Microscopic Anatomy
This structural unit of compact bone consists of an elongated cylinder running parallel to the long axis, made of concentric rings called lamellae.
an osteon (or Haversian system)
This type of cartilage is the most abundant kind in the human body, containing only collagen fibers and providing support, flexibility, and resilience at joints and rib tips.
hyaline cartilage
This type of ossification forms bones from fibrous connective tissue membranes, giving rise to cranial bones (like the frontal and parietal bones) and the clavicles.
intramembranous ossification
This specific type of bone marrow is responsible for hematopoiesis (blood cell formation) and is found within the trabecular cavities of spongy bone and flat bone diploë
red bone marrow
In this classification of bone fractures, the bone breaks completely through, but the skin remains unpenetrated.
closed (simple) complete fracture
These tiny canals run at right angles to the central canal, connecting the blood vessels and nerves of the periosteum, medullary cavity, and central canal.
perforating (Volkmann's) canals
This type of cartilage growth involves chondrocytes within lacunae dividing and secreting new matrix, causing the tissue to expand from within.
interstitial growth
This form of ossification relies on a previously formed hyaline cartilage model, producing nearly all bones inferior to the base of the skull.
endochondral ossification
This type of bone marrow found in adult medullary cavities specializes in storing fat for energy reserves.
yellow bone marrow
This childhood bone disease involves inadequate mineralization of bone matrix, leading to soft, weak bones and bowed legs due to a vitamin D or calcium deficiency.
rickets
These specialized lamellae fill the gaps between forming osteons or represent leftover remnants of osteons that were partially cut down by bone remodeling.
interstitial lamellae
This precise sequence lists the five zones of the epiphyseal plate starting from the epiphyseal side and moving toward the diaphysis side.
1) the resting zone, 2) proliferation zone, 3) hypertrophic zone, 4) calcification zone, and 5) ossification zone
During endochondral ossification of a long bone, these specialized centers appear in the epiphyses around the time of birth.
secondary ossification centers
This hormone is the single most important chemical driver stimulating epiphyseal plate activity during infancy and childhood.
growth hormone
This widespread metabolic bone disease occurs when bone resorption vastly outpaces bone deposit, causing a severe decline in bone mass—particularly in postmenopausal women due to declining estrogen.
osteoporosis
This double-layered membrane covers the outer surface of a bone (except at joints) and features an inner layer containing primitive stem cells.
periosteum
This process allows growing bones to increase in width/thickness throughout life via actions beneath the periosteum and endosteum.
appositional growth
Up until about this week of human embryonic development, the skeleton is made entirely of fibrous membranes and hyaline cartilage before ossification begins.
week 8
This structural characteristic of spongy bone features an internal arrangement of "cables on a suspension bridge" that helps the bone resist stresses from any direction.
trabeculae
This rare bone disorder involves excessive, haphazard bone deposit and resorption, producing a weak structural matrix with an abnormally high ratio of spongy to compact bone.
Paget's disease
This delicate connective tissue membrane lines the internal trabeculae of spongy bone, the medullary cavity, and the canals passing through compact bone.
endosteum
This type of cartilage contains thick collagen fibers and great tensile strength, making it ideal for withstanding heavy pressure in the knee's menisci and intervertebral discs.
fibrocartilage
This specific region of a developing long bone is located between the diaphysis and epiphysis, containing the epiphyseal plate where longitudinal growth occurs.
the metaphyseal region (or metaphysis / epiphyseal plate)
This primary structural feature allows compact bone to withstand twisting forces, featuring collagen fibers that run in opposite, alternating directions in adjacent rings.
alternating/changing direction of collagen fibers
This specific type of fracture is common in children because their bones have relatively more organic matrix and are more flexible, causing the shaft to break on only one side while bending on the other.
greenstick fracture