The Muscular System
6.1.1 Describe similarities and differences in the structure and function of the three types of muscle tissue
and indicate where they are found in the body.
 Muscles are responsible for all types of body movement
 Three basic muscle types are found in the body
 ___________
 ___________
 ___________
 Characteristics of Muscles
 Skeletal and smooth muscle cells are _____________ (muscle cell = muscle fiber)
 Contraction of muscles is due to the movement of microfilaments
 All muscles share some terminology
o Prefixes _____ and _____ refer to “muscle”
o Prefix _____ refers to “flesh”
 Skeletal Muscle Characteristics
 Most are attached by _____________ to bones
 Cells are _____________
 _____________ —have visible banding
 _____________ —subject to conscious control
6.1.2_____ Define and explain the role of the following: endomysium, perimysium, epimysium, tendon, and
aponeurosis.
 Connective Tissue Wrappings of Skeletal Muscle
 Cells are surrounded and bundled by connective tissue
o Endomysium—encloses a _____________ muscle fiber
o Perimysium—wraps around a _____________ (bundle) of muscle fibers
o Epimysium—covers the _____________ skeletal muscle
o Fascia—on the outside of the _____________
 Skeletal Muscle Attachments
 Epimysium blends into a connective tissue
attachment
o _____________ —cord-like structures
 Mostly collagen fibers
 Often cross a joint due to
toughness and small size
o _____________ —sheet-like structures
 Attach muscles indirectly to
bones, cartilages, or connective
tissue coverings
 Skeletal Muscle Attachments
 Sites of muscle attachment
o Bones
o Cartilages
o Connective tissue coverings
6.1.1 Describe similarities and differences in the structure and function of the three types of muscle tissue
and indicate where they are found in the body.
 Smooth Muscle Characteristics
 Lacks _____________
 Spindle-shaped cells
 _____________ nucleus
 _____________ —no conscious control
 Found mainly in the walls of _____________ organs
 Usually _____________ layers
 Cardiac Muscle Characteristics
 _____________
 Usually has a single nucleus
 _____________ cells
 Joined to another muscle cell at an intercalated disc
 _____________
 Found only in the _____________
 Skeletal Muscle Functions
 Produce _____________
 Maintain _____________
 Stabilize joints
 Generate _____________
6.1.3 Describe the microscopic structure of skeletal muscle and explain the role of actin- and myosincontaining myofilaments.
 Microscopic Anatomy of Skeletal Muscle
 Sarcolemma—specialized _____________ membrane
 Myofibrils—long _____________ inside muscle cell
 _____________ reticulum—specialized smooth endoplasmic reticulum
 _____________ are aligned to give distinct bands
o I band = __________ band
 Contains only thin filaments
o A band = _________ band
 Contains the entire length of the thick filaments
 Sarcomere— _____________
unit of a muscle fiber
 Organization of the sarcomere
o Myofilaments
 Thick filaments =
___________
filaments
 Thin filaments =
____________
filaments
 Microscopic Anatomy of Skeletal Muscle
 Thick filaments = myosin filaments
o Composed of the _____________ myosin
o Has ATP enzymes
o Myosin filaments have ___________ (extensions, or cross bridges)
o Myosin and actin ___________ somewhat
 Thin filaments = actin filaments
o Composed of the ____________ actin
o Anchored to the _______
disc
 Microscopic
Anatomy of Skeletal
Muscle
 At rest, there is a bare zone that
lacks actin filaments called the H
zone
 Sarcoplasmic reticulum (SR)
 Stores and releases calcium
 Surrounds the myofibril
Stimulation and Contraction of Single Skeletal Muscle Cells




Excitability (also called responsiveness or irritability)—ability to receive and respond to a __________
