Skeletal System

Question 1

A highly specialized supportive tissue which is characterized by its rigidity and hardness

Answer 1

Bones

Question 2

Four main functions of Bones

Answer 2

● To provide mechanical support
● To permit locomotion
● To provide protection
● To act as metabolic reservoir of minerals

Question 3

● Mesenchymal cells
● Located in the inner layer of the periosteum (fibrous membrane that covers the surface of the bone) they give rise to osteoblasts

Answer 3

Osteogenic cells

Question 4

● Bone secreting cells
● During bone formation, they first secrete the amorphous and fibrous (Collagen) components of unmineralized bone, and later they deposit their stored calcium to mineralized or harden the bone
● They line the trabecular (bone material) surfaces of the bone

Answer 4

Osteoblasts

Question 5

● Mamre bone cells that stop secreting the bone substance
● They are actually osteoblasts which have been trapped in spaces called lacunae in the bone substance during mineralization
● Their main function is to maintain the integrity of the bone by supplying nutrient derived from the blood vessels in thr canaculi

Answer 5

Osteocytes

Question 6

● Believed to rise from the fusing of osteocytes
● Remodeling cells which are multinucleated in the structure and located in a concavity called the Howship’s lacuna at the bone surface

Answer 6

Osteoclasts

Question 7

A non-mineral matrix of collagen and glycosaminoglycan

Answer 7

Osteoid

Question 8

Deposited within the matrix

Answer 8

Inorganic mineral salts

Question 9

It is the spaces between the adjacent trabeculae

Answer 9

Interosseous space

Question 10

A portion of the bone substance which is called the bone spicule

Answer 10

Trabeculae

Question 11

Consisting of few trabeculae and many of the interosseous spaces

Answer 11

Cancellous Bone (Spongy bone)

Question 12

Consist of extensive lamallae and fewer interosseous spaces. This bone develops into existing trabecullae to form layers called lamallae

Answer 12

Compact Bone (Lamellar Bone)

Question 13

● Basic unit structure of a compact bone
● Circular structure composed of a central canal called the “Harversian canal” surrounded by concentric layers (lamellae) of bone substance
● Embeded in the lamellae are the bone caniculi containing the cytoplasmic process of the osteocytes
● The Harvasian canal connects a transversely positioned Volkmann’s canal

Answer 13

Osteon or Harversian system

Question 14

The process by which bone is formed through the secretory activity of the osteoblasts

Answer 14

Osteogenesis

Question 15

Bone develops in pre-exsisting mesenchymal connective tissue (Bones of this type are called membrane bones)

Answer 15

Intramembranous Ossification

Question 16

Bones that are developed from pre-existing cartillage. This type of bone growth is responsible for the longitudinal growth of bones. (E.G. Long bones like femur and humerus)

Answer 16

Endochondral Ossification

Question 17

● Site of bone growth as seen in long bones
● Composed of different zones
    A. Zone of growth
    B. Zone of cartillage transformation
    C. Zone of ossification

Answer 17

Epiphyseal Plate (Epiphyseal Line)

Question 18

“Great Dimension
- e.g., Forelimb = humerus, radius, ulna, metacarpals, phalanges
Hind limb = femur, tibia, fibula, metatarsals, phalanges

Functions: a. Act as levers
b. For support, locomotion

Answer 18

Long Bones

Question 19

“Cuboids or equal shape”
- e.g., carpals, tarsals

Function: absorbs concussion

Answer 19

Short Bones

Question 20

“Thin and expanded”
- e.g., skull, ribs, scapula, pelvic bones

Functions: a. Protect vital organs e.g. brain, lungs
b. Provide areas for muscle attachment

Answer 20

Flat Bones

Question 21

“Sesame-seed shape develops along the course of tendons”
- e.g., patella
Functions: a. Reduce friction
b. Change the course of tendons

Answer 21

Sesamoid Bones

Question 22

“Unpaired bones in median plane
- e.g., vertebral column, some bones of the skull

Functions: a. For protection and support
b. For muscle attachment

Answer 22

Irregular Bones

Question 23

“Presense of air spaces or sinuses that communicate with the exterior”

• e.g., flying birds, maxillary and frontal bones

Answer 23

Pneumatic Bones

Question 24

“Made up of bones of the limbs bones of the front (pectoral) limbs and bones of the hind (pelvic) limbs

Answer 24

Appendicular Skeleton