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: Skeletal Muscle Smooth Muscle Cardiac Muscle

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

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

I bands (light) have actin attached to Z lines. These striations a pattern with 2 parts: I bands (light) have actin attached to Z lines. 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. easttroy. k12. wi http://www.easttroy.k12.wi.us/hs/dept/science/bottum/Adv%20Biology/muscular/manatomy/images/muscle2.gif http://www.ks.uiuc.edu/Research/telethonin/MuscleL1-t.jpg

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 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 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 goes into cycle (to make ATP)   Energy to do work 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)

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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! Major superficial muscles of the body

Head & Neck muscles: Frontalis Occipitalis Orbicularis Oculi Chewing Muscles Frontalis Occipitalis Orbicularis Oculi Orbicularis Oris Buccinator Zygomaticus Masseter Temporalis Platysma Sternocleidomastoid Neck Muscles Facial muscles

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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)

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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.

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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.