ANAT LEC 003 Introduction to the Muscular System PDF

(003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 OUTLINE 1. Movement - Types of Muscles: I...

(003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 OUTLINE 1. Movement - Types of Muscles: I. INTRODUCTION a. Skeletal Muscles II. FUNCTIONS OF THE MUSCLE o Attached to bones by tendons III. MUSCLE CELLS o They cross joints so that when they contract, the joints move IV. MUSCULAR TISSUES b. Smooth Muscles a. Skeletal Muscle Tissue o Found on the walls of organs o Contraction produces movement of organ contents b. Cardiac Muscle Tissue c. Cardiac Muscles c. Smooth Muscle Tissue o Produces atrial and ventricular contractions V. SMOOTH MUSCLES o Causes blood to be pumped out of the heart and into the blood vessels a. Multiunit o Has the property of spontaneous and rhythmic contraction b. Single unit 2. Stability VI. SKELETAL MUSCLES - Helps keep the body in an upright position - Holds bones tightly together which stabilizes joints a. Composition - Small muscles hold the vertebra together which stabilizes the b. Structure spinal column 3. Control of Body Openings and Passages. c. Coverings - Sphincters d. Attachments and Actions o Valve like structures formed by muscles VII. CARDIAC MUSCLES o Control movement of substances in and out of passages o E.g. Urethral sphincter prevents or allows urination VIII. PATTERNS OF FASICLE ORGANIZATION 4. Protection IX. NAMING SKELETAL MUSCLES - Padding for internal organs X. NERVE SUPPLY OF MUSCLES - Acts as shock absorbers and reduces friction at the joints 5. Release Heat via Contraction XI. DIVISIONS OF SKELETAL MUSCULAR SYSTEM - Helps the body maintain a normal temperature - Moving your body can make you warmer if you are cold I. INTRODUCTION III. MUSCLE CELLS - Bones and joints by themselves do not produce movement. - Also known as “Myocytes” or “Muscle Fibers” Muscles, by alternating contraction and relaxation, produce - Sarcolemma – Cell membrane of Myocyte movement - Sarcoplasm – Cytoplasm of Myocyte - Muscles comprise about half of the total body weight. - Myofibrils – Long structures in Sarcoplasm. Its arrangement - Muscle performance vary depending on fiber organization and causes the presence of striations in muscle. skeletal attachment - There are over 600 individual muscles in the human body IV.MUSCULAR TISSUE II. FUNCTIONS OF THE MUSCLE Figure 2. Cross-section images of different types of Muscles A. Skeletal Muscle Tissue - Varies greatly in length - Multinucleated with nuclei at the periphery Figure 1. Types of Muscles - Voluntary (made to contract by conscious control) - Usually attached to bones by tendons - Functions are: motion, posture, heat production, protection - PREPARED AND EDIT BY: QUAMBAO, QUILALA, LUMAYAG, MANLONGAT, MOJICA, PRUDENCIO, PUZON  (003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 B. Cardiac Muscle Tissue VII.SKELETAL MUSCLES - Branched, striated fibers with usually one centrally-located - Major components of the Muscular System. nucleus (occasionally 2) - Composition: - Attach end-to-end by transverse thickenings of plasma 1. Connective Tissue membrane called “intercalated discs” which contains 2. Skeletal Muscle Tissue desmosomes and gap-junctions 3. Blood Vessels - Desmosomes: strengthen tissue and hold fibers together 4. Nerves during vigorous contractions - Structure of Skeletal Muscles - Gap junctions: route for quick electrical conductions a. Belly – Fleshy portion of the muscle - Located at heart walls b. Raphe – Interdigitation of the tendinous ends of the fibers - Function: pump blood to all parts of the body of flat muscles C. Smooth Muscle Tissue - Connective Tissue Coverings - Consists of non-striated fibers (hence, the term smooth) a. Fascia - Tapers at each end o Surrounds and individual skeletal muscle, - With one centrally-located nucleus separating it from other muscles - Usually involuntary o May extend beyond the ends of a muscle to - Location: iris of the eye, walls of hollow internal organs become a tendon which is a tough cord like such as blood vessels, airway to lungs, stomach, intestines, structure gallbladder, urinary bladder o May connect muscles to other muscles, it is then - Function: motion called an aponeurosis which is a tough sheet like structure V.SMOOTH MUSCLES o Many large muscle groups are encased both in a superficial and deep fascia - Skeletal muscle fibers are arranged in bundles called fascicles that are bound by connective tissues a. Epimysium o Closely surrounds skeletal muscles and binds fascicles together o Made up of dense irregular connective tissues o Just below the fascia of the muscle and surrounds the