bone structure Flashcards
How many bones are in the human adult skeleton?
206
What are the two groups of bones based on location?
- Axial
- Appendicular
Name the components of the axial skeleton.
- Skull
- Vertebral column
- Rib cage
Name the components of the appendicular skeleton.
- Upper limbs
- Lower limbs
- Shoulder girdle
- Hip girdle
What are the four classifications of bones by shape?
- Long
- Short
- Flat
- Irregular
Define long bones.
Bones longer than wide
Give two examples of long bones.
- Thigh
- Forearm
Define flat bones.
Thin, flattened, and usually a bit curved bones
Give two examples of flat bones.
- Cranial bones
- Sternum
Define short bones.
Almost cube-shaped bones
Give two examples of short bones.
- Wrist bones
- Ankle bones
What are sesamoid bones?
A special type of short bone that forms in a tendon
Give an example of a sesamoid bone.
Patella
Define irregular bones.
Bones with irregular shapes that fit none of the preceding classes
Give two examples of irregular bones.
- Vertebrae
- Hip bones
What is compact bone?
The outer layer of every bone (80%)
What is spongy bone?
The inner trabeculated layer that usually contains marrow (20%)
What is the diaphysis of a long bone?
The shaft of the bone
What is the medullary cavity?
The central hollow space of a long bone
What is the epiphysis?
The terminal portion of a long bone
What is articular hyaline cartilage?
Cartilage situated at a joint
What is the metaphysis?
The flared portion of the bone where diaphysis and epiphysis meet
What is the periosteum?
The outer covering of a bone
What are the two layers of the periosteum?
- Outer fibrous layer
- Inner osteogenic layer
What is the endosteum?
The delicate connective covering of trabeculae or canals inside a bone
What is red marrow?
Haematopoietic tissue located in certain bones
What is yellow marrow?
Fat storage tissue primarily found in adults
Where is red marrow located in adults?
- Flat bones of the skull
- Sternum
- Ribs
- Clavicles
- Scapulae
- Hip bones
- Vertebrae
- Head of femur
- Head of humerus
What is the composition of the bone matrix?
- 10-20% water
- 60-70% crystallized mineral salts
- Mostly collagen
What are osteogenic cells?
Cells found in periosteum and endosteum that develop into osteoblasts
What do osteoblasts do?
Secrete unmineralized matrix (osteoid)
What are osteocytes?
Mature bone cells that monitor and maintain bone
What are osteoclasts?
Cells that digest bone matrix for normal bone turnover
What is the structural unit of compact bone?
Osteons (Haversian system)
What is the central canal in osteons?
Contains blood vessels, nerves, and lymphatics
What are canaliculi?
Little canals that allow nutrient flow from canals and between osteocytes
What are Volkmann’s canals?
Canals that run at right angles to the shaft, completing the communication pathway from the outside of the bone to its interior
List the functions of bones.
- Support
- Protection
- Leverage for motion
- Mineral homeostasis
- Blood cell production
- Triglyceride storage
- Hormone production
What is osteocalcin?
A hormone produced by bone tissue
