Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 17

MUSCULAR SYSTEM

Human muscle system, the muscles of the human body that work the skeletal system,

that are under voluntary control, and that are concerned with movement, posture, and

balance. Broadly considered, human muscle—like the muscles of all vertebrates—is

often divided into striated muscle (or skeletal muscle), smooth muscle, and cardiac

muscle. Smooth muscle is under involuntary control and is found in the walls of

blood vessels and of structures such as the urinary bladder, the intestines, and the

stomach. Cardiac muscle makes up the mass of the heart and is responsible for the

rhythmic contractions of that vital pumping organ; it too is under involuntary

control. With very few exceptions, the arrangement of smooth muscle and cardiac

muscle in humans is identical to the arrangement found in other vertebrate animals.

The muscular system is the biological system of humans that produces movement.

The muscular system, in vertebrates, is controlled through the nervous system,

although some muscles, like cardiac muscle, can be completely autonomous. Muscle

is contractile tissue and is derived from the mesodermal layer of embryonic germ

cells. Its function is to produce force and cause motion, either locomotion or

movement within internal organs. Much of muscle contraction occurs without

conscious thought and is necessary for survival, like the contraction of the heart or

peristalsis, which pushes food through the digestive system. Voluntary muscle

contraction is used to move the body and can be finely controlled, such as

movements of the finger or gross movements that of the biceps and triceps.

Muscle structure

Muscle is composed of muscle cells (sometimes known as "muscle fibers"). Within

the cells are myofibrils; myofibrils contain sarcomeres which are composed of actin

and myosin. Individual muscle cells are lined with endomysium. Muscle cells are

bound together by perimysium into bundles called fascicles. These bundles are then

grouped together to form muscle, and is lined by epimysium. Muscle spindles are

distributed throughout the muscles, and provide sensory feedback information to the

central nervous system. Skeletal muscle, which involves muscles from the skeletal

tissue, is arranged in discrete groups. An example is the biceps brachii. It is

connected by tendons to processes of the skeleton. In contrast, smooth muscle occurs

at various scales in almost every organ, from the skin (in which it controls erection

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of body hair) to the blood vessels and digestive tract (in which it controls the caliber

of a lumen and peristalsis, respectively).

There are approximately 640 skeletal muscles in the human body (see list of muscles

of the human body). Contrary to popular belief, the number of muscle fibers cannot

be increased through exercise; instead the muscle cells simply get bigger. It is

however believed that myofibrils have a limited capacity for growth through

hypertrophy and will split if subject to increased demand. There are three basic types

of muscles in the body (smooth, cardiac, and skeletal). While they differ in many

regards, they all use actin sliding against myosin to create muscle contraction and

relaxation. In skeletal muscle, contraction is stimulated at each cell by nervous

impulses that release acetylcholine at the neuromuscular junction, createing action

potentials along the cell membrane. All skeletal muscle and many smooth muscle

contractions are stimulated by the binding of the neurotransmitter acetylcholine.

Muscular activity accounts for most of the body's energy consumption. Muscles

store energy for their own use in the form of glycogen, which represents about 1% of

their mass. Glycogen can be rapidly converted to glucose when more energy is

necessary.

Shoulder joint including Chest Muscles

• Pectoralis Major / Latissimus Dorsi / Deltoid / Supraspinatus / Infraspinatus /

Teres Minor / Subscapularis / Teres Major

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Elbow joint muscles / Arm Muscles

Biceps Brachii / Brachialis / Brachioradialis / Triceps Brachii / Anconeus / Supinator

/ Pronator Teres / Pronator Quadratus

Wrist and hand

Flexor Carpi Radialis / Flexor Carpi Ulnaris / Extensor Carpi Radialis Brevis /

Extensor Carpi Radialis Longus / Extensor Carpi Ulnaris / Extensor Digitorum

Communis / Flexor Digitorum Superficialis / Extensor Pollicis Longus / Flexor

Pollicis Longus

Knee joint

Vastus Lateralis / Vastus Intermedius / Vastus Medialis / Popliteus

Hip and pelvis

Iliopsoas / Gluteus Medius / Gluteus Minimus / Gluteus Maximus / Piriformis /

Pectineus / Sartorius / Rectus Femoris / Tensor Fasciae Latae / Biceps Femoris /

Semitendinosus / Semimembranosus / Adductor Brevis / Adductor Longus /

Adductor Magnus / Gracilis

Lower Leg muscles

Gastrocnemius / Soleus / Tibialis Posterior / Flexor Digitorum Longus / Flexor

Hallucis Longus / Peroneus Longus / Peroneal Brevis / Tibialis Anterior / Extensor

Digitorum Longus

Neck and back muscles

Erector Spinae / Multifidus / Rectus Abdominus / Transversus Abdominus / Internal

Obliques / External Obliques / Splenius / Quadratus Lumborum

Types of Muscle

There are three types of muscle found in the human body:

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Skeletal Muscle

Smooth Muscle

Cardiac Muscle (heart muscle)

Skeletal muscle

Skeletal Muscles are those which attach to bones and have the main function of

contracting to facilitate movement of our skeletons. They are also sometimes known

as striated muscles due to their appearance. The cause of this 'stripy' appearance is

the bands of Actin and Myosin which form the Sarcomere, found within the

Myofibrils.

Skeletal muscles are also sometimes called voluntary muscles, because we have

direct control over them through nervous impulses from our brains sending messages

to the muscle. Contractions can vary to produce powerful, fast movements or small

precision actions. Skeletal muscles also have the ability to stretch or contract and

still return to their original shape.

Skeletal muscle fibre type

Not all fibres within Skeletal muscles are the same. Different fibre types contract at

different speeds, are suited to different types of activity and vary in colour depending

on their Myoglobin (an oxygen carrying protein) content.

Smooth muscle

Smooth muscle is also sometimes known as Involuntary muscle due to our inability

to control its movements, or Unstriated as it does not have the stripy appearance of

Skeletal muscle. Smooth muscle is found in the walls of hollow organs such as the

Stomach, Oesophagus, Bronchi and in the walls of blood vessels. This muscle type is

stimulated by involuntary neurogenic impulses and has slow, rhythmical

contractions used in controlling internal organs, for example, moving food along the

Oesophagus or contricting blood vessels during Vasoconstriction.

Cardiac muscle (heart muscle)

This type of muscle is found solely in the walls of the heart. It has similarities with

skeletal muscles in that it is striated and with smooth muscles in that its contractions

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are not under conscious control. However this type of muscle is highly specialized. It

is under the control of the autonomic nervous system, however, even without a

nervous imput contraction can occur due to cells called pacemaker cells. Cardiac

muscle is highly resistant to fatigue due to the presence of a large number of

mitochondria, myoglobin and a good blood supply allowing continuous aerobic

metabolism.

1. Name the three types of muscles

• Skeletal

• Smooth

• Cardiac

2. Give three characteristics of skeletal muscle

• Voluntary contractions

• Attached to bones

• Striated appearance

3. Which type of muscle is unstriated?

• Smooth muscle

4. Which muscle types are involuntary?

• Cardiac muscle

• Smooth muscle

5. Where is smooth muscle found?

• Walls of hollow organs and blood vessels

Skeletal Muscle Cell Structure

Although skeletal muscle cells come in different shapes and sizes the main structure

of a skeletal muscle cell remains the same.

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Muscle Anatomy

If you were to take one whole muscle and cut through it, you would find the muscle

is covered in a layer of connective muscle tissue known as the Epimysium. The

Epimysium protects the muscle from friction against other muscles and bones.

It also continues at the end of the muscle to form (along with other connective

tissues) the muscles tendon. Looking at the cross section of the muscle you can see

bundles of fibres / fibers, known as Fasciculi, which are surrounded by another

connective tissue, called the Perimysium. Each Fasciculi contains anywhere between

10 and 100 muscle fibres, depending on the muscle in question.

A large strong muscle, such as thoses forming your Quadriceps would have a large

number of fibers within each bundle. A smaller muscle used for precision

movement, such as those in the hand would contain far fewer fibres per Fasciculi.

