Muscle & Muscle Movement
Muscles

The Function of the Muscle

Muscles which cause a joint to bend are flexors
Muscles which cause a joint to extend are extensors
Muscles which cause a joint to move away are abductors
Muscles which cause a joint to move back are adductors

Muscles commonly work in pairs called antagonistic pairs - one contracts (agonist) and one relaxes(antagonist). When muscles work in pairs they are know as antagonistic.

Types of Muscle Action

When muscles contract the movement which usually results is normally associated with the muscle length shortening. Exercising where the muscle length shortens is called concentric. Where the muscle length becomes longer is called eccentric.
Two types of concentric muscle action they are called isotonic and iso kinetic. In an isometric muscle action there is no muscle change in length.

The Muscles that you must know

All the muscles must be known and they should be locate on the correct areas in human body.

CLICK HERE TO VIEW WHERE THE MUSCLES ARE

Muscle - Location and Action

Muscle	Position	Action
wrist extensors	wrist	extension, adduction & abduction of wrist
wrist flexors	wrist	flexion, adduction & abduction of wrist
biceps brachii	upper arm	flexion of elbow, supinates forearm, flexion of shoulder
triceps brachii	upper arm	extension of forearm at elbow, extension of armat shoulder
pronator teres	forearm	pronates forearm, flexion of forearm at elbow
supinator muscle	forearm	supinates forearm
deltoid	back of shoulder	abduction of arm, flexion of arm (ant, medially rotates arm(ant), extension of arm (post), laterally rotates arm (post)
pectoralis major	upper chest	flexion at arm (ant), extension of arm, adduction of arm, medially rotates arm
latissimus dorsi	lower back	adduction of of arm, medially rotates arm, extension of arm
teres major	from shoulder blade to front of humerous	adduction of arm, rotates medially (inwards)
supiraspinatus	top of shoulder	adduction of arm (with deltoids)
teres minor	back of shoulder	laterally rotates arm (outwards)
trapizius	back of neck	elevates shoulder girdle, laterally rotates scapula, adduction of scapula
serratus anterior	underneath lats between anterior ribs and shoulder blade	stabilises shoulder blade when hand presses against an object
rhomboids	under trapizius between spine and shoulder blade	adduction and rotation of shoulder blade medially
rectus abdominus	abdominals	flexion of vertabral column, compresses adnomen
external oblique	outer abdomen	flexion of vertabral column, side flexion and rotation of vertabral column, compresses abdomen
internal oblique	outer abdomen (antagonistic pr)	flexion of vertabral column, side flexion and rotation vertebral column, compress adomen
sacrospinalis
ilio psoas (psoas major + iliacus)	lower spine and iliac crest to upper thigh bone	flexion of hip, rotates leg laterally
satorius	from outer hip to inner knee	flexion of hip, abduction of hip anad rotates hip laterally. Flexion of knee and rotates knee medially
gluteus maximus	large ass muscle	extension of hip joint, laterally rotates hip joint
gluteus medius	intermediate ass muscle	abduction of the hip joint and laterally rotates the hip joint, stabilises pelvis, active in walking
gluteus minimus	ickle ass muscle	abduction of hip joint and laterally rotates hip joint, stabilises pelvis, active in walking
gracillis	inner thigh from pubic bone to tibia	adduction of hips, flexion of knee and rotates it medially
adductor longus (long adductor)	inner thigh from fubic bone to femur	adduction of hip joint, medially rotates hip joint
adductor brevis (short adductor)	inner thigh	adduction of hip joint, medially rotates hip joint
adductor magnus (large adductor)	inner thigh	adduction of hip joint, medially rotates hip joint
bicep femoris (hamstring)	back of thigh between hip and fibula/tibia	extension of hip, flexion of knee
semitendinosis (hamstring)	back of thigh between ip and tibia	extension of hip, flexion of knee
semimembranosus (hamstring	back of thigh between hip and tibia	extension of hip, flexion of knee
rectus femoris (quadriceps)	femur to kneecap	extension of knee joint
vastus lateralis (quadriceps)	femur to kneecap	extension of knee joint
vastus medialis (quadriceps)	femur to kneecap	extension of knee joint
vastus intermedius (quadriceps)	femur to kneecap	extension of knee joint
tibialis anterioir	shin	dorsi flexion of ankle joint
soleus	back of leg from head to fubula to heel	plantar flexion of ankle, flexion of knee
gastrocnemius	calf muscle	plantar flexion of ankle, flexion of knee

Types of Muscle Contractions

Isotonic - the sort of exercise which muscles are used in a normal dynamic way, and muscles contract at a speed controlled by the sportsperson in whatever activity is being done, this is called IOTONIC.

Isometric - Used when excerting a force on a fixed position. Used for strength training. Can be done in a short time. Needs no special place or equiptment.

Isokinetic - Exercise the point at which force acts move at constant speed. E.g. in a squat the shoulders move upwards at a constant speed regardless of the exercise put into the exercise.

Eccentric, Contractions - Polymetrics

It is found that if maximum effort is put into an exercise while a muscle group is lengthening, thenthe muscle exerts a bigger force than in any other types of exercisementioned above. In this case the work is labelled eccentric or negative. This is the effect of the stimulus trying to prevent musclular lengthening and it produces the biggest over load possible in a muscle, thereby enhancing its development as far as strengthening is concerned.

