Anatomy Lecture 5&6_Myology PDF

General Myology (Muscular System)  Myology It is the science dealing with the study of muscles and accessory structures (fascia, tendon sheath, bursae). Muscle : A contractile tissue consisting of bundles of muscle fibers, which moves a particular bone or part of the body: ex. the muscles o...

General Myology (Muscular System)  Myology It is the science dealing with the study of muscles and accessory structures (fascia, tendon sheath, bursae). Muscle : A contractile tissue consisting of bundles of muscle fibers, which moves a particular bone or part of the body: ex. the muscles of the arm.  Function of Muscles: 1- Produce movement. 2- Produce heat in homeothermic (warm blooded) animals. 3- Stabilizing the body positions. 4- Storing and moving substances within the body. Classification of Muscles: There are 3 types of muscles in the body: 1- Skeletal muscles: Striated and voluntary 2- Smooth muscle: Non-striated and involuntary 3- Cardiac muscle: Striated and involuntary Types of muscles in the body  Skeletal Muscle - striated fibers - multinucleated - voluntary control  Smooth Muscle No striations Spindle shaped single nuclei autonomic control  Cardiac Muscle Striations Uninucleated intercalated discs to support synchronized contraction of cardiac tissue autonomic control Skeletal Muscle How could skeletal muscle fibers form bundles ? Bundles are formed by: epimysium epi = upon or above perimysium peri = around endomysium endo = within  Each skeletal muscle has three layers of connective tissue (called “mysia”) that enclose it. Each muscle is wrapped in a sheath of dense, irregular connective tissue called the epimysium. Inside each skeletal muscle, muscle fibers are organized into individual bundles, each called a fascicle, by a middle layer of connective tissue called the perimysium. Inside each fascicle, each muscle fiber is encased in a thin connective tissue layer of connective tissue called the endomysium. Because skeletal muscle cells are long and cylindrical, they are commonly referred to as muscle fibers. Forms of skeletal muscles: 1- Long muscles : in limbs. 2- Flat muscles : in abdomen, chest. 3- Short muscles. 4- Sphincter muscles or orbicular muscles : Ring like muscles circumscribe orifices which they close so called sphincters. Sphincter ani (around anus). Orbicularis oris (around mouth). Orbicularis oculi (around eye).  Flat muscle Long muscles sphincters Skeletal Muscle attachment Muscle attachment : 1- origin. 2- Insertion. 3- Tendon. 4- Aponeuroses. 5- Raphae  Origins and Insertions Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion) Most muscles originate or insert on the skeleton Origin is usually proximal to insertion Every Muscle Has... Origin – proximal – least movable Insertion – distal – movable  Muscle attachment Origin: Is the attachment which remains fixed when the muscle contracts (FIXED END). Insertion:Is the movable attachment of the muscle (MOVABLE END).  Tendons They are rounded, cord or band-like fibrous tissue Developed at the end of muscles by which get attached to the bone. Tendon : Cord like band of fibrous tissue. Developed at ends of muscles and by it muscle attached to bones. *Sesamoid bones: present between tendons and bones where tendons subjected to great pressure Ex. 1- Proximal and distal sesamoid. 2- Patella (largest sesamoid ). Difference between tendon and ligaments? Aponeuroses Thin but strong flat sheet of fibrous tissue represent the attachment of flat muscles. e.g oblique Mm of abdomen, Fascia Lata Raphae: Is an interdigitation of aponeurosis of flat muscles : Example: Raphea between short aponeorosis = pharyngeal raphae. Raphea between wide and long aponeorosis = raphae between abdominal muscles = Linea alba.  