Muscular System PDF - General Zoology Lecture Notes

General Zoology (Lecture) FINALS EXAMINATION | 1ST SEMESTER | A.Y. 2024 - 2025 MUSCULAR SYSTEM ANATOMY OF A SKELETAL MUSCLE TOPIC OUTLINE 1 Introduction 2 Ty...

General Zoology (Lecture) FINALS EXAMINATION | 1ST SEMESTER | A.Y. 2024 - 2025 MUSCULAR SYSTEM ANATOMY OF A SKELETAL MUSCLE TOPIC OUTLINE 1 Introduction 2 Types of Muscles 3 Anatomy of a Skeletal Muscle 4 Functional Classifications 5 Major Muscle Groups 6 Types of Motion  Epimysium INTRODUCTION  A connective tissue wraps just under the deep fascia that surrounds the  Muscular System entire muscle  Composed of muscle tissues that are highly specialized to contract and  Perimysium relax in order to produce movement when stimulated  This connective tissue surrounds each individual fascicle (bundle of muscle  Word Muscle came from the Latin word ‘mus’ which means mouse─ fibers) biceps and moves  Endomysium  Muscle tissue is found everywhere within the body, not only beneath the  Wrapped around each individual muscle cell (fiber) skin but deep within the body, surrounding many internal organs and blood vessels  The size and location of muscle tissue helps determine the shape of our bodies and the way we move FUNCTIONS OF MUSCLES  Movement  Gives shape  Stabilize body position  Heat production  Maintains homeostasis  Myofibrils CHARACTERISTICS OF A MUSCLE  Threadlike fibrils that make up the contractile part of a striated muscle fiber  Contractility – ability of muscle to shorten forcefully, or contract  Contains myofilaments (actin and myosin) which are responsible for  Excitability – capacity of muscle to respond to a stimulus (reflexes), which muscle movement doesn’t even reach our brain o Myosin – thick filaments  Extensibility – ability to be stretched beyond its normal resting length (extend  Bound to ATP through the myosin head, which is needed for the and lengthen) and still be able to contract which is similar to a rubber myosin to separate  Elasticity – ability of the muscle to recoil to its original resting length after it  Also bound to actin has been stretched o Actin – thin filaments  Troponin and tropomyosin (cannot bind) TYPES OF MUSCLES o Sarcomere – a unit of thick and thin filaments and are repeating  Skeletal Muscle microanatomical units, which represent the basic contractile units of the  Strong, quick discontinuous voluntary contraction muscle fiber/cell (myocyte)  Striations present and multiple nuclei attached on skeleton  Z Line – boundary of every sarcoplasmic unit, where actin is also  Attached to bone/skin attached  M Line – attached here are the myosin; middle portion  A Band – where the myosin and actin are parallel to each other  H Zone and I Band – spaces in the sarcomere that fills up when the sarcomere shortens  Cardiac Muscle  These structures (myosin, actin, sarcomeres) hold the key to muscle  Strong, quick continuous involuntary contraction contraction─ the staggered thin and thick filaments have the effect as one  Intercalated disk might pull a rope towards oneself hand over hand  Striations absent and single nucleus found on walls of hollow organs  Sarcoplasm – cytoplasm of muscle cells, excluding the myofibrils  Sarcoplasmic Reticulum – smooth endoplasmic reticulum of muscle cells  Sarcolemma – the cell membrane, or plasmalemma  Smooth Muscle  Sarco- refers to muscles  Weak, slow involuntary contraction  Striations present and single nucleus found on walls of the heart To promote the muscular interaction, kapag umurong yung actin papunta sa M Line, liliit and magsshorten siya, meaning there is muscular contraction SLIDING FILAMENT THEORY  Z line closer  Tendons serve as the point of attachment between muscle and bones  How sarcomeres facilitate contractions PETRASANTA, E. | BS PSY 2-B 4 General Zoology (Lecture) FINALS EXAMINATION | 1ST SEMESTER | A.Y. 2024 - 2025 FUNCTIONAL CLASSIFICATIONS  Quadriceps femoris – front part of the thigh bone; quad = 4 