ANATOMY & PHYSIOLOGY

The Muscular System

THE MUSCULAR SYSTEM: Muscles are organs They provide tone, move body

fluids & food, provide the heartbeat & distribute heat.

There are 3 types of muscle:1. Skeletal Muscle2. Smooth Muscle3. Cardiac Muscle

http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/19917.jpg

Types of Muscle:

SKELETAL MUSCLE: Attached to bones

Voluntary

Allow movement

Striated (striped)

Enclosed in endomysium (connective tissue) which forms fibers called fascicles.

The fascicles collectively form aponeuroses, tendon-like structures which attach to bones.

http://www.uic.edu/classes/bios/bios100/labs/skeletal_muscle.jpg

Smooth Muscle

Cardiac Muscle

No striations Involuntary Located in hollow

organs (stomach, bladder, etc.)

Striated Involuntary Located only in

the heart (pump blood)

http://www.victoriacollege.edu/dept/bio/Belltutorials/Histology%20Tutorial/Basic%20Tissues/imageFLL.JPG

http://www.mccc.edu/~falkow/images/cardiac_001.jpg

MUSCLE FUNCTIONS: Movement (contraction &

relaxation)

Posture

Joint stabilization

Heat generation

MICROSCOPIC ANATOMY OF SKELETAL MUSCLE:

Sarcolemma is the plasma membrane.

The contractile unit in the muscle is the sarcomere.

Myofibrils are the organelles.

Myofilaments are the proteins found within the sarcomeres. These form striations.

Actin are thin filaments.

Myosin are thick filaments.

Skeletal Muscle:

http://www.ivy-rose.co.uk/Topics/Muscles/Muscle_Cell_Close-up_1.jpg

These striations a pattern with 2 parts:

1. I bands (light) have actin attached to Z lines.

2. A bands (dark) are myosin overlapping actin, contain an H zone (central thick region) and a M line.

Within the sarcoplasm is the sarcoplasmic reticulum (just like the ER of other cells). These are membranous channels.

Skeletal Muscle Fiber:

http://www.cartage.org.lb/en/themes/sciences/LifeScience/GeneralBiology/Physiology/Muscular/SkeletalMuscle/muscle2.gif

http://www.ks.uiuc.edu/Research/telethonin/MuscleL1-t.jpg

http://www.easttroy.k12.wi.us/hs/dept/science/bottum/Adv%20Biology/muscular/manatomy/images/muscle2.gif

SKELETAL MUSCLE ACTIVITY: Motor neurons (nervous system) connect

to each & every skeletal muscle fiber.

The connection between these two forms a neuromuscular junction.

This is the reason skeletal muscles contract.

Motor neurons branch; their ends contain a lot of mitochondria & synaptic vesicles (responsible for synapses).

They store neurotransmitters.

http://www.shelfieldpeonline.co.uk/assets/images/neuromuscular_junction.jpg

The basic movement of skeletal muscle is a result of a stimulus (via a neuro-transmitter).

The actin & myosin filaments slide past each other, shortening the muscle fiber (contraction).

Acetylcholine is the neurotransmitter responsible for skeletal muscle contraction.

This needs ATP and high [Ca++]

This is called the Sliding Filament Theory.

http://www.dwm.ks.edu.tw/bio/activelearner/38/images/ch38summary.gif

ENERGY FOR MUSCLE CONTRACTION: Aerobic respiration: requires

oxygen and produces ATP, which is used by muscles.

Creatine phosphate: provides phosphate to ADP to make ATP, which is then used by muscles.

Lactic acid fermentation: this is anaerobic respiration (no oxygen used).

Lactic acid is produced (and a small amount of ATP).

Energy to do workEnergy goes into cycle (to make ATP)

http://library.thinkquest.org/C006669/media/Biol/img/atp_cycle.gif

OXYGEN DEBT & MUSCLE TONE: Active muscles tend to become O2

deficient.

An accumulation of lactic acid in muscles causes fatigue, cramping and pain.

Repaying an oxygen debt (after strenuous exercise) may take several hours.

Even at rest, muscle tone exists. This is the sustained contraction of muscles. This is important in maintaining posture.

MUSCLE MOVEMENTS, TYPES & NAMES: Muscles move according to their

location & position.

The immovable end of a muscle is called the origin (head) while the movable end is called its insertion.

Insertion is pulled towards its origin.

Some muscles have more than 1 origin or insertion.

Ex: biceps brachii (in arm) has 2 origins (biceps=2 heads)

http://www.google.com/imgres?

Flexion means decreasing an angle

Extension means increasing an angle

Muscle name usually indicates info about it: its location, size, # of attachments, shape or action.

Examples:deltoid (shaped like a delta or

triangle) biceps brachii (2 heads in the

brachium, or arm) pectoralis major (large in size,

located in pectoral, or chest, region)

MAJOR SUPERFICIAL MUSCLES OF THE

BODY

Look up labeled diagram of muscle system in text or online. Know this diagram!

HEAD & NECK MUSCLES:

Facial muscles

Chewing Muscles

Frontalis Occipitalis Orbicularis Oculi Orbicularis Oris Buccinator Zygomaticus

Masseter Temporalis

Platysma Sternocleidomast

oid

Neck Muscles

http://www.google.com/imgres?

TRUNK MUSCLES: ANTERIOR MUSCLES: Pectoralis Major:

covers chest Intercostal Muscles:

between ribs Rectus Abdominis:

from pubis to rib cage

External oblique

Internal oblique

Transversus abdominus

http://www.google.com/imgres?

TRUNK MUSCLES: POSTERIOR MUSCLES:

Trapezius: kite-shaped muscle over neck & shoulder

Latissimus Dorsi

Erector Spinae (deep back)

Quadratus Lumborum

Deltoid (triangular-shaped muscle of shoulder)

http://www.google.com/imgres?

UPPER LIMB MUSCLES: Biceps brachii

Brachialis

Brachioradialis

Triceps Brachii

http://www.google.com/imgres?

MUSCLES OF LOWER LIMB:Hip Joint Muscles: Knee Joint Muscles:

Gluteus Maximus (buttocks)

Gluteus Medius

Iliopsoas (p is silent; iliac crest to vertebrate)

Adductor Muscles

Hamstrings (includes biceps femoris)

Sartorius

Quadriceps (includes rectus femoris): intramuscular injections usually occur here.

http://www.google.com/imgres?

MUSCLES OF LOWER LIMB:

Ankle & Foot:

Extensor Digitorum Longus

Fibularis Muscles (fibula to metatarsals)

Gastrocnemius (calf)

Soleus

http://www.google.com/imgres?

Look up in text or online! Know the following:

Atrophy, rotation, abduction, adduction, circumduction,

dorsiflexion, plantar flexion, inversion, eversion, supination,

pronation, opposition, prime mover, antagonists, synergists, fixators, muscular dystrophy, Duchene’s

muscular dystrophy, and mysthenia gravis

This slide show was developed by Dana Halloran, Cardinal Mooney High School, Sarasota, FL.

Used with her personal permission, adapted and amended by Rosa Whiting, Manatee School for the Arts, Palmetto, FL.