Functions of Muscle System
Movement, posture, heat production, support of soft tissues, guard entrances/exits to the body
Sensitive to neurons and electric stimuli
Can shorten in length (contraction) MUSCLES can ONLY shorten
Can stretch back to its originality length (relaxation)
Can Contract and relax without deforming
Gross Anatomy - anything that can be seen with the naked eye
Usually proximal - fixed, immoveable attachment (Biceps brachiai)
Usually distal - moveable attachment point
Fleshy - thickened portion consisting of skeletal muscle
Connective Tissue of muscle continuous with periosteum of bone (attaches muscle to bone)
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
Thin, strong, connective tissue covering groups of tendons to hold them in place.
Protective connective tissue that covers tendons passing over bony prominenus.
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
Connective tissue that covers the entire muscle belly
Connective tissue that binds goups of muscle fibers into fasicles.
Connective tissue that covers individual muscle fibers
Microscopic (cellular) Structure
Muscle Fiber (cell)
Cell membrane of skeletal muscle cell. It is constantly charged.
CYTOPLASM OF MUSCLE CELL Lots of mitochondria (site of aerobic respiration)
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.
Invagination of sarcolemma into the cell. Perpendicular to SARCOPLASMIC RETICULUM / next to the terminal cisternae forming a TRIAD. Carry impulses rapidly into large cells.
Group of myofilaments within sarcoplasm.
Groups of proteins responsible for muscle contraction.
Types of Myofilaments
Actin - Myosin
Thin, myofilament (6nm diameter) double strand, helix; each protein has a binding site.
Thick, myofilament (16nm diameter) heads bind to actin forming cross bridges; hinges 9necks0 allow for power stroke.
Tropomyosin and Troponin
Covers binding site on actin unless stimulated (can cover 5 active sites)., A protein that covers actin and blocks the binding sites
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
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.
Sensory Neurons (Afferent)
Carries impulses TOWARD the CNS. Neurons that carry incoming information from the sense receptors to the central nervous system.
Located in the Central Nervous System (these do the thinking).
Carries impulses AWAY from the CNS. Neuron that carries message to the effector.
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
Enlarged ends of axons contains synaptic vesicles.
Located within the synaptic knobs, contains and relases neurotransmitters.
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.
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.
Glucose (stored as glycogen in cell) Oxygen (from CVS and Myoglobin)
Quick but easily exhausted source of energy (creatinine waste)
Energy Sources for Muscles
ATP - Creatine Phosphate
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.
a single contraction followed by relaxation
Time from stimulus to 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)
Temporal Summation - tetanhy (tetanus)
combonation of individual twitches that results in an increased force of contraction
forceful, sustained contraction with no relaxation phase present
types of contractions
isometric - isotonic - isokinetic
cotraction with no shortening of muscle (no net movement)
contraction with shortening of muscle, movement occurs
contraction with lengthening of muscle, force of contration is less than the force being applied
signs of muscle pathology
paresis - athropy - paralysis - myalgia - myositis
decrease cell size
loss of the ability to move body part
inflamation of the muscle
progressive degeration of skeletal muscle tissue
degeneration of the ACh receptors on MEP (Paresis & Paralysis)
Neoplasia (New Growth)
Rhabdomyosarcoma - Leiomyoma - Leiomyosarcoma
highly malignant tumor of striated muscle
benign tumor of smooth muscle (fibroid tumors)
malignant tumor of smooth muscle
muscle acting differently to produce a movement (bicep brachii)
aids the prime mover
works against the prime mover
Muscles of Facial Expression
Epicranius - Obicularis oculi - Orbicularis oris - Buccinator - Zygomaticus - Platysma
moves scalp, eyebrows; wrinkles skin of forehead
Closes the eye
closes lips, protrudes lips as for kissing
Compresses cheeks against teeth and lips, whistling, blowing, keeps food between teeth, not lips
wide, flat muscle, covers lower mandible and anterior neck - draws corner of mouth downward
Muscles of Mastication
Masseter - Temporalis - Medial Pterygoid - Lateral Pterygoid
elevates and protracts mandible; produces side-to-side movement of mandible
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
turns head & flexes neck
superficial back of the neck muscle , can pull the head into an upright position
Extends the head, bends it to one side and rotates it. Sheetlike muscle extending upward from vertebrae in neck and thorax to occipital bone
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
muscles that rotate the scapula and elevate the rib cage
a skeletal muscle that draws down the scapula or raises the ribs
either of two flat triangular muscles of the shoulder and upper back that are involved in moving the shoulders and arms
only neck muscle that moves scapula
Retracts and rotates scapula
Muscles that move the Brachium
Flexors - Extensors - Abductors - Rotators
Coracobrachialis - Pectoralis Major
Teres Major - Latissimus Dorsi
Deltiod - Supraspinatus
Subscapularis - Infraspinatus - Teres Minor
Origin - Coracoid process. Insertion - Proximal end of humerus. Action - Adducts humerus.