whole muscle o It separates the muscle from the other organs in the area o Allows muscle to contract and move powerfully while maintaining its structural integrity b. Perimysium Figure 3. Types of Smooth Muscles o Divides the muscles into fascicles o Allows the activation of a specific subset of muscle 1. MULTIUNIT SMOOTH MUSCLE fibers within a fascicle - Found in the Iris of the eye and walls of blood vessels c. Endomysium - Responds to neurotransmitters and hormones o Made up of collagen and reticular fibers 2. VISCERAL (SINGLE UNIT) SMOOTH MUSCLE o Plays a role in transferring force produced by - Found in the walls of hollow organs muscle fibers to tendons - Respond to neurotransmitters - Stimulate each other to contract so that muscle fibers contract and relax together causing Peristalsis VI.CARDIAC MUSCLES - INTERCALATED DISCS Connect groups of Cardiac Muscles. Allow the fibers in the groups to contract and relax together which allows the heart to work as pump - Cardiac muscles are self-exciting. They do not need nerve stimulation to contract but nerves can speed up or slow down contractions Figure 4. Muscle Attachment Sites PREPARED AND EDIT BY: QUAMBAO, QUILALA, LUMAYAG, MANLONGAT, MOJICA, PRUDENCIO, PUZON  (003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 **Actions depend greatly on what the muscles are VIII.PATTERNS OF FASCICLE ORGANIZATION attached to. - Attachments and Actions of Skeletal Muscles a. Attachment Sites 1. Origin – An attachment for a less movable bone, mostly fleshy, proximal 2. Insertion – An attachment for a more movable bone, mostly fibrous, distal b. Movements usually produced by a group of muscles 1. Prime Mover (Agonist) o Muscle responsible for most of the movement o Contracts concentrically o Uses most of the energy o Some movements may involve more than one prime mover 2. Synergists o Muscles that help the prime mover by stabilizing joints or a fixator on intervening joints when the prime mover passes over more than one joint o Complements the action of the prime mover o May provide a weaker or less mechanically advantaged component that creates the same movement o It is not unusual to have numerous synergists assisting the prime mover 3. Antagonist o Produces movement that is opposite to the prime mover o Before the prime mover can contract, the antagonist must be equally relaxed. This is brough about by the Nervous Reflex Inhibition 4. Fixator o Contracts isometrically to stabilize the proximal 1. Parallel muscles – majority part of a limb while the distal moves so that the - Fascicles are arranged in the same direction as the long prime mover can act efficiently axis of the muscle - When a parallel muscle contracts, it shortens and gets larger in diameter - Sometimes, the same muscle can act a different movement - Some are flat sheets that expand at the ends to make in specific conditions broad attachments - The actual prime mover in a given position may be gravity - Some are rotund with tendons at one or both ends - There is a paradox where the prime mover is being o belly/central body- muscles that seem to be plump and described as the one responsible for the movement is have a large mass of tissue located in the middle of passive/inactive and the controlled relaxation of the the muscle, b/n the insertion and the origin antigravity antagonist is the one in active motion. e.g. Shoulder Adduction when standing erect, the o Fusiform muscles are a kind of parallel muscle Adductor is gravity but the prime movers are the formation Pectoralis Major and Latissimus Dorsi but they are - Ex. Rectus abdominis, external oblique passive in this movement. The muscle being actively innervated is the Deltoid, which is an abductor, is the 2. Circular muscles – sphincters - Fascicles are concentrically arranged around an opening antagonist in this movement. - The size of the opening increases when they relax and shrinks when they contract c. Body Movements (Refer to Anatomy Lec Trans 001) - Surround body openings and hollow organs and acts as o Important to know because each body movement valves as in digestive and urinary tracts involve one muscle or groups of muscles - Ex. Orbicularis oculi, orbicularis oris 3. Convergent - Muscle fascicles extending over a broad area and come together, or converge, on a common attachment site o attachment points maybe: = Tendon (muscle-bone) = Aponeurosis (muscle-muscle; flat broad tendon) PREPARED AND EDIT BY: QUAMBAO, QUILALA, LUMAYAG, MANLONGAT, MOJICA, PRUDENCIO, PUZON  (003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 = Raphe (very slender tendon) X. NERVE SUPPLY OF MUSCLES - Adaptable to different activities because the