Classification of bones, joints and ossification Flashcards
What are the two types of internal structures that bone can have?
Compact and spongy
Another name for compact bone
Cortical
Another name for spongy bone
Trabeular
6 types of bones that have been classified by shape
Long Flat Irregular Short Sutural Sesamoid
Example of long bones
Humerus/metatarsal
Example of flat bones
Sternum/roof of skull
Example of irregular bones
Vertebrae/pelvic bones
Example of short bones
Carpal/tarsal
Example of sutural bones
Skull
Example of sesamoid bones
Patella
Features of long bones
Longer than it is wide
Function of long bones
Leverage
Features of short bones
Cube-like shape, equal length/width/thickness
Functions of short bones
Stability and some motion
Features of flat bones
Thin and curved
Function of flat bones
Point of attachment for muscles, protects internal organs
Features of irregular bones
Complex shape
Features of sesamoid bones
Small and round, embedded in tendons
Function of irregular bones
Protect internal organs
Function of sesamoid bones
Protect tendons from compressive forces
What is intramembranous ossification?
Bone forms on or within fibrous connective tissue (e.g. flat skull bones)
What is endochondral ossification?
Bone forms from cartilage template, e.g. long bones
Process of intramembranous ossification
- Appears as jelly of mesenchyme tissue, within the connective tissue is developing osteoblasts
- Mesenchymal cells differentiate into osteoblasts at the ossification centre
- Osteoblasts are young bone cells that start laying down bone matrix (e.g. calcium/collagen) within mesenchyme tissue
- Gradually matures into osteocyte which continues to lay down bone matrix
- Minerals begin to harden tissue - forms harder bone tissue
- Calcification = hardening of bone = process of ossification and bone formation
- Osteocyte gets trapped within the matrix they are laying down
- Lacunae (space containing osteocyte/chondrocyte) form
- Bone forms
When does trabecular bone form?
Growth occurs, trabecular become inter-connected
Process of endochondral ossification
- An intermediary forms, which is made of cartilage (the cartilage template)
- Cartilage assumes the shape of the bone to be formed
- Perichondrium covers outer surface of cartilage
- In calcified bone, the equivalent of the perichondrium is the periosteum
- Perichondrium is converted to periosteum as the cartilage template hardens due to the action of chondrocytes
Where are secondary ossification centres located?
At the ends of the cartilage model of small, long bones
In what direction do secondary ossification centres work?
From inwards to outwards
In what direction do primary ossification centres work?
From outwards to inwards
Which cells assist primary ossification centres?
Perichondria osteoprogenitor
What is the structural framework of a joint?
The type of connective tissue that joins bones together
What is the functional framework of a joint?
The degree of movement occurring in the joints
Characteristics of fibrous joints
- Bones are united by fibrous tissue
- Permit no or very limited range of movement
Another word for fibrous joints
Synarthroses
What is a syndesmoses joint?
Bones joined by sheet of fibrous tissue band (e.g. interosseous membrane)
What is a suture joint?
Interlocking projectons of adjacent bone plates, joined together by a thin layer of fibrous tissue (e.g. joints between cranial bones)
What is a gomphoses joint?
Joint connected by fibrous tissue called periodontal membrane (e.g. joint between root of the tooth and alveolar process of mandible or maxilla)
Another word for cartilaginous joints
Amphiarthroses
Characteristics of cartilaginous joints
- Bones united by hyaline cartilage or fibrocartilage
- Cartilaginous joints allow for little movement
What is a synchondroses joint?
Bones usually joined by hyaline cartilage, usually temporarily occur during development, e.g. articulation between epiphysis and diaphysis of long bones
What is a primary cartilaginous joint?
Synchondroses
What is a secondary cartilaginous joint?
Symphyses
What is a symphyses joint?
Bones joined by fibrocartilage, e.g. articulation between vertebrae/hip bones
What is Hilton’s law?
Any muscle that crosses a joint acts on that joint. Any nerve supplying a muscle also supplies a joint
How to describe the structure of a joint
- Identify type of joint
- Identify bones involved and articulating parts
- Describe attachment of joint capsule if present
- Describe attachment of joint ligaments
- Describe range of movements occurring at joint and muscles involved
- Describe the bursa (if present)
- Describe neurovascular supply of joint
- Describe clinical anatomy of joint
Which structures are found in synovial joints?
- Joint capsule - fibrous membrane wrapping around joint
- Synovial membrane - thin, inner membrane
- Articular cartilage - normally hyaline cartilage
- Joint cavity with synovial fluid - enclosed by synovial membrane
- Articular disks (menisci)
- Articular ligaments - connects and enforces stability of joints together with capsule and synovial membrane
- Articular bursa - cushion-like padding shock absorber
3 types of synovial joint
Uniaxial/biaxial/multiaxial
Characteristics of uniaxial joints and examples
- Permit movement about one axis and in one plane
- Hinge joints and pivot joints
Characteristics of biaxial joints and examples
- Permits movement about two perpendicular axes in two perpendicular planes
- Saddle joints, e.g. carpometacarpal joints
- Condyloid (ellipsoidal) joints, e.g. metacarphophalangeal joints
Characteristics of multiaxial joints and examples
- Permit movement around three or more axes in three or more planes
- Ball and socket (spheroid) joints
- Gliding (plane) joints
