physiology: muscles

MARGARETTE JOY ALMARIO * CHET DELA CRUZ * AMIEL RUTH DIOLATA * MARK JACOB MARCELO*

MICHAEL TOMACRUZ

The Anatomy of Skeletal or Striated Muscle

• Mature skeletal or striated muscle cells are the longest and most slender muscle fibers, ranging in size from 1 to 50 mm in length and 40 to 50 micrometers in diameter.

• Because of these unique structure of the cell, that is, their length being much greater than their width, skeletal muscle fibers.

• In addition each muscle cell or fiber is multinucleated and is surrounded by a special cell membrane. This cell membrane is electrically polarized and is called a sarcolemma. The sarcolemma is surrounded by the first of three types of connective tissue found in a muscle the endomysium, which is delicate connective tissue.

• We see that the entire muscle consist of a number of skeletal muscle bundles called fasciculi. Each individual bundle of muscle cells, or fascicle, is surrounded by another layer of connective tissue called the perimysium. This is visible to the naked eye. This perimysium connects with the coarse irregular connective tissue that surrounds the whole muscle called the epimysium, these three layers of connective tussue act like cement holding all of the muscle cells and their bundles together.

• In addition, a layer of areolar tissue covers the whole muscle trunk on top of the epimysium and is called the fascia.

INTRODUCTIONMuscles make up about 40% to 50% of

your body’s weight. They allow us to perform extraordinary physical feats of endurance(running, playing sports) and grace(ballet, figure skating). When they contract, they bring about movement of the body as a whole and cause our internal organs to function properly. Muscles of the diaphragm, chest, and abdomen allow us to breath.

Types of Muscles

• Skeletal or striated• -is voluntary• -that is, we can control its contraction.• Under microscope skeletal muscle cells are

multinucleated and striated.• We can see alternating dark and light bands.

• Smooth muscle• Is involuntary• Uninucleated• And non striated• Found in places like digestive tract.

• Cardiac muscle• Is involuntary• Striated• Uninucleated• Found only in the heart

SMOOTH MUSCLEIt is found in hollow structure of the

body.

SMOOTH MUSCLE CELL- contains a single large nucleus- It is involuntary, uni nucleated and non-

striated.

In hollow structure smooth muscle cell is arranged in two layers:A. outer longitudinal B. inner circular layer

It produce a slower contraction than skeletal muscle BUT smooth muscle contraction allow greater extensibility of the muscle.

CARDIAC MUSCLE

Cardiac Muscle cell can receive an impulse contract, immediately relax and receive another impulse.

Naming and action of skeletal muscle

• Action• Shape• Origin and insertion• Location• Direction of their fibers• Division

• FLEXORS - muscles that bend a limb at a joint

• EXTENSORS - straighten a limb• ABDUCTORS - move a limb away from the

midline• ADDUCTORS - bring a limb toward the

midline of the body• ROTATORS - revolve a limb around the

axis• DORSIFLEXORS - muscles that raise the

foot

• PLANTAR FLEXORS- lower the foot.• SUPINATORS- muscles that turn the palm

of hand upward.• PRONATORS- muscles that turn the palm

of hand downward.• LEVATORS- raise a part of the body.• DEPRESSOR- muscles that lower a part of the

body.• PRIME MOVERS are muscles that bring about

action and those that assist the prime movers are SYNERGIST.

The Physiology of Muscle Contraction

Motor Unit

Motor Unit

• On the average, 1:150 muscle cells.

• Properties of muscle cells– Excitability– Conductivity– Contractility– Elasticity

• Muscle contraction is caused by the interactions of three factors:– Neuroelectrical factors– Chemical interactions– Energy sources

Muscle Anatomy

Neuroelectrical Factors

• Sarcollema– Concentration of sodium and potassium ions

Resting potentialInside ↑K⁺, Outside ↑Na⁺

Acetylcholine(Ach) – neurotransmitter

Sodium-potassium pump

Action potential Sarrcollema (muscle cell membrane)T tubulesSarcoplasmic reticulum - Ca⁺⁺myofibrils

actin troponinmyosin tropomyosin

Chemical Interactions

• Ach→ release of Ca⁺⁺→ Ca⁺⁺ + troponin• Actin + myosin + ATP → actomyosin + ADP +

PO4

Energy Sources

• Chemical Energy (ATP) → Mechanical Energy (contraction)

• ATP by glycolysis, Kreb’s cycle, electron transport, breakdown of phosphocreatine

Energy Sources

• Glucose + 2 ATP → CO2 + H2O + 38 ATP (aerobic)

