The Muscular System Part 1 Essentials of Human Anatomy & Physiology Elaine N. Marieb The Muscular System Part 1 Modified by K. Molina Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Major Muscles Memorize the location of the muscles using the diagrams you were provided - (these are the muscles on your worksheet) Hamstrings: biceps femoris, semimembranosus, semitendinosus Quadriceps: rectus femoris, vastus lateralis, vastus medialis, vastus intermedius, sartorius

Hamstrings

Quadriceps

Locations of IM injections deltoid muscle gluteus medius – superior lateral quadrant used in order to avoid damaging underlying sciatic nerve vastus lateralis vastus lateralis and rectus femoris are used for infant injections due to poor development of gluteal muscles and deltoid muscles

Location of IM injections

IM injections in children

Naming of Skeletal Muscles You are responsible for knowing all examples in your textbook & notes !!! Location of the muscle – named for a bone or region with which they are associated Temporalis Shape – named for a distinctive shape Deltoid (triangular) Slide 6.36a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Relative size of the muscle maximus (largest) (i.e gluteus maximus) minimus (smallest) (i. e. gluteus minimus) longus (longer in length than in diameter) (i.e. adductor longus) brevis (short) (i.e. adductor brevis) Direction of muscle fibers rectus (straight) oblique (at an angle or slanted) Transverse (runs perpendicular to midline) Slide 6.36a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Naming of Skeletal Muscles Number of origins Biceps, triceps, quadriceps (# of heads) Slide 6.36b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Naming of Skeletal Muscles Location of the muscles origin and insertion Example: sternocleidomastoid (on the sternum, clavicle, and mastoid process) Action of the muscle Example: flexor and extensor (flexes or extends a bone) Slide 6.37 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Skeletal Muscle A muscle is an ORGAN containing muscle fibers (cells), connective tissue, blood vessels & nerves

Connective Tissue Wrappings of Skeletal Muscle Epimysium – covers the entire skeletal muscle – dense fibrous CT Deep fascia – on the outside of the epimysium Figure 6.1 Slide 6.4b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Connective Tissue Wrappings of Skeletal Muscle Perimysium –collagen around a fascicle (bundle) of fibers Endomysium –reticular tissue around single muscle fiber Figure 6.1 Slide 6.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Importance of CT Wrappings Supports & reinforces each cell and the whole muscle Provides entry and exit points for: Blood vessels Nerves

Nerve Supply Each muscle fiber has its own nerve ending

Blood Supply Each muscle is served by one major artery and one or more veins

IMPORTANT: Dependence Skeletal muscle is dependent on its: Nerve supply because skeletal muscle cannot contract without nerve stimulation Blood supply because Muscles use tremendous amounts of energy so must have lots of oxygen, etc. and wastes that must be removed

Muscle Attachments Sites of muscle attachment Bones Cartilages Connective tissue coverings Slide 6.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Types of Muscle Attachments Direct attachments Muscle is fused directly to bone or cartilage covering (periosteum or perichondrium) Indirect attachments Connective sheaths of muscle extend beyond muscle as a: Tendon – cord-like structure Aponeuroses – sheet-like structure Slide 6.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Direct Muscle Attachment Pectoralis Major Indirect Muscle Attachment Pectoralis Minor

IMPORTANT Indirect is most common due to: Size Durability - Resistance against friction as muscle moves

Fascicle Arrangement The direction and arrangement of the muscle fiber bundles (aka: fascicles) is important to observe. These factors determine what a muscle can do and what it is best for. Fascicle arrangement is also important to take note of in order to maximize the efficiency of your workouts

Fascicle Arrangement Range of Motion Longer muscle fibers along muscle axis = greater range of motion Parallel fascicle arrangement gives greatest ROM Movement Convergent muscle arrangement is best for moving large areas of the body

