Skeletal System Functions and Bone Classification

A complete set of vocabulary flashcards covering the functions, anatomical divisions, bone shape classifications, and long bone structure from Unit 4.1.

Hematopoiesis

Blood cell formation that occurs in the bone marrow.

Skeletal Inorganic Storage

The storage function of bones, specifically holding inorganic materials such as calcium, sodium, and potassium.

Body Movement (Skeletal Function)

The function where muscles pull on bones to produce movement of the body.

Total Bone Count (Birth vs. Adult)

The human skeleton is composed of around $270$ bones at birth, which decreases to around $206$ bones by adulthood as specific bones fuse together.

Axial Skeleton

The division of the skeleton that includes the head, neck, and trunk; specifically composed of the skull, hyoid bone, vertebral column, thoracic cage ($12$ pairs of ribs), sternum, and auditory ossicles (inner ear).

Appendicular Skeleton

The division of the skeleton comprising the pectoral girdle (scapula, clavicle, arms) and pelvic girdle (coxal bones, legs).

Pectoral Girdle

The skeletal structure of the appendicular skeleton that attaches the upper limbs, consisting of the scapula, clavicle, and arms.

Pelvic Girdle

The skeletal structure of the appendicular skeleton that supports the lower limbs, composed of the coxal bones (ilium, ischium, and pubis) and legs.

Flat Bones

Bones that are thin, flattened, and usually curved, consisting of spongy bone between two thin layers of compact bone (e.g., skull, ribs, sternum, scapulae).

Long Bones

Bones that are typically longer than they are wide, featuring a shaft with heads at both ends and composed mostly of compact bone; includes all limb bones except carpals and tarsals.

Short Bones

Bones that are generally cube-shaped and equal in length, width, and thickness, composed mostly of spongy bone (e.g., carpals and tarsals, excluding the patella).

Irregular Bones

Bones with complex structures that do not fit into the long, short, or flat categories (e.g., vertebrae, pelvis, sacrum, and facial bones).

Sesamoid Bones

Specialized bones embedded within tendons (e.g., patella, pisiform, rider's bone).

Diaphysis

The long, main shaft of a long bone, primarily consisting of a thick wall of compact bone.

Epiphysis

The expanded end of a long bone, largely consisting of spongy bone that houses red marrow.

Proximal Epiphysis

The epiphysis of a long bone located closest to the body's center.

Distal Epiphysis

The epiphysis of a long bone located farthest away from the body's center.

Articular Cartilage

A layer of cartilage providing smooth padding at the ends of bones within a joint.

Epiphyseal Line

The remnant line of the growth plate located between the epiphysis and the diaphysis in an adult long bone.

Periosteum

The protective membrane covering the exterior surface of a bone, present everywhere except where articular cartilage is found.

Endosteum

The tissue membrane that lines the inner surface and medullary cavities of bones.

Medullary Cavity

The hollow interior space within the diaphysis of a long bone that houses yellow marrow for fat storage.

Yellow Marrow

Bone marrow found within the medullary cavity that serves as a site for fat storage.

Compact Bone

Dense, solid bone tissue forming the external wall of the diaphysis as well as the outer layers of flat bones.

Spongy Bone (Cancellous Bone)

Lattice-like porous bone tissue located inside the epiphysis and within flat bones that contains red bone marrow.

Diploë

The internal layer of spongy bone found between two layers of compact bone in flat bones, such as those of the skull.

Osteogenesis Imperfecta

A genetic disorder causing brittle bone fragility (referenced through the fictional character Mr. Glass).