Bone structure and core MSK histology Flashcards
Describe the histological appearance of skeletal muscle
- Striated
- Unbranched
- Multinucleated (nuclei located preipherally)
Appreciate that Muscle fibres are grouped into bundles called fascicles and a muscle typically contains several fascicles.
- What is the connective tissue that surrounds the muscle as a whole called ?
- What is the connective tissue which surrounds a fascicle called?
- What is the connective tissue called which surrounds a single muscle fibre called ?
- Epimysium surrounds muscle as a whole
- Perimysium surrounds a single fascicle
- Endomysium surrounds a single muscle fibre
Why do skeletal muscles look striated ?
Because the Z-lines in the sarcomere of one myofibril will be aligned with the Z-lines of the sarcomeres in the surrounding myofibril.
The axon of the motor neurone branches as it nears its termination and each branch ends in a special type of synapse called…?
The neuromuscular junction
What type of muscle is shown in the micro pic ?
Skeletal muscle - note the multiple nuclei and striations
What/where are the cells of the ECM in cartilage ?
Chondrocytes - live in a space within the ECM termed a lacuna
What is the ECM of cartilage made up of ?
- 75% water
- 25% organic material - 60% of which is Type II collagen and 40% is proteoglycan aggregates
Hyaline cartilage is the most common type (also there is fibrocarilage and elastic) where is hyaline cartilage found ?
- Articular surfaces
- Tracheal rings
- Costal cartilage
- Epiphyseal growth plates
- Precursor in fetus to many bones
What are the functions of bone ?
- Support
- Movement
- Protection
- Calcium store
- Haemopoiesis
What is the composition of bone ?
- 65% mineral (calcium hydroxyapatite crystals)
- 23% collagen
- 10% water
- 2% non-collagen proteins
What are the two main types of bone and describe there appearance/where they are in terms of the bone as a whole
Cortical bone - dense outer shell makes up the shaft (diaphysis)
Cancellous or trabecular bone - occupies the ends of bone (epiphysis). It is a fine meshwork that looks like the inside of an aero bar.
Appreciate that in both compact and trabecular bone the only main difference is the presence of spaces the rest is similar
appreciate this
Label the structures in the pic and what type of bone is shown?
Cortical bone
What are cement lines ?
They are lines which often surround osteons, they are formed during remodelling
Appreciate that trabecular bone generally lack haversion canals because the osteocytes can survive with contact with the bone marrow
What is the 4 main types of cells found in bone ?
- Osteoproginator cells
- Osteoclasts
- Osteoblasts
- Osteocytes
Name the type of cell which matches the description:
- Bone forming cells found on the surface of developing bone. They have plentiful RER and prominent mitochondria.
- Large (up to 40µm or more) multinucleated cells. They are found on the surface of bone and are responsible for bone resorption.
- A bone cell trapped within the bone matrix.
- Located on bone surfaces, for example under the periosteum, these cells serve as a pool of reserve osteoblasts
- Osteoblasts
- Osteoclasts
- Osteocytes
- Osteoprogenator cells
Describe the stages of bone remodelling
- Number of osteoclasts drill into bone forming tunnel
- Blood vessel grows into tunnel bringing with it osteoblasts
- Osteoblasts lay down new lamellar bone
- Process continues until only space of haversion canal remains
What does this pic show ?
Osteoclasts (you can see the multinuclei and that they are very large)
Describe the difference between lamellar and woven bone
If bone is broken the collagen fibres are not laid done all in one direction (lamellar) they are laid down in a haphazard fasion (woven). This woven bone is weaker and hence is slowly remodelled into lamellar bone
What do osteoblast secrete ?
They secrete collagen, glycosaminoglycans (GAGs), proteoglycans and other organic components of the matrix which is collectively termed osteoid which becomes minerlaised over time.
