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Functions of Muscle System

Movement, posture, heat production, support of soft tissues, guard entrances/exits to the body

Irritability

Sensitive to neurons and electric stimuli

Contractility

Can shorten in length (contraction) MUSCLES can ONLY shorten

Extensibility

Can stretch back to its originality length (relaxation)

Elasticity

Can Contract and relax without deforming

Gross Structure

Gross Anatomy - anything that can be seen with the naked eye

Origin

Usually proximal - fixed, immoveable attachment (Biceps brachiai)

Insertion

Usually distal - moveable attachment point

Belly

Fleshy - thickened portion consisting of skeletal muscle

Tendon

Connective Tissue of muscle continuous with periosteum of bone (attaches muscle to bone)

Aponeurosis

Flattened sheet like tendon between muscle bellies (muscle to muscle) Broad, flat, sheet like connective tissue that connects muscles to a bone or another muscle

Types of Tendons

Aponeurosis - Retinaculum - Tendon Sheath

Retinaculum

Thin, strong, connective tissue covering groups of tendons to hold them in place.

Tendon Sheath

Protective connective tissue that covers tendons passing over bony prominenus.

Fascia

Connective tissue that seperates and holds muscles in relative position. Thin layer of connective tissue covering, supporting, or connecting the muscles or inner organs of the body

Epimysium

Connective tissue that covers the entire muscle belly

Perimysium

Connective tissue that binds goups of muscle fibers into fasicles.

Endomysium

Connective tissue that covers individual muscle fibers

Microscopic (cellular) Structure

Muscle Fiber (cell)

Sarco

Muscle

Sarcolemma

Cell membrane of skeletal muscle cell. It is constantly charged.

Sarcoplasm

CYTOPLASM OF MUSCLE CELL Lots of mitochondria (site of aerobic respiration)

Sarcoplasmic Reticulum

Smooth ER - Ends in pouch like terminal cisternae, stores calcium ions that are released under stimulations...Takes up Calcium Ions "hostage" Creates strong concentration gradient. Modified form of endoplasmic reticulum, which stores calcium used to trigger contraction when the muscle is stimulated.

Transverse Tubules

Invagination of sarcolemma into the cell. Perpendicular to SARCOPLASMIC RETICULUM / next to the terminal cisternae forming a TRIAD. Carry impulses rapidly into large cells.

Myofibrils

Group of myofilaments within sarcoplasm.

Myofilaments

Groups of proteins responsible for muscle contraction.

Types of Myofilaments

Actin - Myosin

Actin

Thin, myofilament (6nm diameter) double strand, helix; each protein has a binding site.

Myosin

Thick, myofilament (16nm diameter) heads bind to actin forming cross bridges; hinges 9necks0 allow for power stroke.

Regulatory Proteins

Tropomyosin and Troponin

Tropomyosin

Covers binding site on actin unless stimulated (can cover 5 active sites)., A protein that covers actin and blocks the binding sites

Troponin

Attached to move tropomyosin when Calcium is present, will only push the other out of the way if CA is present. , moves tropomyosin aside & exposes myosin binding sites when Ca+ is released

Sarcomere

Contractive unit of the cell (Z line to Z line)

Z - Line

Dense material perpendicular to the long axis of myofibril. Lies in the center of the I band; it is the ancor point for both myofilaments.

M - Line

2nd anchor point for myosin, located in the middle of the H - zone.

I - Band

Lighter band that contains Actin only. Runs from 1 myosin filament to the next crossing consecutive sarcomeres.

A - Band

Actin and Myosin, lenght of 1 myosin filament, contains the M-Line and the H-Zone.

H - Zone

Contains only Myosin. Runs from one Actin filament to the next.

Neuromuscular

Myoneural

Sensory Neurons (Afferent)

Carries impulses TOWARD the CNS. Neurons that carry incoming information from the sense receptors to the central nervous system.

Interneurons

Located in the Central Nervous System (these do the thinking).

Motorneurons

Carries impulses AWAY from the CNS. Neuron that carries message to the effector.

