CHAPTER 6 - MUSCULAR SYSTEM Flashcards
Myology
Study of muscular system
Properties of Muscle Tissues
- Excitability
- Contractility
- Extensibility
- Elasticity
Excitability
Ability of the muscular tissue to carry can electrical impulse called an action potential which initiates the muscle contraction
Contractility
The response of the muscle cell to the electrical impulse. The muscle cell responds bt shortening, pulling the two ends of the muscle toward each other
Extensibility
Allows the muscle to be lengthened without damaging the muscle
Elasticity
Allows the muscle to return to its resting length after being lengthened or shortened
Three Types of Muscle
Smooth, Skeletal and Cardiac
Characteristics of Each of the Three Muscle Types
- Skeletal Muscle: highly controlled. Each muscle cell needs to be stimulated to contract separately
- Cardiac muscle: cells are interconnected so when one cell is stimulated to contract they all contract in a predictable sequence so that the heart can pump blood to tissues
- Smooth Muscle: may work as a collective or independently but their structure does not allow for much force to be generated when contracting
Number of Muscles in Humans
- Over 600 muscles in the body
- 23% of womens weight is muscle and 40% of mens weight is muscle
Function of Skeletal Muscle
- Provide force for movement, maintain posture, generate heat to produce constant body temperature
- Converts ATP to mechanical energy to generate force, perform work and produce movement
Composition of Skeletal Muscle
Made up of water (73%) and a well organized set of protein (24%) and inorganic salts (sodium, potassium, calcium and chloride)
Structure of Skeletal Muscle
- Muscle Body
- Enclosed by Epimysium
- Fascicle
- Include bundles of muscle fibers (10-150)
- Enclosed by perimysium
- Muscle Fiber
- Enclosed by membrane called the sarcolemma
- Covering the sarcolemma is the endomysium
- Many Myofibrils run the length
- Myofibrils
- Composed of long series of saromeres
- Sarcomeres
- Compsed of thin filament, Actin, and thick filement, Myosin.
Muscle Contraction
- When relaxed, myosin and actin have some overlap so they can interact
- Once stimulated by a nerve impulse to contract, the thick (myosin) filaments pull the thin (Actin) filaments causing them to slide and overlap pulling the ends of the sarcomere together. This is called the sliding filament theory of muscle contraction.
Isotonic Muscle Contraction
- Can be concentric or eccentric
- Muscle changes in length
Isometric Muscle Contraction
- Static contraction
- Muscle exerts force to counteract opposing force
- No change in muscle length
Concentric Muscle Contraction
Muscle shortens
Eccentric Muscle Contraction
Muscle lengthens
Parts of the Nervous System
- Central nervous system
- Peripheral nervous system
Central Nervous System
- Brain and spinal cord
- Enclosed by skull and spinal column
- Control center of nervous system as it receives info from peripheral nervous system and develops a response
Peripheral nervous system
System of nerves that connect extremities to central nervous system
Sensory Neurons
Carry information and sensations form the body and environment to the central nervous system
Motor Neurons
Carry information from central nervous system to body
Motor Unit
- Single neuron together with the fibers it commands
- When stimulated all the associated fibers create tension (all-or-none law)
- Motor units with many muscle fibers create strong contractions and ones with few fibers create weak contractions
Proprioceptors
- Specialized sensory receptors found in joints, muscles and tendons
- Sensitive to pressure and tension and are responsible for sending messages to the central nervous system to maintain muscle tone and perform coordinated movements
Muscle Spindles
- A type of proprioceptor that consist of several modified muscle fibers enclosed in a blanket of connective tissue
- These spindles provide information about the length of a muscle fiber and the range of change of its length
- Tell the muscles how much to contract to overcome a given stretch
Golgi Tendon Organs (GTO)
- Proprioceptors located within tendons
- Activated when tendon attached to active muscle is stretched
- Function is similar to muscle simplines in they also measure change in the muscle
- GTOs only become activated when muscles contract
- If stain on muscle and tension become excessive the GTP sends an impulse to the central nervous system, causing the muscle to relax and prevent injury
Difference between GTO and Muscle Spindles
GTOs are concerned with not change in muscle length but with increased tension because of a change in length
Slow Twitch Muscle Fibers
- Type 1 fibers
- Greater ability to use oxygen and resist fatigue
Contain higher amount of mitochondria compared to fast-twitch
Contract slowly and produce a smaller amount of force than fast-twitch
Fast Twitch Muscle Fibers
- Type 2 fibers
- Produce and use ATP quickly
Contact quickly and produce a great deal or force but fatigue quickly
Order of Muscle Fiber Recruitment with Intensity
Slow fibers are recruited first and then fast twitch as exercise intensifies
Factors Relating to Muscle Strength
- Muscle Size
- Muscle Length: greatest force when at resting length
- Speed of Contraction: during concentric max force is achieved through slow motion. during eccentric max force is achieved though fast motion.
