The Muscular System 5 Lesson 5.1: Muscle Tissue Categories and Functions Lesson 5.2: Skeletal Muscle Actions Lesson 5.3: The Major Skeletal Muscles Lesson 5.4: Common Injuries and Disorders of Muscles

Muscle Tissue Categories and Functions Chapter 5: The Muscular System Lesson 5.1 Muscle Tissue Categories and Functions

Muscle Tissue categories functions skeletal smooth cardiac behavioral properties tension and types of skeletal muscle contractions

Muscle Tissue Categories skeletal voluntary striated smooth involuntary no striations cardiac intercalated disks

Muscle Tissue Categories

Skeletal Muscle Organization endomysium - surround the muscle fiber fascicle – bundle of muscle fibers perimysium - bundles groups of muscle fibers to make up a fascicle epimysium - encloses several fascicles to make up a muscle aponeurosis and tendons - connect muscle to other tissues

Skeletal Muscle Organization

Review and Assessment True or False? 1. Smooth muscle is voluntary. 2. Cardiac muscle has branching fibers. 3. Smooth muscle is multinucleate. 4. Perimysium wraps fascicles to make a muscle. 5. Endomysium surrounds the muscle fibers.

Behavioral Properties of Muscle extensibility–stretch elasticity–snap back irritability–respond contractility–shorten

Muscle Tissue Functions tension and types of skeletal muscle contraction agonist–moves bone antagonist–opposes the movement of the agonist

Concentric Contraction agonist contracts, antagonist relaxes

Eccentric Contraction agonist contracts while lengthening, antagonist relaxes the weight of the barbell causes tension of the bicep muscle causing it to lengthen against gravity

Isometric Contraction both agonist and antagonist contract no arm movement

Review and Assessment Match these words with 1–5 below: extensibility, elasticity, irritability, contractility, agonist, antagonist. 1. respond 2. opposes movement 3. stretch 4. shorten 5. causes movement

Heat Production Muscles generate heat when ATP is broken down for energy Even when not exercising, muscle generate heat which helps maintain our normal body temperature

Skeletal Muscle Actions Chapter 5: The Muscular System Lesson 5.2 Skeletal Muscle Actions

Skeletal Muscle the motor neuron – a nerve that stimulates skeletal muscle motor unit – a single motor neuron and all the muscles it stimulates

Skeletal Muscle Fibers A muscle fiber is a long, thin cell Each muscle fiber is composed of myofibrils 2 types of protein filaments that reside in functional units called sarcomeres Thick filaments = myosin Thin filaments = actin Striations are caused by the arrangement of thick and thin filaments within the myofibrils

muscle contraction involves the sliding movement of the thin filaments (actin) past the thick filaments (myosin) sliding continues until the overlapping between the thin & thick filaments is complete. The myosin heads (cross bridges) interact with active sites on thin filaments making linkages between the thick and thin filament.  * Remember that in a relaxed muscle cell, overlapping of thick and thin filaments is only slight (i.e. striations).

What causes the sliding movement of the actin? In order for a skeletal muscle to contract, its fibers must first be stimulated by a motor neuron. The process begins when a motor impulse is initiated by the brain, travels down the spinal cord, into a motor neuron The axon of the neuron branches into axon terminal which then branch out to individual muscle fibers Neuromuscular junctions link the axon terminals to the individual muscle fibers. Synaptic clefts are tiny gaps between the axon terminals and the muscle fibers and are filled with interstitial fluid

When the nerve impulse reaches the axon terminal, the neurotransmitter acetylcholine is released Acetylcholine opens the ion channels, allowing Na+ to enter the muscle fiber and K+ to exit the muscle fiber Greater amount of sodium ions enter than potassium ions exit, creating action potential Action potential activates the sarcomeres causing the sliding of the actin over the myosin

The Motor Unit group of muscle fibers under the control of one motor neuron

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Contraction of the Sarcomeres sarcomeres shorten by actin filaments sliding along myosin filaments

Maximum Tension and Return to Relaxation action potential always causes entire motor unit muscle fibers to contract

Skeletal Muscle Fiber Types slow-twitch – long distance runners fast-twitch - sprinters - type IIa – intermediate in contraction speed type Iib – contract rapidly and fatigue rapidly

Skeletal Muscle Fiber Architecture parallel fiber arrangements fusiform – biceps brachii bundled – rectus abdominis triangular – pectoralis major pennate fiber arrangements – each fiber attaches obliquely to a central tendon unipennate – muscles in the hand bipennate – rectus femoris multipennate - deltoid

The Major Skeletal Muscles Chapter 5: The Muscular System Lesson 5.3 The Major Skeletal Muscles

The Major Skeletal Muscles directional motions head and neck muscles trunk muscles upper limb muscles lower limb muscles

Skeletal Muscle Attachments origin fixed end of a muscle insertion movable end of a muscle

Sagittal Plane Movements flexion extension hyperextension dorsiflexion plantar flexion

Frontal Plane Movements abduction adduction inversion eversion radial deviation ulnar deviation

Transverse Plane Movements medial rotation lateral rotation pronation supination

Multiplanar Movements circumduction opposition

Review and Assessment True or False? 1. Circumduction is a multiple plane movement. 2. Supination is a multiple plane movement. 3. The insertion is the fixed end of a muscle. 4. Extension is a sagittal plane movement. 5. Adduction is a frontal plane movement.

Head and Neck Muscles

Trunk Muscles

Upper Limb Muscles

Lower Limb Muscles

Review and Assessment Match these words with 1–4 below: head, trunk, upper limb, lower limb. 1. temporalis 2. brachioradialis 3. external oblique 4. biceps femoris

Common Injuries and Disorders of Muscles Chapter 5: The Muscular System Lesson 5.4 Common Injuries and Disorders of Muscles

Muscle Injuries strain–overstretched muscle contusion–bruised muscle grade I, II, III contusion–bruised muscle myositis ossificans cramps–spasming muscle delayed onset muscle soreness–tear

Tendon Injuries tendinitis–inflamed tendon tendinosis–degeneration of a tendon Val Thoermer/Shutterstock.com

Joint Injuries rotational injury at shoulder overuse of elbow shin splints whiplash

Muscle Disorders muscular dystrophy hernia

Review and Assessment True or False? 1. Tendinitis is muscle strain. 2. A contusion is a bruise. 3. Whiplash is a joint injury. 4. A hernia is a tendon injury. 5. A strain is an over stretch of a tendon.