passive insufficiency

• the inability of muscle to lengthen

• diminish the capability of achieving the full range of motion associated with the movement

Active insufficiency

• the inability of a muscle to shorten

• diminish the capability of achieving full ROM associated with the movement

You are lying on your back stretching your hamstring by pulling your bent leg up to your chest. You try to deepen the stretch by straightening your leg. Your leg moves farther away from your chest and you are unable to pull it down any further. What is this describing?

passive insufficiency of multiarticular muscles

You cannot have maximum flexion of your fingers and wrist at the same time. Why?

active insufficiency of multiarticular muscles

Concentric muscle contraction

muscle contracts while shortening

Eccentric muscle contraction

muscle contracts while lengthening

Isometric muscle actions are often used to control the motion of an object by slowing down the segments of an articulation

False, eccentric

Isometric muscle contraction

muscle contracts while staying the same length (joint doesn’t move)

Stretch-shortening cycle

• stretch on the muscle increases its tension through storage of potential elastic energy

• the following concentric muscle contraction is enhanced by the previously stored elastic energy (that took place during stretch)

• Result = high-force output at initial portion of concentric muscle action as these tissues return to normal length