stimulation of different portions of the muscle can change the direction it pulls - Ex. Pectoralis major 4. Pennate- penna “feathers” - Fascicles form a common angel with the tendon - Blend into a tendon that runs through the central region of the muscle for its whole length arranged similarly to feathers - Contracting pennate muscles do not move their tendons as far as parallel muscles do - Can hold more muscle fibers/myofibrils within it, thereby producing relatively more tension for its size a. Unipennate- fascicles are located on one side of the tendon; ex. Extensor digitorum b. Bipennate- muscle has fascicles on both sides of the tendon (center) as in the arrangement of a single Figure 6. Innervation of Muscle Fibers feather; ex. Rectus femoris - The nerve usually enters the muscle at about the midpoint on c. Multipennate- like a series of bipennate muscles lying its deep surface, often near the margin. This is called the alongside one another or may have the tendon lying within its center and the muscle fibers passing to it Motor Point from all sides, converging as they go; ex. Deltoid - Mixed Nerve o 60% is Motor a. Alpha fibers – from large cells in the anterior grey horn b. Gamma fibers – small cells in the spinal cord o 40% is Sensory – are myelinated and arise from specialized sensory endings lying within the muscle or tendon a. Muscle Spindles ⮚ Stretch receptors within the body of a muscle that detect changes in the length of a muscle and convey length information to the CNS via the afferent nerve fibers ⮚ This information is processed by the brain as Proprioception (The awareness of body position) ⮚ One of the two proprioceptors that play an important role in flexibility b. Tendon Spindles/Golgi Tendon Organ ⮚ Also, a proprioceptor that is important in flexibility Figure 5. Fascicle Organization ⮚ Works together with muscle spindles to regulate muscle stiffness IX.NAMING OF SKELETAL MUSCLES ⮚ When stimulates, it causes a muscle to relax by interrupting the contraction. When a muscle is inhibited - Uses Latin and Greek terminology or roots by a GTO this is calls Autogenic Inhibition - Follows criteria as in the following: ⮚ Its function is opposite the function of the muscle 1. Direction of muscle fibers spindle which is to contract. They work together to Ex. Rectus (straight) make sure that over contracting of a muscle does not 2. Relative size happen since it may lead to injury Ex. Maximus (largest), Brevis (short), Medius o Sympathetic Fibers – non-myelinated and pass to the smooth (medium) muscle in the walls of the blood vessels supplying the muscle 3. Location of the muscle It also regulates the blood flow to the muscle. Ex. Temporalis 4. Number of origins (less movable bone) XI.DIVISIONS OF THE SKELETAL MUSCULAR SYSTEM Ex. Triceps (3 heads), Quadriceps 5. Location of the muscle’s origin and insertion A. APPENDICULAR DIVISION/ MUSCLES o Origin is always named first followed by the - Support, move and brace the limbs insertion - Stabilize or move structures of the appendicular skeleton Ex. Sternocleidomastoid - 40% of the skeletal muscles 6. Shape of the muscle - Move and support the pectoral and pelvic girdles and the Ex. Deltoid (triangular), Trapezius (trapezoid) upper and lower limbs 7. Action of the muscle Ex. Flexor and Extensor (flexes and extends a bone) PREPARED AND EDIT BY: QUAMBAO, QUILALA, LUMAYAG, MANLONGAT, MOJICA, PRUDENCIO, PUZON  (003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 B. AXIAL DIVISION/MUSCLES - Support and position central skeleton - Arise on the axial skeleton - 60% of the skeletal muscles in the body - Position the head and vertebral column - Move the ribcage, which assists the movements that make breathing possible - Form the pelvic floor - Include Head, Neck, Back, Abdomen, Thorax, Pelvis, Perineum 1. Head a. Scalp Skin – contains the hair Connective tissue – contains nerve and blood supply of scalp Aponeurosis – contains the occipito-frontali muscle which has occipital and frontal belly o Frontal belly – help raise the eyebrows – Superficial scalp wounds do not necessarily require deep sutures because the strength of this aponeurosis limits gaping Figure 7. Muscles of Facial Expression – Deep scalp wounds gape widely when the c. Muscles of Mastication epicranial aponeurosis is lacerated in the coronal - Masticatory muscles are responsible for the chewing plane because of the pull of the frontal and movements of the mandible or lower jaw. occipital bellies in opposite directions (anteriorly - Orginate on the skull and insert onto the mandible, thus and posteriorly). For satisfactory healing, close acting upon the mastication and other movements