Flashcards in MSK - Bones And Joints Deck (38)
How many bones are there in the body?
What are the main functions of the skeleton?
- mineral and growth factor storage
What are the different classifications of bone by shape?
- flat bone (eg frontal part of skull)
- sutural bone
- irregular bone (eg vertebra)
- long bone (eg femur)
- sesamoid bone (eg patella)
- short bone (eg carpal)
What is the function of a sesamoid bone?
- modify pressure
- diminish friction
- alter direction of pull of a tendon
What is the main shaft of a long bone called?
What is the 'neck' of a long bone called?
Describe the composition of short, flat and sesamoid bones
- consist mainly of spongy bone
- thin layer of periosteum covered compact bone on outside
- no epiphysis or diaphysis
- contain bone marrow between trabeculae
What supplies the blood to bone marrow?
Nutrient artery - enters diaphysis via nutrient foramen
What supplies blood to the periosteum and outer third of the cortex?
What supplies blood to the epiphysis of a long bone?
What is avascular necrosis?
Death of bone due to interruption of blood supply. Leads to collapse of necrotic segment and secondary osteoarthritis
(Also known as osteonecrosis, aseptic necrosis, ischaemic necrosis)
What are the causes of avascular necrosis?
- steroid use
- decompression sickness (the bends)
What is a joint?
Articulation between two or more bones
What are the three structural classifications of joints?
Give some examples of fibrous joints
- sutures of skull
- joints between roots of teeth and bone of mandible/maxilla
What is the difference between a primary and secondary cartilaginous joint?
Primary is united by hyaline cartilage, eg. 1st sternocostal joint.
Secondary comprises articulating bones covered with hyaline cartilage, with a pad of fibrocartilage between them, eg. intervertebral disc, manubriosternal joint
Give some characteristics of synovial joints
- ARTICULAR CARTILAGE (hyaline cartilage allows smooth, low friction movement and resists compression)
- FIBROUS CAPSULE (contains collagen, completely encloses joint except synovial protrusions, stabilises joint)
- SYNOVIAL MEMBRANE (thin and highly vascularised, lines capsule but does not cover articular cartilage, produces synovial fluid)
- SYNOVIAL FLUID
- INTRA-ARTICULAR MENISCI
- FAT PADS
What is a bursa?
A sac lined with synovial membrane and filled with synovial fluid. It can be communicating or non-communicating with the joint cavity
What is a tendon sheath?
An elongated bursa which wraps around a tendon to reduce friction
What is the function of synovial fluid?
Reduces friction, shock absorption, nutrient and waste transportation
What is the composition of synovial fluid?
Hyaluronic acid, lubricin, proteinase, collagenase
How is blood supplied to synovial joints?
Via periarticular arterial plexus
What are the differences in blood supply within the synovial joint?
- articular cartilage is avascular
- fibrous capsule and ligaments have poor blood supply
- synovial membrane has rich blood supply
What does Hilton's law suggest about nerve supply of joints?
Nerves supplying the joint capsule also supply the muscles moving the joint and the skin overlying the insertions of these muscles
Describe a planar joint
- articulating surface is flat or slightly curved
- gliding/sliding movements
Eg. Sternoclavicular joint, intercarpal joints
Describe a hinge joint
- convex surface of one bone fits into concave surface of another
Eg. Knee, ankle, humeroulnar joint of elbow
Describe a pivot joint
- rounded/pointed surface of one bone articulates within ring formed by the concavity of another bone and fibrous ligament
Eg. Proximal radioulnar joint
Describe a condyloid joint
- oval shaped condyle of one bone rests on elliptical cavity of another
- movements are flexion, extension, abduction, adduction, circumduction
Eg. Metacarpophalangeal joints
Describe a saddle joint
- biaxial joint
- one bone is saddle shaped, other bone fits on top
- movements include flexion, extension, adduction, abduction, circumduction
Eg. 1st metacarpal joint