THE MUSCULAR SYSTEM
ALL THE MUSCLES
Frontalis
Action: raises eyebrows and wrinkles forehead.
Orbicularis Oculi
Action: closes eyelids; used in blinking, winking, and squinting.
Orbicularis Oculi
Action: closes eyelids; used in blinking, winking, and squinting.
Risorius
Action: draws lips into the grinning expression;
Buccinator
Action: compresses cheek, allowing for rapid changes in volume of mouth cavity
Masseter
Action: raises the lower jaw and is used in chewing.
Temporalis
Action: closes jaw, elevates and retracts mandible; Description: muscle extending from the temporal fossa to the coronoid process of the mandible.
Medial pterygoid
Action: elevates and protracts and moves mandible from side to side
lateral pterygoid
Action: grinding movement, depresses and protracts mandible and moves it from side to side.
Mylohyoid
Action: elevates the hyoid and base of the tongue. Forms the floor of the mouth.
Stylohyoid
Action: elevates and retracts the hyoid bone during swallowing.
Digastric
Action: elevates the hyoid bone. Depresses the mandible (opens the mouth).
Sternohyoid
Action: depresses the larynx and hyoid bone.
Sternothyroid
Action: depresses the larynx and hyoid bone.
sternocleidomastoid
Action: flexion of neck forward, rotates the head to opposite shoulder.
Scalenes
Action: elevates ribs 1 and 2, aid in inspiration.
Splenius
Action: extends or hyperextends the head. rotates head to same side of the muscle.
Diaphragm
Action: Respiration, most important muscle in inspiration.
Internal intercostal
Action: draw ribs downward and inward to compress thoracic cavity and force air from lungs; not needed for relaxed expiration.
External intercostal
Action: pulls ribs toward one another to elevate rib cage.
Rectus abdominus
Action: flexes and rotates vertebral column.
Transverse abdominus
Action: compresses abdominal content.
Quadratus lumborum
Action: laterally flexes the spine.
Erector spinae
Action: extends the vertebral column laterally.
Major pectoralis
Action: rotates the arm.
Minor pectoralis
Action: rotates the arm.
Serratus anterior
Action: prime mover that holds the scapula against the ribs.
Trapezius
Action: raises, rotates, and adducts the arm.
Levator scapula
Action: elevates and adducts the scapula.
Rhomboid
Action: stabilize and retract scapula; pulls shoulders back (2 muscles).
Latissimus Dorsi
Action: extends, adducts, and medially rotates the arm; draws the shoulder downward and backward.
Coracobrachialis
Action: flexes the humerus,assists to adduct the humerus; Origin: coracoid process of the scapula; Insertion: medial shaft of the humerus at about its middle.
Deltoid
A large triangular muscle covering the shoulder joint and serving to abduct and flex and extend and rotate the arm
Teres Major
Action: extends and medially rotates humerus; contributes to arm swinging. Origin: Inferior angle of scapula. Insertion: Medial lip of intertubercular sulcus of humerus.
SUPRASPINATUS
Abducts arm; stabilizes the head of the humerus in glenoid cavity; one of the "rotator cuff" muscles
Infraspinatus
Laterally rotates shoulder; stabilizes the head of the humerus in glenoid cavity; one of the "rotator cuff" muscles
Teres Minor
Teres muscle that adducts the arm and rotates it laterally
Subscapularis
O: inner surface of scapula | I: lesser tubercle of humerus | A: medial rotation of humerus
Brachialis
Muscle that lies underneath the biceps and is the strongest flexor of the forearm.
Brachioradialis
Superficial, lateral forearm muscle. Synergist in forearm flexion. Stabilizes elbow.
Biceps Brachii
A muscle that flexes and supinates the forearm, powerful flexor of forearm; origin is glenoid process and coracoid process of scapula, insertion is radial tuberosity.
Triceps Brachii
The skeletal muscle having three origins that extends the forearm when it contracts.
Supinator
Action: supinates the forearm; Origin: lateral epicondyle of humerus, proximal ulna; Insertion: proximal end of radius
Flexor Carpi Radialis
Powerful wrist flexor; abducts hand. Origin: medial epicondyle of humerus; Insertion: palmar aponeurosis.
Flexor Carpi Ulnaris
Action: flexes wrist and adducts hand; Origin: medial epicondyle of humerus; olecranon of ulna; Insertion: pisiform bone; 5th metacarpal.
Extensor Carpi Radialis
Action: extends & abducts wrist; Orgin: lateral supracondylar ridge of humerous., insertion: base of metacarpal 2 and 3.
Extensor Carpi Ulnaris
Action: extends and adducts wrist; Origin: lateral epicondyle of humerus; posterior border of ulnar. Insertion: Base of metacarpal 5.
Flexor Digitorum Superficialis
Action: flexes wrist and middle phalanges of fingers 2-5. Deeper muscle , visible at distal end of forearm.
Extensor Digitorum
Action: prime mover of finger extension. Extends wrist; Origin: lateral epicondyle of humerus. Insertion: dorsal surfaces of phalanges II - V.
Abductor Pollicis Longus
Action: abducts and extends thumb. Origin: posterior surface of radius and ulna; Insertion metacarpal 1 and trapezium.