Looking at each muscle fiber in detail, you can see they too are covered in a fibrous

connective tissue, known as Endomysium which insulates each muscle fiber. Muscle

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fibers can range from 10 to 80 micrometers in diameter and may be up to 35cm long.

Beneath the Endomysium and surrounding the muscle fibre is the Sarcolemma which

is the fibres cell membrane and beneath this is the Sarcoplasm, which is the cells

cytoplasm, a gelatinous fluid which fills most cells.

This contains Glycogen and Fats for energy and also Mitochondria which are the

cells powerhouses, inside which the cells energy is produced.

Each muscle fiber itself contains cylindrical organelles known as Myofibrils. Each

muscle fiber contains hundreds to thousands of Myofibrils. These are bundles of

Actin and Myosin proteins which run the length of the muscle fiber and are

important in muscle contraction.

Surrounding the Myofibril there is a network of tubules and channels called the

Sarcoplasmic Reticulum in which Calcium is stored which is important in muscle

contraction. Transverse tubules pass inwards from the Sacrolemma throughout the

Myofibril, through which nerve impulses travel.

Each Myofibril can then be broken down into functional repeating segments called

Sarcomeres.

1. What is the name of the connective tissue which surrounds the whole muscle?

• Epimysium

2. How many muscle fibres are contained within one fasciculi?

• Between 10 and 100

3. Where will you find the endomysium?

• Surrounding each muscle fibre

4. Myofibrils consisit of bundles of what?

• Actin and myosin

5. What is stored in the sarcoplasmic reticulum

• Calcium

Muscle Fiber Types

Within skeletal muscle there are three types of fiber:

Type I

Type I fibers are also known as slow twitch fibers. They are red in colour due to the

presence of large volumes of myoglobin and so oxygen and high numbers of

Mitochondria. Due to this fact they are very resistant to fatigue and are capable of

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producing repeated low-level contractions by producing large amounts of ATP

through an aerobic metabolic cycle.

For this reason, the muscles containing mainly type I fibers are often postural

muscles such as those in the neck and spine due to their endurance capabilities Also,

athletes such as marathon runners have a high number of this type of fiber, partly

through genetics, partly through training.

Type IIa

Type IIa fibers are also sometimes known as fast oxidative fibres and are a hybrid of

type I and II fibers. These fibers contain a large number of mitochondria and

Myoglobin, hence their red colour. They manufacture and split ATP at a fast rate by

utilising both aerobic and anaerobic metabolism and so produce fast, strong muscle

contractions, although they are more prone to fatigue than type I fibers. Resistance

training can turn type IIb fibers into type IIa due to an increase in the ability to utilise

the oxidative cycle.

Type IIb

Often known as fast glycolytic fibers they are white in colour due to a low level of

myoglobin and also contain few mitochondria. They produce ATP at a slow rate by

anaerobic metabolism and break it down very quicky. This results in short, fast

bursts of power and rapid fatigue. As mentioned above, this type of fiber can be

turned into type IIa fibers by resistance training. This is a positive change due to the

increased fatigue resistance of type IIa fibers. These fibers are found in large

quantities in the muscles of the arms.

1. Which type of fibers make up the majority of postural muscles?

• Slow twitch

2. Type 2a fibers are red in colour due to the high content of what?

• Mitochondria and myoglobin

3. Type 2b fibers are often called what?

• Fast glycolytic

4. Can training cause changes in muscle fiber type? If so, which?

• Yes, type 2b can change to type 2a

5. Marathon runners would have more of which type of muscle fiber?

• Slow twitch (type 1)

Shapes of Muscles

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 25

What are the different shapes of muscle?

There are 5 different muscle shapes within the human body:

• Circular

• Convergent

• Parallel

• Pennate

• Fusiform

Circular Muscles

These muscles appear circular in shape and are normally sphincter muscles which

surround an opening such as the mouth, surrounded by Obicularis Oris and

Obicularis Oculi surrounding the eyes

Convergent Muscles

These are muscles where the origin (the attachment to a fixed bone, usually the

proximal attachment) is wider than the point of insertion. This fibre arrangement

allows for maximum force production. An example is Pectoralis Major. Convergent

muscles are also sometimes known as triangular muscles.

Parallel Muscles

Parallel muscles have fibres which, as the name suggests, run parallel to each other

and are sometimes called strap muscles.

They are normally long muscles which cause large movements, are not very strong

but have good endurance. Examples include Sartorius and Sternocleidomastoid.

Some textbooks include Fusiform muscles in the parallel group.

Pennate Muscles

Pennate muscles have a large number of muscle fibres per unit and so are very

strong, but tire easily. They can be divided into:

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• Unipennate: These muscles have their fibres arranged to insert in a diagonal

direction onto the tendon, which allows great strength. Examples include the

Lumbricals (deep hand muscles) and Extensor Digitorum Longus (wrist and finger

extensor)

Bipennate: Bipennate muscles have two rows of muscle fibres, facing in opposite

diagonal directions,with a central tendon, like a feather. This allows even greater

power but less range of motion. An example is the Rectus Femoris

• Multipennate: As the name suggests Multipennate muscles have multiple rows

of diagonal fibres, with a central tendon which branches into two or more tendons.

An example is the Deltoid muscle which has three sections, anterior, posterior and

middle.

Fusiform Muscles

Sometimes included in the parallel muscle group, these muscles are more spindle

shaped, with the muscle belly being wider than the origin and insertion. Examples

are Biceps Brachii and Psoas major

1. What does the fibre arrangement of convergent muscles allow?

• Strength

2. Name the three types of pennate muscles

• Unipennate

• Bipennate

• Multipennate

3. Give an example of a fusiform muscle

• Biceps Brachii

4. Parallel muscles are usually long and have good what?

• Endurance

Types of Muscle Contraction

Muscle Contractions can be divided into:

Isotonic (meaning same tension)

Isometric (meaning same distance or not moving)

Isokinetic (meaning same speed)

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Isotonic Contractions

Isotonic contractions are those which cause the muscle to change length as it

contracts and causes movement of a body part. There are two types of Isotonic

contraction:

Concentric

Concentric contractions are those which cause the muscle to shorten as it contracts.

An example is bending the elbow from straight to fully flexed, causing a concentric

contraction of the Biceps Brachii muscle. Concentric contractions are the most

common type of muscle contraction and occur frequently in daily and sporting

activities.

Eccentric

Eccentric contractions are the opposite of concentric and occur when the muscle

lengthens as it contracts. This is less common and usually involves the control or

deceleration of a movement being initiated by the eccentric muscles agonist.

For example, when kicking a football, the Quadriceps muscle contracts

concentrically to straighten the knee and the Hamstrings contract eccentrically to

decelerate the motion of the lower limb. This type on contraction puts a lot of strain

through the muscle and is commonly involved in muscle injuries.

Isometric Contractions

Isometric contractions occur when there is no change in the length of the contracting

muscle. This occurs when carrying an object in front of you as the weight of the

object is pulling your arms down but your muscles are contracting to hold the object

at the same level. Another example is when you grip something , such as a tennis

racket. There is no movement in the joints of the hand, but the muscles are

contracting to provide a force sufficient enough to keep a steady hold on the racket.

The amount of force a muscle is able to produce during an isometric contraction

depends on the length of the muscle at the point of contraction. Each muscle has an

optimum length at which the maximum isometric force can be produced.

1. Isotonic contractions can be either concentric or?

• Eccentric

2. Which type of muscle contraction causes no movement?

• Isometric

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3. Performing a bicep curl involves a _________ contraction of the Biceps

Brachii muscle

• Concentric

4. Which type of contraction is at a constant speed?

• Isokinetic

5. Holding a squat position involves what type of muscle contraction?

• Isometric

SLIDING FILAMENT THEORY - SKELETAL MUSCLE

• The sliding filament theory is the method by which muscles are thought to

contract. It is recommended that you read the muscle structure page before

continuing with the sliding filament theory.