- Neural Control: more muscle units, bigger muscle units, rate of firing is faster
Kinesiology
Study of anatomy
Origin vs Insertion
- In limbs, the origin is usually the proximal bone and the insertion is usually the distal bone
Synergist Muscle
- Muscles working together in coordinated fashion with other muscles
- Helper Muscle
- Also play the role of stabilizers to make movement more efficient and maintain proper alignment
Agonist Muscle
- Prime Mover
- Muscle that provides the most tension
Antagonist Muscle
- Muscle that performs that opposite movement of the prime mover
- Relaxed when the prime mover is active
- Can work with prime mover by providing a slight contraction to stop the movement of the prime mover
Shoulder Girdle
- Articulation between clavicle and scapula
- Floating bones because they are only secured by muscle
Shoulder Girdle Set Position
Tell client to lift shoulder blades and then pull them back and down
Shoulder
Glenohumeral joint, where scapula and humerus articulate to allow movement of the upper limb
Rotator Cuff Muscles
- supraspinatus (posterior)
- infraspinatus (posterior)
- teres minor (posterior)
- subscapularis (anterior)
(SITS)
Rotator Cuff Function
- Allow rotation of humerus in the scapula and stabilize the shoulder joint
- Allows it to produce power and movement through full ROM
Elbow Joints
- Elbow
- Radioulnar joint (between radius and ulna)
Wrist Joint
- Articulation between radius and ulna bones and the proximal carpal bones in the hand
- Tendons of these muscles come together at the wrist and are bound together by a fibrous sheath called the flexor retinaculum, creating what is known as carpal tunnel
Hip Joint
- Articulation of the femur and pelvis
- Several ligaments help supposer this synovial ball and socket joint
Knee Joint
- Articulation between femur, tibia and patella
- Primary knee movements are flexion and extension, although rotation is possible in a fixed position
MCL and LCL
Medial and lateral collateral ligaments (MCL and LCL) provide lateral stability and prevents excessive side to side motion
ACL and PCL
Anterior and posterior cruciate ligaments (ACL and PCL) cross inside the knee joint. Internal stability and preventing displacement of the tibia and femur forwards or backwards
Ankle Joint
- Synovial joint formed by the articulation of the tibia, fibula and foot (talus)
- Synovial condyloid joint provides ability for dorsiflexion and plantar flexion as well as inversion and eversion
- They gain stability from ligaments
Core
- Entire trunk from ribcage and diaphragm to pelvis
- Muscles for the core (active subsystem of spinal stabilization) have been described by function and stabilizers or mobilizers
- Movement of torso comes from two joints - the spine and the pelvis
- Stabilizer and mobilizer systems work together to control neutral spine
Core Stabilizer Muscles
- Deep and short muscles
- Transverse abdominis, multifidus and intervertebral muscles that function to stabilize adjoining vertebrae and sacroiliac joint
- Control movement of spine and facilitate action of the mobilizer muscles
- Slow twitch (mainly) that produce continuous force with little to no shortening or resultant ROM
Core Mobilizer Muscles
- are larger and possess large lever arms that allow them to produce large amounts of torque and movement across greater ROM
Anterior Pelvic Tilt
- Front of pelvis tips forwards
- Increased curve in lumbar spine
- Tight erector spinae, iliopsoas and rectus femoris with weak transverse abdominis, hamstrings, external obliques and gluteus maximus muscles
Posterior Pelvic Tilt
- Back of pelvis tilts backwards
- Decreased curve in lumbar spine
- Tight hamstrings, rectus femoris and tensor fasciae latae and weak iliopsoas, erector spinae and multifidus muscles
Thoracolumbar Fascia (TLF)
- The sheath of connective tissue that covers key muscles in the centre of the trunk and lower back
- It is through this that forces are transferred from upper to lower extremities and vica-versa
Multifidus Muscles
