+

MUSCULAR SYSTEM

Skeletal Muscles and their classifications

+KEY CONCEPTS

Skeletal muscles all have features that distinguish what they can do; in particular, movements that they make and force they can generate.

+KEY FUNCTIONS

Support and posture – muscles are in a continuous state of ‘tone’ that affects their ability to help our body maintain an upright posture.

Poor posture can result in aches and pains

The trapezius, rhomboids and latissimus dorsi are crucialpostural muscles

Movement – voluntary control

Essential body functions – generally under involuntary control (which have little or no conscious control) Digestion Respiration Circulation

+Common features of muscles

Nervous control – CNS stimulus controls muscle action

Contractility – when muscles contract they get shorter

Extensibility – muscles have the capacity to lengthen

Elasticity – muscles return to the original shape/size after stretching

Atrophy – muscles can decrease in size as a result of injury or lack of exercise

Hypertrophy – muscle can increase in size (grow) with increased exercise/training

+MUSCLE FIBER TYPES

Cardiac Muscles of the heart

Smooth Digestive system and

blood vessels

Skeletal Attached to bones

and responsible for movement

+

SKELETAL MUSCLES YOU NEED TO KNOW!

+

CLASSIFICATION OF SKELETAL MUSCLE

+OVERVIEW

Skeletal Muscles can be classified by their fibre arrangement around the tendon.

+FUSIFORM MUSCLES

the muscle fibres run the length of the muscle belly.

Designed for mobility – low force over a long range

E.g. Sartorius, biceps

+PENNIFORM MUSCLES

Fibres run at angles to the tendon. Designed for strength and power.

They make up 75 per cent of the skeletal muscles

Three Categories Unipennate Bipennate Multipennate

+UNIPENNATE

Fibres are found on only one side of a central tendon

E.g. Tibialis Anterior

+BIPENNATE MUSCLES The fibres run off either

side of a central tendon

E.g. rectus femoris (quads)

+MULTIPENNATE MUSCLES Fibres branch out from

several tendons.

This arrangement enables the body the generate the greatest force.

E.g. Deltoid

+Radiate Muscles

These muscles are a compromise between fusiform and pennate muscles because they are capable of producing strength and power without compromising mobility

Eg: pectoralis major, latissimus dorsi