Dr. Pooja Gupta

Physiotherapist

MUSCULAR SYSTEM

Muscles and their types

Muscles are contractile tissues that

bring about movements of

different body parts. They can be regarded as motors of human body because they

provide all the force necessary to perform

different types of movements.

Types of muscles: Muscles are of three types; skeletal, smooth and cardiac.

Skeletal Muscles:

• They are also known as striped, striated, somatic and voluntary

muscles • They are the most abundant type and are found attached to the

skeleton. For this reason they are called skeletal muscles. • They are innervated by somatic nervous system and are

therefore under voluntary control. They obey the will of human beings.

• They respond quickly to stimuli and are capable of rapid contractions. They get fatigued easily because of their rapidity

• Each muscle fiber is multinucleated cylindrical cell containing groups of myofibrils. The myofibrils are in turn made up of myofilaments of three types namely actin, myosin, and tropomyosin. Thus the skeletal muscles have three structural levels namely muscle fibers, myofibrils and myofilaments.

• Examples of skeletal muscles include all muscles of body wall. • d cardiac.

Smooth muscles:

• They are also known as plain, unstriped, visceral and involuntary muscles. • Unlike skeletal muscles, they do not exhibit cross striations under the

microscope and thus they got the name “smooth”. • They are supplied by autonomic nervous system and therefore they are

involuntary in their action. They do not obey the will of human being. • They respond slowly to stimuli but are capable of long time sustained

contractions. They do not get fatigued easily because of their slowness of response.

• They provide motor power for regulating internal environment related to digestion, circulation, secretion and excretion.

• Each smooth muscle fiber is an elongated spindle shaped cell with a single nucleus placed at the center. They also possess actin and myosin filaments but the structural arrangement of these filaments is very different as compared to the skeletal muscles.

• Examples of smooth muscles include muscles of blood vessels, and muscles of the gut etc.

Cardiac muscles:

• They form the myocardium of human heart.

• Cardiac muscle is intermediate in structure lying between the skeletal and smooth muscles. They are striated like skeletal muscles but at the same time they are involuntary and have uninuclear cells like smooth muscles.

• They are meant for automatic rhythmic contractions for long period of time.

• Each muscle fiber has a single centrally placed nucleus.

Parts of a typical skeletal muscle • A typical skeletal muscle consists of

two ends and two parts

Ends: A typical skeletal muscle consists of two ends. These are; Origin is one end of the muscle which remains fixed during its contraction. Insertion is the other end which moves during its contraction. In the limb muscles, the origin is usually proximal to insertion. Parts: A typical skeletal muscle consists of two parts. These are; Fleshy part is contractile, and is called the ‘belly’. Fibrous part is non-contractile and inelastic. When cord-like or rope-like, it is called tendon; when flattened, it is called aponeurosis. The fleshy part of the muscle, the belly, is red in color while the fibrous part is white in color. The difference in color makes it easy to differentiate the active contractile area of the muscle from the non-contractile part.

Basic structure of a skeletal muscle A typical skeletal muscle consists of two types

of tissues: Contractile tissue and Supporting tissue.

Contractile tissue: The contractile tissue of each muscle is composed of numerous muscle fibers. Each muscle fiber is a multinucleated, cross-striated cylindrical cell. The length of each muscle fiber is between 1 and 300 mm. It consists of a cell membrane (sarcolemma), which encloses the cytoplasm (sarcoplasm). There are two types of substances embedded in the sarcoplasm. Several nuclei arranged at the periphery beneath the sarcolemma. A number of evenly distributed longitudinal threads called myofibrils.

Actions of skeletal muscles

• Antagonists:

Prime movers (agonists) bring about the desired movement.

Antagonists (opponents) oppose the prime movers. They help the prime movers by active controlled relaxation, so that the desired movement is smooth and precise. Thus, the antagonists cooperate rather than oppose the prime movers. This is due to reciprocal innervation of the opposite groups of muscles, regulated by the spinal cord through stretch reflex.

Prime Movers:

Fixators: Fixators are the groups of muscles which stabilize the proximal joints of a limb, so that the desired movement at the distal joint may occur on a fixed base. Muscles acting on shoulder joint fix it for better movement of fingers.

Synergists: When the prime movers cross more than one joint, the

undesired actions at the proximal joints are prevented by certain

muscles known as synergists. For example, during making a

tight fist by long digital flexors the wrist is kept fixed in extension

by the synergists (extensors of wrist). Thus, the synergists are

special fixators and partial antagonists to the prime movers. Two

or more muscles causing one movement are synergist.

