1. Anatomy & Physiology Mrs. Halkuff Muscle Naming, Contractions & Diseases

2. Naming a Muscle 1. Location: External/Internal 2. Shape: Deltoid (Triangle)/Trapezius (Trapezoid) 3. Size: Minimus/Maximus/Brevis/Longus 4. Direction of Muscle Fibers: Rectus/Transverse/Oblique 5. Number of Origins: Biceps/Triceps/Quadriceps 6. Location of Origins/Insertion: Sternocleidomastoid

3. Muscle Contractions Skeletal muscle is made up of long fibrous cylinders called myofibrils that run the length of the muscle cell. Muscle cells contract because myofibrils contract. Each myofibril contains a lot of thick and thin filaments, which run parallel to the myofibril axis.

4. Actin: Protein made of thin filaments. Myosin: Protein made of thick filaments. Create an alternating light and dark banding pattern in the myofibrils that can be seen in the light microscope. Myosin: Thick, dark bands called “A Bands” Actin: Thin, light bands called “I Bands” “Z Line” runs through the I band perpendicularly and connect neighboring myofibrils.

5. Sarcomere: Segment of the microfibril that runs between two adjacent Z lines. When contracting, Actin moves past the Myosin causing the sarcomere to shorten. When fully contracted, the Actin overlaps. Actin & Myosin is always the same length. When relaxed, the distance between the two Z lines is great. When contracted, the distance between the two Z lines is very small.

8. Muscle Contraction Animation Muscle Contraction Animation

9. Thick filament (MYOSIN) Thin Filament (Actin) Thick filament (MYOSIN) Thin Filament (Actin)

10. Diseases Myopathies Neuromuscular disorder Muscle weakness due to dysfunction of muscle fiber. Other symptoms: Muscle cramps, stiffness, & spasm 1. Fibromyalgia Chronic muscle, ligament, tendon pain, fatigue, tender points Rarely life-threatening, mostly pain management 2. Muscular Dystrophy Progressive weakness & degeneration of skeletal muscles. Wide spectrum: Some children die in infancy while others have mild symptoms into adulthood.