Anatomy & Physiology
Kasprowicz

Types of Muscle

• muscle cells are elongated = muscle fibers
(smooth, skeletal)
• contain myofilaments (ability to contract)
• terminology: myo-, mys= muscle sarco= flesh
General Muscle Characteristics

1)
2)
3)
4)
Very large, multinucleated cells
Striated (visible stripes or banding pattern)
Voluntary (conscious) control ; can be reflexive too muscle fibers (cells) are bundled together by strong connective tissues  exert great force, but tire easily
Skeletal Muscle

Deep fascia
Connective Tissues in Skeletal Muscle

 Endomysium – around single muscle fiber
 Perimysium – around a fascicle
(bundle) of fibers
 Epimysium – covers the entire skeletal muscle
 Deep Fascia – on the outside of the epimysium
Connective Tissues in Skeletal Muscles

Connective Tissues in Skeletal Muscle

 tendon – dense connective tissue attaching muscle to bone (cord-like)
 aponeuroses – attach muscles indirectly to bone,cartilages or connective tissue coverings (sheetlike)
 Epimysium blends into a connective tissue attachment
Connective Tissues in Skeletal Muscles

Connective Tissues in Skeletal Muscles

Aponeurosis of the external oblique
Connective Tissues in Skeletal Muscles

Refer to pg. 272 in your textbook
Connective Tissues in Skeletal Muscles

1)
2)
3)
4)
5)
Spindle-shaped cells with one nucleus no striations
Involuntary (no conscious control)
Found in hollow visceral organs
Have small amount of endomysium
Smooth Muscle

6) slow, sustained, tireless movement
7) often layers in opposite directions
Smooth Muscle

Smooth Muscle: Stomach Wall

1) Branching cells with one nucleus connected by intercalated discs
2) Striated
3) Involuntary (no conscious control)
4) small amounts of endomysium
Cardiac Muscle

5) Cardiac fibers are arranged in spiral or 8shaped bundles
Cardiac Muscle

1) Producing movement
2) Maintaining posture
3) Stabilizing joints
4) Support soft tissues
5) Generating heat
6) Guard entrances and exits
Muscle Functions

Muscle Functions

Skeletal Muscle Fiber (Cell) Formation

Skeletal Muscle Fiber (Cell) Formation

 Cells are multinucleate
 Nuclei are just beneath the sarcolemma
(1) sarcolemma specialized plasma membrane of muscle cells
Microscopic Anatomy of Muscle

(2) Cytoplasm filled with myofibrils myofibrils – perfectly aligned, ribbonlike organelles; give muscle fiber its striped appearance
Microscopic Anatomy of Muscle

(2) Cytoplasm filled with myofibrils
A closer look at the myofibril
L i ght ( I ) bands
D a rk ( A ) bands
Microscopic Anatomy of Muscle

(2) Cytoplasm filled with myofibrils
Banding Pattern:
L i ght ( I ) bands contain the Z disc
D a rk ( A ) bands contain the H zone
M line - holds adjacent filaments together; center of
H zone
Microscopic Anatomy of Muscle

An even closer look at the myofibril…
(3) Sarcomere
- contractile unit of the myofibril
- Z disc to Z disc
Microscopic Anatomy of Muscle

An even closer look at the myofibril…
(3) Sarcomere
Microscopic Anatomy of Muscle

Zooming in on the sarcomere…
(4) Myofilaments - special proteins that cause muscle to contract
Two Types: a) myosin (thick filament) b) actin (thin filament)
Microscopic Anatomy of Muscle

Two Types: a) myosin (thick filament)
 protein with heads that form cross bridges b/t thick & thin filaments during muscle contraction
 Contain ATPase enzymes
Microscopic Anatomy of Muscle

Two Types: b) actin (thin filament)
 Made of the contractile protein actin
& some other regulatory proteins
Microscopic Anatomy of Muscle

Zooming in around the H zone….
Microscopic Anatomy of Muscle

(5) Sarcoplasmic reticulum (SR) specialized smooth ER surrounding each myofibril stores calcium which is released when muscle is stimulated to contract
Microscopic Anatomy of Muscle

Sarcoplasmic reticulum (SR)
Microscopic Anatomy of Muscle

Sarcoplasmic reticulum (SR)
Microscopic Anatomy of Muscle

Microscopic Organization of Muscle:
Level 1 (refer to Fig. 10-6, pg. 278)
Let’s put this all together….

