Skeletal Muscles PDF

Skeletal Muscles Created by Hung Bui, D.C. Objectives 1. Apply the concepts of unilateral or bilateral concentric, eccentric, and isometric contractions to the actions of back muscle 2. Know active vs. passive components and their examples 3. Know the length vs. tension curve 4. Understand the appli...

Skeletal Muscles Created by Hung Bui, D.C. Objectives 1. Apply the concepts of unilateral or bilateral concentric, eccentric, and isometric contractions to the actions of back muscle 2. Know active vs. passive components and their examples 3. Know the length vs. tension curve 4. Understand the application of AROM and PROM 5. Know the definition of agonist, antagonist, and synergist muscles 6. Know the 5 variables that affects force and velocity relationship 7. Understand different types of muscle fibers SO, FOG, FG, theirs characteristics, and examples of them in the body muscle groups (postural muscles vs. phasic muscles) Muscular Components Passive (non-contractile) components: 1. 2. 3. 4. Epimysium Perimysium Endomysium Tendon 1. 2. 3. 4. Myosin (thick filament) Actin (thin filament) Trypomyosin Troponin Active (contractile) components: Muscle Functions The major function of muscle is to move bone. In order to do so, muscle have the characteristic ability of developing tension. This tension can be either active or passive and it is the sum of both the active and passive components which gives the final total force. 1. Active tension: created by active components of the skeletal muscle. 2. Passive tension: created by the passive components of the skeletal muscle. The passive components are visco-elastic and act in a similar manner of a rubber band Range of Motion Active range of motion (AROM) = Kinetics Passive rang of motion (PROM) = Kinematics – Passive components come into play slightly after the point that the active components have reached their maximum. Length-Tension Curve In the length-tension curve, if the resting length of a muscle equal one (1), we observe the following: 1. The active components of a muscle show the greatest tension just before the resting length. 2. The passive components are just beginning their active tension at the resting length Types of Contraction There are 2 types of contraction: 1. Isotonic contraction: i. Concentric contraction ii. Eccentric contraction 2. Isometric contraction: Terms of Laterality In the back, muscles are arranged into left and right groups. There for the term of laterality of contraction will be considered when talking about the actions of the muscle: – Unilateral contraction: contraction either on the left or the right only – Bilateral contraction: contraction on both left and right sides simultaneously. Actions of Muscles Agonist: primary muscle that initiate movement at the joint. Antagonist: the muscles that oppose the movement of the agonistic muscle. Synergist: the muscles that help the agonistic muscle after the initiating motion or take over the action of the weak agonistic muscle. VARIABLES THAT AFFECT A FORCE VELOCITY RELATIONSHIP 1. Length and direction of the muscle fibers: Pennate muscle fibers of the gastrocnemius are angled at 23 degrees to the tendon tension. This produces an 8% increase in force. Fusiform muscles Pennate muscles PENNATE FIBERS MULTIPENNATE VARIABLES THAT AFFECT A FORCE VELOCITY RELATIONSHIP 2. Temperature of the muscle: Normal/average = 28⁰C -42⁰C or 82.5⁰F – 107.6⁰F VARIABLES THAT AFFECT A FORCE VELOCITY RELATIONSHIP 3. Muscles traversing joints: Those that traverse one joint are used for strength. Those that traverse more than one joint are used to increase range of motion. VARIABLES THAT AFFECT A FORCE VELOCITY RELATIONSHIP 4. Muscle origin and insertion in relation to the joint. Spurt vs. Shunt i.e. supraspinatus versus deltoid VARIABLES THAT AFFECT A FORCE VELOCITY RELATIONSHIP 5. The recruitmennt of muscle fiber composition. There are three types of fibers: 1. SO = Type I fibers for tonic, postural muscles of the back 2. FOG = Type IIA 3. FG = Type IIB for Phasic muscles Assessing Muscle Length & Strength (Janda) Shortened muscles–hyperactive & tight usually due to overuse. Long muscles–inhibited & lengthened; often the antagonist of a tight muscle. – **An imbalance may result in faulty movement patterns which may lead to joint dysfunction. Liebenson C. Rehabilitation of the Spine: A Practitioner's Manual, 2nd ed. Lippincott Williams & Wilkins 2007 Length Assessment Separate the muscle origin & insertion then assess end-feel (position of passive tension) – i.e. Pectoralis Major, clavicular division: Pt. position –supine with arms abducted to 90 degrees & externally rotated. Dr. position –at head of table visualizing the arms Procedure –Dr. visualizes the pt. Normal position –arms should drop 10 to 20 degrees below horizontal Normal end-feel – leathery/springy Rating –normal, long or short with appropriate end-feel description (springy, tight, sluggish, etc.) http://www.ptonthenet.com/images/articles/pec-major-upper.jpg http://www.ptonthenet.com/images/articles/pec-major-lower.jpg Strength Assessment Approximate the muscle origin & insertion placing the muscle at mid-length (position of active tension & mechanical advantage) then assess strength. – i.e. Pectoralis Major, sternal division:  Pt. position –supine with arms flexed to 90 degrees & internally rotated.  Dr. position –standing at the side of table of the tested side, contacting pt.’s forearm while stabilizing the opposite ASIS.  Procedure –Dr. pushes pt.’s arm into abduction along the imainary, oblique line connecting the ASIS with the shoulder while pt. resists for a count of 5  Normal –Pt. should be able to resist steady pressure for 5 seconds  Rating –0 through 5 (3 is the ability to hold against gravity) https://i.ytimg.com/vi/SbBWWMTE-X4/hqdefault.jpg Connective Tissue Damage Any process or event that disturbs the normal function of a specific joint structure, including muscle, will set up a chain of events that eventually affects every part of the joint & its surrounding structures. Disease –effects the normal biological function of tissues Injury/trauma –damages the physical structure leading to weakening and possible instability & failure. Immobilization Detrimental to joint structures & functions may result in: Joint capsules & surrounding structures shorten (contractures) Ligaments & tendons lose collagen & cross-linking ability & thus strength (may lose up to 50% of strength in 8 wks; full recovery may take up to 18 months) Articular surfaces develop fibro-fatty tissue, adhesions, cartilage atrophy, regional osteoporosis, increased water intake, & decreased proteoglycans Immobilization Muscles – Immobilization in a shortened position (worse) – results in significant structural changes due to increased development of C.T., loss of mass & atrophy. – Immobilization in a lengthened position(easier recovery) – fewer detrimental structural changes; responds to rehab much faster. References Kinesiology of the Musculoskeletal System: Foundation for Rehabilitation, 2nd ed. or 3rd ed., chapter 3 by DA Neumann. Liebenson C. Rehabilitation of the Spine: A Practitioner's Manual, 2nd ed. Lippincott Williams & Wilkins 2007 Levangie PK & Norkin CC., editors. Joint Structure and Function, A Comprehensive Analysis, 5th edition. FA Davis Co., Philadelphia, 2011. McGaw-Hill Companies, Inc. Pearson Education, Inc., publishing as Benjamin Cummings http://www.biodex.com/sites/default/files/imagecache/product_landing_large/850000_1_knee_extension_flexion_0.jpg https://44wj5q2j6wo23s4mp6owjohh-wpengine.netdna-ssl.com/wp-content/uploads/2012/02/latextension.jpg https://thumbor.kenhub.com/LrJwrO8s1i6_fft4NUZAfjtAF5s=/fitin/800x800/filters:watermark(/images/logo_url.png,-10,10,0)/images/library/220/Serratus_posterior_muscles.png https://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Serratus_posterior_inferior_muscle _back3.png/250px-Serratus_posterior_inferior_muscle_back3.png The End