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HEALTH SCIENCES 365 Chapter 2 – Neuromuscular Fundamentals Muscular System Over 600 muscles (215 pair) comprising approximately 40% to 50% of body weight Functions Movement Protection Support & Posture Heat Production Muscle Nomenclature – usually named because one or more distinctive characteristics. Often there is crossover among the various nomenclature characteristics. Individual Muscle Muscle Group Shape _______________________________ ______________________ Size _________________________________ Number of divisions ____________________ ______________________ Direction of fibers ______________________ Location ______________________________ ______________________ Points of attachment ____________________ Action _______________________________ ______________________ Action & shape ________________________ Action & size _________________________ Location & attachment __________________ Location & number of divisions ___________ Muscle Shape and Fiber Arrangements Muscle shape and fiber arrangement play a role in the muscle’s ability to exert force and the ROM through which it can effectively exert force. 1. Shape Cross-sectional diameter Ability to shorten 2. Fiber Arrangement (Two major types) Parallel Arrangement (Fibers arranged parallel to length of muscle = § _______) Flat – thin & broad (Rectus Abdominus) Fusiform – spindle shaped with central belly that tapers (Brachialis) Strap – fibers arranged in a long parallel manner (Sartorious) Radiate – combined arrangement of flat & fusiform (Pectoralis Major) Sphincter – circular (Obicularis Oris) Pennate Arrangement (Shorter fibers arranged obliquely to their tendons = § ______) Unipennate – run obliquely from a tendon on one side only (Biceps Femoris) Bipennate – run obliquely on both sides from a central tendon (Rectus Femoris) Multipennate – several tendons with fibers running diagonally between them (Deltoid) Muscle Tissue Properties Irritability – ability to respond to a _______________ Contractility – ability to contract and develop ________________ Extensibility – ability to be _______________________________ Elasticity – ability to return to original ______________________________ Tonus/Tonicity – a state of firmness of a muscle due to _________________ Muscle Terminology Intrinsic – muscle within or belonging solely to body part on which they act Extrinsic – muscles that originate outside a body part on which they act Action – specific movement of a joint resulting from a concentric contraction Innervation – nerve responsible to provide stimulus to muscle fibers Amplitude – range of fiber length between maximal and minimal lengthening Gaster (belly) – portion of muscle that increases in diameter as muscle contracts Origin – proximal attachment, usually least moveable part (exceptions?) Insertion – distal attachment, usually most moveable part (exceptions?) Types of Muscle Contraction (to cause, control, or prevent joint movement) Isometric (__________): A type of muscle contraction in which: Tension develops, no change in length of muscle or angle of joint - “preventing” Muscular Force __ Resistive Force ___________________ effect Isotonic (__________): A type of muscle contraction in which tension develops, “causing” or “controlling” joint movement (Two Types) Concentric (positive contraction) Muscle shortens Muscular force __ Resistive force Body part moves against (_____) gravity or external force _________________ effect Muscle(s) involved and movement are the ____________ Eccentric (negative contraction or “action”) Muscle lengthens Muscular force __ Resistive Force Body part moves with (_________) gravity or external force ___________________ effect Muscle(s) involved and movement are ____________ Muscle Force – Velocity Relationship -Concentric contraction against a light resistance = __________ velocity -Increasing resistance = ___________ in the maximal velocity the muscle can contract -Continuation of increasing resistance eventually = ___________ contraction if equal to muscular force -If resistance increases beyond muscular force = ___________ contraction Role of Muscles Agonist (___________): muscle that when contracting concentrically causes joint motion Q. How do you determine which muscle groups (agonists) are involved? Step #1: Identify what movement(s) the resistance is tending to cause Step #2: The opposite muscle group is involved What does “involved” mean? If contracting: ___________________________ If relaxing: _____________________________ Q. Why do muscles perform their particular actions? 