Axon Terminals

Distal ends of efferent neurons, contacts effector organs at synapse. Bulb like structers at end of axon contain neuro transmitters that carry neuron message into synapse

Synaptic Knobs

Enlarged ends of axons contains synaptic vesicles.

Synaptic Vesicles

Located within the synaptic knobs, contains and relases neurotransmitters.

Synaptic Cleft

Space between axon terminal and effectors.

Motor End Plate (MEP)

Portion of the sarcolemma specialized for neuron contact, it contains receptors.

Sliding Filament Theory of Muscle Contraction

1) Impulses reach axon terminal causing influx of Ca. 2) ACh is released via exocytosis of synaptic vesicles into synaptic cleft. 3) ACh binds to receptors on the MEP, chemically gated Na+ channels open. 4) Intracellular voltage goes from -70mv to -55mv, voltage gated Na+ channels open (Depolarization). 5) Action Potention along the sarcolemma into T-Tublules. 6) The membrane of the terminal cisternae charges, releasing Ca into Sarcoplasm. 7) Ca binds to Troponin, tropomyosin is moved from Actin to binding site. 8) Myosin heads bind to Actin and the POWER STROK occurs. 9) Sarcomere is shortened as Actin is pulled to the center.

Muscle Relaxation

1) Neuron stops firing, release of ACh stops. 2) In the symaptic cleft, ACh is broken down by acetylcholinesterase and reabsorbed. 3) In the muscle, Na+ channels close, Na+ and K+ pump reestablishes the electrical potential (repolarization). 4) Repolarization of the SR causes active transport of Ca back into the SR. 5) The Actin/Myosin bridges are broken, reactivating the myosin head. 6) With out Ca tropomyosin recovers the binding sites on actin. 7) Actin and myosin now passively slid past one another.

ATP

Glucose (stored as glycogen in cell) Oxygen (from CVS and Myoglobin)

Creatine Phosphate

Quick but easily exhausted source of energy (creatinine waste)

Energy Sources for Muscles

ATP - Creatine Phosphate

Muscle Fatigue

Causes 2 problems stemming from lack of oxygen and the switch from AEROBIC to ANAEROBIC cellular respiration. Lack of energy - Build up of Latic Acid

Lack of Energy

Anaerobic cellular respiration is much less efficient (only 2 instead of 32-38 ATP per glucose muscle)

Build Up of Lactic Acid

With no oxygen present, the pyruvate produced during glycolises is converted to latic acid. (disrupts pH balance, makes you sore).

Slow Twitch (Red)

Slow to contract, slow to fatigue. Contains numerous myoglobin. Found in muscles that contract for extended periods of time. Ex: postural muscle of the back.

Fast Twitch (White)

Rapid contraction, fatigue quickly. Little myoglobin, poorer blood supply than slow twitch. Ex: Extrensic eye muscles

All or None

Cell will fully contract is sufficiant stimulus (threshold) is present.

Twitch

a single contraction followed by relaxation

Latent Period

Time from stimulus to contraction

Contraction

Period of shortening of the muscle

Absolute Refractory period

time during which the muscle cell can't respond to stimuli

Realative Refractory Period

may respond if stimulus is great enough (greater than normal)

Contractual response

Temporal Summation - tetanhy (tetanus)

Temporal Summation

combonation of individual twitches that results in an increased force of contraction

Tetanhy (tetanus)

forceful, sustained contraction with no relaxation phase present

types of contractions

isometric - isotonic - isokinetic

isometric

cotraction with no shortening of muscle (no net movement)

isotonic (concentric)

contraction with shortening of muscle, movement occurs

isokinetic (eccentric)

contraction with lengthening of muscle, force of contration is less than the force being applied

signs of muscle pathology

paresis - athropy - paralysis - myalgia - myositis

paresis

muscle weakness

Atrophy

decrease cell size

Paralysis

loss of the ability to move body part

Myalgia

Muscle pain

Myositis

inflamation of the muscle

Muscular Dystrophy

progressive degeration of skeletal muscle tissue

Myasthenia gravis

degeneration of the ACh receptors on MEP (Paresis & Paralysis)

