Human Phys chapter 3

macroscopic structure

macroscopic structure

structural elements that may be viewed with the naked eye

tendon

Connects muscle to bone

myofibril

tightly packed filament bundles found within skeletal muscle fibers

muscle cell

long and slender and contains fibers that aid in contracting and relaxing

muscle fiber

a single muscle cell

fascicle

bundle of muscle fibers

endomysium

Connective tissue surrounding a muscle fiber

perimysium

Connective tissue surrounding a fascicle

epimysium

surrounds entire muscle

frontalis

raises eyebrows, wrinkles forehead

temporalis

elevates and retracts mandible

zygomaticus

smiling muscle

buccinator

Used to suck in your cheeks

orbicularis oculi

Closes eyelids; used in blinking, winking, and squinting

masseter

elevates mandible

orbicularis oris

closes and protrudes lips

sternocleidomastoid

Contraction of one side: laterally flexes neck, rotates head to opposite side; Contraction of both sides together: flexes neck

platysma

Draws down the lower lip and angles of the mouth; tenses skin of the neck; helps depress mandible

trapezius

Elevates, depresses, retracts, and rotates the scapula; rotates the arm

deltoid

shoulder

latissimus dorsi

extends and adducts humerus

erector spinae

prime mover of back extension

gluteus medius

abducts and medially rotates thigh

gluteus maximus

extends thigh at hip joint

hamstring group

located at the back of the upper leg, consists of three separate muscles: biceps femoris, semitendinosus, semimembranosus

biceps femoris

extends thigh and flexes leg

semitendinosus

Flexes leg at the knee and extends thigh at the hip; belongs to the hamstring group

semimembranosus

Flexes leg at the knee and extends thigh at the hip; belongs to the hamstring group

gastrocnemius

plantar flexes foot

soleus

plantar flexion

biceps brachii

flexes forearm

brachialis

flexes forearm

triceps brachii

extends forearm

pectoralis major

Adducts and flexes humerus, chest muscle

intercoastal muscles

in between the ribs, aids breathing

transversus abdominis

compresses abdomen

internal oblique

tenses abdominal wall and compresses abdominal contents

external oblique

Compresses abdomen; laterally flexes and rotates vertebral column

rectus abdominis

flexes vertebral column

iliopsoas

flexes hip

sartorius

Flexes, abducts, and laterally rotates thigh at the hip; flexes knee

adductor muscles

adduct and medially rotate thigh

quadriceps group

rectus femoris, vastus lateralis, vastus medialis, vastus intermedius

rectus femoris

extends leg and flexes thigh

vastus lateralis

extends leg at knee

vastus medialis

extends knee

tibialis anterior

dorsiflexion and inversion of foot

flexion

bending a joint

extension

Straightening of a joint

hyperextension

Excessive straightening of a body part

abduction

Movement away from the midline of the body

adduction

Movement toward the midline of the body

circumduction

circular movement of a limb at the far end

rotation

circular movement around an axis such as the shoulder joint

dorsiflexion

bending of the foot or the toes upward

plantar flexion

bending of the sole of the foot by curling the toes toward the ground

inversion

Turning the sole of the foot inward

eversion

turning the sole of the foot outward

supination

movement that turns the palm up (thumb out)

pronation

turning the palm downward (thumb in)

opposition

Movement of the thumb to touch the fingertips

origin

attachment of a muscle that remains relatively fixed during muscular contraction

insertion

The attachment of a muscle tendon to a moveable bone or the end opposite the origin

applied force

a force that is applied to an object by a person or another object

prime mover

The muscle that acts as the initial and main source of motive power.

synergist

muscle that aids a prime mover in a movement and helps prevent rotation

antagonist

muscle that opposes or reverses a prime mover

fixator

muscle that prevents movement of bone

skeletal muscle

A muscle that is attached to the bones of the skeleton and provides the force that moves the bones.

nuclei

clusters of neuron cell bodies in CNS

sarcolemma

plasma membrane of a muscle fiber

t tubules

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side

sarcoplasmic reticulum

Organelle of the muscle fiber that stores calcium.

sarcomeres

units composed of actin and myosin that contract inside the muscle fiber

a bands

dark bands composed of thick myosin filaments overlapping thin actin filaments

I bands

light bands because they contain only thin filaments

myosin filaments

thick filaments

Extend length of A band

Connected at M line

actin filaments

protein fibers that play a role in movement of cell and organelles

z disc/line

coin-shaped sheet of proteins on midline of light I band that anchors thin filaments and connects myofibrils to one another

myosin heads

Actin binding site

ATP binding site

neuron

a nerve cell; the basic building block of the nervous system

dendrites

Branchlike parts of a neuron that are specialized to receive information.

axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

axonal terminals

the end of the axon branches, contain hundreds of tiny vesicles that contain neurotransmitters.

neuromuscular junction

point of contact between a motor neuron and a skeletal muscle cell

synaptic cleft

This is the space between neurons at a nerve synapse across which a nerve impulse is transmitted by a neurotransmitter-called also synaptic gap

neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

electrical signal

an electric current that carries information

brain

The mass of nerve tissue that is the main control center of the nervous system

action potential

a neural impulse; a brief electrical charge that travels down an axon

spinal cord

Nerves that run up and down the length of the back and transmit most messages between the body and brain

motor neuron

a neuron that sends an impulse to a muscle or gland, causing the muscle or gland to react

sliding filament theory

theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still

calcium ions

Serves as the actual "trigger" for muscle contraction by removing the inhibition of the troponin molecules

myosin binding site

where myosin head attaches during contraction

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

graded responses

different degrees of skeletal muscle shortening