of the aponeurosis layer lower jaw at the temporomandibular joint Loose areolar tissue - Innervated by Trigeminal nerve (V), mandibular branch – dangerous layer which contains emissery veins o Emissery veins are the veins that interconnect the veins of the scalp with M: Masseter the venous sinuses of dura mater. M: Medial pterygoid Pericranium T: Temporalis – periosteum which is adherent to the bone L: Lateral pterygoid b. Muscles of Facial Expression Mom Makes - These muscles have their origins on the surface of Tasty Lasagna the skull and their insertions have fibers intertwined with connective tissue and the dermis of the skin Elevators Figure 8. Muscles of Mastication - Levator labii superioris 2. Neck - Occipitofrontalis - Gross motor movements that move the head in every - Zygomaticus direction, as well as pull the skull towards the shoulders, Depressors spine and scapula - Depressor labii inferioris - Bilaterally control the flexion & extension of head and neck - Platysma - Unilaterally rotate the head or flex the neck laterally to the (those with) varied actions left or right - Buccinator - Adjust posture of the head and have some of the greatest - Orbicularis oculi endurance of any muscles in the body - Orbicularis oris a. Anterior triangle of neck - move the mandible and hyoid Suprahyoid muscles Infrahyoid muscles b. Posterior triangle of neck Semispinalis capitis Splenius capitis Trapezius c. Prevertebral and lateral vertebral muscles Muscles in deeper dissections of neck area PREPARED AND EDIT BY: QUAMBAO, QUILALA, LUMAYAG, MANLONGAT, MOJICA, PRUDENCIO, PUZON  (003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 APPENDIX TEST YOUR KNOWLEDGE A. A Muscle, A Fasiculus, and A Muscle Fiber INDICATE IF THE FOLLOWING STATEMENTS ARE TRUE/FALSE 1. Heat is released when the muscles contract. _____ 2. Gamma fibers are from large cells coming from the spinal cord. _____ 3. It is unusual to have many synergist muscles assisting the prime mover. _____ CHOOSE THE LETTER OF THE CORRECT ANSWER 1. How are parallel muscles arranged? a. Fascicles are arranged in the same direction as the long axis of the muscle. b. Fascicles are arranged in the opposite direction as the long axis of the muscle c. Fascicles are arranged in the opposite direction as the short axis of the muscle d. Fascicles are arranged in the same direction as the short axis of the muscle B. The Organization of a Fasiculus 2. Because you did not do well in your recent anatomy and physiology exam, you leave the classroom pouting. Which one of these muscles are you using? a. Mentalis b. Orbicularis oris c. Risorius d. Levator labii superioris e. Zygomaticus minor 3. In order for movement to occur, (1) muscles generally need to cross a joint, (2) contraction of the muscle will pull the origin, (3) muscles that move a body part cannot cover the moving part, (4) muscles need to exert force on tendons that pull on bones, (5) the insertion must act to stabilize the C. The Organization of a Muscle Fiber joints. a. 1,2,3,4,5 b. 1,2,3,4 c. 1,2,4 d. 1,3 e. 3,4 4. The rectus femoris has fascicles arranged on both sides of a centrally-positoned tendon. The pattern of fascicle arrangement is: a. Unipennate b. Fusiform c. Multipennate d. Parallel e. Bipennate 5. Which of the ff muscle names and their naming descriptions are mismatched? a. Adductor brevis; short muscle that moves a bone closer to the midline b. Rectus abdominis; muscle with fibers parallel to the midline of the abdomen c. Levator scapula; muscle that raises the scapula PREPARED AND EDIT BY: QUAMBAO, QUILALA, LUMAYAG, MANLONGAT, MOJICA, PRUDENCIO, PUZON  (003) INTRODUCTION TO THE MUSCULAR SYSTEM DR. VILLANUEVA - DE GRANO | 09/23/2020 d. Sternohyoid; muscle attached to the sternum and hyoid e. Serratus anterior; comb-like muscle located on the body’s anterior surface MATCH THE FOLLOWING A. Muscle that stabilizes the origin of the (1) Compartment prime mover (2) Origin B. Site of muscle attachment to a (3) Insertion stationary bone (4) Belly C. Muscle that stretches to allow desired (5) Synergist motion (6) Fixator D. Muscle that contracts to stabilize (7) Prime mover intermediate joints (agonist) E. Site of muscle attachment to a (8) Antagonist movable bone F. Group of muscles, along with their blood and nerves, that have a common function G. Contracting muscle that produces the desired motion H. Fleshy part of the muscle ANSWERS: TRUE, FALSE, FALSE, A, A, D, E, E, 6, 2, 8, 5, 3, 1, 7, 4 We will power through the difficulties and become excellent physicians one day. Don’t forget to rest,1E and 1F! PREPARED AND EDIT BY: QUAMBAO, QUILALA, LUMAYAG, MANLONGAT, MOJICA, PRUDENCIO, PUZON