At a very basic level each muscle fibre is made up of smaller fibres called

myofibrils. These contain even smaller structures called actin and myosin filaments.

These filaments slide in and out between each other to form a muscle contraction,

hence called the sliding filament theory!

The diagram above shows part a myofibril called a sarcomere. This is the smallest

unit of skeletal muscle that can contract. Sarcomeres repeat themselves over and

over along the length of the myofibril.

Here is a quick reminder of all the structures involved:

• Myofibril: A cylindrical organelle running the length of the muscle fibre,

containing Actin and Myosin filaments.

• Sarcomere: The functional unit of the Myofibril, divided into I, A and H bands.

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• Actin: A thin, contractile protein filament, containing 'active' or 'binding' sites.

• Myosin: A thick, contractile protein filament, with protusions known as Myosin

Heads.

• Tropomyosin: An actin-binding protein which regulates muscle contraction.

• Troponin: A complex of three proteins, attached to Tropomyosin.

Here is what happens in detail. The process of a muscle contracting can be divided

into 5 sections:

➢ A nervous impulse arrives at the neuromuscular junction, which causes a release

of a chemical called Acetylcholine. The presence of Acetylcholine causes the

depolarisation of the motor end plate which travels throughout the muscle by the

transverse tubules, causing Calcium (Ca+) to be released from the sarcoplasmic

reticulum.

➢ In the presence of high concentrations of Ca+, the Ca+ binds to Troponin,

changing its shape and so moving Tropomyosin from the active site of the Actin.

The Myosin filaments can now attach to the Actin, forming a cross-bridge.

➢ The breakdown of ATP releases energy which enables the Myosin to pull the

Actin filaments inwards and so shortening the muscle. This occurs along the entire

length of every myofibril in the muscle cell.

➢ The Myosin detaches from the Actin and the cross-bridge is broken when an ATP

molecule binds to the Myosin head. When the ATP is then broken down the Myosin

head can again attach to an Actin binding site further along the Actin filament and

repeat the 'power stroke'. This repeated pulling of the Actin over the myosin is often

known as the ratchet mechanism.

➢ This process of muscular contraction can last for as long as there is adequate ATP

and Ca+ stores. Once the impulse stops the Ca+ is pumped back to the Sarcoplasmic

Reticulum and the Actin returns to its resting position causing the muscle to lengthen

and relax.

It is important to realise that a single power stroke results in only a shortening of

approximately 1% of the entire muscle. Therefore to achieve an overall shortening of

up to 35% the whole process must be repeated many times. It is thought that whilst

half of the cross-bridges are active in pulling the Actin over the Myosin, the other

half are looking for their next binding site.

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Stretched Muscle

Looking at the diagram above again, shows a stretched muscle where the I - bands

and the H - zone is elongated due to reduced overlapping of the myosin and actin

filaments. There would be reduced muscle strength because few cross bridges can

form between teh actin and myosin.

Partially Contracted Muscle

The diagram above shows a partially contracted muscle where there is more

overlapping of the myosin and actin with lots of potential for cross bridges to form.

The I - bands and H - zone are shortened.

Fully Contracted Muscle

The diagram above shows a fully contracted muscle with lots of overlap between the

actin and myosin. Because the thin actin filaments have overlapped there is a

reduced potential for cross bridges to form again. Therefore there will be low force

production from the muscle.

1. What is released from the neuromuscular junction?

• Acetylcholine

2. What is the name given to the connections between Myosin and Actin?

Cross-bridges

3. What pulls the actin filaments inwards to shorten a muscle?

• Myosin

1. When the nervous impulse stops, what happen

Calcium is pumped back to the sarcoplasmic reticulum and the actin returns to its resting

position so the muscle lengthens

ATP in the Human Body

Muscles cells, like all cells, use ATP as an energy source. The total quantity of ATP

in the human body at any one time is about 0.1 Mole. The energy used by human

cells requires the hydrolysis of 200 to 300 moles of ATP daily. This means that each

ATP molecule is recycled 2000 to 3000 times during a single day. ATP cannot be

stored, hence its consumption must closely follow its synthesis. On a per-hour basis,

1 kilogram of ATP is created, processed and then recycled in the body. Looking at it

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another way, a single cell uses about 10 million ATP molecules per second to meet

its metabolic needs, and recycles all of its ATP molecules about every 20-30

seconds.

Lactic Acid

Catabolized carbohydrates is known as glycolysis. The end product of glycolysis,

pyruvate can go into different directions depending on aerobic or anaerobic

conditions. In aerobic it goes through the Krebs cycle and in anaerobic it goes

through the Cori cycle. In the Cori cycle pyruvate is converted to lactate, this forms

lactic acid, lactic acid causes muscle fatigue. In the aerobic conditions pyruvate goes

through the Krebs cycle. For more about Krebs cycle refer to chapter 2 Cell

Physiology.

Glossary

Actin: A protein that forms a long polymer rods called microfilaments; Interacts

with myosin to cause movement in muscles.

ATP: Adenosine Triphosphate" is a nucleotide that comes from adenosine that takes

place in muscle tissue: This provides a large source of energy for cellular reactions.

Cardiac Muscle: is also an "involuntary muscle" but it's a specialized kind of

muscle found only within the heart.

Clostridium botulinum: A pathogen that causes botulism, gram stain positive,

morphology is rod shaped, grows in anaerobic conditions, and produces spores.

Clostridium tetani: A pathogen that causes lock jaw, gram stain positive,

morphology is tennis racket shaped rod, grows in anaerobic conditions, and produces

spores.

Cori cycle: In anaerobic conditions produces lactic acid.

Cramp: A localized muscle spasm that happens after strenuous activity.

Glycogen: Glucose that has been converted for energy storage. Muscles store energy

for their own use in this form.

Lactic acid: Causes muscle fatigue.

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Muscle: Contractile tissue that is derived from the mesodermal layer of embryonic

germ cells.

Muscular Dystrophy: A hereditary disease characterized by progressive atrophy of

muscle fibers

Myosin: The fibrous motor protein that uses ATP to drive movements along actin

filaments.

Sarcoplasmic Reticulum: Smooth-surfaced tubules forming a plexus around each

myofibril that function as a storage and release area for calcium ions (CA+2).

Skeletal muscle: this "voluntary muscle" is anchored by tendons to the bone and is

used to affect skeletal movement such as locomotion.

Smooth muscle: this "involuntary muscle" is found within the walls of organs and

structures such as the esophagus, stomach, intestines, bronchi, uterus, ureters,

bladder, and blood vessels.

Sprain: Injuries that involves a stretched or torn ligament.

Strain: A injury to the muscle or tendon attachment

The Muscle Groups and Their Actions

The following sections provide a basic framework for the understanding of gross

human muscular anatomy, with descriptions of the large muscle groups and their

actions. The various muscle groups work in a coordinated fashion to control the

movements of the human body.

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THE NECK

The motion of the neck is described in terms of rotation, flexion, extension, and side

bending (i.e., the motion used to touch the ear to the shoulder). The direction of the

action can be ipsilateral, which refers to movement in the direction of the contracting

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muscle, or contralateral, which refers to movement away from the side of the

contracting muscle.

Rotation is one of the most-important actions of the cervical (neck) spine. Rotation is

accomplished primarily by the sternocleidomastoid muscle, which bends the neck to

the ipsilateral side and rotates the neck contralaterally. Together, the

sternocleidomastoid muscles on both sides of the neck act to flex the neck and raise

the sternum to assist in forced inhalation. The anterior and middle scalene muscles,

which also are located at the sides of the neck, act ipsilaterally to rotate the neck, as

well as to elevate the first rib. The splenius capitis and splenius cervicis, which are

located in the back of the neck, work to rotate the head.

Side bending also is an important action of the cervical spine. The

sternocleidomastoid muscles are involved in cervical side bending. The posterior

scalene muscles, located on the lower sides of the neck, ipsilaterally bend the neck to

the side and elevate the second rib. The splenius capitis and splenius cervicis also

assist in neck side bending. The erector spinae muscles (iliocostalis, longissimus,

and spinalis) are large, deep muscles that extend the length of the back. All three act

to ipsilaterally side bend the neck.

