Neuromuscular Fundamentals Chapter 2

Muscular System Over 600 muscles (215 pair) approximately 40% to 50% of body weight Functions Movement Protection Support and Posture Heat Production

Muscular Nomenclature Usually named because of one or more distinctive characteristics. Often there is a crossover among the various nomenclature. Shape Size Number of Division Location Direction Action Action & Shape Action & Size Point of Attachment Location & Attachment Location & Number of Divisions

Muscular 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 onto the bones to which it is attached. . Cross-sectional Ability to shorten Parallel arrangement (Fibers arranged parallel to length of muscles) =  ROM ) Flat Fusiform Strap Radiate Sphincter Pennate Arrangement (Shorter fibers arranged obliquely to their tendons) =  Force ) Unipennate Bipennate Multipennate Shape Fiber Arrangements

Muscle Tissue Properties Irritability — ability to respond to a stimulus Contractility — ability to contract and develop tension Extensibility — ability to be stretched beyond resting length Elasticity — ability to return to original length following stretching Tonicity — state of firmness of a muscle due to nerve stimulation and motor unit contraction

Muscle Terminology Intrinsic- muscles within or belonging solely to a body part it acts upon Extrinsic- muscles that originate outside a body part on which it acts Action- specific movement of a joint resulting from a concentric contraction Why do Muscles perform their particular actions? Line of pull Planes of motion of a joint 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 Insertion- distal attachment, usually most moveable part Exceptions

Muscle Contractions Isometric – (Static): muscle contraction in which: Tension develops, no change in length of muscle Muscular Force = Resistive Force Stabilization effect Isotonic – (Dynamic): muscle contraction in which: Tension develops, “causing” or “controlling” joint movement Concentric (positive contraction) Muscle shortens Muscular force > Resistive force Body part moves against (_____) gravity or external force Acceleration 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 Deceleration effect Muscle(s) involved and movements 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 (prime mover): muscle that when contracting concentrically causes joint motion How do you determine which muscle groups are involved? Step #1: Identify what movement the resistance is tending to cause Step #2: The opposite muscle group is involved If contracting = ______ If relaxing = _______ Antagonist: opposite side of the joint from the agonist

Straight leg raise lying supine Role of Muscles Stabilizer (fixator): a muscle(s) that contracts to fix or stabilize a bone so that a muscle can do its intended work/movement Straight leg raise lying supine Crunch/Curl up Neck flexion Bench press

Dynamic Stabilization Role of Muscles Static Stabilization vs Dynamic Stabilization

Role of Muscles Movement/ Action: Neutralizer: Muscle that contracts to counteract or neutralize the action of another muscle to prevent undesirable motions Resulting from the combination of: The Common action of muscles The antagonistic action of muscles Movement/ Action: Muscles: Common Actions: Neutralizing Actions:

Role of Muscles Synergist: A muscle(s) that works with an agonist, is partial antagonist, and contracts to prevent an undesired movement Agonist(s) Synergist(s) Undesired Movement Making a fist Kicking a football Biceps curl (dumbbell) Note: A muscle tends to perform all its actions when it contracts unless something prevents those movements from occurring.

Role of Muscles 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 “____________”

Central Nervous System

Peripheral Nervous System

Myotome

Dermatome

Stretching

Myotatic Reflex (Stretch Reflex)

Inverse Myotatic Reflex

Neuromuscular Concepts Motor Unit All or none principle Increasing Fiber Recruitment

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Neuromuscular Concepts Muscular Length- Tension Relationship The greatest muscle tension can be developed when a muscle is stretched. Why? Greatest tension: Between 100% and 130% of resting length Least tension: Muscle shortened to approx. 50 – 60% of resting length Seated leg extension Prone hamstring curl Vertical jump

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

Neuromuscular Concepts Angle of Pull The angle between the 1) line of pull of the muscle and the 2) bone on which it inserts Rotary components– 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 Component Angle of pull >90° Angle of pull <90° Angle of pull = 90° If angle of pull is <90° =___________ Why? If angle of pull is >90° =___________

Neuromuscular Concepts Angle of Resistance The angle between the: 1) direction of resistance and the 2)lever to which the resistance is attached or applied 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 ___________ Rotary Component At a 90° angle of resistance 100% of the energy of resistance is causing the lever to __________________________________ At a 0° angle of resistance 100% the energy of resistance is causing either: ___________________ element There is no force causing movement of the bone/lever around its axis 90º

Biarticular Muscles & Movement Patterns 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. Parallel Squat Rectus Femoris Contraction = __________ Hamstrings = ___________ Biceps Femoris Contraction = __________ Quadriceps = ___________ Lombard’s Paradox? Involves comparison between two antagonistic muscles Both muscles must be biarticular Parallel Squat: Rectus Femoris Biceps Femoris Knee Hip MFA Rectus Femoris 4.4 3.9 Longer @ Knee Biceps Femoris 3.4 6.7 Longer @ Hip

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 antagonist muscle.

Guidelines for Muscle Testing and Exercise Test both sides – comparison “Isolate” the muscle Stabilize the proximal segment Apply a 90º angle of resistance Apply resistance to the distal end of distal segment To overcome a deformity Stretch tight muscle groups Strengthen the weak muscle groups Maintain ______ _________ (24-7) External force is usually required

Questions Person has a weak right biceps. To strengthen, would you perform biceps curl with a barbell? Person has a weak left triceps. Would push-ups be a good exercise to strengthen the left triceps? Person has weak right rhomboids. How would you strengthen? How would you isolate the soleus to stretch/strengthen? How would you isolate the gluteus maximus?

Stages of Development of Acquired Musculoskeletal Deformities First Degree (curable by exercise – strengthening the weak, stretching the tight) A. Soft tissue: Changes in muscle tone and habitual posture B. Bone tissue: No bony change C. Corrective treatment: The patient can himself correct the position of the affected part Second Degree (improvable by exercise) A. Soft tissue: Contracture of soft tissue structures B. Bone tissue: Slight degree of bony change C. Corrective treatment: Patient cannot himself correct the deformity, but can be corrected to some extent by another person (external source) Third Degree (little if any change achieved with exercise) A. Bone tissue: Serious bony change

Lateral Line of Gravity Anterior Line of Gravity Posture The relationship of body segments to one another Lateral Line of Gravity Anterior Line of Gravity