Sliding Filament Theory and Major Muscles of the Human Body

Sliding Filament Theoryand

Major Muscles of the Human Body

Lesson

Skeletal Muscle

• Human body contains over 400 skeletal muscles– 40-50% of total body weight

• Functions of skeletal muscle– Force production for locomotion and breathing– Force production for postural support– Heat production during cold stress

Structure of Skeletal Muscle:Connective Tissue Covering

• Epimysium– Surrounds entire muscle

• Perimysium– Surrounds bundles of muscle fibers

• Fascicles

• Endomysium– Surrounds individual muscle fibers

Structure of Skeletal Muscle:Microstructure

• Sarcolemma– Muscle cell membrane

• Myofibrils– Threadlike strands within muscle fibers– Actin (thin filament)

• Troponin• Tropomyosin

– Myosin (thick filament)

Structure of Skeletal Muscle:The Sarcomere

• Further divisions of myofibrils– Z-line– A-band– I-band

• Within the sarcoplasm– Sarcoplasmic reticulum

• Storage sites for calcium

Muscular Contraction

• The sliding filament model– Muscle shortening occurs due to the

movement of the actin filament over the myosin filament

– Formation of cross-bridges between actin and myosin filaments

– Reduction in the distance between Z-lines of the sarcomere

The Sliding Filament Model of Muscle Contraction

Cross-Bridge Formation in Muscle Contraction

Sliding Filament Theory

• Rest – uncharged ATP cross-bridge complex

• Excitation-coupling – charged ATP cross-bridge complex, “turned on”

• Contraction – actomyosin – ATP > ADP & Pi + energy

• Recharging – reload cross-bridge with ATP

• Relaxation – cross-bridges “turned off”

http://www.youtube.com/watch?v=0kFmbrRJq4w&feature=related

Muscles Origins and Insertions

Muscles from pg. 46 in text

Muscle Name Function Describe movements

Origin Insertion

SternocleidomastoidBroad superficial muscle running up each side of the neck

Agonist Flexes and rotates the head

Sternum

Clavicle

Mastoid process

Muscle Name Function Describe movements

Origin Insertion

Splenius

Runs posterior joins skull and spine

Agonist Flexes and rotates the head

Cervical & thoracic vertebrae

Temporal &occipital lobes

Neck Muscles

Muscles of Vertebral Column

Muscle Name Function Describe movements

Origin Insertion

Longissimus

Lateral to spinalis

Agonist Laterally Flexes and extends the spine

Cervical,

Thoracic,

Lumbar vertebrae

Mastoid process & cervical vertebrae

Spinalis

Most medial attaches to vertebrae

Agonist Laterally Flexes and extends the spine

Cervical,

Thoracic,

Lumbar vertebrae

Mastoid process & cervical vertebrae

Illiocostalis

Most lateral

Agonist Laterally Flexes and extends the spine

Saccrum,Lumbar vertebrae, Ribs

Cervical vertebrae

&

Ribs

Back Muscles

SpinalisIliocostalisLongissiumus

Thoracic Cage Muscles

Muscle Name Function Describe movements

Origin Insertion

Diaphragm

Anatomical Divider

Agonist Decreases pressure in the thoracic cavity

Sternum,

Ribs,

Lumbar vertebrae

Central tendon

Intercostals

Muscles in between ribs

Agonist Elevates,

Depresses ribs

Inferior aspect of all ribs

Superior aspect of all ribs

Transverse

Thoracis

Triangle muscles under ab wall

Agonist Pulls abdominal wall invward

Sternum,

Xiphoid process

Cartilidge of ribs 2-6

Thoracic Cage

Abdominal Muscles

Muscle Name Function Describe movements

Origin Insertion

Rectus Abdominus

Wash board look

Agonist Flex trunk,

Aids in some expiration

Child birth

Symphysis pubis & pubic crest

Xiphoid Process

Inferior ribs

External Obliques

Agonist Flex and rotate the vertebral column

Lower eight ribs

Iliac Crest,

Pubis

Quadratus Lumborum

Deep muscle

Agonist Extend and laterally bends the vertebral column

Iliac Crest and Lumbar vertebra

12th Rib and upper lumbar vertebrae

Abdominals

Moving Upper Limb

Muscle Name Function Describe movements

Origin Insertion

Pectoralis

Major

Thick Muscles covering the chest

Prime Mover

Internal rotation, adduction and flexion of the arm

Clavicle,

Sternum,

Costal cartilage of first 6 ribs.

Intertubercular groove

Latissimus Dorsi

“Lats”

V shape

Prime Mover

Adductor, Extensor and internal rotator of the arm

Lower Thoracic and Lumber verts. Iliac Crest and sacrum

Humerus

Rotator CuffMuscle Name Function Describe

movementsOrigin Insertion

Supraspinatus Agonist Stabilize shoulder joint. Abducts shoulder

Above scapular spine

(supraspinous fossa)

Greater Tubercle of Humerus

Infraspinatus Agonist Stabilize shoulder joint. Lateral rotation

Below scapular spine

(infraspinous fossa)

Greater Tubercle of Humerus

Teres Minor Agonist Stabilize shoulder joint. Lateral rotation.

