Skeletal System Flashcards
What are the functions of the skeletal system?
- supports the body
- facilitates movement
- protects internal organs
- produces blood cells
- stores and releases minerals and fat
Function of cartilage
- provide flexible strength and support for body structures
- Unite adjacent bones/provide cushioning at joints
Function of ligaments
- Strong connective tissue bands that hold bones at a moveable joint together
- Prevent excessive movements of the joint that would result in injury
- Dense regular connective tissue
Describe long bones and give examples
- cylindrical (longer than wide)
- Function: levers (move when they contract)
- Central chamber in the shaft (medullary or marrow cavity)
- Eg: humerus, ulna, radius, femur…
Describe short bones
- cube-like shape
- Function: stability, support and limited motion
- E.g: carpal bones, tarsal bones
Describe sesamoid bones
- Sesame shape (small, round)
- Contained within tendons/joint capsules
- Function: protect tendons by preventing wear and tear when a tendon moves adj to bony surface or joint
- also important in increasing the distance between the tendon and a joint. This improves the leverage of the muscle so that it requires less energy to move the joint providing the muscle a mechanical advantage in movement.
- E.g: patella
Describe flat bones
- quite thin
- curved rather than flat
- Function: serve as points of attachment for muscles and often protect internal organs
- E.g: cranial bones, scapulae, sternum, ribs
Describe irregular bones
- bones that don’t fulfil the above criteria
- E.g: vertebrae, facial bones
Main parts of long bone
- diaphysis: walls are cortical bone tissue
- epiphysis: trabecular bone tissue, red bone marrow in spaces of this tissue
- medullary cavity: hollow region in diaphysis (yellow bone marrow)
- metaphysis: between epiphysis and diaphysis
- epiphyseal growth plate: at junction b/n epiphysis and metaphysis. hyaline cartilage
- changes to epiphyseal line once growing stops
What is the endosteum?
- membranous lining of medullary cavity
- dense irregular connective tissue
- function: bone growth, repair and remodelling
What is the periosteum
- dense irregular connective tissue
- covers external surface of the bone
- has BVs, nerves, lymph vessels that nourish cortical bone tissue
- Attachment site for tendons and ligaments
- covers the entire external surface except where the epiphyses meet other bones to form joints (covered with articular cartilage (hyaline) that reduces friction and is a shock absorber)
Describe primary ossification centre
- first site of bone ossification - in diaphysis (central part for short and irregular)
- typically forms prenatally
- Some bones have > 1 (e.g os coxae/vertebrae)
What are secondary ossification centres
- additional ossification sites at ends of the bone
- appear postnatally (around puberty)
How do bones grow?
- occurs at epiphyseal plate (hyaline cartilage)
- Longitudinal growth: cartilage forms on epiphyseal side, and diaphyseal side cartilage is ossified and it grows in length
- Rate of growth controlled by hormones
Epiphyseal line
Osseuous scar of where epiphyseal plate was
Appositional growth
While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases.
Appositional growth
While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases.
Hyoid bone
- Small U shaped bone in superior aspect of neck (U points posteriorly)
- independent (doesn’t contact others)
- function: stabilisation of tongue during speech and swallowing
