muscles

Question 1

What is a muscle function

Answer 1

all skeletal movements result from muscles pulling on bones.
- provide us with support
allows us to maintain an upright posture
- muscles found in the legs and torso contract statically,
or isometrically, for extended periods of time (also known as muscle
tone) to enable us to stay upright
- the ability to produce heat when energy is produced from
foods and other stored fuels, allowing muscle contractions to occur
skeletal muscles can also contract involuntarily when it is very cold in order to release heat and maintain a stable core temperature – this is experienced as shivering

Question 2

What two actions are muscles capable of

Answer 2

each muscle is capable of only two actions: contractions and relaxation

Question 3

Types of muscles

Answer 3

Skeletal
Smooth
Cardiac
Muscle fibres

Question 4

Skeletal muscle

Answer 4

muscles external muscles that are attached to the bones, make up the skeleton. under your own control and are voluntary muscles

Question 5

Smooth muscle

Answer 5

intestinal smooth muscles are found in blood vessels and walls of the intestine. they are known as involuntary muscles, because you have no control over them. smooth muscles are made up of spindle cells

Question 6

Cardiac

Answer 6

heart cardiac muscles make up the heart’s walls. they are involuntary and have a striped appearance.

Question 7

Muscle fibres (fasicles)

Answer 7

all skeletal muscle is made up of fascicles (bundles of muscle fibres), but fascicle arrangements vary considerably, resulting in muscles with different shapes and functional
capabilities.

Question 8

Circular

Answer 8

the fascicular pattern is circular, with the fibres arranged in concentric rings. muscles with this arrangement surround external body openings, which they close by contracting. the general term used for these kinds of muscles is ‘sphincter’. examples include the orbicularis muscles that surround the mouth and eyes.

Question 9

Convergent

Answer 9

a convergent muscle has a broad origin, and its fascicles converge towards a single tendon of insertion. such a muscle is triangular or fan-shaped, like the pectoralis major muscle of the anterior thorax.

Question 10

Parralell

Answer 10

in a parallel arrangement, the length of the fascicles runs parallel to the long axis of the muscle. These muscles are either straplike, like the sartorius muscle of the thigh, or spindle-shaped with an extended belly, like the biceps brachii muscle of the arm. However, some scientists classify spindle-shaped muscles into a separate class, fusiform muscles.

Question 11

Pennate

Answer 11

n a pennate pattern, the fibres are short and they attach obliquely to a central tendon that runs the length of the muscle. pennate muscles come in three forms:
» unipennate, in which the fascicles insert into only one side of the tendon, as in the semimembranosus of the leg.
» bipennate, in which the fascicles insert into the tendon from opposite sides so the muscle ‘grain’ resembles a feather. The rectus femoris of the quadriceps is bipennate.
» multipennate, which looks like many feathers side by side, with all their quills inserted into one large tendon. The deltoid muscle, which forms the roundness of the shoulder, is multipennate. Pennation allows considerably more fibres to be packed into a muscle; so the amount of force that can be generated also increases by a proportional amount. muscle length and speed of contraction affect the ability of fusiform and pennate muscles to develop force. to investigate this, consider the ‘opposite’ muscles of the upper and lower leg. The quadriceps and plantar flexors are able to develop high forces because of their low fibre length (FL) to muscle length (ML) ratios, relatively large cross-sectional area and short fibres. The hamstrings and dorsiflexion are utilised for speed due to their high fibre length-to-muscle length ratios and long fibres.

Question 12

Fusiform

Answer 12

fusiform muscles such as those of the biceps muscle in the arm, run in the same direction as the tendon, or longitudinally. they produce low force but can shorten over a large range. long-running parallel

Question 13

Isometric

Answer 13

contraction against a force with no significant movement
tension is produced, but no joint movement or action takes place.
examples - arm wrestling, wall sit
disadvantage - can results in elevated systolic blood pressure because muscles contract around blood vessels and restrict blood flow

Question 14

Isokenetic

Answer 14

maximum tension throughout the whole range of movement the speed or velocity of movement is held constant regardless weight
the magnitude of force applied to the resistance. typically this occurs with the use
of resistance machines, which use hydraulics to regulate the resistance, matching any increases in contraction speed.
-develop the greatest improvements in both strength and endurance, leaving none of the ‘weak spots’ that are common to the isometric workouts exemplified by free weights.

Question 15

Concentric

Answer 15

muscle shortens with tension (bicep curl up)
if the muscle shortens during an effort, a concentric contraction has occurred; for example, in the upward phase of a biceps curl, during elbow flexion. this is the most common type of contraction undertaken by most muscles. the action produced by a concentric contraction brings together or approximates the origin and insertion of the contracting muscle. in a concentric exercise, tension is developed and the muscle shortens to overcome an external force, such as a weight.

Question 16

Eccentric

Answer 16

muscle lengthens with tension (curl down)
an eccentric muscle contraction is sometimes referred to as a lengthening contraction. if the muscle lengthens while tension is developed, an eccentric muscular contraction has occurred. this occurs in all gravity-resisting movements, such as lowering the barbell from the bent arm position during a biceps curl. the origin and insertion of the contracting muscle move further apart during the contraction. the eccentric exercise involves loading a muscle, causing a physical lengthening of the muscle as it attempts to control the load when lowering the weight. for example, as a person slowly lowers themselves into a chair, the quadriceps muscles must eccentrically contract to control the rate of descent, otherwise, the person would fall into the chair.