L12- Muscular System PDF

L12- MUSCULAR SYSTEM GENERAL ANATOMY OF MUSCULAR SYSTEM Dr.Pugazhandhi Bakthavatchalam, Dept. of Anatomy and Physiology, AUACAS LECTURER PUGAZHANDHI.B LEARNING OUTCOMES At the end of this session you will be able to List...

L12- MUSCULAR SYSTEM GENERAL ANATOMY OF MUSCULAR SYSTEM Dr.Pugazhandhi Bakthavatchalam, Dept. of Anatomy and Physiology, AUACAS LECTURER PUGAZHANDHI.B LEARNING OUTCOMES At the end of this session you will be able to List different types of skeletal muscle Properties of Muscular Tissue Enumerate the terms related to attachment of skeletal muscle Describe fascia and fascial compartments at various locations of the muscular system Muscle Tissue One of the basic tissues Specialized for contraction Produces all body movements Definition : Contractile tissue which brings about movements Three types of muscle tissue  Skeletal muscle  Cardiac muscle  Smooth muscle CARDIAC MUSCLE Found only in heart and in the walls of large veins where they enter the heart Cardiac muscle cells Are called cardiocytes Single nucleus Striations present Form branching networks connected at intercalated discs Controlled by Autonomic nervous system SMOOTH MUSCLE  Found in walls of hollow, contracting organs (blood vessels, urinary, respiratory, digestive, and reproductive tracts) Smooth muscle cells - Properties Spindle shaped Single nucleus No striations Can divide and regenerate Controlled by Autonomic nervous system SKELETAL MUSCLE The term muscular system refers only to the skeletal muscles The study of this system is called myology Skeletal Muscle Cells Long and thin, called muscle fibers Multinucleate Cross striations present Mostly Voluntary – Under conscious control FUNCTIONS OF SKELETAL MUSCLES Produce skeletal movement Maintain body position Support soft tissues Guard openings Maintain body temperature Store nutrient reserves PROPERTIES OF SKELETAL MUSCLE Excitability (responsiveness) Conductivity Contractility Extensibility Elasticity PARTS OF SKELETAL MUSCLE Two ends: Origin: muscle attachment at the relatively stationary end Insertion: end which is more mobile during contraction Most muscles originate from or insert to bones Now the terms “proximal” and “distal attachments” are preferred PARTS OF SKELETAL MUSCLE Parts: Fleshy part Contractile, called Belly Fibrous part Noncontractile, inelastic Cord like – Tendon Flattened – Aponeurosis Muscle or its tendon crosses a joint between its origin & insertion PARTS OF SKELETAL MUSCLE CLASSIFICATION OF SKELETAL MUSCLE CLASSIFICATION OF SKELETAL MUSCLE  Direction of fibres  Colour Parallel Red Oblique White Twisted Mixed Cruciate  Function Agonist Antagonist Fixators Synergists MUSCLE FIBER TYPES FAST FIBERS / WHITE SLOW FIBERS / RED  Contract very quickly  Contract slowly  Fatigue quickly  Fatigue slowly  Have large diameter, few  Have small diameter, more mitochondria mitochondria  Contain abundant myoglobin  Less myoglobin (red pigment, binds oxygen)  Have high oxygen supply  Ex. Gastrocnemius  Ex. Postural muscles 2-Sep-24 14 FASCICLE ARRANGEMENT Arrangement of muscle fascicles vary with the movements possible at a particular joint. Force of movement is directly proportional to number & size of muscle fibres Range of movement is directly proportional to length of the muscle fibres  FASCICLE ARRANGEMENT PARALLEL FASCICULI Fibers parallel to the long axis of muscle Quadrilateral – Quadratus lumborum Strap like – Sternohyoid Strap like with tendinous intersections – Rectus abdominis Fusiform – Biceps brachii PARALLEL FASCICULI PARALLEL- STRAP MUSCLES Rectus abdominis Sartorius Sternohyoid PARALLEL- QUADRATE MUSCLE Quadratus Lumborum Pronator Quadratus PARALLEL- FUSIFORM MUSCLE Biceps brachii OBLIQUE FASCICULI Form an angle with the tendon Do not move as far as parallel muscles Contain more myofibrils than parallel muscles Develop more tension than parallel muscles Unipennate Fibers on one side of tendon Ex. Extensor digitorum Bipennate Fibers on both sides of tendon Ex. Rectus femoris Multipennate Tendon branches within muscle Ex. Deltoid  OBLIQUE FASCICULI Circumpennate- Tibialis Anterior Bipennate- Dorsal Interossei Unipennate- Palmar Interossei OBLIQUE FASCICULI Circumpennate – Tibialis anterior Triangular - Temporalis SPIRAL / TWISTED FASCICULI Spiral / Twisted fibres Ex. Trapezius, Pectoralis major Cruciate muscles – The fasciculi are crossed Ex. Sternocleidomastoid, Masseter CIRCULAR FASCICULI Also called sphincters Open and close to guard entrances of body EX. orbicularis oris  FUNCTIONAL CLASSIFICATION Agonist (or prime mover) (Biceps) Produces max force during a particular movement Antagonist (triceps) Opposes movement of a particular agonist Fixator (Rhomboideus major & minor) Stabilizes the proximal joint, so movement can occur at distal joint with a fixed base Synergist (brachialis) A smaller muscle that assists a larger agonist Helps start motion or stabilize origin of agonist APPLIED ANATOMY Muscle spasm Muscle Hypertrophy Muscle Atrophy Paralysis – loss of motor power Muscular dystrophy Associated connective tissue SUPPORTING TISSUE SUPPORTING TISSUE Muscles have three layers of connective tissues Epimysium: Surrounds entire muscle Connected to deep fascia Separates muscle from surrounding tissues Perimysium: Surrounds muscle fiber bundles (fascicles) Contains blood vessel and nerve supply to fascicles Endomysium: Surrounds individual muscle cells (muscle fibers) Contains capillaries and nerve fibers contacting muscle cells Contains myosatellite cells (stem cells) that repair damage Come together at the end of muscles and form tendon or aponeurosis and get attached to bones SUPPORTING TISSUE FASCIA Fibrous connective tissue of varying thickness that covers muscle and attaches to the skin Superficial fascia secures the skin to the underlying structures. Deep fascia is an inward extension of the superficial fascia and blends with the epimysium of muscle and thus surrounds adjacent muscles FASCIA MODIFICATION OF DEEP FASCIA Forms a protective sheath Intermuscular septae in the around vessels when they cross Limbs from one region to another MODIFICATION OF DEEP FASCIA Forms capsule, synovial membrane, ligaments and bursae of Joints MODIFICATION OF DEEP FASCIA Thick aponeurosis in the palm and sole MODIFICATION OF DEEP FASCIA Retinacula around the wrist and ankles MODIFICATION OF DEEP FASCIA Forms interosseous Forms synovial sheaths for membrane in forearm & leg tendons  REFERENCES Drake R.L., Gray’s Anatomy for Students, 2nd Edition, 2009, Churchill Livingstone Moore, Clinically Oriented Anatomy, 6th Edition, 2009, Lippincott Williams & Wilkins Standring, Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 40thEdition, 2008 Johannes W Rohen, Color Atlas of Anatomy: A photographic study of the human body, 7th Edition, Lippincott Williams & Wilkins Kenneth S Saladin, Human Anatomy, 2nd Edition, 2008, McGraw-Hill Companies 2-Sep-24 39