Skeletal System Flashcards
Skeletal System
system of the body, which forms a solid framework around which the body is built
1. it is composed of bones and cartilage
Functions
A. Framework of the body
B. Attachment for skeletal muscles (origin, insertion)
C. Protection of certain vital organs
1. Example: brain by skull and heart by thoracic cage
D. Manufacture certain blood cells: hemopoiesis (bone marrow)
E. Storage of certain chemical substance
1. Example: calcium, phosphate
Bone Types
- Long bone: a bone in which the length exceeds the width, and is characterized by having a medullary (marrow) canal
a. example: humerus - short bone: a bone in which the length equals the width
a. example: carpal bones - Flat bone: a bone expanded into 1 plane
a. example: scapula - Irregular bone: a bone that does not fit into any of the other 3 categories
a. example: vertebrae
Axial Skeleton
occupies the central axis of the body
- skull and hyoid (23)
- vertebral column (7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, 1 coccyx=26)
- Ribs and sternum (12 pairs of ribs + sternum=25)
- Bones of middle ear (6, 3 per side)
Appendicular Skeleton: Bones of the upper limb
part of the skeleton that comprises the appendages
- Bones of the upper limb (64)
a. clavicle
b. scapula: shoulder blade
c. humerus
d. ulna and radius
e. eight carpal bones: wrist
f. five metacarpal bones: palm
g. fourteen phalanges: fingers
Appendicular Skeleton: Bones of the lower limb
62 a. hip bone b. femur: thigh c. patella d. tibia and fibula: leg e. seven tarsal bones: ankle f. five metatarsal bones: foot g. fourteen phalanges: toes 206 TOTAL NUMBER OF BONES
Aside from 206 named bones
- sesamoid bone: located in tendones
2. ectopic bone: pathological bone formation
Diagram of a long bone
page 13
Epiphysis
the two ends of a long bone, which are wider than the shaft and take part in the formation of a joint
Diaphysis
shaft of a long bone
Compact bone
bone laid down in concentric layers making it appear solid
- this type of bone forms the outer surface of all bones
- it is thicker in the diaphysis and thinner at the epiphysis
Spongy bone
composed of very thin plates of bone that meet other plates of bone at various angles, leaving spaces between them
1. spongy bone is found in the epiphysis
Periosteum
connective tissue sheath composed of 2 layers
- outer layer: tough fibrous layer that serves as a place of insertion for muscle tendons
- inner layer: delicate cellular layer responsible for producing groth in the diameter of the bone
Endosteum
Thin, cellular layer found lining the medullary cavity and the cavities of spongy bone
1. its primary function is to destroy bone, thus allowing for growth in the diameter of the marrow cavity, which prevents bone from becoming too solid and heavy as it increases in size
Medullary (marrow) cavity
cavity running the length of the diaphysis that contains either red marrow (which actively forms blood cells), yellow marrow (where fat cells are stored), or combinations of the two
Articular Cartilage
thin layer of hyaline cartilage conceding the articular surface of each epiphysis
Articular capsule
connects together the 2 bones and completely encircles the joint, thus enclosing a cavity that is called the joint cavity or synovial cavity
1. the capsule itself is composed of 2 layers:
A. outer fibrous layerL continuous with the periosteum of bone
B. an inner layer: lines the inside of the fibrous layer
i. the inner layer is also called the synovial membrane
ii. it is quite vascular and produces synovial fluid that fills the joint cavity, lubricates the joint, and nourishes the articular cartilage
Epiphyseal disc
in embryo of a growing child, it is a cartilaginous plate located at the junction of epiphysis and diaphysis that allows for growth in the length of a bone
Metaphysis
spongy bone tissue located at the junction of the diaphysis and the epiphyseal disc
1. in the adult, the bony tissue of the metaphysics is continuous with the epiphysis
Cartilage
cartilage is a tough connective tissue, which is composed of cells embedded in a firm, gel-like intercellular substance
- It is not as hard as bone
- It is called gristle by laymen
- It lacks nerves
- It lacks blood vessels
a. nutrients diffuse through the intercellular substance - The entire embryo skeleton is initially cartilage, but it is replaced by bone during growth (ossification)
- The classification of cartilage is via the histologic appearance of the intercellular matrix
Hyaline cartilage
so named because it has a glassy, translucent appearance
a. embryo
b. epiphyseal discs
c. articular cartilages
d. costal carilages (btwn ribs and sternum)
e. larynx, trachea, and bronchi
f. nasal cartilages
Fibrocartilage
Interpubic disc (symphysis pubis) Intervertebral discs (btwn adjacent vertebrae)
Elastic Cartilage
A. auricle (part of external ear)
B. auditory tube (connects ear and pharynx
C. Epigiottis (flap that keeps food from entering lungs)
