muscular system anatomy

muscular tissue properties

electrical excitability, contractility, extensibility, elasticity

functions of muscular tissue

producing body movements, stabilizing body positions, storing and moving substances within body, generating heat

belly

part of the muscle made of skeletal muscle tissue that contracts

fassicles

Bundles of muscle fibers separated by layers of connective tissue

muscle fibers

individual skeletal muscle cells, within own sheath of connective tissue

organization order of skeletal muscle

muscle, fascicle, fiber, myofibril, myofilaments

sacromere

basic unit of muscle contraction and where myofibril is divided into

Z disc of sarcomere

boarder between adjacent sarcomeres

I band of sarcomere

area either side of Z-line composed of only thin filaments

A band of sarcomere

both thick and thin filaments

H zone of sarcomere

only contains thick filaments

M line of sarcomere

fine line marking center of sarcomere

rigor mortis

no ATP cross bridges cannot detach, and calcium leaks from the sarcoplasmic reticulum

parallel skeletal muscle fibers

long strap like and terminate at tendons on each end

fusiform skeletal muscle fibers

fascicles nearly parallel, terminate on flat tendons at ends and bulging center

example of parallel muscle fiber

sternohyoid, sartorius

example of fusiform muscle fiber

biceps brachii, digastric

circular skeletal muscle fibers

parallel fibers around body orifice

example of circular muscle fibers

orbicularis oculi and orbicularis oris

convergent muscle fibers

fan shaped muscle fibers converging at tendon

example of convergent muscle fibers

pectoralis major

unipennate

fibers arranged on only one side of tendon

example of unipennate

extensor digitorum longus

bipennate

fibers on both sides on tendon

example of bipennate

rectus femoris, flexor digitorum longus

multipennate

short fibers on numerous tendinous slips

example of multipennate

deltoid

orgin

place where the stationery end of muscle attached to the bone or cartilage

insertion

site where the moveable end of muscle attached to another structure

agonist

biceps brachii

antagonist

triceps brachii

synergists

muscles that assist the agonist and steads the movement; crosses the same joint as agonist

fixators

stabilize the origin of the agonist by restricting movement in a joint

the functional unit of any striated muscle is the ___

sacromere

what are the structural components of a sarcomere?

alternating thick and think protein

thick and thin protein filaments that contribute the most to the sarcomere are called ___ and ___

myosin and actin

why do skeletal muscle fibers appear striated under the microscope?

regular repeating arrangement of myofilaments

what are the different fascicle arrangements of muscles and why are they different?

circular, convergent, parallel, fusiform and pennate, they are different to serve different functions

what are the functional parts of a musculoskeletal lever?

fulcrum, effort and load

agonist role

muscle primarily responsible for a particular movement

antagonist role

muscles that opposes a particular movement, stretch, or slows down action

synergist

muscle that helps the prime mover by adding extra force or reducing unnecessary movements

fixator

immobilizes a bone or muscle’s origin so the prime mover has a stable base to act upon

muscles have at least 2 attachment points, the ___ is usually proximal and is fixed during a muscle contraction while the ___ is the usually more distal attachment and mobile during a muscle contraction

origin and insertion

What four muscles make up the rotator cuff?

supraspinatus, infraspinatus, subscapularis, teres minor

flexes neck

sternocleidomastoid

depress hyoid

sternohyoid

closes eye

obicularis oculi

elevates the mandible ___ and ___

masseter and temporalis

flexes trunk ___ and ___ and ___

rectus abdominis, external oblique, internal oblique

extends trunk

erector spinae

rotates trunk ___ and ___

external oblique and internal oblique

expands ribcage for inhalation

diaphragm

flexes and adducts shoulder

pectoralis major

elevates scapula

levator scapulae

flexes elbow ___ and ___

biceps brachii, brachialis, brachioradialis

extends shoulder

latissimus dorsi

extends elbow

triceps brachii

pronates forearm

pronator teres

supinates forearm

supinator

flexes hip ___ and ___

iliopsoas and rectus femoris

extends the hip ___ and ___

gluteus maximus and hamstrings

abducts the hip

gluteus medius

adducts the hip

adductor group

flexes the knee

hamstrings

extends the knee

quadriceps femoris

plantar flexes the foot

soleus

dorsiflexes the foot

tibialis anterior

flexes the big toe

flexor haliucis longus