• Glucose + 2 ATP → 2 lactic acid + 2 ATP (anaerobic)

• Phosphocreatine + ADP ↔ creatine + ATP• Free fatty acids → CO2 + H2O + ATP

Muscle Tone

Muscle Tone

• Tone - steady or constant state of partial contraction is maintained in a muscle.–Maintain body posture

2 Types of Contraction

MUSCLE CONTRACTION

THE FUNCTION AND LOCATION OF SELECTED

SKELETAL MUSCLES

Muscles of Facial Expression

Levator labii superioris

Procerus

Orbicularis oris

Mentalis

Frontalis

Orbicularis oculi

Zygomaticus minor

Zygomaticus major

Frontalis

Orbicularis oculi

zygomaticus

buccinator Masseter

Temporalis

Occipitalis

Orbicularis oris

MUSCLE FUNCTION

Occipitalis Draws scalp backward

Frontalis Elevates eyebrows, wrinkles forehead

Zygomaticus minor Draws upper lip upward and forward

Levator labii superioris Elevates upper lip

Levator labii superioris alaeque nasi Raises upper lip and dilates nostril

Buccinator Compresses cheeks and retracts angle

Zygomaticus major Pulls angle of mouth upward and backward

Mentalis Raises and protrudes lower lip

Orbicularis oris Closes lips

FACIAL EXPRESSION

Muscles of Mastication and of the Eye

Temporalis

Masseter

Lateral pterygoid

Medial pterygoid

Muscles of Mastication and of the Eye

MUSCLE FUNCTION

Masseter Closes jaw

Temporalis Raises mandible backward and closes mouth

Medial pterygoid Raises mandible and closes mouth

Lateral pterygoid Brings jaws forward

MUSCLE FUNCTION

Superior rectus Roll upward

Inferior rectus Roll downward

Medial rectus Roll medially

Lateral rectus Roll laterally

Superior oblique Rotates on axis

Inferior oblique Rotates on axis

MASTICATION

EYE

Muscles moving the Head and Shoulder Girdle

Muscles moving the Head and Shoulder Girdle

Pectoralis minor

Serratus anterior

MUSCLE FUNCTION

Sternocleidomastoid Flexes vertebral column and rotates head

MUSCLE FUNCTION

Levator scapulae Elevates scapula

Rhomboid major Moves scapula backward and upward; slight rotation

Rhomboid minor Elevates and retracts scapula

Pectoralis minor Depresses shoulder and rotates scapula downward

Trapezius Draws head to one side; rotates scapula

Serratus anterior Moves scapula forward away from spine and downward and inward toward chest wall

Head

Shoulder Girdle

Muscles moving the humerus

MUSCLE FUNCTION

Coracobrachialis Flexes, adducts arm

Pectoralis major Flexes, adducts, rotates arm medially

Teres major Adducts, extends, rotates arm medially

Teres minor Rotates arm laterally and adducts

Deltoid Abducts arm

Supraspinatus Abducts arm

Infraspinatus Rotates humerus outward

Latissimus dorsi Extends, adducts, rotates arm medially, draws shoulder downward and backward

Humerus

Muscles moving the Elbow

anconeus

MUSCLES FUNCTION

Brachialis Flexes forearm

Triceps brachii (3 heads) Extends and adducts forearm

Biceps brachii (2 heads) Flexes arm and forearm; supinates hand

Anconeus Extends forearm

brachioradialis Flexes forearm

Elbow

Muscles moving the Wrist

Extensor digitorum communis

Palmaris brevis

MUSCLE FUNCTION

Flexor carpi radialis Flexes, abducts wrist

Flexor carpi ulnaris Flexes, adducts wrist

Extensor carpi radialis brevis Extends and abducts wrist joint

Extensor carpi radialis longus Extends and adducts wrist

Extensor carpi ulnaris Extends, adducts wrist

Palmaris longus Flexes wrist joint

Palmaris brevis Tenses palm of hand

Extensor digitorium communis Extends wrist joint

WRIST

MUSCLE OF MOVING THE HAND

• Intrinsic Muscles– Thenar Muscles (thumb)– Hypothenar Muscles (little finger)– Interossei Muscles– Lumbar Muscles

