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 • multinucleated • 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
No striations • Involuntary • Located in hollow organs (stomach, bladder, etc.) • Striated • Involuntary • Located only in the heart (pump blood) • branching Smooth Muscle Cardiac Muscle http://www.mccc.edu/~falkow/images/cardiac_001.jpg http://www.victoriacollege.edu/dept/bio/Belltutorials/Histology%20Tutorial/Basic%20Tissues/imageFLL.JPG
Muscle functions: • Movement (contraction & relaxation) • Posture • Joint stabilization • Heat generation
Microscopic anatomy of skeletal muscle: • Sarcolemmais the plasma membrane. • The contractile unit in the muscle is the sarcomere. • Myofibrilsare the organelles. • Myofilamentsare the proteins found within the sarcomeres. These form striations. • Actinare thin filaments. • Myosinare 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: • I bands (light) have actin attached to Z lines. • A bands (dark) are myosin overlapping actin, containan H zone (central thick region) and a M line. • Within the sarcoplasm is thesarcoplasmic 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
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 thereason skeletal muscles contract. • Motor neurons branch; their ends contain a lot of mitochondria & synaptic vesicles (responsible for synapses). • They storeneurotransmitters.
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.
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 toneexists. 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 itsinsertion. • 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)
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)
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 • Orbicularis Oris • Buccinator • Zygomaticus • Masseter • Temporalis • Platysma • Sternocleidomastoid Neck Muscles Facial muscles Chewing Muscles
Trunk muscles: anterior muscles: • Pectoralis Major: covers chest • Intercostal Muscles: between ribs • Rectus Abdominis: from pubis to rib cage • External oblique • Internal oblique • Transversusabdominus http://www.google.com/imgres?
Trunk muscles: Posterior muscles: • Trapezius: kite-shaped muscle over neck & shoulder • LatissimusDorsi • Erector Spinae(deep back) • QuadratusLumborum • Deltoid (triangular-shaped muscle of shoulder)
Upper limb muscles: • Biceps brachii • Brachialis • Brachioradialis • Triceps Brachii http://www.google.com/imgres?
Muscles of lower limb: • 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. Hip Joint Muscles: Knee Joint Muscles:
Muscles of lower limb: • Extensor DigitorumLongus • Fibularis Muscles (fibula to metatarsals) • Gastrocnemius (calf) • Soleus Ankle & Foot: 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