Neck flexion refers to the motion used to touch the chin to the chest. It is

accomplished primarily by the sternocleidomastoid muscles, with assistance from

the longus colli and the longus capitis, which are found in the front of the neck. Neck

extension is the opposite of flexion and is accomplished by many of the same

muscles that are used for other neck movements, including the splenius cervicis,

splenius capitis, iliocostalis, longissimus, and spinalis muscles.

THE BACK NECK

The back contains the origins of many of the muscles that are involved in the

movement of the neck and shoulders. In addition, the axial skeleton that runs

vertically through the back protects the spinal cord, which innervates almost all the

muscles in the body.

Multiple muscles in the back function specifically in movements of the back. The

erector spinae muscles, for example, extend the back (bend it backward) and side

bend the back.

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The semispinalis dorsi and semispinalis capitis muscles also extend the back. The

small muscles of the vertebrae (the multifidi and rotators) help rotate, extend, and

side bend the back. The quadratus lumborum muscle in the lower back side bends

the lumbar spine and aids in the inspiration of air through its stabilizing affects at its

insertion at the 12th rib (the last of the floating ribs). The scapula (shoulder blade) is

elevated by the trapezius muscle, which runs from the back of the neck to the middle

of the back, by the rhomboid major and rhomboid minor muscles in the upper back,

and by the levator scapulae muscle, which runs along the side and back of the neck.

THE SHOULDER

The shoulder is a complex ball-and-socket joint comprising the head of the humerus,

the clavicle (collarbone), and the scapula. The shoulder’s main motions are flexion,

extension, abduction, adduction, internal rotation, and external rotation.

Shoulder flexion is movement of the shoulder in a forward motion. An example of

shoulder flexion can be seen when reaching forward to grasp an object. That action

is accomplished primarily by the combined actions of the deltoid muscle in the

uppermost extent of the arm, the pectoralis major muscle in the chest, the

coracobrachialis muscle on the inside of the upper arm, and the biceps brachii

muscles on the front of the upper arm.

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Extension of the shoulder is opposite to flexion. Pure shoulder extension is the

movement of the arm directly behind the body, as in receiving a baton in a relay

race. That movement is accomplished by the actions of the deltoid muscle, the

latissimus dorsi muscle in the back, the teres major muscle in the armpit area, and

the triceps muscle in the back of the upper arm. The triceps, as the name suggests,

consists of three heads that originate from different surfaces but share the same

insertion at the olecranon process of the ulna (a bone in the forearm); the three heads

together act to extend the elbow.

Shoulder adduction and abduction serve to lower the arm toward and lift the arm

away from the body, respectively. They can be visualized by picturing someone

doing jumping jacks. Adduction is accomplished primarily by the pectoralis major,

latissimus dorsi, teres major, triceps, and coracobrachialis. The deltoid and the

supraspinatus, a muscle that runs along the scapula in the back, are the two main

abductors of the shoulder.

An example of external rotation of the shoulder is seen in a tennis backhand stroke.

External rotation is attributed primarily to the deltoid, the teres minor in the armpit

area, and the infraspinatus muscle, which covers the scapula. Internal rotation of the

shoulder is the opposite of external rotation. An example is the shoulder movement

that occurs when reaching into a back pocket. That movement is achieved through

the coordinated action of the pectoralis major, latissimus dorsi, deltoid, teres major,

and subscapularis muscles. (The subscapularis is a deep muscle situated on the

anterior, or front-facing, surface of the scapula.)

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 37

The teres minor, subscapularis, supraspinatus, and infraspinatus muscles together

form the rotator cuff, which stabilizes the humeral head (the ball portion of the ball-

and-socket shoulder joint). The muscles of the rotator cuff are common sites of

injury in adults, particularly among people who perform overhead motions

repeatedly (e.g., throwing a baseball or painting a ceiling). Several of the rotator cuff

muscles have tendons that run under the acromion, a bony prominence at the distal

end of the scapula. (The term distal describes a relative position away from the

centre of the body; it often is contrasted with the term proximal, which describes a

relative position near to the centre of the body.) The position of the tendons and of

the subacromial bursae (fluid-filled sacs located beneath the acromion) leaves them

vulnerable to compression and pinching, which can result in an injury known as

shoulder impingement syndrome.

THE ARM

In addition to aiding the movement of the shoulder, the muscles of the upper arm

produce various movements of the forearm. For example, the primary muscles

involved in forearm flexion, in which the angle formed at the elbow becomes smaller

(i.e., the hand moves closer to the shoulder), are the biceps brachii, the brachialis

(situated beneath the biceps brachii in the upper arm), and the brachioradialis (the

origin of which is on the humerus). Minor contributions to forearm flexion are

provided by the coracobrachialis and by flexor muscles situated in the anterior

compartment of the forearm (the palm side of the forearm; also known as the flexor

compartment), including the pronator teres, the flexor carpi radialis, the flexor

digitorum superficialis, the palmaris longus, and the flexor carpi ulnaris.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 38

Extension of the forearm increases the angle at the elbow, moving the hand away

from the shoulder. That action is accomplished primarily by the triceps brachii.

Other muscles that make minor contributions to forearm extension include the

extensor muscles of the posterior compartment of the forearm (the side of the

forearm that is contiguous with the back of the hand; also known as the extensor

compartment), including the extensor carpi radialis longus, the extensor carpi

radialis brevis, the extensor digitorum, the extensor carpi ulnaris, and the anconeus.

THE WRIST

Wrist flexion refers to movement of the wrist that draws the palm of the hand

downward. That action is carried out by the flexor carpi radialis, the flexor carpi

ulnaris, the flexor digitorum superficialis, the flexor digitorum profundus, and the

flexor pollicis longus.

Wrist extension, by contrast, shortens the angle at the back of the wrist. The muscles

responsible for that action are the extensor carpi radialis longus and the extensor

carpi radialis brevis, which also abduct the hand at the wrist (move the hand in the

direction of the thumb, or first digit); the extensor digitorum, which also extends the

index to little finger (the second to fifth digits); the extensor digiti minimi, which

also extends the little finger and adducts the hand (moves the hand in the direction of

the little finger); and the extensor carpi ulnaris, which also adducts the hand. Other

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 39

small muscles that cross the wrist joint may add to wrist extension, but they do so to

only a small degree.

Wrist supination is the rotation of the wrist that brings the palm facing up. The

supinator muscle in the posterior compartment acts to supinate the forearm. The

biceps brachii also adds to supination. Pronation is the opposing action, in which the

wrist is rotated so that the palm is facing down. The pronator quadratus, a deep

muscle in the anterior compartment, along with the pronator teres, pronates the

forearm.

The Hand

The hand is a complex structure that is involved in fine motor coordination and

complex task performance. Its muscles generally are small and extensively

innervated. Even simple actions, such as typing on a keyboard, require a multitude of

precise movements to be carried out by the hand muscles. Because of that

complexity, the following paragraphs cover only the primary action of each hand

muscle.

Several muscles that originate at the posterior surface of the ulna or the radius (the

other bone in the forearm) have their actions in the hand. Those include the abductor

pollicis longus, which abducts and extends the thumb; the extensor pollicis brevis,

which extends the metacarpophalangeal (MCP) joint of the thumb; the extensor

pollicis, which extends the distal phalanx (finger bone) of the thumb; and the

extensor indicis, which extends the index finger at the MCP joint. (MCP joints are

located between the metacarpal bones, which are situated in the hand, and the

phalanges, which are the small bones of the fingers.)

