Human body systems, Skeletal, muscular, skin 2026

Periosteum

is the tough outer covering of bones

Marrow

is substance in the center of bones that makes blood cells

Joint

is any place where two or more bones meet.

Ligament,

tough band of tissue that holds bones together at joints.

Muscles

are organs that relaxes and contracts.

Involuntary Muscles

any muscle that are not consciously controlled.

Tendons are

thick band of tissues that attach bones to muscles.

Smooth Muscles are

the involuntary muscles of the digestive system

Epidermis

is the outermost layer of skin.

Dermis

is the middle layer of the skin