L2 - Skeletal Muscles PDF

Lecture 2 SKELETAL MUSCLES Color Index: Main text Boys' Slides Girls' Slides...

Lecture 2 SKELETAL MUSCLES Color Index: Main text Boys' Slides Girls' Slides Important Dr's Notes Extra Editing File OBJECTIVES Describe the main criteria of skeletal muscles. Describe the attachments of skeletal muscles. Describe the different directions of skeletal muscle fibers. Describe the mode of action of skeletal muscles. Describe briefly the naming of skeletal muscles. Describe briefly the nerve supply of skeletal muscles.  Girls' Introduction Slides Musculoskeletal is a general term which is defined as relating to muscles and bones of the skeleton. The musculoskeletal system comprises (composed of) bones, joints, cartilage, bursae, tendons, muscles and ligaments. It is the system that moves the body and maintains its form. Study of this system consists of osteology (the study of bones), arthrology (the study of joints), and myology (the study of muscles). The musculoskeletal system does not work in isolation. It is closely linked with many other systems in the body, including the nervous system, genitourinary system, circulatory system, immune system, respiratory system, digestive system and endocrine system. Boys' Slides Muscle Tissues Muscle tissue is a As a result of this The structural and unique tissue ability, muscles functional unit of which has the are responsible for all the body muscle tissue is ability to contract. movements. “muscle cell”. The ability of muscle to All muscle cells contract (or to shorten), depends on two are elongated types of myofilaments: and are called 1- actin “muscle fibers”. 2-myosin Helpful Video in the muscle fibers. Extra image for further clarification Myofilaments are the three protein filaments of myofibrils in muscle cells. The main proteins involved are myosin, actin, and titin. Myosin and actin are the contractile proteins and titin is an elastic protein.  Classification of Muscles Muscles are classified based on the following: Microscopic Action Location structure Visceral Non Skeletal Cardiac or Striated Voluntary Involuntary Striated Muscles Muscles Smooth muscles muscles The muscle (Smooth) Muscles fibers show Subject to Attached Walls of transverse Not under No conscious to bones & the Heart striations conscious Walls of striations control. produce visceral control. Movement example: organs example: example: skeletal & example: visceral Muscles cardiac Muscles of the muscles attached to muscles heart & skeleton other organs examples of visceral organs: Involuntary (Heart) stomach, liver, pancreas, Voluntary (Muscle tissue) small intestine, large intestine Involuntary (Stomach) Classification Overview Skeletal Muscle Cardiac Muscle Smooth Muscle Boys' Voluntary Involuntary Involuntary Slides Striated Striated Non Striated Skeletal Muscles Main Criteria ▪ Striated ▪ Attached to skeleton ▪ Produce movement of skeleton ▪ Voluntary ▪ Supplied by Somatic Nerves Functions ▪ Body Movement ▪ Maintain Posture ▪ Generate Heat ▪ Stabilizing Joints Attachments ▪ The skeletal muscles are attached to bones at not less than two points: Origin Insertion Attached to less mobile or Attached to the movable immovable bone bones Least movable Most movable Mostly fleshy Mostly fibrous Proximal end Distal end When the muscle contracts, the insertion moves toward the origin. At insertion, the muscles are attached by means of strong cord-like tendons or by sheet-like aponeurosis. Types of Attachments Types of Attachments Muscles are attached to bones, cartilage or ligaments by: 1) Tendons A tough cord of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. 2) Aponeurosis A thin broad and strong sheet of fibrous tissue.(scalp) 3) Raphe An interdigitation of the tendinous ends of the flat muscles. example: Mylohyoid Raphe Interdigitate: to become Boys' Girls' Slides interlocked like the fingers of folded hands. Slides Directions of Muscles The range of motion and the power of a muscle depends on the arrangement of its fascicles (a group of muscle fibers “bundled” as a unit within the whole muscle is called a fascicle). The fiber arrangement can be: 1 Fusiform Spindle-shaped (round, thick belly, & tapered ends). 