muscles
músculos - tissue
bones
huesos - osseous matter
to contract
contraerse - to tighten
relaxes
relajarse - soften
bend
doblar/flexionar - curve
upper arm
biceps - biceps
skeleton
esqueleto - frame
organs
órganos - body parts
joints
ligamentos - connections
spine
columna vertebral - backbone
jaw
mandíbula
skull
cráneo
rib cage
caja torácica
tendons
tendones
straighten
estirar/enderezar
vertebrate
vertebrado
