Human Anatomy

The anatomical position is a standard reference posture where the body stands upright facing the observer, feet together and parallel, arms at the sides with palms forward, and head and eyes directed forward.
This position ensures consistent anatomical descriptions.

The three main planes are the sagittal plane (divides body into left and right), coronal plane (divides into anterior and posterior), and transverse plane (divides into superior and inferior).
These planes allow for standardized views of body structures.

The major body cavities are the dorsal cavity (cranial and spinal) and ventral cavity (thoracic, abdominal, and pelvic).
The ventral cavity is separated by the diaphragm into thoracic and abdominopelvic regions.

The four primary tissue types are epithelial (covering and lining), connective (support and binding), muscle (contraction), and nervous (communication and control).
These tissues combine to form organs.

The skeletal system provides support, protection for organs, enables movement via muscle attachments, stores minerals like calcium, and produces blood cells in bone marrow.
It consists of 206 bones in adults.

The axial skeleton forms the central core (skull, vertebral column, rib cage; 80 bones), while the appendicular skeleton includes limbs and girdles (126 bones).
Together they total 206 bones.

The five types are long bones (e.g., femur), short bones (e.g., carpals), flat bones (e.g., skull), irregular bones (e.g., vertebrae), and sesamoid bones (e.g., patella).
Classification relates to function and structure.

A long bone has a diaphysis (shaft), epiphyses (ends), metaphysis (growth zone), periosteum (outer membrane), endosteum (inner lining), and medullary cavity (marrow space).
Compact bone surrounds spongy bone trabeculae.

The three types are fibrous (immovable, e.g., sutures), cartilaginous (slightly movable, e.g., intervertebral discs), and synovial (freely movable, e.g., knee).
Synovial joints have capsules, fluid, and subtypes like hinge or ball-and-socket.

Synovial joints include articular cartilage, synovial membrane (secretes fluid), joint capsule, ligaments, and bursae for cushioning.
This structure reduces friction and allows smooth movement.

Skeletal muscle is voluntary and striated, smooth muscle is involuntary and non-striated (in organs), and cardiac muscle is involuntary, striated, and found only in the heart.
Each type has unique functions in contraction.

Skeletal muscle consists of muscle fascicles (bundles of fibers), each fiber containing myofibrils with sarcomeres (actin and myosin).
Connective tissue sheaths (endo-, peri-, epimysium) protect and transmit force.