2 Circular Surround a body opening or orifice, constricting it when contracted. 3 Convergent When a muscle has a widespread expansion over a sizable area and the fascicles come to a single, common attachment point. 4 Parallel More range of movement , less powerful. The long parallel arrangement gives more range of motion but is not usually very powerful. 5 Pennate More powerful, less range of movement. Unipennate(Uni=1)/Bipennate(Bi=2)/Multipennate(Multi=3,4,5....) The pennate muscles shorten very little but are very powerful. Girls' Slides Mode of Actions It is the chief (main) Muscles that assist the Extra images for muscle responsible for a prime mover in a particular movement. particular movement. further clarification Prime Mover Antagonist Synergist Fixator (Agonist) It opposes the action of the Its contraction does not prime mover. produce movement by itself, Before the contraction of the but it stabilizes the origin of prime mover, the antagonist the prime mover so that it can must be relaxed. act efficiently.  PRIME MOVER (AGONIST) It is the chief muscle responsible for a particular movement. Examples: Quadriceps Femoris is the prime mover for extension of the knee joint. Extra Extraimage imageforfor further furtherclarification clarification Biceps Brachii is the prime mover for flexion of the elbow joint and forearm. Extra image for further clarification  ANTAGONIST ▪ It opposes the action of the prime mover. ▪Before contraction of prime mover, antagonist must be relaxed. ▪ex: o Triceps Brachii is the antagonist for prime mover for flexion of the elbow joint and forearm. o Biceps Femoris (Flexor of knee). o It opposes the action of quadriceps when the knee joint is extended.  SYNRGIST ▪ Muscles that assist the prime mover in a particular movement. crossed by the Prime Mover. Helps prime movers by adding a little extra force to the same movement OR By reducing undesirable or unnecessary movement. Brachialis muscle for Biceps prime ▪ Synergists are sometimes called neutralizers because they help cancel out, or neutralize, extra motion from the agonists to make sure that the force generated works within the desired plane of motion. ▪ Example: o Brachialis muscle for Biceps prime mover muscle. another Example : The biceps is the prime mover in the elbow joint. Bracioradialis acts as a synergistic muscle to stabilize the joint thus aiding in the motion. o Flexors and Extensors of wrist joint: they contract to fix wrist joint in order that flexors and extensors of fingers work efficiently.  FIXATOR ▪ Its contraction does not produce movement by itself but it stabilizes the origin of the prime mover so that it can act efficiently. ▪ Example: o Deltoid muscle for Biceps prime mover muscle. o Muscles attaching the shoulder girdle to the trunk contract to fix shoulder girdle, allowing deltoid muscle (taking origin from shoulder girdle) to move shoulder joint (humerus).  Major or Maximus (large) o Minor or minimus (small) o Superficialis (superficial) o Latissimus (broad) o Profundus (deep) o Longus (long) o Externus (external) o Brevis (short) Size Position Depth Shape Pectoralis (pectoral o Deltoid (triangular) region) o Teres (rounded) o Rectus (straight) NAMING OF MUSCLES o Coracobrachialis o Biceps (2 heads) from coracoid o Triceps (3 heads) process to arm o Quadriceps (4 heads) Number Attachments Action of heads Flexor digitorum: flexion of digits  TYPES OF BODY MOVEMENTS 1 2 Flexion Extension Movement that brings the two Movement that increases the bones closer to each other angle, or the distance between (decreases the angle of joint). the two bones. 3 Adduction (Adding) Movement of the limb toward the midline of the body. 4 Abduction Movement of the limb away from the midline of the body. 5 6 Rotation Circumduciton Movement of a bone around a Combination of all the vertical axis above movements. MUSCLE EXERCISE MUSCLES INNERVATION The somatic nervous system (is the The amount of work done by a part of the peripheral nervous system) muscle is reflected in changes associated with skeletal muscle in the muscle itself. voluntary control of body movements. Muscle inactivity leads to The nerve enters the muscle at about muscle weakness and wasting. the middle point of its deep