Muscular System

prime movers (agonists)

responsible for producing a specific motion (biceps)

antagonists

oppose a particular movement; provide resistance and produce more delicate motions (triceps)

synergists

help prime moves by adding additional force or reducing undesirable movements that could occur as the prime mover contracts

fixators

immobilize a bone, much like those needed to maintain our posture

orbicularis

circular muscles in concentric rings

convergent

spread out over a region but all converge towards a tendon or insertion

fusiform

fascicles taper down to a tendon at two ends (bicep)

pennate

short and run at oblique angles

unipennate

muscles sit on one side of a tendon

bipennate

muscle on both sides to resemble a feather

multipennate

several feathers inserted into the same tendon

maximus

large

minimus

small

longus

long

brevis

short

rectus

parallel

transverse

perpendicular

oblique

at some angle

origin

proximal side of muscle; attaches to stationary bone

insertion

distal side of muscle; attaches to the moving bone

sternocleidomastoid

origins on the sternum and clavicle, inserts on the mastoid process

myocytes

individual muscle cells; muscle fibers

fascicle

muscle fibers in a bundle

connective tissue

tissue that connects, supports, __binds__, or separates other tissues or organs, typically having relatively few cells embedded in an __amorphous__ matrix, often with collagen or other fibers, and including __cartilaginous__, fatty, and elastic tissues.

flexors

close a joint

extensors

extend or open a joint

adductors

pull appendages back towards the midline

abductors

pull appendages away from midline

sarcolemma

membrane surrounding fascicles with striated muscle fiber cells

myofibril

basic rod-like unit of a muscle cells made of parallel filaments; multi-nucleated, striated strands and made of sarcomeres

actin

thin protein filament in sarcomeres that look like strands of beads wrapped around one another; appears as light bands

myosin

thick motor protein that uses ATP to drive movements along action filaments; appears as dark bands

sarcomeres

made of actin and myosin

z-line

outermost edge of sarcomere

I band

lighter region inside z-line that is made of only thin actin filaments

a band

darker region of thick myosin filaments and thin actin filaments stretching between I bands

H zone

centermost portion of a sarcomere made of only myosin and decreases in size as the sarcomere shortens

muscular dystrophy

group of diseases causing progressive muscle weakness

duchenne’s muscular dystrophy

most common form of md; genetic and interrupts the production needed for healthy muscles; most often affects young men and can be treated with medication and physical therapy

fibromyalgia

chronic, widespread pain that can be described as tingling, burning, itching, etc; can be triggered by temperature or touch and often affects tender points like elbows and neck

myasthenia gravis

characterized by weakness and rapid fatigue of any skeletal muscle caused by a breakdown in the normal communication between nerves and muscles; most common in women under 40 and men over 60, symptoms like a stroke

bell’s palsy

often the effect of a viral infection and is seen only about 200,000 times per year; sudden muscle weakness on one side of face and can last from a few weeks to up to six months

strain

stretch, tear, or rip in the muscle belly or tendon; caused at the junction between the muscle belly and its tendon; usually caused by excessive force or tension within the muscle fibers

sprain

stretch, tear, or rip in a ligament or joint capsule; usually occurs when a joint is pushed beyond its normal anatomical limits, resulting in a tearing or stretching of the ligaments, joint capsule, or both

muscle strength

amount of force that a muscle can produce in a single contraction

muscle endurance

amount of force a muscle can produce over an extended period of time

muscle cramps

sudden and involuntary contraction of one or more of your muscles; causes vary, but a popular one is long periods of exercise especially in hot weather

treatment of muscle cramps

* massage the cramped muscle
* cool skin with a cold, moist cloth
* stretch
* drink more fluids

epimysium

outermost level of muscle

perimysium

covers fascicles

endomysium

covers muscle fibers

tropomyosin

blocks myosin binding sites on actin subunits

troponin

in the presence of calcium ions, it binds to both tropomyosin and calcium at the same time to pull tropomyosin off those binding sites so that the myosin heads can pull the actin filaments

titin

largest known protein; helps align the thick myosin filament and adds an elastic element to the sarcomere; anchored at the m-line at the center of the h zone

afferent nerve

sensory neurons that carry nerve impulses from sensory stimuli towards the central nervous system and brain

efferent nerves

motor neurons that carry neural impulses away from the central nervous system and towards the muscles to cause movement

neuromuscular junction

point where the end of one axon terminal comes close, but does not touch, a muscle fiber

synaptic cleft

space in between one axon terminal and the muscle

acetylcholine

neurotransmitter; released by axon terminal into the synaptic cleft

junctional folds

located in post-synaptic membrane; have acetylcholine receptors that respond

acetylcholinesterase

starts to break down acetylcholine as a mechanism to close off those receptors, stops more sodium from coming through

cardiac

connections are intercalated disks

cardiac

myogenic and influences by autonomic nervous system

cardiac

functional network called syncytium

skeletal

voluntary and striated

skeletal

controlled by somatic nervous system

smooth

synonymous with visceral

smooth

found in bladder and blood vessels

smooth

cells are thin, elongated, no striations, one nucleus

bicep

flexor, scapula origin, radius insertion

tricep

extensor, humerus and scapula origin,

scapula

triangular bone at the shoulder

ball and socket

type of joint found in the shoulder

hinge joint

type of joint found in the elbow