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

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

The Muscular System

Lesson 5.1

Muscle Tissue Categories and

Functions

Chapter 5: The Muscular System

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• categories– skeletal– smooth – cardiac

• functions– behavioral properties– tension and types of skeletal muscle contractions

Muscle Tissue


• skeletal– voluntary– striated

• smooth– involuntary– no striations

• cardiac– involuntary– striated– intercalated disks

Muscle Tissue Categories


Muscle Tissue Categories


• 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


Skeletal Muscle Organization


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.

Review and Assessment


• extensibility–stretch• elasticity–snap back• irritability–respond• contractility–shorten

Behavioral Properties of Muscle


• tension and types of skeletal muscle contraction– agonist–moves bone– antagonist–opposes the movement of the agonist

Muscle Tissue Functions


• agonist contracts, antagonist relaxes

Concentric Contraction


• agonist contracts while lengthening, antagonist relaxes

• the weight of the barbell causes tension of the bicep muscle causing it to lengthen against gravity

Eccentric Contraction


• both agonist and antagonist contract

• no arm movement

Isometric Contraction


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



• Muscles generate heat when ATP is broken down for energy

• Even when not exercising, muscle generate heat which helps maintain our normal body temperature

Heat Production

Lesson 5.2

Skeletal Muscle Actions



• the motor neuron – a nerve that stimulates skeletal muscle

• motor unit – a single motor neuron and all the muscles it stimulates

Skeletal Muscle


• 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

Skeletal Muscle Fibers



• 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


• group of muscle fibers under the control of one motor neuron

The Motor Unit


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http://www.g-wlearning.com/healthsciences/9781619604124/student/ch05_02/identify01/story.html


• sarcomeres shorten by actin filaments sliding along myosin filaments

Contraction of the Sarcomeres


• action potential always causes entire motor unit muscle fibers to contract

Maximum Tension and Return to Relaxation


• slow-twitch – long distance runners• fast-twitch - sprinters

- type IIa – intermediate in contraction speed– type Iib – contract rapidly and fatigue rapidly

Skeletal Muscle Fiber Types


• 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

Skeletal Muscle Fiber Architecture

Lesson 5.3

The Major Skeletal Muscles



• directional motions• head and neck muscles• trunk muscles• upper limb muscles• lower limb muscles

The Major Skeletal Muscles


• origin – fixed end of a muscle

• insertion– movable end of a muscle

Skeletal Muscle Attachments


• flexion• extension• hyperextension• dorsiflexion• plantar flexion

Sagittal Plane Movements


• abduction• adduction• inversion• eversion• radial deviation• ulnar deviation

Frontal Plane Movements


• medial rotation• lateral rotation• pronation• supination

Transverse Plane Movements


• circumduction• opposition

Multiplanar Movements


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


Match these words with 1–4 below: head, trunk, upper limb, lower limb.

1. temporalis

2. brachioradialis

3. external oblique

4. biceps femoris


Lesson 5.4

Common Injuries and Disorders of

Muscles



• strain–overstretched muscle– grade I, II, III

• contusion–bruised muscle– myositis ossificans

• cramps–spasming muscle• delayed onset muscle soreness–tear

Muscle Injuries


• tendinitis–inflamed tendon

• tendinosis–degeneration of a tendon

Tendon Injuries

Val Thoermer/Shutterstock.com


• rotational injury at shoulder• overuse of elbow• shin splints• whiplash

Joint Injuries


• muscular dystrophy• hernia

Muscle Disorders


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.


Documents

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