Muscle Anatomy and Movements: Key Terms and Definitions

Epimysium

Covers the entire muscle

Fascicles

A group of muscle cells surrounded by Perimysium

Perimysium

Covering of fascicles

Muscle fiber

A single muscle cell

Endomysium

covering of a single muscle cell

tendon

Attaches muscle to bone

Aponeurosis

A fibrous or membranous sheet connecting a muscle to the part it moves

Origin

Attachment of a muscle that remains relatively fixed during muscular contraction

insertion

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

action

what the muscle does

Flexion

Decreases the angle of a joint

extention

increases joint angle

Hyperextension

extension beyond anatomical position

Abduction

Movement away from the midline of the body

Adduction

Movement toward the midline of the body

Rotation

CIRCULAR MOVEMENT AROUND AN AXIS

Dorsiflexion

bending of the foot or the toes upward

plantar flexion

bends the foot downward at the ankle

Agonists

A contraction that generates movement

Antagonists

relaxation required for movement

Synergists

Contract with the agonist to aid movement

Fixators

Synergists that stabilize joints

orbicularis oculi

closes eye

orbicularis oris

kissing muscle

masseter

prime mover of jaw closure

temporalis

elevates and retracts mandible

sternocleidomastoid

flexes neck; rotates head

trapezius

upper back

pectoralis major

Adducts and flexes humerus

pectoralis minor

protracts and depresses scapula

internal intercostals

depress ribs

external intercostals

elevates ribs

deltoid

abducts arm

rectus abdominis

flexes vertebral column

external oblique

compresses abdomen

internal oblique

compresses abdomen

transversus abdominis

compresses abdomen

latissimus dorsi

extends and adducts humerus

triceps brachii

extends forearm at elbow

triceps brachii origin

humerus

triceps brachii insertion

olecranon process of ulna

biceps brachii

Flexes and supinates forearm

biceps brachii origin

scapula

biceps brachii insertion

radius

brachialis

flexes elbow

brachialis origin

humerus

brachialis insertion

ulna

extensor carpi radialis longus

Extends wrist and abducts hand

extensor digitorum

Extends fingers and the wrist

flexor digitorum superficialis

flexes wrist and middle phalanges of fingers 2-5

flexor carpi redialis

flexes and abducts wrist

gluteus maximus

extends thigh

gluteus medius

abducts and medially rotates thigh

sartorius

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

gracilis

adducts thigh

quadriceps femoris

Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius.

hamstrings

biceps femoris, semimembranosus

Gastrocnemius

plantar flexes foot

gastrocnemius origin

femur

gastrocnemius insertion

calcaneus

flexor digitorum longus

flexes toes

flexor digitorum longus origin

tibia

flexor digitorum longus insertion

distal phalanges of digits 2-5

extensor digitorum longus

extends toes

extensor digitorum longus origin

tibia/fibula

extensor digitorum longus insertion

middle and distal phalanges of toes 2-5

tibialis anterior

dorsiflexes and inverts foot

tibialis anterior origin

tibia

tibialis anterior insertion

1st metatarsal

dendrite

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

cell body

Largest part of a typical neuron; contains the nucleus and much of the cytoplasm

axon

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

axon hillock

Cone shaped region of an axon where it joins the cell body.

myelin sheath

covers the axon of some neurons and helps speed neural impulses

Node of Ranvier

gaps in the myelin sheath

Axon terminal

The endpoint of a neuron where neurotransmitters are stored

synapse

Gap between neurons

multipolar neuron

A neuron with a single axon and multiple dendrites; the most common type of neuron in the nervous system.

bipolar neuron

a neuron with one axon and one dendrite attached to its soma

unipolar neuron

a neuron with one process extending from its cell body

Sensory (Afferent)

transmits action potentials from receptors to CNS

Motor (efferent)

transmits action potentials from CNS to effectors (muscles, glands)

Interneurons (association)

connect sensory and motor neurons

Nuclei

Groups of Cell bodies in the CNS

Ganglia

Groups of cell bodies in the PNS

Tract

Bundle of axons in the CNS

Nerve

Bundle of axons in the PNS

Conus medullaris

end of the spinal cord

Filum terminale

cauda equina

meninges (Spine)

dura mater, arachnoid mater, pia mater

dura mater (spine)

1 layer in spine and is fat filled

arachnoid mater (spine)

middle layer of the meninges

pia mater

thin, delicate inner membrane of the meninges

white columns (White Matter)

gray commissure (Gray matter)

dorsal root

dorsal root ganglion

dorsal horns

ventral root