ANTC47 Osteology

Ontogeny

Growth and development of a species

Crural Index

The relative measurement of lower limb length. Impacted by lattitude as an example of geographic bone variation

Bone

Lightweight but strong biological material composed of collagen and hydroxyapatite

Shear

Force exercised on bones when two bones come into contact with each other and create friction

Hydroxyapatite

Mineral that is a form of calcium phosphate that is responsible for the mineralization of connective tissues to create the rigidity of bone

Collagen

A protein that composes 90% of the bone’s organic content. Fibrous and allows for bones to be able to flex and withstand forces acted upon them

Wolff’s Law

Bone is deposited where needed and reabsorbed where it is not

Joint

Articulations and connections between bones with ligaments and cartilage

Ligaments

Connective tissue that connects bone to bone

Tendons

Connective tissue made up of tightly packed bundles of collagen fibers that connect muscle to bone

Synovial Joint

Most common type of joint in the human body. Comprises of articular cartilage to allow bones to glide against each other, and is encapsulated with fluid. There are multiple different subtypes

Shperoidal Joint

Type of Synovial joint that resembles a ball and socket. Eg. the hip

Hinge Joint

Type of Synovial joint that includes the elbow and the knee

Sellar Joint

Type of Synovial joint that resembles a saddle. Eg. the base of the thumb

Planar Joint

Type of Synovial joint that comprises of two surfaces sliding against one another. Eg. Tibiotalar

Spheroidal, hinge, sellar, planar

Types of Synovial Joints

Hyaline Cartilage

AKA articular cartilage. Type of cartilage that is present in joints, especially synovial joints

Synovial Fluid

Fluid found in the synovial joints that reduces friction and provides nutrients to articular cartilage

Synchondroses

AKA Cartilagenous joints. Unite two bones with very little movement using fibrocartilage

Symphasis

Cartilaginous joint that also has articular cartilage

Fibrous Joint

AKA Syndesmoses. Joints that incorporate a dense fibrous membrane or liagments. Eg. cranial sutures

Synostosis

The fusion of two bones together

Gomphosis

Joint between the roots of the teeth and the bones of the jaws

Antagonist Muscles

Muscle groups that do opposite motions. Eg. Triceps brachii and Brachialis

Cortical Bone

AKA Compact bone. Dense & solid bone that make up the walls of the bone shaft

Subchondral Bone

Compact bone that is covered by articular cartilage and found in joints

Trabecular Bone

AKA Spongy Bone. Has a honeycomb-like structure which is lightweight and comprises thin bony spicules

Medulary Cavity

Hollow middle of the bone containing marrow and later stores fat

Epiphyses

The ends of the bone

Diaphysis

The middle/shaft of the bone. Primary centers of ossification

Metaphysis

Found between the Diaphysis and a Epiphysis; usually where growth plates are located

Periosteal Surface

Exterior surface of the bone where it comes into contact with the Periosteum

Periosteum

Connective, vascularized membrane which provides nutrients to the bone

Endosteal Surface

The surface on the inside of the Medulary Cavity that comes into contact with the Endosteum

Endosteum

Connective vascularized tissue on the inside of the bone

Osteogenic Tissues

Type of tissue that the periosteum and endosteum are. They promote bone-growing cells

Histology

Study of tissues at the microscopic level

Immature Bone

Rapidly formed temporary bone that is eventually replaced by mature bone. Sometimes referred to as woven bone. Contains more osteocytes and is made up of coarsly bundled collagen fibers arranged in a random pattern. Found in embryonic skeleton, sites of fractures, and some bone tumors

Mature Bone

AKA Tribecular or Compact Bone. Made up of lamellar bone

Lamellar Bone

Bone formed by the lamellae getting added as concentric layers during appositional growth

Lamellae

Thin mineralized layers of collagen that are layed down in concentric layers to form bone

Appositional Growth

When bone is added on the periosteal surface and then absorbed endosteally

Osteocytes

Bone-forming cells. Osteoblasts that have been surrounded by calcified bone

Secondary Osteons

Functional units of bone that are made up of Haversion Lamellae and bring blood and nutrients to osteocytes

Haversion Lamellae

Lamellae layers that compose secondary osteons. Each layer has collagen fibers that differ slightly in orientation to provide more strength

Haversian Canal

Tunnel at the core of every secondary osteon that contains a blood vessel, nerves, and lymph

Volkmann’s Canals

Canals that run perpendicular to secondary osteons, connecting them together and forming a network of blood supply

Lacunae

Cavities in each Haversian Lamellae that contain an osteocyte

Canaliculi

Minute, fluid-filled channels that radiate out from the Haversian Canals by way of other Lacunae, allowing for nutrients to be passed to Osteocytes

Osteoblasts

Bone-forming cells that make the uncalcified Osteoid. Concentrated just beneath the periosteum

Osteoid

Uncalcified organic tissue made by Osteoblasts that is then calcified with crystals of Hydroxyapatite to become bone

Osteoclasts

Cells responsible for the reabsorption of bone

Primary Osteon

Composed of just the vascular canal that will eventually be replaced with Secondary Osteons

Bone Remodelling

The process of bone removal and deposition throughout life

Mesenchyme

Tissue comprising stem cells

Intramembrous Ossification

Ossification that occurs in cranial bones

Endochondral Ossification

Ossification that occurs in long bones, where bone is added to the periostal surface and removed from the endosteal surface, creating a larger diameter

Hydroxyproline

One of the amino acids in collagen that is critical for collagen stability. Created by modifying the acid proline after the collagen chain is built, a process that requires Vitamin C