1. Line of Muscle Pull – relationship of a muscle/tendon as it crosses a joint a. __________________________________________________ b. __________________________________________________ c. __________________________________________________ 2. Joints Functional Design – diarthrodial classification (planes of motion of a joint) Antagonist: opposite side of the joint from the agonist Stabilizer (__________): a muscle(s) that contracts to fix or stabilize a bone so that a muscle can do its _____________________. Agonist Stabilizer Stabilized Part Straight leg raise lying supine _________ _________ ____________ Crunch/Curl up Abdominals _________ Pelvis Neck Flexion _________ _________ ____________ Handing off a gallon of milk _________ _________ ____________ “Static” Stabilization vs “Dynamic” Stabilization Q. Why take a deep breath before performing a bench press? Neutralizer: Muscle that contracts to counteract or neutralize the action of another muscle to prevent undesirable motions. The result of the combination of: 1) ____________________________, and 2) ______________________________. Movement/ Action: Inversion of foot Muscles: ____________________ ____________________ Common Action: Subtalar Inversion Neutralizing Actions: ____________________ ____________________ Movement/Action: Lateral Arm Raises Muscles: ____________________ ____________________ Common Action: _____________________ Neutralizing Actions: ____________________ ____________________ Movement/Action: ___________________________ Muscles: ____________________ ____________________ Common Action: ____________________ Neutralizing Actions: ____________________ ____________________ Synergist: a muscle(s) that works with an ____________, yet is a partial ______________, and contracts to prevent __________________________________. Agonist(s) Synergist(s) Undesired Movement Making a fist ________ ________ _________________ Biceps curl (dumbbell) ________ ________ _________________ Hip flexion against resistance ________ ________ _________________ Important: A muscle tends to perform all its actions when it contracts unless something prevents those movements from occurring. -If the stabilizer muscle is a non-antagonistic muscle it is called a “_____________” -If the stabilizer muscle is an antagonistic muscle it is called a “_____________” -If the stabilizer muscle is an antagonistic muscle + a common action it is called a “_____________” Neuromuscular Interaction Peripheral Nervous System (PNS) – Spinal Nerves Spinal Cord – pathway between Central Nervous System and PNS Motor (efferent) nerves & Sensory (afferent) nerves Myotome – a muscle or group of muscles supplied by a specific spinal nerve Dermatome – a defined striplike or band area of skin supplied by a single spinal nerve root (dorsal) Cutaneous Distribution – an area or patch of skin supplied by a specific nerve Reflexes a. Biceps Brachii (C5) c. Patella – knee extensors (L3 & L4) b. Triceps Brachii (C7) d. Achilles (S1) Proprioception and Kinesthesis Proprioception – the process/mechanism by which the body is able to regulate posture and movement by responding to stimuli originating in the proprioceptors (sensory receptors located in the skin, joints, muscles, and tendons). They provide feedback relative to tension, length, contraction state of muscle, position of body and limbs, and movements of joints. These sense organs are vital to kinesthesis – the conscious awareness of the position and movement of the body in space and aid in the performance of complex coordinated movements. STRETCHING TECHNIQUES, PROPRIOCEPTORS, & REFLEX ACTIVATION There are basically three stretching techniques (Ballistic, Static, & Proprioceptor Neuromuscular Facilitation). All three types of stretching are effective in developing flexibility. One however, ballistic stretching, can be harmful by causing tears in muscle membranes and therefore is not the recommended technique for development of flexibility. 1. Ballistic Stretching Technique: stretching where there is a rapid bouncing movement in and out of the stretch position, where the end position is not held. 2. Static Stretching Technique: stretching is slow and constant where the end position is held. 3. Proprioceptor Neuromuscular Facilitation (PNF) Stretching Technique: stretching performed usually with a partner and involves both passive movement and active (concentric and isometric) muscle actions. All stretching techniques require movement of a body segment to a point of resistance in the ROM. This stretching movement can be done either actively or passively. Active stretch: when the person stretching supplies the force of the stretch. Passive stretch: when a partner or stretching machine provides the force for the stretch. Muscle Spindles & the Myotatic Reflex (also called the Stretch Reflex) During a ballistic stretching movement, the muscle spindle is activated and a sensory neuron sends an impulse to the spinal cord, where it synapses with a motor neuron which carries a message back to he muscle being stretched causing it to contract, called a myotatic reflex (or stretch reflex). Muscle spindles, being sensitive to the length and rate of