Microscopic Organization of Muscle:
Level 2
Let’s put this all together….

Microscopic Organization of Muscle:
Level 3
Let’s put this all together….

Microscopic Organization of Muscle:
Level 4
Let’s put this all together….

Microscopic Organization of Muscle:
Level 5
Let’s put this all together….


Irritability – ability to receive and respond to a stimulus
( a property shared with neurons )

Contractility – ability to shorten when an adequate stimulus is received
Special Functional Properties of Muscle

Quick Review of Neurons & Synapses

Quick Review of Neurons & Synapses

Quick Review of Neurons & Synapses

:
One neuron & the muscle cells stimulated by that neuron
Nerve Stimulus to Muscle

Neuromuscular junctions
 the neuron & muscle fibers do NOT touch
 separated by a gap called the synaptic cleft which is filled w/ interstitial fluid
Nerve Stimulus to Muscle

Neuromuscular junctions
Nerve Stimulus to Muscle

 chemical released by neurons used to
“carry” the impulse across the synaptic cleft
Acetylcholine (ACh) is the neurotransmitter used at the neuromuscular junction of skeletal muscle
Transmission of Nerve Impulse to Muscle

 ACh is released by the pre-synaptic axon terminal of the motor neuron
 ACh crosses the synaptic cleft & attaches to receptors on the sarcolemma
 Sarcolemma becomes permeable to sodium (Na + )
Transmission of Nerve Impulse to Muscle

Steps in Impulse Transmission
 Sodium floods into the cell generating an action potential (electrical current)
 Once started, muscle contraction cannot be stopped !!
 ACh is broken down by the enzyme acetylcholinesterase
This prevents continued contraction of the muscle cell in the absence of additional nerve impulses.
Transmission of Nerve Impulse to Muscle


When an action potential sweeps along the sarcolemma and a muscle cell is excited, calcium ions are released from the sarcoplasmic reticulum
Transmission of Nerve Impulse to Muscle


The flood of Ca + ions is the final trigger for the contraction of the muscle
Transmission of Nerve Impulse to Muscle

Sliding Filament
Theory: Overview

Myosin heads form cross bridges with binding sites on actin
Resting Sarcomere

Myosin heads detach & then bind to the next site on actin
Sarcomere Contracts
Mechanism of Muscle Contraction

Sliding Filament
Theory: Overview
 This action continues, causing the myosin & actin to slide past each other
Resting Sarcomere
Sarcomere Contracts
Mechanism of Muscle Contraction

Sliding Filament
Theory: Overview
 Collective shortening of the muscle cell sarcomeres = muscle contraction
Resting Sarcomere
Sarcomere Contracts
Mechanism of Muscle Contraction

Step 1:
 Ca + ions released from the SR attach to the troponintropomyosin complex
 Binding sites on the actin filament are exposed
The Contraction Cycle : The Nitty Gritty

Step 1:
The Contraction Cycle : The Nitty Gritty

Step 2:
 myosin heads attach to actin binding sites, forming cross bridges
 ATP was required to prep the myosin head (ATP  ADP + P)
The Contraction Cycle : The Nitty Gritty

Step 2:
The Contraction Cycle : The Nitty Gritty

Step 3:
 ADP + P released from myosin head
 myosin head flexes/pivots =
“power stroke”
The Contraction Cycle : The Nitty Gritty

Step 3:
The Contraction Cycle : The Nitty Gritty

 ATP binds to myosin head, causing it to detach from the actin filament
The Contraction Cycle : The Nitty Gritty

Step 5:
 myosin head re-energized
(ATP  ADP + P)
Step 6:
 Ca + ions pumped back into the SR
 troponin-tropomyosin complex moves back to its original position
The Contraction Cycle : The Nitty Gritty

