Muscular System

Types of MuscleSkeletal – striated & voluntary

Smooth – involuntaryCardiac - heart

Muscles and Muscle Fibers    

Muscles are composed of many fibers that are arranged in bundles called FASCICLES

Individual muscles are separated by FASCIA, which also forms tendons and aponeuroses (sheet-like coverings)

FascicleFascia

Muscle Layers

Epimysium – fascia around the entire muscle bundle

Muscle cell or fiber

Perimysium- fascia around a group of fibers

Endomysium – fascia around the cell or fiber

Lets get the hierarchy straight

Musclesare made from a lot of

Muscle Fiber Bundleswhich are made of

Individual Muscle Fibers (cells)which are made of

Myofibrilswhich are rows of

Sarcomeres

Muscles & Nervous SystemMuscles receive their information from the nerve

cells at the Neuromuscular junction.

The means of contracting comes Sarcoplasmic Reticulum. It is like the smooth and rough E.R. in form and stores calcium .

When the signal comes from the nerves (acetylcholine), it floods the cell with calcium which causes a chemical reaction between the thin and thick filaments.

Myofibril – thick and thin filamentsThese filaments are:       – ACTIN (thin) and MYOSIN (thick) 

These filaments overlap to form dark and light bands on the muscle fiber

A band = dArk • thick (myosin)I band = lIght • thin (actin)

• In the middle of each I band are Z lines. A sarcomere is one Z line to the other

What are the Thin and Thick filaments?

Actin fibers bind to make the thin filaments

Myosin fibers combine to make the thick filaments.

Together they oppose each other to form the “bands” of the Sarcomere

SLIDING FILAMENT THEORY (MODEL)The theory of how muscle contracts is the sliding filament theory. The contraction of a muscle occurs as the thin filament slide past the thick filaments. 

DLC the anatomy of a skeletal muscle cell from fiber to sarcomere.

Page 167 will be helpful

Where does the cell get it’s energy?Fibers contain multiple mitochondria for energyATP is made here! 

 

Energy Source•Provided by ATP from cellular

respiration  (mitochondria) Usually only 4-6 seconds worth is stored

•Aerobic respiration creates 36 ATP molecules/Glucose – must have O2

•Anaerobic Respiration creates 2 ATP and Lactic Acid – absence of O2

Threshold StimulusThreshold Stimulus

Minimal strength required to cause a contraction 

Motor neuron releases enough acetylcholine to reach threshold

Fibers do not contract partially, they either do or don't.

All-or-None ResponseAll-or-None Response

Muscles and their movements:

Every one of the 600+ skeletal muscles is connected to bone or connective tissue at two points!1. Origin – attachment to

immovable bone

2. Insertion – attachment to a movable bone

Naming MusclesThere are certain things used when naming muscles.1. Direction of the muscle fiber

Rectus– (straight ) Rectus Femoris

2. Size of the muscle

Maximus –(largest) or Minimus – (smallest)

Gluteus Maximus

3. Location of the muscle in the bodyFrontalis – (in the front) Frontalis muscle

4. The number of originsBiceps – (two origins) Triceps – (three origins) Quadriceps – (four origins)

5. Location of the muscle’s origin and/or insertion.

Sternocleidomastoid (sternum-collar bone-mastoid process of the Temporal bone)

6. Shape of the muscle.Deltoid – (triangular muscle)

7. Action of the muscle.Flexor – (decrease bone angle)Extensor – (increases bone angle)Adductor – (brings bone toward the median)

Deltoid muscle

Flexor Carpi RadialisExtensor Carpi RadialisAdductor Magnus

Muscles perform different types of movements:

All contract and relax, but these movements are what it does to the body. It all has to do with what the joint does.

Flexion:Flexion:Decreases the joint angle.Brings bones closer together.

Extension:Extension:Increases the Joint Angle.Pushes bones farther apart.

Rotation:Rotation:Movement around the longitudinal axis

Abduction:Abduction:Movement away from the median plane.Adduction:Adduction:Movement toward the median plane.Circumduction:Circumduction:

Combining Flexion, Extension Abduction, and adduction (moving in a circle)

Dorsiflexion and Dorsiflexion and Plantar FlexionPlantar Flexion

Up and Down movement of the foot

Inversion and Inversion and Eversion:Eversion:Face the sole of the foot medially or laterally.

Supination Supination and and Pronation:Pronation:Lateral or medial rotation of a limbOpposition:Opposition:Moving one finger to oppose the others.

Muscles of the Face and Skull (Front view):Frontalis

Orbicularis Oculi

Zygomaticus

Orbicularis Oris

Temporalis

Platysma

Muscles of the Skull (side view):

Occipitalis

Sternocleidomastoid

Masseter

Trapezius

Muscles of the Chest and Shoulder

Trapezius

Deltoid

Pectoralis Major

Biceps Brachii (long head)

Biceps Brachii (short head)

Latisimus Dorsi

Serratus Anterior

External Obliques

Muscles of the abdomen (anterior)

Pectoralis Major

Rectus Abdominis

Transverse AbdominisInternal Oblique

External Oblique

Linea Alba

Aponeurosis

Muscles of the abdomen (posterior)

Trapezius

Deltoid

Latissimus Dorsi

Rhomboid

Muscles of the Upper Leg (posterior)

Gluteus Medius

Gluteus Maximus

Adductor Magnus

Gracialis

Biceps Femoris (long head)

SemitendonosisSemimembranosis

Biceps Femoris (short head)

Gastrocnemius

Muscles of the Upper Leg (posterior)Sartorius

Rectus Femoris

Vastus medialis

Adductor Group (groin)

Vastus Lateralis

Qua

dric

eps

Tibialis Anterior

Fibular Longus

Soleus

Muscles of the lower arm and leg

The only muscles that are important are the highlighted ones

Muscle ReviewCardiac muscle Smooth muscle Skeletal muscleFascicle Fascia EndomysiumPerimysium Epimysium MyofibrilSarcomere Sarcoplasmic reticulum ActinMyosin A-band I-bandAerobic respiration Anaerobic respiration Threshold stimulusOrigin Insertion Prime moverAntagonist Tendon

Questions:1. What is the sliding filament theory?2. List and describe the different types of muscle movements (flexion

extension, etc).3. What are the different ways muscles are named?4. Know all muscle names – Arm/Leg/Torso/Head