change in muscle length, indicate the degree to which the muscle must be activated to contract to overcome a given resistance. As a load increases, the muscle is stretched to a greater extent, and engagement of muscle spindles results in greater activation of the muscle. This muscle activation process is thought to aid in athletic performance, maintaining of functional position, and in maintaining upright positioning. However, its use in stretching for the development of flexibility is questioned because of the increased risk of muscle injury, especially if a previous injury exists. Golgi Tendon Organs & the Inverse Myotatic Reflex During a static stretch movement (slow, sustained motion that lasts at least 10 seconds), tension increases within the muscle and a sensory neuron from the Golgi tendon organ (GTO) is activated and sends an impulse to the spinal cord, where it synapses with an inhibitory interneuron in the spinal cord, which in turn synapses with and inhibits a motor neuron serving the same muscle. As tension in the muscle increases, discharge of the GTO increases. The result is a reduction in tension within the muscle, causing it to reflexively relax, called an inverse myotatic reflex (sometimes called autogenic inhibition). Note: Because of the slow rate of change of the muscle length the muscle spindles are not activated. Thus, whereas muscle spindles facilitate activation of the muscle, neural input from GTOs inhibits muscle activation. This inhibitory process is thought to provide a protective mechanism from development of excessive tension and potential muscle tearing. Myotatic Reflex (Stretch Reflex) Inverse Myotatic Reflex (autogenic inhibition) Proprioceptive Neuromuscular Facilitation (PNF) Stretching PNF stretching was originally developed as part of a neuromuscular rehabilitation program designed to relax muscles with increased tone. It has since expanded to the training of athletes as a method of increasing muscular flexibility. PNF techniques are usually performed with a partner and involve both passive movement and active (concentric and static) muscle contractions. PNF stretching may be superior to other stretching methods because they facilitate muscular inhibition. During PNF stretching, three specific muscle actions are used to facilitate the passive stretch. A static (isometric) muscle contraction of the antagonist (the muscle being stretched), which produces tension within the muscle, is used before the passive stretch to cause a reflexive relaxation of the muscle during the subsequent passive stretch, called the inverse myotatic reflex (or autogenic inhibition). A static stretch of the antagonist muscle increases tension within the muscle activating the GTO resulting in the associated activation of the inhibitory interneuron and corresponding reduction in tension within the muscle, causing it to reflexively relax, called an inverse myotatic reflex (sometimes called autogenic inhibition). A concentric muscle contraction of the agonist (opposing muscle to the antagonist or muscle being stretched) performed simultaneously while the muscle is being passively stretched results in reciprocal inhibition (relaxation of the muscle being stretched via activation of the GTO and the associated inhibitory interneuron). The static (isometric) muscle contraction is referred to as contract. The concentric muscle contraction of the agonist is referred to as agonist contract. The passive, static muscle stretch is referred to as relax. Contract-Relax (CR) technique Contract-Relax-with Agonist Contract (CRAC) technique Neuromuscular Concepts Motor Unit – a single motor neuron and all the muscle fibers it innervates All or None Principle – all muscle fibers in a motor unit contract maximally or not at all Muscle Tension Development – the difference between a muscle contracting to lift a small resistance verses a muscle contracting to lift a heavy resistance is the number of muscle fibers recruited. The number of fibers recruited may be increased by: 1. ________________________________________________________________ 2. ________________________________________________________________ 3. ________________________________________________________________ Muscle Length – Tension Relationship The greatest muscle tension can be developed when the muscle is stretched between _____% and _____% of its resting length. Why? Seated leg extension Prone hamstring curl Vertical jump The least muscle tension results when a muscle is shortened to approximately _____% to _____% of resting length. Active & Passive Insufficiency Active Insufficiency: When a muscle becomes shortened to the point at which it cannot generate or maintain active tension. Passive Insufficiency: When the opposing muscle becomes stretched to the point at which it can no longer lengthen and allow movement. Angle of Pull The angle formed between the 