Lecture 2 - Muscular System.pdf

Official Business MUSCULAR SYSTEM SYSTEMS PHYSIOLOGY 1 The Unity of Form and Function by Kenneth Saladin, 10e | McGraw Hill Official Business Agenda Describe the various functions of muscular tissu...

Official Business MUSCULAR SYSTEM SYSTEMS PHYSIOLOGY 1 The Unity of Form and Function by Kenneth Saladin, 10e | McGraw Hill Official Business Agenda Describe the various functions of muscular tissue. Describe the connective tissue components of a muscle and their relationship to the internal organization of a muscle and compartmentalization of muscle groups. Relate muscle fascicles to the shapes and relative strengths of muscles. Name the types of muscle–bone attachments and explain the shortcoming of calling their attachments origins and insertions. Official Business Anatomy of “Muscle” Muscle … Little mouse Coined by ancient Green authorities who thought that skeletal muscles rippling under the skin resembled mic Official Business Muscular Tissue These types of tissues are specialized to contract when stimulated, exerting an external force on other tissues, organs, or fluids. There are three types: Skeletal Cardiac Smooth Official Business Skeletal Muscle a: ©Ed Reschke/Photolibrary/Stone/Getty Images Made of muscle fibers. Most are attached to bone by tendons. Contains multiple nuclei. Striations – alternating dark and light bands. They can be moved voluntarily. Official Business Skeletal Muscle Official Business Cardiac Muscle a: ©Ed Reschke/Photolibrary/Stone/Getty Images Limited to the heart wall. Cardiomyocytes are short and branched with one centrally located nucleus. Intercalated discs join cardiomyocytes end to end. Striated and involuntary (not under conscious control). Official Business Smooth Muscle a: Dennis Strete/McGraw-Hill Made of short, fusiform-shaped cells. Cells have one central nucleus, no striations. Involuntary function. Most is visceral muscle—making up parts of walls of hollow organs. Official Business Smooth Muscle a: Dennis Strete/McGraw-Hill Official Business Functions of our Muscles Muscle functions: Movement — move body parts; move body contents in breathing, circulation, and digestion; roles in communication (speech, writing, facial and nonverbal expressions) Stability — maintain posture; stabilize joints Control of body openings and passages — muscles control food intake and movement of materials through body; control elimination of waste; admission of light to the eye Heat production (thermogenesis) — skeletal muscles produce 20% to 30% of body heat at rest, up to 85% during exercise Official Business Functions of our Muscles Muscle functions (cont’d): Hormone secretion—exercised muscles release hormones (myokines) that stimulate glucose synthesis by liver and breakdown of visceral fat Glycemic control—skeletal muscles absorb, store, and use a large share of body’s glucose, so play a significant role in stabilizing its blood concentration. Official Business Structural Organization of Muscles Three kinds of muscle tissue: skeletal, cardiac, smooth. All three types specialized for one major purpose: converting the chemical energy in ATP into the mechanical energy of motion. Muscular system refers only to the skeletal muscles (about 600 in human body) Official Business Muscle Connective Tissues, Fascicles, and Compartments Skeletal muscles contain muscular tissue, connective tissue, nerves, and blood vessels. Connective tissue components, from deep to superficial: Endomysium—thin sleeve of loose connective tissue around each fiber Allows room for capillaries and nerve fibers; provides chemical environment for muscle fiber and nerve ending Perimysium—thicker layer of connective tissue that wraps fascicles Fascicles are bundles of muscle fibers wrapped together Carries nerves, blood vessels, and stretch receptors Epimysium—fibrous sheath surrounding entire muscle; blends with fascia and deeper connective tissues Fascia—sheet of connective tissue between muscles or muscle groups Official Business Connective Tissue Official Business Connective Tissue Official Business Connective Tissue Official Business Muscle Connective Tissues, Fascicles, and Compartments Strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles. Fusiform muscles — thick in the middle with fascicles converging on each tapered end Parallel muscles — uniform width and parallel fascicles Triangular (convergent) muscles — broad