The Contraction Cycle : The Nitty Gritty

The Contraction Cycle : The Nitty Gritty

Muscle Contraction Animations http://www.mhhe.com/biosci/bio_animations/09_MH_MuscleContraction_Web/index.html
Muscle Contraction 3-D Animation http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and_muscle_contraction.html
Action Potentials & Muscle Contraction https://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter10/animation__breakdown_of_atp_and_crossbridge_movement_during_muscle_contraction.html
Break Down of ATP & Cross Bridge Attachment https://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.html
Sarcomere Contraction


The “all-or-none” response of muscle contraction refers to the muscle cell ,
NOT the whole muscle
 Whole muscle reacts with a graded response (different degrees of shortening)
Contraction of the Whole Muscle

Graded responses are produced in 2 ways:
1) Change the frequency of stimulation
2) Change the # of muscle cells stimulated/time
- more activated muscle cells stronger FORCE of contraction
Contraction of the Whole Muscle

Changing Stimulation Frequency
1
Muscle Twitch – 1 stimulus; single, brief, jerky contraction
Contraction of the Whole Muscle

Changing Stimulation Frequency
2
Wave Summation – frequency of stimulus increases; less time to relax; contraction strength “summed”
Contraction of the Whole Muscle

Changing Stimulation Frequency
3
Incomplete Tetanus – frequency of stimulation increases even more
Contraction of the Whole Muscle

Changing Stimulation Frequency
4
Tetanus – frequency of stimulation very rapid; no evidence of relaxation; smooth, sustained contraction
Contraction of the Whole Muscle

 Initially, muscles used stored ATP for energy

ATP is hydrolyzed into ADP + P

Only 4-6 seconds worth of ATP is stored by muscles
 After this, other metabolic pathways must be used to produce ATP
Energy for Muscle Contraction

Pathway 1 : Direct Phosphorylation
 Muscle cells contain creatine phosphate (CP)

CP is a high-energy molecule that transfers energy to ADP, regenerating
ATP
 CP supplies are exhausted in about
20 seconds
Energy for Muscle Contraction

Pathway 1 :
Direct
Phosphorylation
Energy for Muscle Contraction

Pathway 2 : Anaerobic Respiration
(a.k.a. lactic acid fermentation)
 breaks down glucose without oxygen
 Glucose is broken down to pyruvic acid; 2 ATP are produced
 Pyruvic acid  lactic acid
Energy for Muscle Contraction

Pathway 2 :
Anaerobic Respiration
(lactic acid fermentation)
Energy for Muscle Contraction

Pathway 2 : Anaerobic Respiration
 This reaction is not as efficient, but it is fast

Huge amounts of glucose are needed

Lactic acid produces muscle fatigue
 Duration: 30-60 seconds
Energy for Muscle Contraction

Pathway 3 : Aerobic Respiration
 Series of metabolic pathways that occur in the mitochondria & require oxygen
 Glucose is broken down to carbon dioxide and water releasing energy
 This is a slower reaction that requires continuous oxygen
 High energy pay-off: 36 ATP
Energy for Muscle Contraction

Pathway 3 :
Aerobic Respiration
Energy for Muscle Contraction

 When a muscle is fatigued, it is unable to contract
 The common reason for muscle fatigue is oxygen debt
 Oxygen must be “repaid” to tissue to remove oxygen debt

Oxygen is required to get rid of accumulated lactic acid
 Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less
Muscle Fatigue & Oxygen Debt

Isotonic Muscle Contraction
 The myofilaments slide past each other  muscle shortens
 movement occurs
Examples: bending knee, rotating the arms, smiling
Types of Muscle Contraction

Isometric Muscle Contraction
 muscle is not able to shorten
 muscle tension keeps increasing
Examples: lifting a 1000 lb. object alone; pushing against an object that doesn‘t move
Types of Muscle Contraction

 state of continuous partial contractions
 Different fibers contract at different times to provide muscle tone
 muscle remains firm, healthy & ready for action