The cheif practical use of this is in plyometrics, in which sportspersons jump down from a box and immediately jumps back over a bar or hurdle.

Shapes of Muscles

Pennate - means featherlike. A pennate muscle is a flat muscle in which fibres are arranged around a central tendon, like barbs of a feather.

The major types of pennate muscle are grouped according to the way in which the fibres are arranged around the central tendon.

Fusiform - means spindle shaped, since the muscle fibres run the length of the muscle belly to converge at each end. The strip-like, round shape enables the muscle to perform large ranges of movement and fluidity.

Types of Muscle Fibres

Muscle tissue is composed of muscle fibres which contain two main types which contact at different speeds. The two type of muscle fibres are Fats Twitch Fibres or Type II and Slow Twitch Fibres or Type I.

Within an individual there are different proportions of the fibre types to be found in different muscles and evidence shows that fibre types are inherited.

All muscle contain a mixture of slow and fast twich fibres. The major types between the two types are related to:

1. Speed of Contraction - slow twitch fibres contract at a rate of about 20% when compared with fast twitch fibres.

2. Muscle Fibre Force - fast twitch fibres are bigger in size and slow twitch fibres, have larger motor neurons and therefore can generate high force rapidly.

3. Muscle Endurance - Slow twitch fibres are capible of resisting fatigue whereas fast twitch fibres are easily fatigued.

More recently, it has been discovered that type II is subdivided into type IIa and type IIb. Type IIa, otherwise known as FOG (Fast twitch high Oxidation Glycolytic), have greater resistance to fatigue when compared with type IIb FTG (Fast Twitch Glycotic).

Structure of Muscles

The skeletal muscle is involuntry - it can be controlled

It is called striped or striated because of its appearence. A muscle organ e.g. biceps brachii is surrounded by connective tissue called EPIMYSIUM. Inside are bundles of fibres called FASCIULI and inside these are musle cells of fibre made of MYOFIBRILS.

The connective tissue around the muscle (outside) is made of COLLAGEN. It is a tough protien. The reason for its striped appearence is because of each muscle cell is composed of two different sorts of protien, one thick and the other thin which overlaps each other. The thick one is MYOSIN. The thin one is ACTIN.

The Muscle Cell

(i) MULTINUCLEATE FIBRE (contraction)
(ii) Cell membrane or SARCOLEMMA allows diffusion of O² and glucose into the cell and CO² out of the cell
(iii) SARCOPLASM specialised cytolasm containing SARCOPLASMIC RECTICULA*, 'T' VESICLES**, ENZYMES*** and MITOCHONDRIA

* - Network responsible for transportation of materials in cells.
** - Cell contain sac for cellular secretion such as calcium.
*** - Organic catalyst which regulates chemical reactions in the cell. ATPase activates ATP which provides energy for contraction.
MITOCHONDRIA - organelle where respiration takes place

Some muscle fibres contain more SARCOPLASM than others and appear darker due to the presents of MYOGLOBIN this muscle is then called red muscle and is best suited in the long term powerful contractions. White muscle contains more ATPase and less sarcoplasm and myoglobinand is therefore more suited for speed.

Red muscle are slow twitch and white muscle are fast twitch.

Muscle Myoglobin

Similar to haemoglobin it has a temporary but greater storage for oxygen and transfers oxygen into the muscle cell. Oxygen is transfered until it reached the mitochondria. This process is an addition to the diffusion of oxygen between capillaries and muscle cells, caused by a larger concentration of oxygen in cells caused by a larger concentartion of oxygen in the haemoglobin than in the muscle cells.

Sarcomere

Each fibre of sarcomere bunch together the thousands od sarcomere form a long chain within each microfibril. The Z membrane indicates the boundry from one sarcomere to the next. The reason for this light dark straited bonding pattern (striped muscle) composed of two longitudinal protein filaments.

Thick filaments of myosin- confined to the dark A band and H zone has only thick myosin.

Thin filament of actin - light I band at the end of the myosins dark A band

The A bands are positioned at the center of the sacromere of thick and thin filaments seperated by an H zone which has only thick filaments. The I band at both ends of the sacromere and consists of only thin filaments. The thin filament connect the Z membrane and the inner edge of the nearer A band at each end of the sacromere. The thick filament join the outer edge of both A bands and therefore overlap the thin filaments in the A band. (see fig 1.2 for more detail).

The theory of muscle contraction is based on Huxely's Sliding Filament theory of muscle contraction. In the relaxed muscle all the bands are visable, whereas in the contracted muscle the light I band narrows then disappears, since the thin actin filaments are being drawn futher in between the thick myosin filaments.


fig 1.2 - Sarcomere contraction - click on picture to enlarge

Muscle, Tendons, Ligaments

Each structure serves different purpose, thus has different requirements:

Ligaments

• connects bone to bone. Thus stabalising function . Made of white fiberous tissue.
• non elastic
• extremely strong

Tendons

• connects muscle to bone
• Absorber of shock and connecting tissue
• made of % white fiberous and % red elastic tissue

Muscle

• Contractile tissue
• connected to tendon and tendon
• Elastic structure - absorbent of damaging shock in movement
• 45% of total body weight is muscle
• three main types:
  a) skeletal muscle
  b) smooth muscle
  c) cardiac muscle