Extensor Pollicis Longus
Action: extends thumb; Origin: dorsal shaft of ulna and radius; Insertion: base of distal phalanx of thumb
Iliacus
Flexes thigh at the hip
Psoas
either of two muscles of the abdomen and pelvis that flex the trunk and rotate the thigh
Gluteus Maximus
heaviest muscle in body, extends/straightens leg at hip during walking
Gluteus Medius
Medially rotates thigh; abducts the hip
Gluteus Minimus
Medially rotates thigh; abducts the hip
Piriformis
originates on anterior surface of pelvis, inserts on greater trochanter, rotates hip laterally and abducts flexed thigh at hip
Adductor Longus:
Adducts and flexes thigh at the hip; assists in medial rotation
Adductor Magnus: Adducts and extends thigh at the hip; assists in medial rotation
Pectineus
Adducts and flexes thigh at the hip
Gracilis
Adducts thigh at the hip and flexes leg at the knee; assists in medial rotation
Sartorius
a muscle in the thigh that helps to rotate the leg into the sitting position assumed by a tailor
Rectus Femoris
part of quadriceps group, extends leg at knee
Vastus Lateralis
Extends leg at the knee; part of the quadriceps group
Vastus Medialis
Extends leg at the knee; part of the quadriceps group
Vastus Imtermedius
Action: extension of leg; Origin: femur (anterolateral surface of shaft); Insertion: patella (via a common quadriceps tendon)
Hamstrings Semitendinosus
Action: flexes leg at knee; extends thigh at hip. Origin: ischial tuberosity. Insertion: shaft of tibia. Location: medial to biceps femoris, superficial to semimembranosus. Nerve: sciatic
Hamstrings Semimembranosus
Action: flexes leg at knee; extends thigh at hip. Origin: ischial tuberosity. Insertion: medial condyle of tibia. Location: medial hamstring. Nerve: sciatic
Hamstrings Bicep Femoris
O:ischial tuberosity, distal femur
I: tendon to insert into head of fibula and lateral condyle of tibia
A: Extends thigh and flexes knee
Popliteus
originates on lateral condyle of femur, inserts on posterior surface of tibia, brings knee out of locked full extension
Gastrocnemius
the muscle in the back part of the leg that forms the greater part of the calf
Soleus
a broad flat muscle in the calf of the leg under the gastrocnemius muscle
Anterior Tibialis
front of shin, flexes ankle
Tibialis Posterior
Plantar flexion and inversion of foot
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
Extensor Digitorum Longs
O: lateral tibial condyle, interosseous membrane, fibula (prox 3/4) I: via tendon to middle and distal phalanges of 2-5 toes A: PRIME MOVER toe ext, dorsiflexion of foot synergist of tib ant and extensor hallicus longus
Peroneus Longus
Plantar flexion and eversion of foot; stabilizes the lateral ankle and arch of the foot
Tensor Fascia Lata
anterior part of the external lip of iliac crest, outer surface of ASIS, and deep surface of fascia lata
MUSCLE TYPES
attaches to bones (skeletal)
found in walls of hollow organs, blood vessels, and glands (smooth muscle)
found in heart (cardiac)
involuntary (no conscious control) (SMOOTH AND CARDIAC)
voluntary control (skeletal)
has striations (skeletal and cardiac)
has intercalated disks (cardiac)
long, cylindrical cell shapes with no branching (skeletal)
cells are branched cylinders (cardiac)
cells contain many nuclei (multi-nucleated) that are peripherally located (skeletal)
cells are uninucleated (smooth and cardiac)
THREE TYPES: SKELETAL, CARDIAC, SMOOTH
Physiology of Muscle Contraction (SLIDING FILAMENT THEORY)
(Step 1:) Muscle activation: The motor nerve stimulates an action potential (impulse) to pass down a neuron to the neuromuscular junction. This stimulates the sarcoplasmic reticulum to release calcium into the muscle cell.
(STEP 2): Muscle activation: The motor nerve stimulates an action potential (impulse) to pass down a neuron to the neuromuscular junction. This stimulates the sarcoplasmic reticulum to release calcium into the muscle cell.
(STEP 3): Recharging: ATP is re-synthesised (re-manufactured) allowing actin and myosin to maintain their strong binding state
(STEP4): Relaxation: Relaxation occurs when stimulation of the nerve stops. Calcium is then pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin. Actin and myosin return to their unbound state causing the muscle to relax.
HOW TO STOP MUSCLE CONTRACTION:
. Energy system fatigue: There is no more ATP left in the muscle cell so it can’t keep contracting
Nervous system fatigue: The nervous system is not able to create impulses sufficiently or quickly enough to maintain the stimulus and cause calcium to release.
Voluntary nervous system control: The nerve that tells the muscle to contract stops sending that signal because the brain tells it to, so no more calcium ions will enter the muscle cell and the contraction stops.
Sensory nervous system information: For example, a sensory neuron (nerves that detect stimuli like pain or how heavy something is) provides feedback to the brain indicating that a muscle is injured while you are trying to lift a heavy weight and consequently the impulse to that muscle telling it to contract is stopped.
Body
movement terminology structure and organizational levels of the skeletal muscle (pg 283 and 285)
MUSCLE: a muscle consists of hundreds to thousands of muscle cells, plus connective tissue wrappings, blood vessels, and nerve fibers. It is covered externally by the Epimysium
FASCICLE: a fascicle is a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath. Surrounded by perimysium
MUSCLE FIBER: a muscle fiber is an elongated multinucleate cell; it has a banded (striated) appearance. Surrounded by endomysium
MYOFIBRIL: myofibrils are rodlike contractile elements that occupy most of the muscle cell volume. Composed of sarcomeres arranged end to end, they appear banded, and bands of adjacent myofibrils are aligned.
SARCOMERE: a sacromere is the contractile unit, composed of myofilament made up of contractile proteins.
MYOFILAMENT: contractile myofilament are two types--thick or thin. Thick filaments contain bundled myosin molecules; thick filaments contain bundled myosin molecules; thin filaments contain actin molecules (plus other proteins). The sliding of the thin filaments past the thick filaments produces muscle shortening. Elastic filaments provide elastic recoil when tension is released and help maintain myofilament organization.
SACROMERE
M line
Thick (myosin) filament
A band
Thin (actin) filament
I band
Sacrolemma= membrane