MUSCLES THAT ACT ON ANTERIOR ARM (HUMERUS):DELTOID PECTORALIS MAJOR

BICEPS BRACHII CORACOBRACHIALIS

SUBSCAPULARIS TERES MAJOR (shown from the back)

LATISSIMUS DORSI (shown from the back) MUSCLES THAT ACT ON POSTERIOR ARM

(HUMERUS):DELTOID SUPRASPINATUS INFRASPINATUS TERES MINOR

TRICEPS BRACHII (LONG HEAD)

" MUSCLES THAT ACT ON THE SHOULDER (SCAPULA) "

• MUSCLES THAT ACT ON ANTERIOR SHOULDER:SERRATUS ANTERIOR

• PECTORALIS MINOR • MUSCLES THAT ACT ON

POSTERIOR SHOULDER:LEVATOR SCAPULAE

• TRAPEZIUS • RHOMBOID MAJOR • RHOMBOID MINOR

MUSCLES THAT ACT ON THE FOREARM (RADIUS/ULNA)"

• MUSCLES THAT ACT ON ANTERIOR FOREARM:BICEPS BRACHII

• BRACHIALIS • BRACHIORADIALIS • PRONATOR TERES • MUSCLES THAT ACT ON

POSTERIOR FOREARM:TRICEPS BRACHII - LONG HEAD

• TRICEPS BRACHII - MEDIAL HEAD • TRICEPS BRACHII - LATERAL HEAD • ANCONEUS

MUSCLES THAT ACT ON WRIST, PALM, & DIGITS "

MUSCLES THAT ACT ON ANT. WRIST/HAND:

•FLEXOR CARPI RADIALIS •PALMARIS LONGUS •FLEXOR CARPI ULNARIS •FLEXOR DIGITORUM SUPERFICIALIS

MUSCLES THAT ACT ON POST. WRIST/HAND:

•EXTENSOR CARPI RADIALIS LONGUS •EXTENSOR CARPI RADIALIS BREVIS •EXTENSOR DIGITORUM •EXTENSOR CARPI ULNARIS

MUSCLES THAT ACT ON ANTERIOR THIGH (FEMUR) "

ILIACUS PSOAS MAJOR TENSOR FASCIAE LATAE SARTORIUS RECTUS FEMORIS PECTINEUS ADDDUCTOR LONGUS ADDUCTOR BREVIS ADDUCTOR MAGNUS GRACILIS

MUSCLES THAT ACT ON POSTERIOR THIGH (FEMUR) "

• GLUTEUS MAXIMUS

• GLUTEUS MEDIUS

• GLUTEUS MINIMUS

• PIRIFORMIS

• QUADRATUS FEMORIS

• BICEPS FEMORIS: LONG HEAD

• SEMIMEMBRANOSUS

• SEMITENDINOSUS

MUSCLES THAT ACT ON THE LEG (TIBIA & FIBULA) "

• MUSCLES THAT ACT ON ANTERIOR LEG:RECTUS FEMORIS

• SARTORIUS • GRACILIS • VASTUS LATERALIS • VASTUS MEDIALIS • VASTUS INTERMEDIUS • MUSCLES THAT ACT ON POSTERIOR

LEG:SEMIMEMBRANOSUS • SEMITENDINOSUS • BICEPS FEMORIS: LONG HEAD • BICEPS FEMORIS: SHORT HEAD • GASTROCNEMIUS • PLANTARIS • POPLITEUS

" MUSCLES THAT ACT ON THE FOOT "

ANTERIOR COMPARTMENT LEG MUSCLES:

•TIBIALIS ANTERIOR •EXTENSOR DIGITORUM LONGUS •EXTENSOR HALLUCIS LONGUS •FIBULARIS (PERONEUS) TERTIUS

POSTERIOR COMPARTMENT LEG MUSCLES:

•GASTROCNEMIUS •SOLEUS •PLANTARIS •FLEXOR HALLUCIS LONGUS •FLEXOR DIGITORUM LONGUS •TIBIALIS POSTERIOR

LATERAL COMPARTMENT LEG MUSCLES:

•FIBULARIS LONGUS •FIBULARIS BREVIS

MUSCLES THAT ACT ON THE ABDOMEN "

• EXTERNAL OBLIQUE

• INTERNAL OBLIQUE

• TRANSVERSUSABDOMINIS

• RECTUS ABDOMINISTRUNK FLEXORS

" MUSCLES OF MASTICATION (CHEWING) "

• MASSETER

• TEMPORALIS

• LATERAL PTERYGOID MEDIAL PTERYGOID

MUSCLES OF FACIAL EXPRESSION "

• FRONTALIS • Orbicularis oculi ( • Nasalis • Orbicularis oris • Levator labii superioris () Levator anguli oris • Zygomaticus major • Zygomaticus minor • Risorius • Depressor anguli) oris • Depressor labii inferioris) • Mentalis

:: Muscles That Act On The Head and Neck ::

Posterior Neck Muscles:EXTENSORS OF NECK Trapezius Splenius Capitis Splenius Cervicis Semispinalis Capitis Semispinalis Cervicis Semispinalis Thoracis Rectus Capitis Rectus Capitis Posteror Major Rectus Capitis Posteror Minor Obliquus Capitis Superior Obliquus Capitis Inferior

:: Muscles That Act On The Back ::

• Deep Back Muscles:EXTENSORS OF BACK • Erector Spinae Group

– Iliocostalis Cervicis – Iliocostalis Thoracis – Iliocostalis Lumborum – Longissimus Capitis – Longissimus Cervicis – Longissimus Thoracis – Spinalis Cervicis – Spinalis Thoracis

• Multifidus • Rotators

• THANK YOU