Lateral border of scapula

Greater Tubercle of Humerus

Subscapularis Stabilizer Rotates medially and stabilizes shoulder

Iliac Crest and Lumbar vertebra

Lesser Tubercle of Humerus

Scapular MusclesMuscle Name Function Describe

movementsOrigin Insertion

Trapezius Agonist Scapular elevation, adduction, retraction, upward rotation & extends neck

Occipital bone,

Cervical & thoracic vertebrae

Spine of Scapula, acromion process &clavicle

Rhomboids

Major & Minor

Agonist Assist Traps in downward rotation of scapular &adduction of scapula

Maj. T2-T5

Min. C1-T1

Medial border of the scapula

Levator Scapulae

Agonist Elevates scapula Base of skull & upper cervical vertebrae

Upper medial border of scapula

Serratus anterior

Stabilizer Upward rotation & abduction of the scapula

Ribs 1-8 Medial border of the scapula

Scapular Muscles cont.

Muscle Name Function Describe movements

Origin Insertion

Pectoralis

Minor

Agonist Elevates ribs & Depresses Scapula

Ribs 3,4,5 Coracoid process

Muscles that move Humerus

Muscle Name Function Describe movements

Origin Insertion

Deltoids

Three heads

Anterior, lateral, posterior

Agonist Laterally abducts arms,

Medial and lateral rotation

From the clavicle to the acromion to scapular spine

Humerus

(Deltoid tuberosity)

Coracobrachialis Agonist Flexor and arm adductor

Coracoid Process

Humerus

Teres

Major

Agonist Medial rotator and adductor

Lateral Border of the scapula

Humerus

Elbow Flexors & ExtensorsMuscle Name Function Describe

movementsOrigin Insertion

Bicep

Brachii

Agonist Supinator and flexor of the arm

2 places

Short head on corracoid

Long Head superior glenoid fossa

Radius

Radial

Tuberosity

Brachialis Agonist Pronator and arm flexor

Anterior surface of humerus

Coronoid process

Tricep Brachii Agonist Arm Extensor 1)Lateral head – posterior humerus

2)Long Head – infragleniod fossa

3)Medial head posterior humerus

Olecranon

Brachioradialis Agonist Elbow flexor, very powerful when arm is pronated

Lateral epicondyle of humerus

Olecranon

Supination and Pronation of the Forearm

Muscle Name Function Describe movements

Origin Insertion

Pronator Quadratus

Agonist Pronates forearm

Anterior surface of distal ulna

Distal surface of radius

Pronator teres Agonist Pronates forearm

Medial epicondyle of the humerus and the coronoid porcess

Lateral mid shaft of radius

Supinator Agonist Supinates forearm

Lateral epicondyle of humerus

Lateral aspect of radius

Extrinsic Hand MusclesMuscle Name Function Describe

movementsOrigin Insertion

Flexor – Pronator

Group

Agonist Pronator and flexor of the wrist and digits

Medial epicondyle of the humerus

Meta carpals

Phalanges

Extensor –

Supinator

Group

Agonist Supinator and flexor of wrist ad digits

Lateral epicondyle of humerus

Meta Carpals

Phalanges

Pelvic Muscles

Muscle Name Function Describe movements

Origin Insertion

Gluteus

Maximus

Agonist Hip extension and external rotation

Illiac crest saccrum and coccyx

Greater trochanter

Gluteus

Medius

Agonist Abduction and internal rotation

Anterior surface of the illiac crest

Posterior surface of greater trochanter

Sartorius Agonist Hip Flexion

Outward rotation

Medial surface of the tibia

Medial surface of the tibia

Gluteus Max, Med, Min

Hip Adductors

Muscle Name Function Describe movements

Origin Insertion

Illiopsoas Agonist Hip and trunk felxion

Ilium and lumbar vertebrae

Lesser Trochanter of the Femur

Adductor

longus

Agonist Hip Adduction Pubis Femur

Adductor

magnus

Agonist Hip adduction and extension

Pubis and ischium

Femur

Hip Muscles

QuadricepsMuscle Name Function Describe

movementsOrigin Insertion

Rectus Femoris

Agonist Knee Extension and Hip Flexion

Iliac crest Patellar

Tendon

Vastus Lateralis

Agonist Knee Extension Femur Patellar

Tendon

Vastus intermedius

Agonist Knee Extension Femur Patellar

Tendon

Vastus Medialis

Agonist Knee Extension Femur Patellar

Tendon

Quadriceps

HamstringsMuscle Name Function Describe

movementsOrigin Insertion

Bicep Femoris Agonist Flexes knee, Rotates knee externally, extends hip

Ischium Head of Fibula

Semi-membranosus

Agonist Flexes knee, Rotates knee internally, extends hip

Ischium Medial tibial condyle

Semi-tendinosus

Agonist Flexes knee, Rotates knee internally

Ischium Medial tibial condyle

Hamstrings

Lower LegMuscle Name Function Describe

movementsOrigin Insertion

Tibialis Anterior

Agonist Dorsi Flexes ankle and inverts foot

Anterior shaft of tibia

Metatarsals

Gastrocnemius Agonist Plantar Flexes ankle and felxes knee

Medial and Lateral Condyles

Calcaneous

Soleus Agonist Plantar Flexes ankle Fibula Calcaneous

Lower Leg Muscles