Skelatal System Flashcards
What is the intra-membranous ossification and give examples
a- Intra-membranous ossification: e.g. clavicle and skull cap. The bones develop directly from CT membrane (mesenchyme). It begins at one or more centers of ossification.
What is intro cartilaginous ossification?
b- Intra-cartilaginous ossification: e.g. in long bones, vertebrae, ribs and base of skull. The mesenchyme is changed at first into a cartilage model, and then the cartilage is dissolved and disappears, and in its place is changed into bone.
When are long bones located? (Site)
Upper and lower limbs
What is the structure of long bones
[A] Long bones
Structure: two ends (epiphyses) and a shaft (diaphysis) in between.
•Epiphysis: it is the expanded upper and lower ends of the long bone. It is used for articulation and its articular surface is covered with a layer of articular hyaline cartilage.
• Diaphysis (Shaft):
A tube of compact bone with a central medullary cavity lined with endosteum and is filled with bone marrow (soft vascular tissue).
■The shaft is covered with fibrous sheath called periosteum.
The long bones increase in width from periosteum.
■In the growing long bones, the epiphysis and the diaphysis are separated by a disc of hyaline cartilage called epiphyseal cartilage which is responsible for the growth in length.
• Metaphysis: lies in the upper and lower parts of the long bone just beneath the epiphyseal cartilage. It is the most active part of long bone.
Describe the diaphysis?
• Diaphysis (Shaft):
A tube of compact bone with a central medullary cavity lined with endosteum and is filled with bone marrow (soft vascular tissue).
■The shaft is covered with fibrous sheath called periosteum.
The long bones increase in width from periosteum.
■In the growing long bones, the epiphysis and the diaphysis are separated by a disc of hyaline cartilage called epiphyseal cartilage which is responsible for the growth in length.
Functions of Skeleton:
a. Gives the specific shape to the body.
b. Provides the central axis of the body.
C. Protects the vital organs: the skull protects the brain, and thoracic cage protects the heart and lungs.
d. Provides surface area for muscular attachment.
e. Transmits and supports the body weight
f. Forms the joints
g. Forms the blood elements in the bone marrow.
h. Stores calcium salts.
What are Pneumatic Bones:
Bones containing air
Site: Skull bones mainly those surrounding the nose (e.g. maxillary and frontal bones), so the air cavities are called paranasal sinuses.
Structure: the bone may contain one air cavity (maxillary sinus) or multiple small air cells (mastoid air cells).
Describe the Arterial supply of bones
Nutrient artery supplies 2/3 of the thickness of the shaft and the bone marrow.it enters the middle of the shaft and runs away from the growing end.it divides into two branches
Periosteal artery in the periosteum supplies 1/3 of the shaft
Metaphysical artery supply the metaphysics but after ossification of the
Epiphyseal plate it anastomose with the nutrient-artery.
Epiphysial artery supply the epiphysis but after ossification of the
Epiphyseal plate it anastomose with the nutrient-artery.
What are the properties of cartilage?
It is rubbery type of CT
Tough and resilient
No blood vessels nerves or lymphatics
Consist of nature cartilage cells, matrix fibers
Resists compression
Growth by multiplication
What are types of cartilage?
1) hyaline 2) white fiber cartilage 3) yellow elastic fiber cartilage
What are the characteristics and site of hyaline cartilage?
Most widespread in human body
Sites: 1) developing bones in fetus
2) epiphyseal plates
3) particular cartilage in joints
4) the larynx and tracheal rings
5) costal cartilage and xiphoid in sternum
What are the characteristics and site of white fiber cartilage?
Opaque because it is rich in collagen bundles _ few cartilage cells
Sites → invertebrate disc
What are the characteristics and site of yellow fiber cartilage?
Yellow because it is rich in yellow elastic fibers _ cartilage cells are abundant
Sites → tip of nose, auricle of the ear, epiglottis of the larynx
What are the types of bones?
1) long bones 2) short bones 3) flat bones 4) pneumatic bones 5) irregular bones 6) sesamoid bones
What are the positions of bones in the body?
Axial: skull, mandible hyoid, ribs and vertebrae sternum
Appendicular: upper and lower limbs