_________________ —ability to shorten when an adequate stimulus is received
Extensibility—ability of muscle cells to be ______________
Elasticity—ability to ____________ and resume resting length after stretching
6.2.1 Describe how an action potential is initiated in a muscle cell.
The Nerve Stimulus and Action Potential - How a muscle actually contracts
 Skeletal muscles must be stimulated by a ____________________ (nerve cell) to contract
 Motor unit—one motor neuron and all the skeletal muscle cells stimulated by that neuron
 Neuromuscular junction Association site of axon terminal of the motor
neuron and muscle
 ______________ cleft
 __________ between nerve and muscle
 Nerve and muscle __________ make contact
 Area between nerve and muscle is filled with
interstitial fluid
 Transmission of Nerve Impulse to Muscle
1) Neurotransmitter—____________ released by
nerve upon arrival of nerve impulse
i. The neurotransmitter for skeletal muscle
is acetylcholine (______)
2) Acetylcholine attaches to receptors on the
_______________
3) Sarcolemma becomes permeable to
____________________
4) Sodium rushes into the cell generating an action
potential
6.2.2 _____ Describe the events of muscle cell contraction
 The Sliding Filament Theory of Muscle Contraction
1) Regulatory proteins are in the _____________
sites
2) Activation by a nerve causes __________ to be released from the sarcoplasmic reticulum.
3) Ca+2 binds to ______________ _______________
4) Regulatory proteins change shape and ____________________________________
5) _________ __________
(cross bridges) attach to
binding sites on the thin
filament
6) Myosin heads then bind to
the next site of the thin
filament and pull them
toward the center of the
______________
7) This continued action causes a sliding of the myosin along the actin
8) There is always myosin heads attached to the _________
9) The result is that the muscle is shortened (contracted)
6.3.1 Define origin, insertion, prime mover, antagonist, synergist, and fixator as they relate to muscles.
6.3.2 Demonstrate or identify the different types of body movements.
Muscles and Body Movements
 Movement is attained due to a muscle moving an attached bone
 Muscles are attached to at least two points
 ___________ - Attachment to a moveable bone
 ___________ - Attachment to an immovable bone
Types of Ordinary Body Movements
 Flexion
 Decreases the angle of the joint
 Brings two bones ________________________
 Typical of hinge joints like knee and elbow
 Extension
 ______________ of flexion
 Increases angle between two bones
 ______________
 Movement of a bone around its ___________________ axis
 Common in ball-and-socket joints
 Example is when you move atlas around the dens of axis (shake your head “no”)
 Abduction
 Movement of a limb ___________ from the midline
 Adduction
 Opposite of abduction
 Movement of a limb ____________ the midline
 ________________
 Combination of flexion, extension, abduction, and adduction
 Common in ball-and-socket joints
 You make an imaginary cone
Special Movements
 Dorsiflexion
 ____________ the foot so that the superior surface approaches the shin
 Plantar flexion
 Depressing the foot ( ____________________ )
 Inversion
 Turn sole of foot __________ . Toward the inside
 _____________
 Turn sole of foot laterally. Toward the outside
 Supination
 Forearm rotates laterally so palm faces _____________
 Pronation
 Forearm rotates medially so palm faces ____________
 ______________
 Move thumb to touch the tips of other fingers on the same hand
Types of Muscles
 Prime mover—muscle with the major ____________________ for a certain movement
 Antagonist—muscle that _____________ or reverses a prime mover
 ______________—muscle that aids a prime mover in a movement and helps prevent rotation
 Fixator—_____________ the origin of a prime mover
6.3.3_____ List some criteria used in naming muscles.
Naming Skeletal Muscles
 By ______________ of muscle fibers
 Example: Rectus (straight)
 By relative ___________ of the muscle
 Example: Maximus (largest)
 By _____________ of the muscle
 Example: Temporalis (temporal bone)
 By number of ___________
 Example: Triceps (three heads)
 By location of the muscle’s origin and insertion
 Example: Sterno (on the sternum)
 By _____________ of the muscle
 Example: Deltoid (triangular)
 By _____________ of the muscle
 Example: Flexor and extensor (flexes or extends a bone)