Cartilage

Question 1

CARTILAGE Properties

Answer 1

1. It is a rubbery type of connective tissue, it is tough and resilient.
2. It has no blood vessels, nerves or lymphatics .It gets its nutrition by diffusion
   from the blood vessels of the perichondrium.
3. It consists of mature cartilage cells (chondrocytes), fibers and matrix.
4. Its function to resist compress forces and friction.

Question 2

A- Hyaline Cartilage: (Glass like):
Structure:

Answer 2

1. Matrix: Homogenous and translucent.
2. Cartilage cells: Numerous, small rounded cells, present as single separate cells or
   2-3 cells present in one capsule (cell nest).
3. Fibers: Collagen fibres which are very thin and few.
4. This cartilage is covered with perichondrium.
5. It is present in the following sites:
   a- In the developing bones in the fetus.
   b- In the epiphyseal plates of the long bones in children.
   c- The articular cartilage in joints.
   d- The costal cartilage and xiphoid process (sternum).
   e- The larynx (except the epiglottis) and tracheal rings.
6. In certain sites it is replaced by bone in old age e.g. in larynx and epiphyseal cartilages.

Question 3

B- White Fibrocartilage structure

Answer 3

1. Matrix: It is obaque and not translucent because it is rich in collagen bundles.
2. Cells: They are few in number.
3. Fibers: It contains large amount of collagen fibres.
4. This cartilage is tough and has a great tensile strength.
5. It is present in the following structures: intervertebral discs and symphysis pubis
6. It does not show ossification in old age.

Question 4

C- Yellow Elastic Fibrocartilage structure

Answer 4

1. Matrix : Its yellow in appearance because it is rich in yellow elastic fibers.
2. Cells : They are abundant.
3. Fibers : Very rich elastic fibers.
4. It is present in tip of nose, auricle of ear, epiglottis (larynx) and eustachian tube.
5. It does not show ossification in old age.

Question 5

Functions of Skeleton:

Answer 5

1.Gives a specific shape to the body and provides it with a central axis.
2. Protects the vital organs, the skull protects the brain, and thoracic cage protects
the heart and lungs.
3. Provides surface area for muscular attachment.
4. Forms the joints which make the important part of the locomotor system.
5. Transmits and supports the body weight. The vertebral column transmits the
weight of the head and trunk to the bony pelvis then through the bones of
lower limbs to the feet and lastly to the ground.
6. Forms the blood elements in the bone marrow.
7. Stores calcium salts

Question 6

Classification of Bones (Skeleton):
I. According to their position in the body:

Answer 6

a. Axial skeleton: Skull, mandible, hyoid bone, sternum, ribs and vertebral column.
b. Appendicular (peripheral) skeleton: Bones of upper and lower limbs.

Question 7

II. According to the process of ossification:

Answer 7

1-Intra-membranous ossification
2-Intra-cartilaginous ossification

Question 8

III. According to their shape

Answer 8

A- Long bones
B- Short Bones
C- Flat Bones
D- Pneumatic Bones
E- Irregular Bones
F- Sesamoid Bones

Question 9

Functions of Pneumatic Bones:

Answer 9

1. They decrease the weight of skull.
2. Resonance of voice.

Question 10

Functions of Sesamoid Bones

Answer 10

They diminish friction between tendons and underlying bones e.g. patella which is the
largest sesamoid bone, embedded in the tendon of the quadriceps femoris muscle in front of knee joints