Muscular System Galena Park High School A&P Instructor: Terry E. Jones

Muscular System

Galena Park High SchoolA&

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Instructor: Terry E. Jones

A. Support 1. Movement of the body 2. Maintains body posture


P I. Function

B. Protection 1. Reinforces joints 2. Holds vital organs in placeC. Moves food through the

digestive systemD. Generates body heat


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A. Tissue Types 1. Skeletal Muscle a. Attached to bones and skin b. Multinucleate long cells c. Voluntary control , quick


P II. Anatomy

2. Cardiac Muscle a. Walls of the heart b. Branched, single nucleus cells c. Involuntary control , slow


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3. Smooth Muscle a. Walls of visceral organs b. No striations, single nucleus c. Involuntary control , very slow


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A. Contraction 1. Muscle can only contract or pull 2. The contraction is stimulated by an electrical impulse sent from the brain.


PIII. Muscle Function

B. Micro-Anatomy of a muscle 1. Muscle is a bundle of fibers 2. A fiber is full of myofibrils which are protein strands. 3. The proteins contain two filaments called actin and myosin


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4. Myosin is a thick filament 5. Actin is a thin filament 6. The filaments lie next to each other


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7. When stimulated, myosin makes cross bridges with the actin 8. The myosin pulls the actin passed it making the muscle get shorter or contract 9. The filaments relax until stimulated again


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A. Nerve Damage 1. Nerve death cause a muscle to cease functioning 2. The muscle becomes flaccid and dystrophy sets in because the muscle is not used


P IV. Homeostasis

B. Causes of Neuromuscular Disorders 1. Poor Circulation - Stroke 2. Genetic – Faulty DNA 3. Autoimmune- breakdown of insulation sheath around nerve cells


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4. Heavy Metal Poisoning 5. Nerve Cord Damage-Accidents 6. Muscle Inflammation


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C. Muscular Dystrophy 1. A group of diseases 2. Genetically Inherited 3. Fat deposits in muscles grow 4. Muscle degenerates 5. Duchenne MD most common


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D. Huntington’s Disease 1. Inherited 2. Poor movement coordination 3. Mutant protein destroys brain

cells effecting muscle coordination


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E. Stroke 1. Blocked blood supply to parts of the brain 2. Brain cells in that area die 3. Muscle controlled by effected part of brain cease function. They get no signals 4. Brain cells once dead do not regenerate


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F. Nerve Cord Damage 1. Cutting /bruising of the nerve cord 2. Depending on where the damage occurs different muscles are

affected 3. Lower nerve cord effects legs , but not the arms


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G. Inflammatory Muscle Disease 1. Auto-immune Disease 2. Direct cause unknown 3. Muscles become swollen – myositis 4. Interferes with muscle function and

electrical impulses that stimulate muscles


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A. Rules of Muscle Activity 1. All muscles cross at least one joint. 2. Typically, the bulk of the muscle lies proximal to the joint crossed. 3. Muscles have at least two attachments; the origin and the

insertion.


PV. Muscle Identification

4. Muscles can only pull; they never push. 5. During contraction, the muscle insertion moves toward the origin.


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B. Types of Movement 1. Flexion a. Decrease the angle of the joint b. Bones get closer together 2. Extension a. Angle of joint increases b. Bones move farther apart


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3. Rotation a. Movement is circular b. Radius and ulna 4. Circumduction a. Combination of flexion, extension, adduction and abduction all together b. Ball and Socket joint


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5. Adduction a. Movement of limbs toward body b. Closing fingers together 6. Abduction a. Movement of limbs away from body b. Spreading fingers apart


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7. Dorsiflexion/Plantar flexion a. Dorsiflexion - Bending foot upward b. Plantar flexion- pointing toes downward 8. Inversion/Eversion a. Inversion – sole of foot turns medially b. Eversion – Sole of foot turns outward


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9. Pronation – radius and ulna are crossed 10. Supination – radius and ulna are parallel 11. Opposition – touching the tips of fingers to the tip of the thumb


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C. Naming Muscles 1. Direction of muscle fibers a. rectis – straight b. oblique – slanted or on an angle 2. Relative size a. maximus - largest b. minimus – smallest c. longus - longest


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3. Location a. temporalis – over the temporal bone b. frontalis – over the frontal bone 4. Number of Origins a. biceps- two head attachments b. triceps – three head attachments


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5. Location of Muscle Origin a. sternocleidomastoid b sterno-sternum c. cleido- clavicle 6. Shape of Muscle a. deltoid- triangular shape b. trapezius – trapezoid


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7. Action of the Muscle a. flexor – Muscle flexes b extensor-Muscle extension c. adductor- adducts muscle


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A. Facial Muscles 1. Frontalis – raises eyebrows 2. Obicularis Oculi - closes eyes, squint 3. Buccinator – whistling, blowing chewing


PV. Superficial Muscles

4. Zygomaticus – raises corner of mouth 5. Masseter- closes the lower jaw 6. Temporalis – aids in closing jaw 7. Occipitalis – moves skin on back of head


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8. Platysmus – lowers corners of mouth 9. Sternocleidomastoid- pulls head downward, if only one side is contracted the head rotates10. Trapezius – retracts and rotates the scapula; supports the arm


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B. Anterior Trunk Muscles 1. Pectoralis Major – flex, adduct arm 2. Intercostal Muscles- raise and lower ribs for breathing; there are many 3. Rectus Abdominis – flex vertebrae, aid in child birth and defecation


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4. External Oblique– flexes, rotates vertebra 5. internal Oblique - flexes, rotates vertebra for breathing; there are many 6. Transverse Oblique– compresses abdominal contents


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B. Posterior Trunk Muscles 1. Latissimus Dorsi– extends, adducts humerus 2. Deltoid – primary humerus adductor 3. Erector Spinae– many spanning the entire spine, control bending motions


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C. Arm Muscles 1. Biceps Brachii– flexes the forearm 2. Brachialis – elbow flexion 3. Triceps brachii – extensor of the forearm


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D. Leg Muscles 1. Gluteus Maximus– pulls thigh in line with hips, used in jumping, stair climbing 2. Gluteus Medius – stabilizes the hip 3. Iliopsoas– hip flexor, keeps us from falling backward


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4. Adductor Group– pulls thighs together 5. Hamstring Group a. Biceps femoris-extends hip and thigh b. Semimembranosus- extends hip/ thigh c. Semitendinosus - extends hip/ thigh


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6. Qudracep Group- femoris rectis, vastus muscles (3) – flex the thigh and hip for walking, lifts the thigh 7. Sartorius – flexor allowing people to sit cross legged.


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8. Tibialis Anterior – flexes or bends foot toward the leg, inverts foot 9. Extensor Digitorum Longus – extends the toes 10. Fibularis Muscle Group (3) – plantar flexes the foot and everts it


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11. Gastrocnemius– plantar flexion, lifts heal12. Soleus– plantar flexor of the foot


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Muscular System Galena Park High School A&P Instructor: Terry E. Jones