Neoplasia (New Growth)

Rhabdomyosarcoma - Leiomyoma - Leiomyosarcoma

Rhabdomyosarcoma

highly malignant tumor of striated muscle

Leiomyoma

benign tumor of smooth muscle (fibroid tumors)

Leiomyosarcoma

malignant tumor of smooth muscle

lavador muscle

elevates scapula

prime mover

muscle acting differently to produce a movement (bicep brachii)

Synergist

aids the prime mover

Antagonist

works against the prime mover

Muscles of Facial Expression

Epicranius - Obicularis oculi - Orbicularis oris - Buccinator - Zygomaticus - Platysma

Epicranius

moves scalp, eyebrows; wrinkles skin of forehead

Obicularis oculi

Closes the eye

Orbicularis oris

closes lips, protrudes lips as for kissing

Buccinator

Compresses cheeks against teeth and lips, whistling, blowing, keeps food between teeth, not lips

Zygomaticus

smiling muscle

Platysma

wide, flat muscle, covers lower mandible and anterior neck - draws corner of mouth downward

Muscles of Mastication

Masseter - Temporalis - Medial Pterygoid - Lateral Pterygoid

Masseter

Elevates mandible

Temporalis

Elevates mandible

Medial Pterygoid

elevates and protracts mandible; produces side-to-side movement of mandible

Lateral Pterygoid

elevates and protracts mandible; produces side-to-side movement of mandible

Muscles that move Head, nec, and Vertebral Column

Sternocleidmastoid - Splenius Capitis - Semispinalis capitis - Erector Spinae

Sternocleidmastoid

turns head & flexes neck

Splenius Capitis

superficial back of the neck muscle , can pull the head into an upright position

Semispinalis capitis

Extends the head, bends it to one side and rotates it. Sheetlike muscle extending upward from vertebrae in neck and thorax to occipital bone

Erector Spinae

iliocostalis group - longissimus group - spinalis group O: iliac crest; sacrum; lumbar spinous processes | I: iliocostalis = ribs; spinalis = spinous processes & skull; longissimus = ribs, transverse processes & mastoid process | A: extend vertebral column; maintain upright posture

Muscles that move the pectoral girdle

Serratus anterior - Pectoralis minor - Trapezius - Levator Scapulae - Rhomboid Major

Serratus anterior

muscles that rotate the scapula and elevate the rib cage

Pectoralis minor

a skeletal muscle that draws down the scapula or raises the ribs

Trapezius

either of two flat triangular muscles of the shoulder and upper back that are involved in moving the shoulders and arms

Levator Scapulae

only neck muscle that moves scapula

Rhomboid Major

Retracts and rotates scapula

Muscles that move the Brachium

Flexors - Extensors - Abductors - Rotators

Flexors

Coracobrachialis - Pectoralis Major

Extensors

Teres Major - Latissimus Dorsi

Abductors

Deltiod - Supraspinatus

Rotators

Subscapularis - Infraspinatus - Teres Minor

Coracobrachialis

Origin - Coracoid process. Insertion - Proximal end of humerus. Action - Adducts humerus.

Pectoralis Major

Chest muscle that causes shoulder flexion, adduction and horizontal adduction

Teres Major

teres muscle that moves the arm and rotates it medially

Latissimus Dorsi

Back muscle that causes shoulder extension, adduction, horizontal abduction and horizontal abduction

Deltiod

o: clavicle and acromion process, i: deltoid tuberosity, a: abducts brachium (shoulder)

Supraspinatus

O: supraspinous fossa of scapula | I: greater tubercle of humerus | A: enforce joint security of glenohumeral joint; abduction

Subscapularis

O-SUBSCAPULAR FOSSA OF SCAPULA/ I- LESSER TUBERCLE OF THE HUMERUS/ A- MEDIALLY ROTATES THE ARM (right below the shoulder)

Infraspinatus

muscle beneath the spine of the scapula (shoulder blade) O-INFRASPINOUS FOSSA OF THE SCAPULA/ I- GREATER TUBERCLE OF THE HUMERUS/ A- LATERALLY ROTATES HUMERUS