Increasing muscle tone increases metabolic energy used, even at rest
Muscle Tone

Muscle Tone

If the nerve supply to a muscle is destroyed, the muscle is no longer stimulated in this manner, and it loses tone and becomes paralyzed. Soon after, it becomes flaccid (soft and flabby) and begins to atrophy (waste away).
Muscle Tone

Muscle Tone

Aerobic (Endurance) Exercise
 Examples: jogging, biking, swimming
 stronger, more flexible muscles w/ greater resistance to fatigue
Effects of Exercise

Aerobic (Endurance) Exercise
 Physiological Effects
1) increased blood supply to muscles
2) more mitochondria
3) increased metabolism
4) keeps bones strong
5) improves neuromuscular coordination
Effects of Exercise

Resistance (Isometric) Exercise
 Examples: weight training
 increased muscle size and strength
Effects of Exercise

Aerobic (Endurance) Exercise
 Physiological Effects
1) increased # of myofilaments  increased size of muscle fibers
2) more connective tissue
3) keeps bone strong
Effects of Exercise

1) All (almost  ) skeletal muscle cross a least one joint
2) Most of a skeletal muscle lies proximal to the joint crossed
3) All skeletal muscles have at least 2 attachments: the origin and the insertion
4) Skeletal muscles can only PULL (create tension)
5) When a muscle contracts, the insertion moves toward the origin
“Golden Rules” of Skeletal Muscle Activity

 Movement occurs when a muscle contracts and moves an attached bone
 Muscles are attached to at least two points

Origin – attachment to a immoveable bone

Insertion – attachment to an movable bone
Types of Body Movements

When a skeletal muscle contracts, its insertion moves toward its origin
Types of Body Movements

 prime mover – muscle primarily responsible for a certain movement
Example: biceps, hamstrings
(a.k.a. agonist )

Antagonist – muscle that opposes or reverses a prime mover

Triceps when biceps flexes; quads when hamstrings flex
Body Movements: Muscle Interactions

Prime Mover – biceps
Antagonist – triceps
Prime Mover – triceps
Antagonist – biceps


Synergist – muscle that aids a prime mover in a movement and helps prevent rotation
Example: finger flexor muscles brachioradiulus & brachialis in the forelimb
Body Movements: Muscle Interactions

1) Flexion decreases angle of joint, bringing
2 bones closer together common in hinge, ball & socket joints
2) Extension increases the angle of a joint, moving the bones apart hyperextension >180° angle
Types of Body Movements

Hyperextension

3) Rotation movement of a bone around its longitudinal axis common in ball & socket joints atlas (C1) around the axis (C2)
Types of Body Movements

4) Abduction movement of a limb away from the medial plane also used to refer to fanning of finger or toes
5) Adduction movement of a limb toward the midline
Types of Body Movements

6) Circumduction proximal end is stationary; distal end moves in a circle limb moves in a cone shape common in ball & socket joint combo of flexion, extension, abduction & adduction
Types of Body Movements

1) Dorsiflexion (point toes up towards shin) & Plantar
Flexion (pointing the toes)
Special Body Movements

2) Inversion (turn sole of foot medially) & Eversion of foot laterally)
(turn sole
Special Body Movements

3) Supination & Pronation movements of the radius around the ulna supination: palm forward; radius & ulna are parallel (anatomical position); thumb lateral pronation: palm facing back; radius crosses ulna; thumb medial
Special Body Movements

3) Supination & Pronation
Special Body Movements

4) Opposition movement of thumb across palm to touch fingertips
Special Body Movements

Elevation & Depression

Protraction &
Retraction

1) Direction of muscle fibers in reference to an imaginary line
(midline of body, long axis of limb) ie. Rectus (fibers parallel to line)
Oblique (fibers at a slant to line)
Naming Skeletal Muscles

2) Relative Size
Longus = long
Longissimus = longest
Teres = long and round
Brevis = short
Magnus = large
Major = larger
Maximus = largest
Minor = small
Minimus = smallest
Naming Skeletal Muscles

