L1: Skeletal system Flashcards
What are bones?
Calcified connective tissue.
How many bones are found in the body?
206
What are the functions of bones?
1) Support body & shapes it (framework for the body)
2) Protection of certain organs e.g. skull protects brain.
3) gives attachment to muscles & joints
4) Long bones provide levers for muscles to move joints
5) Formation of blood cells in red marrow.
6) Store & provide body with minerals; Calcium & phosphorus in emergencies.
What are bones classified according to?
According to:
A. Position.
B. Development.
C. Structure.
D. Shape.
Classification of bones according to position
Axial and appendicular
What is the axial skeleton?
skull, vertebral column, Sternum & Ribs
What is the appendicular skeleton?
Bones of upper and lower limbs
Describe the vertebral column
has 32-33 vertebrae, divided into:
1) Cervical (neck): 7 cervical vertebrae.
2) Thoracic (chest): 12 thoracic vertebrae.
3) Lumbar (low back): 5 lumbar vertebrae.
4) Sacrum: 5 fused sacral vertebrae.
5) Coccyx (tail): 3-4 fused coccygeal vertebra
What is the function of the thoracic cage?
It protects heart & lungs & allows breathing
What does the thoracic cage consist of?
1) Sternum: anteriorly.
2) Ribs: 12 pairs laterally.
3) 12 Thoracic vertebrae: posteriorly.
Compare between the upper limb and lower limb
What is the mechanism of formation of intramembranous bones?
The condensed mesenchymal tissue → undergoes bone formation directly
What are examples of intramembranous bones?
shaft of clavicle
skull cap
Bones of face.
What is the mechanism of formation of intra-cartilaginous bones?
- The condensed mesenchymal tissue → chondrification first to form a cartilaginous model
- Then bone is deposited in this model
What are examples of intra-cartilaginous bones?
All bones of limbs except shaft of clavicle.
Compare between cancellous (spongy) bones and compact bones
What are bones classified into according to ossification?
Intramembranous and intra-cartilaginous bones
What are bones classified into according to structure?
Cancellous (spongy) and compact
What are bones classified into according to shape and give examples for each one?
What are the parts of a long bone?
A long bone consists of 2 ends & a shaft.
What is (epiphysis)?
The end of long bone.
What is the epiphyseal Cartilage?
- a hyaline cartilaginous plate separate the end from
the shaft - It is the site of growth in length of bone.
- It ossifies at a certain age forming epiphyseal
line.
What is the diaphysis and what is it composed of?
- The shaft of long bone
- Composed of:
a cylinder of compact bone with a cavity
Medullary cavity contains bone marrow.
Bone marrow occupies the marrow cavity in long & short bones & cancellous bone in flat & irregular bones: - At birth, marrow is red & hematopoietic.
- At 7 years of age, yellow marrow begins to appear in distal bones of limbs.
What is the metaphysis?
Wide expanded end of shaft close to epiphyseal cartilage.
What is the periosteum and what is its function?
- A fibrous membrane covering Shaft.
- responsible for growth of bone in thickness
What is the blood supply of long bones?
Nutrient artery: Passes through nutrient canal
Periosteal arteries
Metaphyseal arteries
Epiphyseal arteries
NB. The epiphyseal plate is avascular (= doesn`t have blood supply) & is supplied by diffusion.
❖ A 67-year-old woman presented to the emergency department with 4-month history of worsening lower back pain.
❖ There was no history of trauma or falls.
❖ She completed her investigations with serology and radiology.
❖ Based on the mentioned history and investigations, the patient was diagnosed with severe osteoporosis.
What are the main cells responsible for bone formation and resorption?
- osteoblast cell is responsible for bone formation
- while osteoclast is responsible for bone resorption
What are the two main hormones responsible for calcium deposition and removal from bones?
- calcitonin is responsible for calcium deposition in bone
- while parathormone is responsible for mobilization of calcium from bone