• Extrinsic Muscles– Wrist extensors and flexors

MUSCLE OF MOVING THE HAND

MUSCLES OF THE MOVING THUMBMUSCLE FUNCTION

Flexor pollicis longus Flexes 2nd phalanx of thumb

Flexor pollicis brevis Flexes thumb

Extensor pollicis longus Extends treminal phalanx

Extensor pollicis brevis Extends thumb

Adductor pollicis Adducts thumb

Abductor pollicis longus Abducts, extends thumb

Abductor pollicis brevis Abducts thumb

Opponens pollicis Flexes and opposes thumb

MUSCLES OF THE MOVING THUMB

MUSCLES OF THE ABDOMINAL WALLMUSCLES ORIGIN INSERTION FUNCTION

External oblique Lower 8 ribs Iliac crest, Anterior rectus sheath

Compresses abdominal contents

Internal oblique Iliac crest Costal cartilage lower 3 or 4 ribs


Transverse abdominis

Iliac crest cartilage of lower 6 ribs

Xiphoid cartilage linea alba


Rectus abdominis Crest of pubis, pubis symphysis

Cartilage of the 5th, 6th, 7th rib

Flexes vertebral column, assists in compressing abdominal wall

MUSCLES OF THE ABDOMINAL WALL

MUSCLES OF RESPIRATIONMUSCLES ORIGIN INSERTION FUNCTION

Diaphragm Xiphoid process, costal cartilage, lumbar vertebrae

Central Tendon Increases vertical diameter of thorax

External intercostals

Lower border of rib

Upper border of rib below

Draws adjacent ribs together

Internal intercostals

Ridge on inner surface of rib

Upper border of rob below

Draws adjacent ribs together

Quadratus lumborum

Iliac crest Last rib and upper 4 lumbar vertebrae

Flexes trunk laterally

MUSCLES OF RESPIRATION

MUSCLES MOVING THE FEMURMUSCLES ORIGIN INSERTION FUNCTION

Psoas major Transverse preocess of lumber vertebrae

Femur Flexes, rotates thigh medially

Psoas minor Last thoracic and lumbar vertebrae

Junction of Ilium and pubis

Flexes trunk

Iliacus Last thoracic and lumbar vertebrae

Junction of Ilium and pubis

Flexes rotates thigh medially

Gluteus maximus Ilium, sacrum, and coccyx

Fascia lata, gluteal ridge

Flexes rotates thigh laterally

Gluteus medius Ilium Tendon on femur Abducts, rotates thigh medially

Gluteus minimus Ilium Femur Abducts, rotates thigh medially

MUSCLES MOVING THE FEMURMUSCLES ORIGIN INSERTION FUNCTION

Tensor fascia lata Ilium Femur Tenses fascia lata

Abductor brevis Pubis Femur Abducts, rotates thigh

Adductor magnus Ischium, ischiopubic ramus

Femur Adducts extends thigh

Abtrutor externus Ischium, ischiopubic ramus

Femur Rotates thigh literally

Pectineus Junction ilium and pubis

Femur Flexes, adducts thigh

Adductor longus Crest and symphysis of pubis

Femur Adducts, rotates, flexes thigh

MUSCLES MOVING THE FEMUR

MUSCLES OF THE KNEE JOINTMUSCLE FUNCTION

Biceps femoris Flexes leg; rotates laterally after flexed

Semitendinosus Flexes leg; extends thigh

Semimembranosus Flexes leg; extends thigh

Popliteus Flexes leg;rotates it

Gracilis Adducts thigh, flexes leg

Sartorius Flexes thigh, rotates it literally

Quadriceps femoris Extends leg and flexes the thigh

MUSCLES OF THE KNEE JOINT

MUSCLES OF THE FOOTMUSCLES FUNCTION

Gastrocnemius Plantar, flexes foot, flexes leg, suppinates foot

Soleus Plantar flexes foot

Tibialis posterior Plantar flexes foot

Tibialis anterior Dorsally flexes foot

Peroneus tertius Dorsally flexes foot

Peroneus longus Everts, plantar flexes foot

Peroneus brevis Everts foot

Plantaris Plantar flexes foot

MUSCLES OF THE FOOT

MUSCLES OF THE TOESMUSCLES FUNCTION

Flexor hallucis brevis Flexes great toe

Flexor hallucis longus Flexes great toe

Extensor hallucis longus Extends great toe, dorsiflexes ankle

Interossei dorsales Abduct, flexes toes

Flexor digitorum longus Flexes toes. Extends toes

Extensor digitorum longus Extends toes

Abductor hallucis Abducts, flexes great toes

Abductor digiti minimi Abducts little toes

MUSCLES OF THE TOES

MUSCULAR DISORDERS

CONTRACTURE CRAMPS

MYALGIA ATROPHY

MYOSITIS

MUSCULAR HYPERTROPHY

TENDINITIS

MUCULAR DYSTROPHY

physiology: muscles

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