3) Location of the Muscle in reference to the associated bone ie. temporalis (temporal bone) frontalis (frontal bone)
Naming Skeletal Muscles

4) Number of origins ie. biceps, triceps, quadriceps
5) Location of the muscle’s origin and insertion ie. Sternocleidomastoid muscle
Naming Skeletal Muscles

6) Shape of the muscle ie. Deltoid (triangular)
7) Action of the muscle ie. adductor muscle, extensor muscle
Naming Skeletal Muscles

•
Facial Muscles
Frontalis raises eyebrows and wrinkles the forehead
• Orbicularis Oculi close, squint, blink and wink the eyes
• Orbicularis Oris closes the mouth and protrudes the lips; the “kissing” muscle
Head and Neck Muscles

• Buccinator flattens the cheek (whistling or playing a trumpet); also a chewing muscle
• Zygomaticus
“smiling” muscle; raises the corners of the mouth upward
Head and Neck Muscles

• Buccinator
• Masseter closes the jaw by elevating the mandible
(prime mover)
• Temporalis helps masseter close the jaw (synergist)
Head and Neck Muscles

Frontalis
Orbicularis oculi
Zygomaticus
Orbicularis oris
Buccinator
Temporalis
Masseter

Frontalis
Orbicularis oculi
Orbicularis oris
Temporalis
Zygomaticus
Buccinator
Masseter

Frontalis
Temporalis
Zygomaticus
Orbicularis oris
Orbicularis oculi
Buccinator
Masseter

• Platysma pulls down corners of the mouth, downward sag of the mouth
• Sternocleidomastoid two-headed muscle; flex your neck (bowing of head); tilt head to side
Head and Neck Muscles

Frontalis
Orbicularis oculi
Zygomaticus
Orbicularis oris
Buccinator
Platysma
Temporalis
Masseter
Sternocleidomastoid

Frontalis
Orbicularis oculi
Orbicularis oris
Zygomaticus
Buccinator
Sternocleidomastoid
Plastysma
Temporalis
Masseter

Frontalis
Temporalis
Zygomaticus
Orbicularis oris
Sternocleidomastoid
Orbicularis oculi
Buccinator
Masseter platysma

• move the vertebral column (mostly posterior, anti-gravity muscles)
• anterior thorax muscles (move ribs, head & arms)
• muscles of the abdominal wall (help move vertebral column & form the
“girdle” holding internal organs in place)
Trunk Muscles

• Pectoralis Major
- fan-shaped muscle
- origin: sternum, pectoral girdle, ribs
- insertion: humerus
- adduct & flex the arm
Trunk Muscles

Pectoralis major
Pectoralis minor

• Intercostal Muscles
- deep muscles between the ribs
- aid in breathing
(external – inhale, internal – forcible exhale)
Trunk Muscles

External intercostals
Internal intercostals

Anterior Muscles: Abdominal Girdle
• Rectus abdominus
- pubis to rib cage
- flex the vertebral column
- compression of abdominal contents
Trunk Muscles

Anterior Muscles: Abdominal Girdle
• External Oblique
- lateral walls of abdomen
- origin: ribs insertion: illium
- flex the vertebral column, rotate/bend trunk
Trunk Muscles

Anterior Muscles: Abdominal Girdle
• Internal Oblique
- origin: iliac crest insertion: ribs
- function same as external oblique
• Transversus abdominis
- deepest muscle in abdomen
- fibers run horizontally
- compresses the abdominal contents
Trunk Muscles

Posterior Muscles
• Trapezius
- kite-shaped muscle
- origin: occipital bone to last thoracic vertebrae insertion: scapula & clavicle
- head extension & movement of scapula
Trunk Muscles

Posterior Muscles
• Latissimus Dorsi
- 2 large, flat muscles in the lower back
- origin: lower spine & ilium insertion: proximal end of humerus
- arm extension & adduction
(“power stroke”)
Trunk Muscles

Posterior Muscles
• Erector Spinae
- prime mover of back extension
(keep your body “erect”); control bending at the waist
- paired; deep in the back
- span vertebral column
Trunk Muscles