Teres Minor

O-LATERAL BORDER OF THE SCAPULA/ I-GREATER TUBERCLE OF THE HUMERUS/ A-ADDUCTS AND LATERALLY ROTATES HUMERUS (Axillary)

Muscles of the Antibrachium

Flexors - Rotators - Extensor

Flexors

Biceps brachii - Brachialis - Brachoradialis

Rotators

Supinator - Pronator teres - Pronator quadratus

Extensor

Triceps barchii

Biceps brachii

ORIGIN
Long head:supraglenoid tubercle of scapula. Short head: coracoid process of scapula with coracobrachialis
INSERTION
posterior border of bicipital tuberosity of radius (over bursa) and bicipital aponeurosis to deep fascia and subcutaneous ulna
ACTION
Supinates forearm, flexes elbow, weakly flexes shoulder
NERVE
Musculocutaneous nerve (C5, 6) (from lateral cord)

Brachialis

O: scapula | I: radial tuberosity (radius) | A: flexes shoulder; flexes elbow; supinates hand

Brachioradialis

O-RIDGE ABOVE LATERAL EPICONDYLE OF THE HUMERUS/ I-ABOVE THE STYLOID PROCESS ON THE RADIUS/ A-FLEXES FOREARM

Supinator

O: lateral epicondyle of humerus | I: radius | A: supinate forearm

Pronator teres

O= medial epicondyle of humerus and coronoid process of ulna. I= lateral radius, midshaft. F= forearm pronation

Pronator quadratus

O= anterior distal ulna. I= anterior distal radius. F= forearm pronation

Triceps brachii

Origin - Scapula and Humerus; Insertion - Ulna; Action - Extend the forearm

Muscles that move the hand

Flexors - Extensors

Flexors

Flexor carpi radialis - Palmaris longus - Flexor Carpi Ulnaris - Flexor digitorum superficialis

Flexor carpi radialis

O: medial epicondyle of humerus | I: 2nd and 3rd metacarpels | A: flexes hand at the wrist; aids in wrist abduction

Palmaris longus

Origin - Medial epicondyle of humerus. Insertion - Proximal phalanges of digits 2 to 5. Action - Flexes proximal phalanges.

Flexor Carpi Ulnaris

O: medial epicondyle of humerus; olecranon of ulna | I: pisiform bone; 5th metacarpel | A: flexes and adducts hand at the wrist

Flexor digitorum superficialis

Origin: Humeroulnar Head: Medial Epicondyle of Humerous (common flexor tendon) & Coronoid on Ulna,Insertion: Four tendons attaching to anterior of middle phalanges on fingers 2-5 Actions: Flexes Fingers 2-5 at PIP, Flexion of Hand at Wrist and Flexion of arm at elbow.

Extensors

Extensor carpi radialis longus - Extensor carpi radialis brevis - Extensor digitorum - Extensor carpi unlaris

Extensor carpi radialis longus

originates on lateral epicondoyle, inserts on base of second metacarpal, extends and radially deviates hand at wrist

Extensor carpi radialis brevis

Origin - Lateral epicondyle of humerus. Insertion - Base of thrid metacarpal. Action - Extends hand.

Extensor digitorum

O: lateral epicondyle of humerus I: 4 tendons to the base of proximal phlanx of 4 fingers PRIMARY ACTION: finger extension

Extensor carpi ulnaris

O= lateral epicondyle of humerus and posterior ulna. I= dorsal base of 5th metacarpal. F= wrist extension and ulnar deviation

Abdominal Muscles

External abdominal oblique - Transversus abdominus - Internal abdominal oblique - Rectus abdominus

External abdominal oblique

origins-thoracolumbar fascia of last rib, insertion-linea alba, use-flexes vertebral column/ abdominal press

Transversus abdominus

Innermost abdominal muscle; fibers run transversely; attaches to the 7-12th costal cartilages, iliac crest, lateral third of inguinal ligament and linea alba

Internal abdominal oblique

o: iliac crest; i: linea alba and costal cartilage of last 3-4 ribs; compresses abdomen

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