Organization or arrangement of Skeletal Muscle Fibers 4 patterns of fascicle organization: 1) Parallel – Fibers parallel to the long axis of muscle - e.g., biceps brachii 2) Convergent 3) Pinnate 4) Circular  Parallel Muscles Classified into: a) Strap muscle e.g sartorius b) Strap with tendinous intersection e.g rectus abdominis c) Rhomboid e.g Rhomboideus d) fusiform The center or body of the muscle thickens when parallel muscle contracts  Convergent Muscles A broad area converges on attachment site (tendon, aponeurosis, or raphe) e.g., pectoralis muscles  Pennate Muscles The muscle fibers are obliquely arranged  Pennate Muscles Unipennate: – fibers on 1 side of tendon – e.g., extensor digitorum Bipennate: – fibers on both sides of tendon – e.g., rectus femoris Multipennate: – May be arranged as series of bipennate alongside each other – - may have tendon within its center and the fibers passing to it from all muscle so called Centropennate – e.g., deltoid 7 types of muscle forms Circular Muscles Also called sphincters Open and close to guard entrances of body e.g., obicularis oris  Actions Movements produced by muscle contraction Body movements – e.g., flexion, extension, adduction, etc. Described in terms of bone, joint, or region  Grouping by Function Flexors Extensors Adductors Abductors Cutaneous  Muscle Terminology Based on Function Agonist (prime mover): – produces a particular movement Antagonist: – opposes movement of a particular agonist Synergist: – a smaller muscle that assists a larger agonist – helps start motion or stabilize origin of agonist (fixator) Terms Plasmalemma = Sarcolemma Sarcoplasm = Cytoplasm Sarcoplasmic Reticulum = Endoplasmic Reticulum Sarcomere It is the Basic structural and functional unit Of the muscle  Contractile Proteins Actin- thin myofilament Myosin- thick filament Tropomyosin- thin filament Troponin- thin filament Actin and Myocin contribute 55% of total protein in skeletal muscle How to describe the muscle? 1) The name is determined by: a) Action: extensor, adductor,… b) Shape: quadratus, triangularis,….. c) Direction: rectus, oblique,… d) Position: subscapularis, iliacus,… e) Division: biceps, triceps,… f) Size: major, minor,… g) Attachment: sterno-cephalicus,…. h) Structure: semitendinosus,… 2) The shape: triangular, quadrilateral, fusiform,.... 3) attachment: cartilage, bone, skin…. 4) Action 5) Structure: including direction and arrangement of muscle fiber. 6) Relations Naming Skeletal Muscles Table 11–1 (1 of Naming Skeletal Muscles Table 11–1 (2 of  Descriptive Names for Skeletal Muscles 1. Location in the body-Identifies body regions: e.g.- temporalis muscle 2. Origin and insertion- First part of name indicates origin, Second part of name indicates insertion: e.g. genioglossus muscle 3. Fascicle organization-Describes fascicle orientation within muscle: – i.e., rectus (straight), transversus, oblique  Descriptive Names for Skeletal Muscles 4. Relative position- Externus (superficialis): – visible at body surface Internus (profundus):deep muscles Extrinsic:muscles outside an organ Intrinsic:muscles inside an organ 5. Structural characteristics- Number of tendons: – bi = 2, tri = 3 Shape: trapezius, deltoid, rhomboid Size- 6. Action- Movements: e.g., flexor, extensor, retractor Occupations or habits: e.g., risor = laughter Superficial Fascia : 1- Formed of loose connective tissue. 2- May contain fat. 3- Subcutaneous fascia. Deep Fascia: 1- Formed of one or more layers of Dense Fibrous tissue. 2- Spread over muscles. 3- May fuse with Epimysium. Tendons, Bones or Ligaments. 4- Form Fibrous Sheaths Around Muscles. 5- Stretch across grooves which lodged tendons converting these grooves into canals by bands termed = Annular Ligaments. BURSA SYNOVIAL SHEATH  TENDON SHEATH (VAGINA TENDINIS) layers of synovial sheath Peritendon Tendon mesotendon BONE Periosteum  Smooth Muscle No striations Spindle shaped single nuclei autonomic control Cardiac Muscle Thank You