Although several of the muscles that move the hand have their origins in the

forearm, there are many small muscles of the hand that have both their origin and

their insertion within the hand. Those are referred to as the intrinsic muscles of the

hand. They include the palmaris brevis, which assists with grip; the umbricals, which

flex the MCP joints and extend the interphalangeal joints (IPs; the joints between the

phalanges) of the fingers; the palmar interossei, which adduct the fingers toward the

middle finger (the third digit); and the dorsal interossei, which abduct the fingers

away from the middle finger. All the interossei flex the MCP joints and extend the IP

joints.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 40

The thenar eminence is located on the palm side of the base of the thumb and is

composed of three muscles, the abductor pollicis brevis, the flexor pollicis brevis,

and the opponens pollicis, all of which are innervated by the median nerve. The

abductor pollicis brevis abducts the thumb; the flexor pollicis brevis flexes the MCP

joint of the thumb; and the opponens pollicis acts to oppose the thumb to the other

fingers. The adductor pollicis, which is not part of the thenar eminence, acts to

adduct the thumb.

The hypothenar enimence is located on the palm side of the hand below the little

finger. It contains three muscles that are innervated by the deep branch of the ulnar

nerve. The abductor digiti minimi abducts the little finger. The flexor digiti minimi

flexes the little finger. The opponens digiti minimi opposes the little finger with the

thumb.

THE ABDOMEN

There are three muscular layers of the abdominal wall, with a fourth layer in the

middle anterior region. The fourth layer in the midregion is the rectus abdominis,

which has vertically running muscle fibres that flex the trunk and stabilize the pelvis.

To either side of the rectus abdominis are the other three layers of abdominal

muscles. The deepest of those

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 41

layers are the transversus abdominis, which has fibres that run perpendicular to the

rectus abdominus; the transversus abdominis acts to compress and support the

abdomen and provides static core stabilization. The internal oblique layers run

upward and forward from the sides of the abdomen, and the external oblique layers,

which form the outermost muscle layers of the abdomen, run downward and

forward. The internal oblique layers act in conjunction with the external oblique on

the opposite side of the body to flex and rotate the trunk toward the side of the

contracting internal oblique (“same-side rotator”).

THE HIP

The hip joint is a complex weight-bearing ball-and-socket joint that can sustain

considerable load. The socket of the joint is relatively deep, allowing for stability but

sacrificing some degree in range of motion. The movements described in this section

include flexion, extension, abduction, and adduction.

Hip flexion is the hip motion that brings the knee toward the chest. The major

muscles of hip flexion include the iliopsoas, which is made up of the psoas major,

psoas minor, and iliacus. Together, those muscles act mainly to flex the hip, but they

also contribute to abdominal flexion and hip stabilization. Other hip flexors include

the sartorius, the rectus femoris, the pectineus, and the gracilis. The sartorius also

contributes to external hip rotation and knee extension and abduction, and the rectus

femoris also acts in knee extension. The pectineus is also involved in hip adduction

and internal rotation.

Hip extension is accomplished primarily by the muscles of the posterior thigh and

buttocks, which when contracted serve to move the thigh from a flexed position

toward the midline of the body or the trunk of the body from a bent position toward a

more-erect posture. Hip extension is accomplished mostly by the gluteus maximus,

the biceps femoris (which is divided into two heads, the long head and the short

head), the semitendinosus, and the semimembranosus. A minor contribution is also

provided by the adductor magnus and other small pelvic muscles.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 42

The movement of adduction is used to describe a direction of limb motion that serves to

take the limb from a lateral position to its more-axial alignment. During a jumping-jack

exercise, for example, abduction of the leg occurs when it is moved away from the

midline and adduction when it is moved back toward the midline. The main abductors of

the hip are the gluteus medius, gluteus minimus, and tensor fascia lata. Those three

muscles also serve to internally rotate the thigh in an extended position and externally

rotate the thigh in the flexed position. Another minor contributor is the piriformis. The

main hip adductors are the adductor magnus, the adductor brevis, and the adductor

longus. A minor contribution to hip adduction is performed by the pectineus and the

gracilis.

THE UPPER LEG AND KNEE

Extension of the knee is accomplished by a group of muscles collectively referred to as

the quadriceps femoris, which increases the angle of the knee, bringing the lower leg into

a straight position. Knee extension is used in the forward, swing phase of the gait and is

integral in movements such as kicking. The quadriceps femoris group includes the vastus

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 43

medius, vastus lateralis, vastus intermedius, and rectus femoris. A minor contribution to

knee extension is provided by the sartorius.

Knee flexion refers to bending of the knee from the straight position. The muscles that

perform that action oppose those of knee extension and are generally referred to as the

hamstring muscles. The hamstring muscles are situated in the back of the thigh and

include the biceps femoris, the semitendinosus, and the semimembranosus. Small

contributions to knee flexion are made by the gastrocnemius muscle in the back of the

calf and by several small muscles that cross the knee joint posteriorly.

THE LOWER LEG AND FOOT

The muscles of the lower leg and foot are complex and work in many planes. Their

actions depend on whether the person is bearing weight, as well as on the position of the

foot. The following paragraphs provide a brief overview of the actions of the muscles of

the lower leg and foot.

Dorsiflexion refers to ankle flexion in the direction of the dorsum, or anterior surface

of the foot (the surface of the foot viewed from above). Dorsiflexion is accomplished

by several muscles, including the tibialis anterior, which in addition to dorsiflexion

also inverts the foot (tilts the foot toward the midline), stabilizes the foot when

striking the ground, and locks the ankle when kicking. The extensor digitorum

longus (EDL) also acts in dorsiflexion and functions to extend the last four toes. In

addition to the EDL, some individuals also have a muscle called the peroneus tertius

(fibularis tertius), which participates to a limited extent in dorsiflexion and eversion

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 44

of the foot (tilting of the foot away from the midline). The extensor hallucis longus

primarily acts in big toe (hallux) dorsiflexion, but it also acts to dorsiflex, as well as

weakly invert, the ankle.

Plantarflexion refers to flexion of the ankle in the direction of the sole of the foot.

That is most easily demonstrated by having a person stand on his or her toes. The

majority of ankle plantarflexion is performed by the large calf musculature,

including the gastrocnemius and the soleus, which lies just behind the

gastrocnemius. It is generally accepted that those are two distinct muscles; however,

there is some debate as to whether the gastrocnemius and the soleus are two parts of

the same muscle.

Other muscles of the lower leg and foot include the plantaris, which runs obliquely

between the gastrocnemius and the soleus; the flexor hallucis longus, which

contributes to ankle flexion but is involved primarily in big toe flexion; the flexor

digitorum longus, which also flexes the second to fifth toes; the peroneus longus,

which flexes the ankle and everts the foot; and the peroneus brevis, which is

involved in plantarflexion and eversion of the foot.

Intrinsic muscles (originating and included wholly within an organ or part) of the

foot arise in the foot and do not cross the ankle joint. Hence, their action is confined

to the foot. The intrinsic muscles of the foot include the abductor hallucis, which

abducts the big toe; the flexor digitorum brevis, which flexes the second to fifth toes;

the abductor digiti minimi, which abducts and flexes the fifth toe; the quadratus

plantae, which assists in toe flexion; the lumbricals, which flex the

metatarsophalangeal (MTP) joints and extend the distal IP and proximal IP joints of

the toes; the flexor hallucis brevis, which flexes the big toe; and the adductor

hallucis, which flexes and contracts the big toe. The adductor hallucis has two heads,

the oblique head and the transverse head, which share an insertion on the lateral

(outer) side of the base of the proximal phalanx of the big toe. The oblique head

arises from the base of the second to fourth metatarsal bones, and the transverse head

arises from the ligaments of the MTP joints of the third to fifth toes. The flexor digiti

minimi brevis extends and adducts the fifth toe. The dorsal interossei abduct the toes,

and the plantar interossei adduct the toes.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 45

Meaning of extrinsic muscle (originating outside a part and acting upon the part as a

whole) Ex : extrinsic muscles of the tongue

Reference by Shane W. Cummings, Christopher Tangen of Britannica

MOVEMENT & LOCOMOTION

Points to remember

➢ Kinesiology – Science of body movements.

➢ Sella turcia – Depression in the sphenoid of the skull that lodges the pituitary

body.

➢ Strongest muscle – Masseters of Jaw

➢ Largest muscle – gluteus maximus; Smallest Muscle – Stapedius.