Chest muscle that causes shoulder flexion, adduction and horizontal adduction
teres muscle that moves the arm and rotates it medially
Back muscle that causes shoulder extension, adduction, horizontal abduction and horizontal abduction
o: clavicle and acromion process, i: deltoid tuberosity, a: abducts brachium (shoulder)
O: supraspinous fossa of scapula | I: greater tubercle of humerus | A: enforce joint security of glenohumeral joint; abduction
O-SUBSCAPULAR FOSSA OF SCAPULA/ I- LESSER TUBERCLE OF THE HUMERUS/ A- MEDIALLY ROTATES THE ARM (right below the shoulder)
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
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
Biceps brachii - Brachialis - Brachoradialis
Supinator - Pronator teres - Pronator quadratus
Long head:supraglenoid tubercle of scapula. Short head: coracoid process of scapula with coracobrachialis
posterior border of bicipital tuberosity of radius (over bursa) and bicipital aponeurosis to deep fascia and subcutaneous ulna
Supinates forearm, flexes elbow, weakly flexes shoulder
Musculocutaneous nerve (C5, 6) (from lateral cord)
O: scapula | I: radial tuberosity (radius) | A: flexes shoulder; flexes elbow; supinates hand
O-RIDGE ABOVE LATERAL EPICONDYLE OF THE HUMERUS/ I-ABOVE THE STYLOID PROCESS ON THE RADIUS/ A-FLEXES FOREARM
O: lateral epicondyle of humerus | I: radius | A: supinate forearm
O= medial epicondyle of humerus and coronoid process of ulna. I= lateral radius, midshaft. F= forearm pronation
O= anterior distal ulna. I= anterior distal radius. F= forearm pronation
Origin - Scapula and Humerus; Insertion - Ulna; Action - Extend the forearm
Muscles that move the hand
Flexors - Extensors
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
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.
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.
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
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
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
O- SUPERIOR RAMUS OF PUBIS/ I- XIPHOID PROCESS AND COSTAL CARTILAGE OF RIBS 5 TO 7/ A- COMPRESS ABDOMEN AND FLEX VERTEBRAL COLUMN
Muscles that move the thigh
Iliacus - Psoas - Gluteus Maximus - Gluteus Medius - Gletus Minimus - Tensor fasciae latae - Pectineus - Gracilis - Adductor longus - Adductor magnus
O-ILIAC FOSSA/ I-LESSER TROCHANTER VIA ILIOPSOAS TO FEMUR/ A-WITH PSOAS MAJOR FLEXES THIGH; FLEXES VERTEBRAL COLUMN AND PELVIS ON FEMUR AS IN SIT UP
O: anterior surface and transverse processes of T12-L5. I: lesser trochanter. A: flexion at the hip
O: iliac crest; sacrum; cocyx | I: femur | A: extends and laterally rotates thigh; abducts and adducts thigh
o: illiam; i: proximal femur; abducts thigh
O: ilium | I: greater trochanter of femur | A: abducts and medially rotates thigh
Tensor fasciae latae
o: iliac crest i: tibia a: flexes, abducts and medially rotates thigh
O: pubic bone | I: femur | A: adducts and flexes thigh; assists with medial rotation of thigh
O-INFERIOR RAMIS OF THE PUBIS/ I- PROXIMAL MEDIAL SURFACE OF THE TIBIA/ A- ADDUCTS THE THIGH
O: public bone | I: linea aspera of femur | A: adducts the thigh
O: pubic bone; ischium | I: gluteal tuberosity of femur; linea aspera of femur | A: adducts thigh
Muscles that move the leg
Extensors (Vastus lateralis, Rectus femoris, Vastus medialis, Vastus intermedius, sartorius) Felxors (Biceps femoris, semitendinosus, Semimembranosus)
O: greater trochanter and linea aspera of femur | I: quadriceps tendon | A: extends knee