muscles, femoris =  Agonists - prime movers that are responsible for the movement legs  Antagonists - oppose the agonists to prevent overstretching of them  Triceps Brachii – posterior portion of the humerus; tri = 3 muscles  Synergists - assist the agonists and sometimes fine-tune the direction of movement ORIGIN AND INSERTION OF MUSCLES  Origin - the point where the tendon attaches to the bone which does not move during muscle action  Insertion - the point where the tendon attaches to the bone which moves during an action Example: In action of biceps muscle, scapula is the origin (proximal point) and radius is the insertion. (distal point) ANTERIOR MUSCLE GROUPS  Deltoid BASIS IN NAMING SKELETAL MUSCLES  Pectoralis Major and Minor  Location  Iliopsoas  Shape  Sartorius  Deltoid – delta, meaning triangle  Quadriceps Group  Trapezius – similar to a trapezoid  Rectus femoris that looks like a diamond  Vastus intermedialis – in between the lateralis and medialis  Size  Vastus medialis – middle part; innermost  Gluteus Maximus – largest muscle of  Vastus lateralis – side the body  Tibialis anterior  Maximus – large, Minimus – small;  Abdominus rectus Major – larger part of the muscle,  External oblique Minor – smaller part of the muscle  Biceps brachii  Number of Origin  Attachment of the origin and insertion  Direction of the fascicles  Rectus – straight vertical arrangement  Oblique – slanted arrangement  Action MAJOR MUSCLE GROUPS  Brachii – meaning, present in the forelimb  Biceps Brachii – anterior portion of the forelimb; bi = 2 muscles  Pectoralis Major – forms the major part of the chest muscles  Tibialis Anterior (Shin) – found below the thigh bone, in the tibia and fibula  Posterior (Lateral)  Deltoid – shoulder muscles  Trapezius - upper middle back  Latissimus Dorsi – below the trapezius, side part of the back muscle (lat- meaning in the sides)  Gluteus Maximus – forms the butt  Biceps Femoris – one part of the hamstring  Gastrocnemius – calf muscle  Rectus abdominis (abs) - abdomen, found in the belly region PETRASANTA, E. | BS PSY 2-B 5 General Zoology (Lecture) FINALS EXAMINATION | 1ST SEMESTER | A.Y. 2024 - 2025 TYPES OF MOTION  Gliding Movements – one flat bone slides over another  Angular Movements – increase or decrease the angle between 2 bones  Flexion – bending motion that decreases the angle of the joint bringing the 2 bones closer together  Extension – movement that increases the angle between the 2 bones POSTERIOR MUSCLE GROUP  Hyperextension – bending the head  Trapezius backward  Triceps brachii  Dorsiflexion (of the foot) – lifting the foot  Latissimus dorsi up so that it points to the shin  Gluteus maximus  Plantar (of the foot) – pointing the foot  Hamstrings group – has three muscles down  Biceps femoris  Abduction – raising an arm laterally or  Semitendinosus spreading the fingers  Semimembranosus  Adduction – movement of the limb  Gastrocnemius toward the body  Soleus  Circumduction – movement of a limb in a  Erector spinae circle or cone shape  Rotation – turning of the bone along its own long axis; only movement allowed between first 2 cervical vertebra  Lateral – towards the outer side of the body  Medial – towards the inner side of the body  Special Movements  Supination – movement of the radius around the ulna (palm faces up)  Pronation – movement of the radius around the ulna (palm faces down)  Inversion – sole of the foot turns medially  Eversion – sole of the foot turns laterally  Protraction – nonangular anterior motion along the transverse plane  Retraction – nonangular posterior motion along the transverse plane  Elevation – lifting a body part superiorly; shrugging shoulders closing the mouth  Depression – moving a body part inferiorly; opening the mouth PETRASANTA, E. | BS PSY 2-B 6 General Zoology (Lecture) FINALS EXAMINATION | 1ST SEMESTER | A.Y. 2024 - 2025  Opposition – movement of the thumb in relation to other digits PETRASANTA, E. | BS PSY 2-B 7