➢ Excessive stretching of ligament by sudden violent twist or pull is called

sprain.

➢ Longest bone in human body – Femur.

➢ Funny bone – Humerus (Fore arm).

➢ Largest foramen – Foramen magnum (skull base).

➢ Electromyography – Graphic recording of electric currents produced by an

active muscle, as during muscle twitch, EMG is electromyogram May be used to

determine the cause of muscular weakness or paralysis.

➢ Pygostyle – Bone supporting the oil glands in birds is mid dorsally located in

the posterior part.

➢ Uncinate process – Small bony projections running from one rib to the second

rib in birds providing a uniform surface during flight.

➢ Lordosis – When spine becomes stri\aight and loses its flexion curves.

➢ Chevron bones – Y shaped bones found in snakes and lizards.

➢ Birds have spongy bones with air filled space called pneumatic bone.

➢ Diploid bones have both cancellous and spongy region . E.g. femur, humerus,

flat bones of skull and ribs.

➢ Sacrum is absent in Whales.

➢ Strongest bone – Tibia (Shine bone).

➢ Smallest bone – Stapes.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 46

High Yield Facts

❖ Movement & locomotion are two important characteristics of living

organisms.

❖ Scientific study of body movement is called kinesiology.

❖ Movement (change in body position) is always autonomic in living organisms.

❖ Movement helps in equilibrium, food capturing, reception of stimuli, visceral

functions like peristalsis, respiration, blood circulation, sound production etc.

❖ Non-muscular movement occur in Protists and some unicellular parts of

multicellular organisms.

❖ Type of nonmuscular movements are pseduopodial (Amoeba, macrophages,

leucocytes), Cytoplasmic or protoplasmic (inside eukaryotic cells), Flagellar

(Chlamydomanas, sperms, unicellular green alage, sponges) & ciliary movement

(Paramecium & other ciliates).

❖ In multicellular organisms, locomotion occurs by means of muscles with or

without skeletal & its joints.

❖ Locomotion occurs by running (lion, dog), walking (men), creeping or crawling

(leech, earthworm etc.,), hopping (frog), Swimming (fish, whale), flying (birds, bats,

insects).

❖ Locomotion in tetrapods takes place by limbs/legs.

❖ Locomotion helps in defnece from predators & unfavourable conditions, food &

water, procuring, mating, egg laying etc.

❖ Locomotion in starfish takes place by tube feet.

❖ Non-living objects may show induced movements due to some external force.

❖ Locomotion is brought about by coordination of both the system i.e., skeletal &

muscular system.

❖ Skeletal system from the supportive framework of the body giving its shpe

physical strength & protection to softer parts & place for attachments of muscles.

❖ Exoskeleton is the hard protective & supportive framework present on the outside of

the body.

❖ Exoskeleton is found in both invertebrates (eg. Shall of snails, bivalves, corals, &

Vertebrates (eg. Claw, nails, horns, feather, scales etc).

❖ It can be epidermal or mesodermal.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 47

❖ Epidermal/ectodermal exoskeleton occurs in mammals, birds & many reptiles.

❖ Mesodermal / dermal exoskeleton occurs in fishes (scales) & some reptiles

(crocodiles, turtles & tortoises).

❖ Exoskeleton is made of either dead tissues or biochemical secretion.

❖ Endoskeletal occurs inside the body.

❖ It is present in corals, echinoderms & vertebrates.

❖ It is made of Cartilages & bones.

❖ Bones can be long (femur, tibia, fibula), Short (metacarpals, metatarsals, phalanges),

flat (Cranial, Scapula, innominte) & irregular (vertebrae, carpals & tarsals).

❖ Extremities of long bones posses hyaline cartilage.

❖ Longest bone of frog is tibio-fibula.

❖ Spongy bones (cancellous bones) have bony matter as bar or trabeculae & space

filled with red bone marrow.

❖ These bones occur at the ends of long bones (femur end, humerus end), Flat bones

(skull bones), Vertebrae, Sternum & rib.

❖ In birds the spongy bone has air filled spaces and called as pneumatic bones.

❖ Compact bones have compact/dense matrix and occur in the form of lamellae. Eg.

Clavicles & scapulae of pectoral girdle, innominate of pelvic girdle, arm bones & leg

bones.

❖ Diploid bones have both compact (on surface) & spongy (inside) regions. Eg.

Femur, humerus, flat bones of skull & ribs.

❖ Cartilage bones or replacing bones are produced by endochondral ossification (i.e.

internal ossification of cartilage). Eg. Limb bones, vertegrae, girdle bones (except

clavicle), occipital & sphenoid.

❖ Sesamoid bones are produced through ossification of tendons. Eg. Patella.

❖ Investing bones are formed by transformation of connective tissue. Eg. Clavicle,

ace bones.

❖ Visceral or heterotypic bones occur by the separation form th rest of the skeleton.

Eg. Oscordis (heart of deer), os penis (penis of rodents, bats & some carnivores) etc.

❖ Epiphysial plate is involkved in elongation of bone.

❖ Human bones are made up of 260 bones which are fused bariously to become 206.

❖ Axial skeleton occurs in mid axial part or longitudinal axis of the body.

❖ Skull is the endoskeleton of head & jaws and contains 29 skeletal elements.

❖ Skull consists of three parts - cranium, face, hyoid.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 48

❖ Human skull is dicondylic with 2 occipital condyle.

❖ Cranium is made up of 8 bones: 1 frontal, 2 parietals, 1 Occipitals, 2 Temporal, 1

Sphenoid & 1 echinoid.

❖ Pterygoid is a wing like extension of sphenoid bone.

❖ The only movable bone in the skull is mandible.

❖ Face makes the front & lower part of the skull.

❖ It consists of 14 bones viz. 2 zygomatic bones, 2 maxilla, 2 nasal bones, 2 lacrimal

bones, 1 vomer, 2 palatine bones, 2 inferior nasal chonchae or tubinated bones and 1

mandible.

❖ Maxillae form the upper jaw while mandible forms the lower jaw.

❖ These bones are joined by immovable fibrous joints called sutures.

❖ Hyoid or tongue bone (1) occurs at the base of tongue and above the larynx.

❖ 6 bones occur as ear ossicle (2 malleus, 2 incus & 2 stapes) I the skull.

❖ Vertebral column is made up of 33 vertebrae in which only 26 are visible due to

fusion of sacral & coccygeal region.

❖ All the vertebrae of man are amphiplatyan type i.e. centrum is flat on both side.

❖ Vertebral formula of vertebral column of human is C7T12L5S5C4.

❖ Cervical vertebra are present in the neck region.

❖ Atlas, the first cervical vertebra has reduced centrum, rudimentary neural spine &

concave superior articular facets to provide nodding movements of head.

❖ The second cervical vertebra axis is characterized by odontoid process.

❖ Odontoid process fits into canal of atlas to provide head with sideways rotation.

❖ 12 thoracic vertebrae occur in thoracic region.

❖ 5 lumber vertebrae occur in the abdominal region.

❖ Five sacral vertebrae occur in pelvic region as a fused wedge-shaped sacrum

attached to pelvic girdle.

❖ Coccygeal vertebrae are found in coccyx region as a fused tail bone.

❖ Sternum is a flat narrow long bone present in the middle front of chest.

❖ Sternum is also called breast bone.

❖ It has 3 regions – manubrium for attachment of clavicles & first pair of ribs, body

with articular surface or attachment of 2nd to 6th ribs & axiphoid process.

❖ Sternum protects the internal organs, provide surface for muscle attachment and

also help in respiratory mechanism.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 49

❖ First 7 pairs are known as true ribs due to their attachment with sternum directly

by means of hyaline cartilage.

❖ 8, 9 & 10 are false ribs as they are attached to coastal cartilage of seventh rib.

❖ 11 & 12 are known as floating ribs because these ribs are imperfectly formed and

do not reach the sternum.

❖ Floating ribs protect the kidney.

❖ Rib cage is formed of thoracic vertebrae, sternum & ribs.

