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Natalia Hernandez P.2 Muscular System - Coggle Diagram
Natalia Hernandez P.2
Muscular System
Major Functions
Produce movement: all locomotion & manipulation (ex:walking, digesting, pumping blood)
Maintain posture and body position (ex:upright)
Stabilize joints: muscle tendons stretch over joints & contribute to joint stability
Generate heat as they contract (ex: shivering)
Muscle Coverings: CT sheaths support cells & reinforce whole muscle
Epimysium:
dense irregular CT surrounding entire muscle; may blend w/ fascia
Endomysium:
fine areolar CT surrounding each muscle fiber
Perimysium:
fibrous CT surrounding fascicles (groups of muscle fibers)
Types of Muscles
Skeletal muscle
Function
: allow for voluntary movement
Location:
attached to bones or skin
Description
: long & cylindrical, cells have multiple nuclei, there are striations (linear marks); have nerve &
blood supply, connective tissue sheaths, & attachments
Cardiac muscle
Description
: tissue branches, have striations, usually one nucleus; interrelated discs (where cells connect)
Function
: propels blood into circulation through contraction; involuntary
Location
: walls of the heart
Smooth muscle
Description
: cells taper at ends (spindle shape), have central nuclei, no striations, close to one another
Function
: propels substances or objects (baby) along internal passageway; involuntary
Location
: walls of hollow organs
*All muscles have excitability (responsiveness), contractility (ability to shorten), extensibility (ability to be stretched), & elasticity (ability to recoil).
Name of all the Skeletal Muscles
Head & Neck
Frontalis
(muscle of forehead)
Temporalis
(temporal muscle)
Orbicularis oculi
(eyelid muscles)
Zygomaticus
Masseter
( thick, rectangular facial muscle)
Orbicularis oris
(muscle around mouth
Occipitalis
(muscle arising from occipital bone)
Sternohyoid
(flat muscle extending between sternum & hyoid bone)
Sternocleidomastoid
(superficial and largest muscle in front neck)
Trapezius
(extends from back of neck & shoulders trapezoid-shaped)
Upper limbs
Deltoid
(muscles in shoulder
Biceps brachii
(large anterior muscle in upper arm)
Brachialis
(muscle just beneath beneath the biceps brachii muscle)
Triceps brachii
(large muscle on dorsal part of upper arm
Brachioradialis
(superficial, lateral forearm muscle)
Flexor carpi radialis
(superficial forearm msucle responsible for wrist flexion & abduction)
Palmaris longus
(between radialis & ulnaris
Flexor carpi ulnaris
(adducts and flexes wrist)
Extensor carpi radialis longus
(posterior compartment)
Extensor digitorum
(muscle of the posterior forearm)
Extensor carpi ulnaris
(posterior compartment)
Lower Limb
Iliopsoas
(muslce connecting spine to lower limbs)
Pectineus
(flat quadrangular muscle situated in the upper thigh
Tensor fasciae latae
(muscle in lateral portion of upper thigh)
Sartorius
(long, superficial muscle running down anterior thigh
Adductor longus
(large, fan-shaped muscle located in medial part of thigh.
Gracilis
(thin muscle located in medial thigh)
Vastus lateralis
(lateral side of the thigh, a quadricep)
Rectus femoris
(middle quadricep)
Vastus medialus
(medial quadricep)
Iliotibial band
(band of tissue that runs down outside of thigh)
Biceps femoris
(long muscle in posterior, a hamstring)
Semitendinosus
(hamstring)
Semimembranosus
(medial hamstring)
Tibialis
(long muscle in anterior compartment of leg)
Extensor digitorum longus
(lateral muscle in anterior)
Fibularis longus
(also lateral)
Gastrocnemius
(chief calf muscle)
Soleus
(just below knee to the heel)
Calcaneal
(Achilles) tendon
Torso
Pectoralis major
(large, superficial muscle found in anterior chest wall
Serratus anterior
(fan-shaped muscle below armpits)
External oblique
Rectus abdominis
(ab muscles)
Trapezius
Infraspinatus
(thick triangular muscle located at back of shoulder
Teres major
(rectangular muscle attaching to scapula)
Rhomboid major
(quadrangular muscle connecting scapula with the vertebrae
Latissimus dorsi
( flat muscle on back)
Gluteus maximus
Gluteus medius
Disorders associated with the Muscular system
Muscular Dystrophy:
genetic disease that damages muscle fibers; symptoms include muscle atrophy; treatment = no known cure, but surgery is a possibility
Fibromyalgia:
pain & tenderness of the muscle, joints, & tissues; can be caused by physical trauma and infection; more common in women; symptoms include depression; treatment: physical therapy
Myasthenia Gravis:
autoimmune disease that causes muscle weakness; more common in women; can cause facial paralysis & drooping eyelids; no known cure, thymectomy an option
Cerebral Palsy:
injury/abnormality to brain resulting in disconnect between brain & muscle movement; hypoxia a cause; can cause seizures and abnormal gait; no cure but surgical intervention possible
Myositis:
inflammation of skeletal muscles caused by an infection; autoimmune; can cause muscle weakness & myalgia; treatment includes antibiotics
Rigor mortis:
muscle stiffening after death (3-4 hours after); peak rigidity about 12 hours post.; due to increase of calcium levels b/c ATP no longer synthesized
Action potential in a muscle fiber
End plate potention:
ACh binds to ACH receptors, causes chem. gated ion channels to open so Na+ diffuses (some K+ too), interior of sarcolemma becomes postive; local depolarization called end plate potential
Depolarization:
generation & propagation of action potential; voltage-gated Na+ channels open when end plate potential causes enough change in membrane voltage to reach threshold (30); Na+ triggers AP for contraction, AP depolarizes sarcolemma
Repolarization:
restoration of resting conditions; Na+ v-gates close (Na+ pumped back) & K+ v-gates open, efflux of K+ brings cell back to initial resting membrane voltage; restored by 𝑁𝑎+ −𝐾+ pump
Refractory period
: muscle fiber cannot be stimulated for a specific amount of time, until repolarization complete
Neuromuscular Junction (also called motor end plates)
Synaptic cleft:
gel-filled space separating axon terminal & muscle fiber
Acetylcholine (ACh) floating around
Junctional folds:
infoldings of sarcolemma
contain millions of ACh
receptors
Axon terminal:
end of axon (extensions of motor neurons)
Synaptic vesicles: sac-like structures containing neurotransmitter acetylcholine (ACh)
Mitochondria: cell organelles; powerhouses that generate chem. energy
Sliding filament theory of muscle contraction
States that during contraction, thin actin filaments
slide past thick myosin filaments, causing actin & myosin to overlap more (in relaxed state, overlap only slighty @ ends)
Contraction:
the activation of cross bridges to generate force; shortening occurs when tension generated by cross bridges on thin filaments exceeds forces opposing shortening
Cross bridges form when nervous system stimulates muscle fiber (by sending an impulse) & then myosin heads bind to actin; thin filaments pulled little closer toward center of sarcomere
binding site revealed when calcium attaches to troponin, which causes tropomyosin to move & expose binding site
Sarcomere: smallest contractile unit of muscle fiber
A band (dark regions)
H zone (lighter region): only thick myosin filament & M line (myomesin)
overall, consists of myosin, thin actin filament & myomesin
1/2 of
I band
(lighter region)
Z line (sarcomere ends here): coin-shaped sheet of proteins
Thin actin filament (tropomyosin, troponin, actin)
Titin (elastic filament)