Fascicle arrangment Strength (Power) Depends on # of Muscle fibers Greater # = greater power Bipennate – shorten very little but have a greater # of muscle fibers collectively so best for strength Circular muscles cause both internal and external body openings to: Open when relaxed Close when contracted Aka. Sphincter muscles

Fascicle Arrangement – see notes

Overview of Muscle Tissue Nearly 40% of body mass Transforms chemical energy (ATP) into mechanical energy(motion) myo-, mys- (muscle) and sarco- (flesh) all refer to muscle Contraction of muscles is due to the movement of microfilaments – actin & myosin that slide & overlap each other

Functional Characteristics of Muscles Contractility – ability to shorten forcibly Excitability – ability to receive and respond to stimuli Elasticity – ability to resume resting length (recoil) Extensibility – ability to be stretched or extended Slide 6.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Function of Muscles Responsible for all locomotion & manipulation Smooth: vasoconstriction, peristalsis Skeletal: locomotion & manipulation Cardiac: pump Slide 6.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Know your 3 muscle slides Also know the main features of each type of tissue – review your tissue chart and tissue unit notes

Smooth

Skeletal

Cardiac

Keeps organs etc in position to function correctly Function of Muscle Maintain posture Keeps organs etc in position to function correctly CORE training, strengthening, machine weights vs. free weights

Function of Muscles Generate heat Heat is a by-product of muscle metabolism & contractile activity (40% of body mass) 75% of energy escapes as heat, 25% used for cellular activities Example: shivering uses muscle activity to generate heat when you are cold Stabilize joints – muscle tone & tendons extremely important to stabilize joints Slide 6.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The 5 Golden Rules of Skeletal Muscle Activity

Muscles and Body Movements All muscles cross at least one joint But may cross multiple joints The bulk of the acting muscle typically lies proximal to the joint crossed Figure 6.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscles and Body Movements Muscles are attached to at least two points Origin – attachment to the immovable or less movable bone Insertion – attachment to the movable bone Figure 6.12 Slide 6.30b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscles and Body Movements Muscles can only pull, they never push During contraction, the muscle insertion moves toward the origin Figure 6.12 Slide 6.30b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscle Interactions Prime mover (Agonist) – muscle with the major responsibility for a certain movement Antagonist – muscle that opposes or reverses a prime mover Slide 6.35 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscle Interactions Synergist – muscle that aids an agonist in a movement and helps stabilize the motion Fixator – synergists that helps immobilize a bone or muscle origin (while the insertion point moves) Slide 6.35 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Coordination Actions of antagonistic and synergistic muscles are important in causing smooth, coordinated, and precise muscle motions.

Biomechanics Muscles exert force by use of lever action Bones act as levers for muscles to pull on. Each type of lever has advantages and disadvantages in either the strength required to move the body part or the distance (ROM) that the body part can be moved or the speed of the motion.

Modifying muscle activity Differences in the positioning of the fulcrum. load, and effort modify muscle activity with respect to: speed of contraction Direction of motion range of motion (ROM) Strength - weight that can be lifted

Terms to understand Fulcrum – fixed point - joints Effort – applied force – provided by muscle contraction Load – resistance – bone, overlying tissues, and any other object you are trying to move

Application Understanding lever action, angles and position, and muscle fiber direction is extremely important: To maximize the effectiveness of your work outs To prevent injury

First class lever Fulcrum is in the middle - between load and effort The main advantage is the change in direction of the force – force exerted is equal to force lifted Example: Muscle pulls downward to lift body part upward or vice versa Example: Extension of head

Second class lever Load is in the middle - between effort and fulcrum Uncommon in the body The main advantage is multiplication of force (strength)– force exerted is less than force lifted Levers of strength BUT Range of motion is sacrificed Example: Standing on your toes (contraction of calf muscle) lifts your whole body but only a small distance

Third class lever Effort is in the middle - between load and fulcrum Most common in the body The main advantage is range of motion Strength is sacrificed Speed is gained Example: Flexing at elbow using bicep muscle

Examples