surface. Regular exercise increases The nerves supplying the skeletal muscle size, strength and muscles are Mixed. endurance. - 60% are Motor - 40% are Sensory It contains some Autonomic fibers (sympathetic)  Girls' BLOOD SUPPLY Slides ▪During extreme physical exertion, more than 80% of cardiac output can be directed to contracting muscles. ▪ The vascular inflow to skeletal muscles is provided by primary arteries, which represent the last branches of the arterial supply that arise before entry into the tissue. ▪ The primary arteries are appropriately distributed along the long axis of the muscle and give rise to feed arteries that course toward the epimysium of the muscle at right or oblique angles to the primary arteries.  Boys' Clinical Anatomy Slides MUSCLE DISEASES ▪ Muscle diseases and injuries are common, especially in sports activities. A severe muscle injury can keep you from participating in the activities that you love and enjoy for living. ▪ Muscle diseases and injuries could be one of the major factors that threat someone’s professional career(s). FIBROMYALGIA ▪ Fibromyalgia is a term used to describe a common syndrome in which people experience long-term, widespread pain and tender points in joints, muscles, tendons and other soft tissues. ▪ It also results in disturbed sleep and exhaustion. ▪ The cause is unknown but possible triggers include viral infection, physical and emotional stress. ▪ It tends to be more common in people with pre-existing lupus, rheumatoid arthritis, or ankylosing spondylitis. ▪ There is no cure but symptomatic treatment can help some patients.  MUSCLE CRAMP Boys' Slides ▪ The muscle cramp is a sudden and involuntary contraction of one or more of your muscles. ▪ If you've ever been awakened in the night or stopped in your tracks, you know that muscle cramps can cause severe pain. ▪ Muscle cramps can make it temporarily impossible to use the affected muscle. ▪ Long periods of exercise or physical labor, particularly in hot weather, can lead to muscle cramps. ▪ Some medications and certain medical conditions also may cause muscle cramps. ▪ Overuse of a muscle, dehydration, muscle strain or simply holding a position for a prolonged period can cause a muscle cramp. ▪ You might be at higher risk of muscle cramps if you have diabetes, or nerve, liver or thyroid MUSCLE DYSTROPHY disorders. Muscular dystrophy (MD) refers to a group of hereditary diseases that weaken different muscle groups in various ways. ▪ A person affected with MD has a genetic mutation that prevents the repair of muscle tissue. ▪ This muscle weakening occurs gradually over time. ▪ Symptoms may start at any time from infancy through to adulthood. ▪ By age 10 to 12 years children will often be in a wheelchair. ▪ This disease also affects other body systems so patients need regular respiratory and cardiac assessment. ▪ It is likely that these patients will eventually need a ventilator to breathe. ▪ People with DMD usually do not survive beyond their late teens or early adulthood. Boys' Slides STRAIN A strain occurs when a muscle and/or tendon is overstretched or torn. ▪ There is no fracture or dislocation present. ▪ Pain, weakness and muscle spasms are common symptoms experienced after a strain occurs. ▪ Rest, application of ice and a compression bandage are effective treatments.  MCQs 1 The pennate muscles shorten very little and are very weak. A) True B) False 2 Quadriceps Femoris is the _______ for extension of the knee joint. A) Synergist B) Fixator C) Agonist D) Antagonist 3 Somatic Nerves supply? 4 A) Cardiac Muscles B) Skeletal Muscles C) Visceral Muscles D) All of the above It opposes the action of the prime mover A)Fixator B)Antagonist C)Agonist D)Synergist 5 The amount of work done by a muscle is reflected in changes in the muscle itself: A)Muscles exercise B)muscles innovation C)tendons D)Action Answer Key: 1) B (but are very powerful) 2) C or “Prime mover” 3)B 4)B 5)A  Leaders Nisreen Alotaibi Omar Alattas MEMBERS Shaden Alotaibi Abdulhadi Alqahtani Danah Khallaf Turki Alanzi Elaf Alshamlan Talal Alrobaian Jana Alahaideb Abdulmalik Aldafas Dana Alotaibi Ahmad Addas Noorah Alkhilaiwi Salman Al Hakeem Orjwan Alharthi Ziyad Bukhari Lana Alfouzan [email protected]