❖ Pectoral girdle consists of clavicle & a scapula.

❖ Clavicle or collar bone is a rod like F – Shaped bone extending between neck &

shoulder.

❖ Scapula or shoulder blade is a tin curve triangular bone that has glenoid cavity,

coracoid process & a spine with acromion process, present at the back of the shoulder.

❖ Glenoid cavity as a deep cup like concavity is located at the end of scapula close to

coracoid process.

❖ Coracoid process is a knob like inwardly bent fused scapula blade.

❖ The head of humorous bone fits into glenoid cavity to form shoulder joint for the

articulation of pectoral girdle with the forelimb of this side.

❖ Pelvic girdle/hip girdle is a trough like bony structure formed by the union of two

similar halves or innominates/hip bones.

❖ Each half is formed by 3 bones – ischium (below the pubis); ilium (on upper side)

& pubis (on inner side).

❖ Acetabulum is a cup like cavity present at the junction of 3 bones.

❖ Obturator formen is present as a large oval gap between the pubis & ischium.

❖ Humerus had rounded head at the proximal end, a middle ord like shaft with

deltoid ridge for attachement of muscle & a pully like trochlea at the distal end.

❖ Radius is shorter than ulna.

❖ Thumb of hand is called pllex.

❖ Ulna has an olecranon process for forming elbow.

❖ Head of femur fits into the acetabulum of hip/pelvic girdle.

❖ Tibia & fibula are bones of lower leg (shank).

❖ Femur is the longest bone in human body.

❖ Tibio – Fibula is the longest bone in frog.

❖ patellar grove is found in femur.

❖ sigmoid notch is found in radio-ulna.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 50

❖ Grater trochanter occurs in femur.

❖ Smallest bone in human body is stapes of middle ear.

❖ Sella turcica is the depression in sphenoid of skull that lodges pituitarybody.

❖ Joints are the points of articulation between two bones.

❖ Fixed or fibrous joint (synarthrosis) are joined by strong bundle of collagen with

no movements. Eg. Bones of skull (sutures), hip girdle amongst ischium, ilium &

pubic.

❖ Slightly movable joint (amphiarthrosis) are cartilaginous or imperefect joints.

❖ In this joint, a disc of fibrocartilage occurs between the articular ends in a joint.

Eg. Public symphysis, ribs & sternum.

❖ Synovial Joinws/freely movable joints (diarthrosis) are perfect joints in which

bones are not fused with each other.

❖ These joints allow free movement in one or more direction and whose bone ends

bear fibrous synovial memrane enclosing a cushion of synovial fluid.

❖ Ball & socket joint have one bone end like a ball & other like a cup shaped socket.

Eg. Shoulder joing & hip joint. This type of joint allow movement in may planes.

❖ Saddle joint is an imperfectly developed ball & sacket joint in which one obone is

movable on another fixed bone in many direction. Eg. Carpometacarp0al joint of

human thumb.

❖ Ellipsoid or angular joint have one moveble bone on another bone in two planes.

Eg. Wrist or radio carpal joint of humans, toes 7 sole.

❖ In this join one articular end is oval & convex while the other end is elliptical &

concave.

❖ In pivot joint articular end of one bone is fixed while that of the other can rotate

over it. Eg. Between atlas & axis in humans, upper ends of radius & ulna.

❖ In hinge joint articular end of one bone is deeper convex & that of other is deeper

concave, allowing movement in one plane. Eg. Elbow joint, knee joint (condylar

joint), ankle joint, interphalangeal joints.

❖ In gliding joint articular ends of two bones are either flat or slightly curved to allow

sliding or gliding movement. E.g. Bones of palm & sole, between pre-zygapophyses

& post-zygapophyses of vertebrae.

❖ Arthritis is painful inflammation & stiffness of joints caused by infection, allergy,

hormonal disturbance & always.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 51

❖ Osteoathritis is a tearing of articular cartilage & development of bony lumps at

places causing pain, stiffness due to inhibited secretion of synovial find & permanent

bending.

❖ In rheumatoid arthritis, a hard tissue deposits over articular cartilage along with

higher secretion of synovial fluid causing pain & stiffness.

❖ Gout is the accumulation o furic acid crystals in the region opf joints results in

painful movements.

❖ Injury to joint due to overstretching or tearing of ligament of tendon is called sprain.

❖ Slipped disc ( the displacement of a vertebra from its normal position) is caused due

to degeneration of a part of intervertebral disc, deposition of hard tissue around

it, mechanical injury & ossification of ligaments holding the vertebrae.

❖ Fracture is breaking of bone accidently.

❖ It is a following types – greenstick fatcture (simple crack without breaking into 2

pieces, occurs in kids); simple fracture (breaking into 2 parts which remain nearby);

compound fracture (breaking into 2 or more parts with some protruding out);

comminuted fracture (breaking into more than two pieces) & evulsive fracture ( a

small piece breaks but remains attached to ligament).

❖ Human body has about 639 types of muscle.

❖ Muscles specialized to contraction are of 3 types – striated, unstrained & cardiac.

❖ Striated muscle are also called skeletal muscle.

❖ These muscles are mostly attached to bones and take part in moving them like

levers.

❖ Most striated muscles generally bring about voluntary movements under conscious

control of brain. Therefore they are called as voluntary muscle.

❖ Non-striated muscle is also called smooth muscle / involuntary muscle / visceral

muscle.

❖ These muscles occur in the internal hollow organs like alimentary canal, bile duct,

gall bladder, Urinary bladder etc. & help in their movement.

❖ Cardiac muscles as involuntary, striated & non-fatigued fibre.

❖ These muscles occur in the wall of heart & bases of great blood vessels.

❖ Muscular tissues develop from embryonic mesoderm except for those of iris and

ciliary body of eyes.

❖ Sliding filament theory of muscle contraction was proposed by A.F. Huxley & H.E.

Huxley (1954).

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 52

❖ It was confirmed by electron microscope studies.

❖ According to this theory, during muscle contraction, actin filaments slide inward on

the myosin filament of A-band.

❖ Myofibrils, proteinaceous fibrils are the contractile elements of muscle fibre.

❖ Sarcomere are the contractile units of myofibrils.

❖ During muscle contraction chemical energy is changed to mechanical energy.

❖ During contraction of muscle, length of A band remains unchanged, distance

between two lines shortens & size of sarcomere decreased by 60% - 70%.

❖ Energy for contraction of muscle fibre is provided by ATP.

❖ ATP is produced by cratine phosphate & respiratory breakdown of

glycogen/glucose.

❖ Myosin is a major protein present in the thick filament of skeletal muscle fibre.

❖ Actin is the contractile protein of muscle.

❖ Biochemical & electrical changes occurring during muscle contraction were

explained by Albert Szent – Gyorgi in 1942.

❖ Muscle contraction of shortest duration occurs in Eye lids.

❖ Arranged group of muscle fibre are called motor unit.

❖ Based upon the sarcoplasmic content, situation of nuclei & number of formed

elements, two types of fibres are recognized in striated muscle – white fibre & red

fibres. White muscle fibre are fst muscle fibre which lack myoglobin & have fewer

mitochondria.

❖ These muscle perform fast work for short duration as a result of which these muscle

fibre get fatigued quickly. Eg. Eye ball muscle, flight muscle of sparrow.

❖ Red muscle fibre are slow muscle fibre possessing red haemo protein called

myoglobin & abundant mitochondria.

❖ These muscles can perform slow sustained work over long period without getting

fatigued. E.g. Extensor muscle at back & floght muscle in kites.

❖ Antagonistic muscle are those muscle which act in opposition to other muscle. Eg.

The bicep muscle extended from shoulder to radius bends or flexes the arm at elbow

whereas triceps extending from ulna to shoulder straightens the arm.

❖ Bending of one part of a limb on another part at a joint is called flexor. Eg. Biceps

bend the forearm towards the upper arm.

