The Muscular System

the three muscles on the posterior thigh they have extremely tough tendons that can be felt at the back of the knee where they insert on both sides of the tibia

- biceps femoris - semimembranosus - semitendinosus

the cytoplasm of muscle fibers (cells) are nearly filled in by myofibrils which are long ribbonlike organelles. these myofibrils have alternating dark and light bands which give the whole muscle cells its striped appearance. what are the dark bands called? the light bands?

- dark bands: A bands - light bands: I bands

how is an isotonic muscle contraction different than an isometric muscle contraction?

- isotonic - the muscle shortens (bending knee) - isometric - the muscle doesn't shorten, they stay the same length

what are intercalated discs? in which type of muscle tissue would you find them?

- join cardiac muscle fibers - cardiac muscle

what would cause a person's muscles to move in a twitchy or jerky manner rather than a smooth fluid motion? what needs to increase?

- nervous system problems or the impulses are slow - the stimulation needs to increase

are all muscle fibers arranged the same way? what are the different types of shapes we see in skeletal muscles?

- no - convergent, parallel, and pennate

when identifying muscles, what are some clues you can use to figure out its name?

- oblique - at slant - maximus - largest - minimus - smallest - rectus - straight - bi-tri-quad - # of muscles in group location - deltoid - triangular

what is a motor unit? do all motor units stimulate the same amount of muscle cells?

- one neuron and all the skeletal muscle cells it stimulates - no

how is a prime mover different from an antagonist?

- prime mover - particular movement - antagonist - reverse the movement

what are four functions of muscle?

- producing movement - maintaining posture - stabilizing joints - generating heat

these three muscles make up the superficial muscles of the quadriceps muscle

- rectus femoris - vastus lateralis - vastus medialis

where are each of the three types of muscle tissue found?

- skeletal - bones, facial muscles, skin - cardiac - heart - smooth - hollow visceral organs

how do shape of the muscle fibers differ between the three types of muscle tissue?

- skeletal - single, long, multinucleate with striations - cardiac - branching, uninucleate, striations, intercalated discs - smooth - single, uninucleate

what causes a very strong muscle contraction as opposed to a very weak muscle contraction? remember an individual muscle fiber (cell) can not partially contract

- strong - many muscle cells stimulated at once - weak - only some muscle cells are stimulated

within each subunit of the myofibril there are two protein fibers that are very important in muscle contraction. what are they? which is thicker? thinner?

- thick - myosin filaments; have small projections; split ATP - thin - actin filaments; twist and overlap each other

which types of muscle tissue are voluntary? involuntary? what do those terms mean?

- voluntary: skeletal - involuntary: cardiac, smooth - voluntary - you command or active the reflexes - involuntary - without command

what is muscle fatigue and how is it related to oxygen debt?

- when the muscle is unable to contract even though it is still being stimulated - it is the result of oxygen debt

what is muscle tone?

a state of continuous partial contraction

moving a limb away from the midline of the body. also applies to the "fanning" of the fingers or toes

abduction

the movement of a limb toward the body midline

adduction

this muscle flexes the forearm. its the most familiar muscle in the forearm because it bulges when the forearm is flexed

biceps brachii

if you were to flatten your cheek to hold food between your teeth while chewing or to blow a trumpet, you would be using this muscle

buccinator

these 3 muscles are considered your "chewing muscles"

buccinator, masseter, and temporalis

which types of muscle tissue have rhythmic contractions?

cardiac and smooth

combination of flexion, extension, adduction and abduction. proximal end is stationary and the distal end moves in a circle

circumduction

what is the essential function of a muscle that sets it a part from any other body tissue?

contraction or shortening

these are fleshy, triangle-shaped muscles in your shoulders. they are the prime movers in arm abduction

deltoid

these 3 muscles are common sites for injections

deltoid, gluteus medius, and vastus lateralis

what are graded responses?

different degrees of shortening

lifting the foot so that its superior surface approaches the shin

dorsiflection

a special movement of the foot in which the sole is turned laterally

eversion

a movement that increases the angle or distance between two bones or part of the body

extension

these muscles, like the rectus abdominis, flex the spine but they also rotate and bend the trunk

external oblique

a movement that decreases the angle of a joint and brings two bones closer together

flexion

this muscle raises and lowers the eyebrows

frontalis

what is it called when the muscle is stimulated so rapidly that no evidence of relaxation is seen?

fused, or complete, tetanus

this is a two-bellied muscle that forms the calf

gastrocnemius

this muscle forms most of the flesh of the buttock. it is not important in walking but its the most important muscle for extending the hip, like in climbing the stairs or jumping

gluteus maximus

what are synergists?

help prime movers by producing the same movement or by reducing undesirable movements

what are fixators?

hold a bone still or stabilize the origin of a prime mover so all the tension can be used to move the insertion bone

an extension greater than 180 degrees like when you tip your chin up to the ceiling

hyperextension

these muscles are found between the ribs

intercostal muscles

these muscles have the same function as the external obliques but they are deep

internal oblique

special movement of the foot in which the sole is turned medially

inversion

what occurs in your body when it goes into oxygen debt?

lactic acid begins to accumulate in the muscle

these two muscles are the "chicken dance" muscles, they adduct and extend the humerus

latissimus dorsi

this large flat pair of muscles cover your lower back. these muscles are important to bring down the arm in a power stroke like when swimming or striking a blow

latissimus dorsi

this muscle closes the jaw

masseter

what are the three types of muscle tissues?

skeletal, cardiac, and smooth

this muscle allows your to nod or shake your head "no"!

sternocleidomastoid

forearm rotates laterally so that the palms faces anteriorly and radius is parallel to ulna

supination

this fan-shaped muscle acts as a synergist with the masseter in closing the jaw

temporalis

these are the deepest muscles of the abdominal wall and their muscle fibers run horizontally across the abdomen

transversus abdominis

the diamond or kite-shaped muscle of the back that extends the neck and elevates and depresses the scapula

trapezius

this muscle is the antagonist of the biceps brachaii. this is called the "boxers" muscle because it can deliver a straight-arm, knock out punch

triceps brachii

the smiling muscle

zygomaticus

action in which you move your thumb to touch the tips of all of the other fingers on the same hand

opposition

the two muscles that have fibers organized into circular pattern

orbicularis oculi and oris

kissing muscle

orbicularis oris

depressing the foot and pointing the toes

plantar flexion

this sheet-like muscle forms a "frown" by pulling the corners of the mouth inferiorly

platysma

when the forearm rotates medially so that the palm is down and the radius and ulna are crossed

pronation

what are the functions of a tendon and why are they important?

providing durability, conserving space, and anchor muscles

these paired, strap-like muscles, flex the vertebral column. they also compress the abdominal contents during defecation and childbirth. if these muscles are especially well developed, they might be referred to as a "six pack"

rectus abdominals

movement of a bone around its longitudinal axis

rotation

the myofibril is made up of tiny subunits that can contract when stimulated. what are these small units of a myofibril called?

sarcomere

this strap-like muscle is the most superficial muscle of the thigh. it runs obliquely across the thigh from the iliac crest to the medial side of the tibia

sartorius

which type(s) of muscle tissue have striations? which do not?

skeletal and cardiac have, smooth does not

when we describe the "muscular system" which type of muscle tissue does that refer to?

skeletal muscle

which type of muscle tissue is multinucleate?

skeletal muscle