1)__________________________________ and the 2) _____________________________________ a. Reference angle is the angle toward the joint b. Rotary component - that muscular force that acts perpendicular to the long axis of the bone/lever When angle of pull is 90° = ______% rotary force Note: At all other degrees of angle of pull, one or two of the other components of force (non-rotary) is operating “in addition to” the rotary component. Non-Rotary Components If angle of pull is <90° = _____________ Why? _____________________________ If angle of pull is >90° = _____________ Why? _____________________________ Angle of Resistance The angle formed between the: 1)_________________________________ and the 2) _______________________________________________________. Differentiate between applied and attached The angle of resistance is zero if the *center of gravity at the segment lies on a line between the ____________ and the _______________________ *Center of Gravity: a point representing the weight center of an object. A point in a body (segment) about which all the parts exactly balance each other. Rotary Component a. At a 90° angle of resistance 100% of the energy of resistance is causing the lever to __ _______________________________________________________________________ b. At a 0° angle of resistance 100% of the energy of resistance is causing either a: _________________ element _________________ element There is no force causing movement of the bone/lever around its axis Biarticular Muscles 1. Can cause, control, or prevent movement at more than one joint 2. Increased flexibility 3. Decrease the number of muscles required for same movements ( muscle mass) 4. Can maintain a relatively constant length and tension at both joints as go through a range of motion Biarticular Muscles & Movement Patterns 1. CONCURRENT MOVEMENT PATTERN Muscle movement pattern that allows the muscles to maintain a relatively constant length and tension at both joints as go through a range of motion. Squat: 1. When concentrically contract Rectus Femoris = knee extension puts hamstrings on stretch. Why? ____________________________________________________________ Benefit? __________________________________________________________ 2. When concentrically contract Biceps Femoris = hip extension puts quadriceps on stretch. Why? ____________________________________________________________ Benefit? __________________________________________________________ Lombard’s Paradox: Question: How is it possible for two muscles that are antagonistic to each other contract and both contribute to the desired action or movement? Involves comparison between two antagonistic muscles Both muscles must be biarticular Parallel Squat Rectus Femoris Biceps Femoris Muscle Knee Rectus Femoris 4.4 Biceps Femoris 3.4 Hip 3.9 6.7 MFA Longer at knee Longer at hip 2. COUNTERCURRENT MOVEMENT PATTERN Muscle movement pattern that results from the concentric contraction of a biarticular muscle that produces its intended movements. Results in increased tension and stretch of the antagonistic muscle. Guidelines for Muscle Testing and Exercise 1. Test both sides - comparison 2. _______________ the muscle 3. Stabilize the _______________ segment 4. Apply a _____° angle of resistance (or as close as possible) 5. Apply the resistance to the _______________ end of distal segment 6. To overcome a deformity Stretch tight muscle groups Strengthen the weak muscle groups Maintain _______________ _______________ An external force is usually required Stages of Development of Acquired Musculoskeletal Deformities 1. First Degree (curable by exercise – strengthening the weak, stretching the tight) a. Soft tissue: _______________________________________________ b. Bone tissue: ______________________________________________ c. Corrective treatment: _______________________________________ 2. Second Degree (improvable by exercise) a. Soft tissue: _______________________________________________ b. Bone tissue: ______________________________________________ c. Corrective treatment: _______________________________________ ________________________________________________________ 3. Third Degree (little if any change achieved with exercise) a. Bone tissue: ______________________________________________ Assessing Posture: the relationship of body segments to one another Four (4) Key Words: Straight, Vertical/Horizontal, Symmetrical, Non-rotated Lateral Line of Gravity Anterior Line of Gravity a. *Mastoid process a. Anterior superior iliac spine (ASIS) b. Posterior to cervical spine b. Bisects knee c. Bisects cervical-thoracic spine c. Bisects ankle d. Anterior to thoracic spine d. Bisects foot at second toe e. Bisects thoracic-lumbar spine f. Posterior to lumbar spine g. *Bisects shoulder joint h. *Bisects greater trochanter i. *Bisects knee (posterior to patella) j. *Ant. to lateral malleolus (1-1.5”)