❖ Strengthening of a bent part is called extensor. Eg. Triceps extends forearm away

from the upper arm.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 53

❖ Adductors move a limb towards median axis of the body. Eg. Latissimus dorsi

brings the arm away fro the body.

❖ To move a limb away from the median axis is called abductors. Eg. Deltoid draws

the arm away from the body.

❖ Pronator are those muscle which rotates the forearm to bring palm downward or

backward.

❖ Supinator rotates the forearm to bring surface upward or forward.

❖ Muscle raises a body part is called elevator. Eg. Massetor raises low jaw.

❖ Muscles lowering a body part is called depressor. Eg. Depressor mandibulae moves

down the lower jaw to open the mouth.

❖ Muscle rotting a part is called rotator. Eg. Pyriformis raises & rotates the thigh.

❖ Muscle used for widening an aperture is called dilato. Eg. Iris.

❖ Muscle used for closing and opening or decreasing the size is called sphincters.

❖ Turning the sole inward & outwards are called invertor and evertor respectively.

❖ Largest muscle is gluteus maximum.

❖ Smallest muscle is Stapedius of stapes.

❖ Longest muscle is quadriceps femories.

❖ Strongest muscle is massetors.

❖ Sharpey’s fibre are calcified bundles of white & yellow fibres perforating and

holding periosteal bone lamellae.

❖ Threshold stimulus is the minimum strength of stimulus required to initiate muscle

contraction.

❖ Oxygen debt is the requirement of extra oxygen during recovery phase of muscle

over the period of resting stage.

❖ The extra oxygen required during recovery phase is for regeneration of

oxymyoglobin, restoration of depleted ATPs & CP & oxidation of lactic acid.

❖ It is the passage of lactic acid produced in muscle into liver where 80% of it is

changed to glycogen / glucose of continued supply.

❖ Tetanus is sustained muscle contrition due to succession of nerve impulses being

received by it.

❖ The force produced during contraction of muscle is called muscle tension.

❖ Muscle fatigue is a failure of muscle to respond a fresh stimulus after a prolonged

previous activity.

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 54

❖ It is caused due to accumulation of lactic acid, consumption of stored glycogen

ATP changes in neuromuscular junction which is sensitive to lactic acid.

QUESTION BANK

1 The study of muscles is called Myology

2 The cell that has many nuclei Muscle fiber

3 The movement of the joint is possible because of

the force generated by The muscles

4 Special character of striated muscle is They are not tired

immediately

5 In the skeletal muscle fober, a series of light and

dark bands area visible due to

Arrangement of

myofibrils

6 The muscles that do not show the striations on

them are Smooth muscles

7 The involuntary muscles in the body are Smooth muscles and

cardiac muscles

8 name of the heart muscle Myocardium

9 The layer of connective tissue that encloses muscle

fiber is Endomysium

10 The layer of connective tissue that encloses

fascicle Perimysium

11 The layer of connective tissue that enclose the

muscle Epimysium

12 The factore that determines the ratio of slow and

fast twitch fibers in a muscle Genetic factor

13 The muscle fibers that react slowly to the impulse

are

Slow twitch fibers or

type I fibers

14 Between the ‘type II A’ and ‘type II B’ which

muscle fiber is fatigue resistant Type II A

15 Will the ratio between slow and fast twitch fibers is

same in all muscles in the same individual

No. the ratio change

from muscle to

muscle

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 55

16 The muscle fibers that react quickly to the impulse

are

Fast twitch fibers or

type II fibers

17 With the training, can ;the slow twitch fibers be

transformed into fast twitch fibers or vice versa No

18 The cells in which myoglobin is preserved Muscle cells

19 What is the tissue that contains myofibrils Muscle tissue

20 The bundle of the muscle fibers is called Fasciculae

21 The cell layer of the muscle fiber is called Sarcolemma

22 The fluid in the muscle fiber is called Sarcoplasm

23 Skeletal muscle fiber is activated by Nerve impulse

24 The role of sarcoplasmic reticulam is To pass the impulses

deep into the cell

25

When a muscle reacts to the external stimuli

without involvement of higher centers of nerves

system, such response is called

Reflex action

26 When the muscle is stretched, the mechanism that

opposes the stretching action is Stretch reflex

27 The nerves that control the muscle fibers Motor nerves

28 The neurotransmitter that initiates contraction of

muscle fiber through neuro muscular junction is Acetyl choline

29 Example for Bipenni form muscle is Rectus femoris

30 Which is the example for spindle muscle Biceps muscles

31 The tendon that attaches the gastrocnemious with

calcanious bone

Achilles tendon

(tendon calcanious)

32 Longest muscle in the body Sartorious

33 Gastrocnemius is in the region of Calf

34 The understanding between opposite muscles in a

joint is called

Reciprocal

enervation

35 Quadriceps muscle is at Front of the thigh

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 56

36 Hamstring muscle is in the region of Back of the thigh

37 The muscle that flexes the knee joints Hamstrings

38 The major group of muscle that help in the

extension of knee joint Quadriceps

39 The major muscle involved in raising on toes Gastronemus

40

In a reciprocal enervation, if the quadriceps muscle

acts as an agonist, which muscle acts as an

antagonist

Hamstring muscle

41 Gluteus muscles are in the region Buttocks

42 the sartorious is in the region of Thigh

43 Example of fusiform muscle Biceps

44 Example of triangular muscle Pectoralis major

45 The shape of sortorious muscle Longitudinal

46 What is the shape of pectorolis major Triangular

47 In which part the sartoroius muscle is situated Leg

48 The muscle that helps in extending the knee joint is Quadriceps

49 The major muscle ;involved in extending the elbow Triceps

50 The area in which the trepegious muscle is situated Neck and back

region

51 Deltoid muscle is in the region of Shoulder

52 Biceps muscle is the major muscle involved in Flexion of the elbow

53 Pectoralis muscle is at the region of Chest

54 Latismus dorsi is at

Extends on the

lateral side of the

thoracic cavity

55 Sternocledo mastoidus is in the region of Neck

56 The rectos abdominous is in the region of Abdominal

57 Illiopsoas is in the region of Hip

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 57

58 The muscle that extends the forearm is Triceps

59 In reciprocal enervation, if the biceps muscle acts

as agonist, which muscle acts as antagonist Triceps muscle

60 Give an example of two headed muscle Biceps

61 An example of three headed muscle Triceps

62 The muscles situated in the internal organs like

digestive tubes, blood vessels etc Smooth muscles

63 The major muscle involved in flexion of elbow Biceps

64 The movement of the bones at joint is possible

because of the force developed by the

Muscular contraction

65 The joining point of the muscle with the bone at a

distal end is Insertion

66 The joining point of the muscle with the bone at a

proximal end is Origin

67 The co-ordination of opposite muscles is Reciprocal

enervation

68 In isometric contraction, the length of the muscle is Unchanged

69 In isotonic contraction the length of the muscle is Reduced

70 What is the difference between concentric and

eccentric contractions

In concentric, the

muscle over cornes

the resistance where

as in eccentric

negative work is

done

71

In the process of muscle contraction, if the origin

and insertion of the muscle are pulled away

because of the over power of the resistance, that

type of contraction is

Eccentric contraction

72 What is the difference among unicep, biceps and

triceps muscle

Unicep has one

muscle end, biceps

has two and triceps

Dr.Y.Kalyan Kumar, Lecturer in Physical Education, SJGC(A), Kurnool, A.P., INDIA.| 58

has three muscle

ends

73 If the muscle is shortened in the process of

contraction that type of contraction is called

Concentric

contraction

74 What is cardiac hyper trophy

Increase of size in

the heart muscle due

to training

75 What is muscle ‘dystrophy’ Reduction of size

due to retraining

76 Dose the training increase the number of muscle

fibers in a muscle

No. only

hypertrophy is

possible

77 Due to perfect stretching of the muscles, what type

of change is expected in the number of sarcomeres Number increases

78 Longest muscle in the body Sartorius

79 The strength of the individual muscle is measured

through Electromyography

80 Is the muscle soreness is a disease

No. it is the state of

muscle ;caused due

to over use