- Entire length of spine attaching from one vertebra to another
- Muscles travels superiorly and medially from posterior surface of sacrum (origin) to attach to spinous processes of lumbar and sacral vertebrae (insertion)
- Because it is mainly slow twitch, multifidus acts primarily as a stabilizer, preparing the spine for movement, preventing injury and increasing stability in sacroiliac joint
- Atrophy in people with lower back pain and may compound lower back pain
Transverse Abdominis
- Deepest layer of abdominal muscles (under internal obliques)
- Fibers run in transverse plane (side to side) and wraps from posterior to anterior
- Origin: iliac crest and thoracolumbar fascia
- Insertion: midline of abdominal muscles (linea alba)
- Stabilize pelvis and spine as well as compress internal organs
Internal and External Obliques
- Stabilization of lumbar
- Internal pulls thoracolumbar fascia to increase lumbar stability but also works contralaterally with the opposite external oblique to create rotation in one direction and prevent rotation in the other
Erector Spinae: Superficial and Deep Muscles
- Erector spinae is a muscle group that runs vertically along spinal column
- Muscle mass is most pronounced in lumbar region and becomes smaller as muscle ascends
- Function: contract concentrically to produce lumbar extension, eccentrically to produce lumbar flexion and isometrically to control position of lower thorax with respect to the pelvis during functional movement
- Mainly slow twitch which makes you less susceptible to injury by eccentric contractions
Erector Spinae: Superficial and Deep Muscles Structure
- Erector spinae is a muscle group that runs vertically along spinal column
- Deep muscles originate from ilium and travel superiorly, medially and anteriorly to insert onto the lumbar transverse processes
- Attachment of deep erector spinae to lumbar transverse processes indicates that its function is not lumbar extension or flexion as superficial fibers do, but to compress the lumbar spine on to the sacrum, providing a stabilizing role
Iliopsoas
- Psoas Major and Iliacus Muscles
- Works with rectus femoris as a hip flexor and external rotator of the femur
- One tight side of hip flexor causes rotation of pelvis and may affect function of quadratus lumborum
Quadratus Lumborum
- Lower back
- Functions concentrically and eccentrically to control rate of descent in side bending
- Tight quadratus lumborum causes a lateral pelvic tilt
- This causes tension and dysfunction in other muscles leading to lower back pain
Raise in strength comes from
- Muscle fiber size
- Muscle contractile strength
- Coordination among muscle groups
- Muscle fiber recruitment
- Tendon and ligament contractile strength
- Bone strength
Muscle Strength
Max amount of force a muscle or group can generate
Muscle Power
Explosive strength and speed combined (force*distance)/time
Muscle Endurance
Ability of muscle to exert force over time
Frequency for Resistance Training Program Design
- 3 or more sessions a week
- 48 hours of rest is a general rule
- Endurance can train every other day
- Strength, power and hypertrophy may need more rest
Intensity for Resistance Training Program Design
- Choose reps they can complete with good form while considering their goal
- First 6-8 weeks provide extreme benefits due to improvements in motor unit recruitment of previously unused fibers
- Beginners start at low intensity and learn form
- Conditioned clients train at intensity higher than 70% of 1RM. Lower conditioned clients train at intensity lower than 70% of 1RM
- Consider goals
Type for Resistance Training Program Design
- Isometric; Gains only occur at specific joint angle at which exercise takes place rather than full ROM
- Isotonic: Concentric, Eccentric, Constant resistance, Variable Resistance
- Isokinetic: Controls speed of ROM
- Beginners start on machines. Move on to free weights and pulleys
- General strength and endurance: machines
- Functional strength and muscle growth: combination of equipment