O-ANTERIOR INFERIOR ILIAC SPINE/ I-TIBIAL TUBEROSITY/ A-FLEXES THIGH
O- LINEA ASPERA/ I- TIBIAL TUBEROSITY/ A-EXTENDS THE LEG
O: femur | I: quadriceps tendon | A: extends knee
O-ANTERIOR SUPERIOR ILIAC SPINE OF THE ILIUM/ I-PROXIMAL MEDIAL SURFACE OF THE TIBIA/ A- FLEXES AND ROTATES THIGH LATERALLY AND FLEXES THE LEG THUS PLACING THE HEAL ON OPPOSITE KNEE
O-ISCHIAL TUBEROSITY AND THE LINEA ASPERA/ I-HEAD OF FIBULA/ A-EXTENDS THIGH AND FLEXES LEG
O: ischial tuberosity | I: tibia | A: flexes knee; medially rotates tibia; extends thigh/hip
O: ischial tuberosity | I: medial epicondyle of tibia | A: flexes leg at knee; rotates flexed log laterally; extend thigh at hip joint
Muscles that move the foot
Dorsal Flexors (Tibialis anterior, Peroneus tertius, Extensor Digitorum Longus) Plantar Flexors (Gastrocnemius, Flexor digitorum longus, soleus) Everter (peroneus longus) Inverter (Tibialis posterior)
O: ANTEROLATERAL SURFACE OF THE TIBIA/ I: METATARSAL 1/ A: DORSIFLEXES THE FOOT
Origin - Middle of fibula. Insertion - Tendon of extensor digitorum longus. Action - Extends and abducts digits.
Extensor Digitorum Longus
O: tibia; fibula | I: middle and distal phalnges of toes | A: dorsiflexion; extends toes
O-ABOVE LATERAL AND MEDIAL CONDYLE OF FEMUR/ I-CALCANEUS BY WAY OF ACHILLES TENDON/ A-PLANTAR FLEXES THE FOOR AND FLEXES LEG
Flexor digitorum longus
O: tibia | I: bases of distal phlanges of toes | A: flexes 4 lateral digits; plantarflexion; aids with inversion; supports foot longitudinal arches; helps toes grip the ground
O: fibula; tibia | I: calcaneal tendon | A: plantarflexion
Origin - Head and shaft of fibula. Insertion - Bases of metatarsals. Action - Extends foot.
O: interosseous membrane; tibia; fibula | I: metatarsels; tarsels |A: plantarflexion; inversion
Extrensic Ocular Muscles
Lateral rectus, Medial Rectus, Superior Rectus, Inferior Rectus, Superior Oblique, Inferior Oblique
ORIGIN: tendinous ring attached to bony orbit around optic foramen. INSERTION: lateral side of eyeball. Action: rolls eyeball laterally.
ORIGIN: tendinous ring attached to bony orbit around optic foramen. INSERTION: medial side of eyeball. ACTION: rolls eyeball medially.
ORIGIN: tendinous ring attached to bony orbit around optic foramen. INSERTION: superior and central part of eyeball. ACTION: rolls eyeball superiorly.
ORIGIN: tendinous ring attached to bony orbit around optic foramen. INSERTION: inferior and central part of eyeball. ACTION: rolls eyeball inferiorly.
[O] Sphenoid [I] Sclera of eyeball [A] Rotates eye inferiorly and laterally (intortion—eye looks down simultaneously )
[O] Maxilla (Orbit) [I] Sclera of eyeball [A] Rotates eye superiorly and laterally (extortion—eyes look down simultaneously)
Muscles of the tongue
Genioglossus, Styloglossus, Hyoglossus
Origin - Medial surface of mandible. Insertion - Root of tongue. Action - Draws root of tongue forward.
Origin - Mastoid process of skull. Insertion - Apex of tongue. Action - Retracts tongue.
Origin - Body of hyoid bone. Insertion - Dorsum of tongue. Action - Retracts tongue.
Muscles of Resperation
Internal intercostals, external intercostals, Diaphragm
O: superior border of rib I: inferior border of rib A: depresses ribs
O: inferior border of rib I: superior border of rib A: elevates ribs
O: xiphoid process; costal cartilage of lower 6 ribs; L1-L3 vertebrae | I: central tendon (connects two 1/2's of diaphragm) | A: increases volume of thoracic cavity during inspiration