Posterior Muscles
• Qudratus lumborum
- posterior abdominal wall
- flex spine laterally, extend vertebral column
- origin: iliac crest insertion: upper lumbar vertebrae
Trunk Muscles

Posterior Muscles
• Deltoids
- triangular muscle forming shoulder
- origin: spine of scapula to clavicle insertion: proximal humerus
- prime mover of arm abduction
Trunk Muscles

• The anterior arm muscles cause elbow flexion strongest: brachialis biceps brachii
“weakest”: brachioradialis
• posterior arm: triceps brachii
Muscles of the Upper Limb

Anterior Arm Muscles
• Biceps brachii
- origin: 2 heads in pectoral girdle insertion: radius
- prime mover of forearm flexion & supination
Muscles of the Upper Limb

Anterior Arm Muscles
• Brachialis
- origin: humerus
- forearm flexion insertion: ulna
• Brachioradialis
- origin: humerus insertion: distal forearm
Muscles of the Upper Limb

Posterior Arm Muscles
• Triceps brachii
- origin: 3 heads in pectoral girdle insertion: olecranon process of ulna
- prime mover of elbow extension
- biceps brachii antagonist
Muscles of the Upper Limb

• cause movement of hip, knee & foot joints
• some of the largest, strongest muscles in the body
• specialized for walking & balance
• many of the muscles cross 2 joints and can cause movement at both
Muscles of the Lower Limb

Muscles that Move the Hip Joint
• Gluteus Maximus
- forms most of the flesh of the buttock
- origin: sacrum & illiac insertion: femur & iliotibial tract
- hip extensor (important when climbing and jumping)
Muscles of the Lower Limb

Muscles that Move the Hip Joint
• Gluteus Medius
- beneath gluteus maximus
- hip abductor; steadies pelvis when walking
• Iliopsoas (two, fused muscles)
- prime mover of hip flexion; keeps upper body from falling backward when standing
Muscles of the Lower Limb

Muscles that Move the Hip Joint
• Adductor Muscles
- group of muscles; medial thigh
- adduct, or press, thighs together
- origin: pelvis insertion: femur
- tend to get flabby
Muscles of the Lower Limb

Iliopsoas
Anterior
View
Adductor muscles

Posterior
View
Gluteus medius
Gluteus maximus
Adductor magnus
Iliotibial tract

Muscles that Move the Knee Joint
• Hamstring Group
- group of muscles; posterior thigh
biceps femoris , semimembranosus , semitendinosus
- origin: ischium insertion: tibia
- prime movers of thigh extension & knee flexion
Muscles of the Lower Limb

Muscles that Move the Knee Joint
• Sartorius
- thin, strap-like, relatively weak flexor
- most superficial thigh muscle
- synergist in sitting
“criss cross applesauce”
Muscles of the Lower Limb

Muscles that Move the Knee Joint
• Quadriceps Group
- group of muscles; anterior thigh
rectus femoris & 3 vastus muscles
- origin: pelvis & thigh insertion: tibia via patellar ligament
- prime movers of knee extension; hip flexion
Muscles of the Lower Limb

Iliopsoas
Q
U
A
D
S
Iliopsoa
Rectus femoris
Vastus lateralis s
Vastus medialis
Adductor muscles
Anterior
View

Posterior
View

Muscles that Move the Ankle & Foot
• Tibialis Anterior
- superficial muscle of anterior leg (shin)
- origin: tibia insertion: tarsals
- dorsiflex & invert the foot
• Fibularis Muscles
plantar flexion and eversion
- origin: fibula insertion: metatarsals
Muscles of the Lower Limb

Muscles that Move the Ankle & Foot
• Gastrocnemius
- forms curved calf; 2 parts
- origin: femur insertion: heel using Achille’s tendon
- prime mover of plantar flexion
Muscles of the Lower Limb

Muscles that Move the Ankle & Foot
• Soleus
- deep to gastrocnemius
- origin: tibia & fibula (no effect on knee) insertion: heel using Achille’s tendon
- plantar flexion
Muscles of the Lower Limb

Anterior
View
Posterior
View