at one end with fascicles converging on the other, narrower end Official Business Muscle Connective Tissues, Fascicles, and Compartments Fascicle orientation of muscles (continued): Pennate muscles—feather-shaped; fascicles attach obliquely on a tendon that runs full length of muscle Unipennate—fascicles approach tendon from one side Bipennate—fascicles approach tendon from both sides Multipennate—bunches of feathers converge to single point Circular muscles (sphincters)—fascicles form rings around body openings and passages When contract, constrict the opening and prevent passage of material Official Business Muscle Connective Tissues, Fascicles, and Compartments Official Business Muscle Connective Tissues, Fascicles, and Compartments Fasciae package groups of functionally related muscles into muscle compartments. A compartment also contains nerves and blood vessels that supply the muscle group Some fasciae between compartments are extra thick, called intermuscular septa Official Business Muscle Compartments Official Business Muscle Compartments Official Business Muscle Attachments Muscles have direct or indirect attachments to bones Direct (fleshy) attachment to bone—little separation between muscle and bone Indirect attachment to bone—fibrous cord called a tendon connects muscle to bone Collagen fibers of the endo-, peri-, and epimysium continue into the tendon and from there into periosteum and matrix of bone Aponeurosis—tendon is a broad, flat sheet (palmar aponeurosis) Retinaculum—connective tissue band that tendons from separate muscles pass under Official Business Synergistics and Antagonistic Pairs Official Business Functional Groups of Muscles Some muscles are intrinsic or extrinsic to the organ they control Intrinsic muscle — entirely contained within a region Example: intrinsic muscles of the hand that are contained entirely within the hand Extrinsic muscle — acts on a designated region but arises from another region Example: extrinsic hand muscles that arise from the forearm Additional intrinsic-extrinsic muscle examples in tongue, larynx, back, foot, and other regions Official Business Functional Groups of Muscles Muscles perform an action — effect produced by a muscle to produce or prevent movement. Muscles usually act in groups Four categories of muscle action: Prime mover — muscle that produces most of the force of a movement; example: brachialis flexes elbow Synergist — muscle that aids the prime mover; example: biceps brachii assists brachialis Antagonist — muscle that opposes the prime mover; example: triceps brachii extends elbow Fixator — muscle that prevents a bone from moving; example: rhomboid muscles fix scapula when biceps contracts Official Business Synergistics and Antagonistic Pairs Official Business Muscle Names Muscle naming: Latin-based Describe distinctive aspects of the structure, location, or action of a muscle Examples: Depressor labii inferioris — lowers (depresses) the bottom (inferior) lip (labium) Flexor digiti minimi brevis — short (brevis) muscle that flexes (flexor) the smallest (minimi) finger (digit) Official Business The Muscular System, Anterior Official Business The Muscular System, Anterior Official Business The Muscular System, Anterior Official Business The Muscular System, Anterior Official Business The Muscular System, Anterior Official Business The Muscular System, Anterior Official Business The Muscular System, The Face Official Business Hernias A hernia is any condition in which the viscera protrudes through a weak point in the muscular wall of the abdominopelvic cavity Types of hernias: Inguinal hernia Most common type of hernia (rare in women) Viscera enter inguinal canal or even the scrotum Hiatal hernia Stomach protrudes through diaphragm into thorax Overweight people over 40 Umbilical hernia Viscera protrude through the navel Official Business Inguinal hernia Official Business The Carpal Tunnel Official Business Carpal Tunnel Syndrome Prolonged, repetitive motions of wrist and fingers cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic. Puts pressure on median nerve of wrist that passes through the carpal tunnel along with flexor tendons Tingling and muscular weakness in the palm and medial side of the hand Pain may radiate to arm and shoulder Treatment: anti-inflammatory drugs, immobilization of the wrist, and sometimes surgery to remove part or all of flexor retinaculum Official Business