Bones and Joints Flashcards
The skeleton contains 206 bones: 26 vertebral, 64 upper IMDb, 62 lower limb. What are the functions? (5)
Support, protection, movement (acts as levers), mineral and growth factor storage (main calcium and phosphate reservoir) and haemopoiesis (children - long bones of femur and tibia, adults - pelvis, skull, vertebrae and sternum).
Bones may be classified by shape, what are the categories? (6)
Flat bones - curved, protect organs,
Sutural - within cranial structure,
Short bones - equal in height and width,
Irregular bones - e.g. Vertebrae
Sesamoid - embedded within a tendon/muscle
Long bone - longer than wide, muscles act on them a rigid levers.
What is the structure of long bones?
Primarily compact bone, with perhaps spongy bone at the extremities.
When describing a long bone, what is the diaphysis, metaphysis and epiphysis? What are the other components?
The diaphysis is the main shaft, the metaphysis is the flare adjacent to the epiphyseal growth plate, with the epiphysis on the other side. Then there is the articular cartilage (hyaline on the ends). Periosteum lines the rest of the bone with endosteum lining the medullary cavity (red in a child and yellow in an adult).
How is the medullary cavity/bone marrow supplied in a long bone?
A Nutrient artery enters near the middle of the diaphysis via the Nutrient foramen.
What’s the structure of short, flat and sesamoid bones?
Short (carpal and tarsal) consist mainly of spongy bone with a thin layer of periosteum, covered by compact bone on the outside with not epiphysis/diaphysis, the bone marrow is in the trabeculae. The base of the carpal bone comes after the proximal articular cartilage, then the shaft, the neck and the head.
Apart from the medullary cavity of long bones, how is it supplied?
Periosteal arteries supply the periosteum and the outer 1/3 of the cortex, with the metaphyseal entering the metaphysis at the site of attachment to the capsule.
There’s an anastomoses between the the metaphyseal and epiphyseal arteries after epiphyseal fusion.
What is avascular necrosis and how is it caused?
Death of bone due to interruption of blood supply.
Varied causes include: fracture, dislocation, steroid use, radiation and decompression sickness. It leads to the collapse of the necrotic segment and secondary osteoarthritis.
What are joints and what are the 2 ways of classifying them?
Articulations between 2 or more bones.
Structural classification is based on the tissue between the bones and functional classification is according to the degree of movement.
The sutures of the skull, the radioulnar interosseous membrane and the posterior sacroiliac joint are all examples of which type of joint (structural classification)?
Fibrous joints.
A joint may be structurally classified as a cartilaginous joint, which can be primary or secondary, what’s the difference? Give examples.
A primary cartilaginous joint is one where the bones are united by hyaline cartilage e.g. At epiphyseal growth plates and the 1st sternocostal joint.
A secondary cartilaginous joint is where articulating bones are covered in hyaline cartilage with a pad of fibrocartilage between them e.g. At the pubic symphysis, intervertebral discs and manubriosternal joint.
What is the third structurally classification of a joint, after fibrous and cartilaginous?
Synovial joint - a joint capsule containing synovial fluid, freely movable.
What are the characteristics of a synovial joint?
Articular (hyaline, with some exceptions) cartilage, fibrous capsule, synovial membrane, bursts, tendon sheath, synovial fluid, fat pads, interarticular menisci/discs.
Which element of a synovial joint has the function of:
- Sacs lined with synovial membrane filled with synovial fluid, communicating or noncommunicating with joint cavity (cushion between bone and tendon/muscles around joint) - what’s it called when elongated?
- For smooth, low friction movement, that resists compression?
- Bursae - tendon sheaths are elongated bursae.
2. The articular hyaline cartilage.
Which element of a synovial joint has the function of:
- Thin, high vascularised and lines the capsule, as well as covering exposed osseous surfaces, tendon sheaths and bursae and produces synovial fluid - what does it not cover?
- Pieces of fibrocartilage not covered by synovium.
- The synovial membrane, which does does cover the articular cartilage or intraarticular discs/menisci.
- Intraarticular discs/menisci.
What is this describing?
Collagen (interlacing and longitudinal bundles), which completely encloses the joint except where interrupted by synovial protrusions (e.g. Bursae), which stabilises the joint, permits movements and resists dislocation?
The fibrous capsule.
Synovial fluid is clear/pale _______, viscous and slightly ________ (pH) at rest. The volume is < ___ml in a large knee joint. It is composed of ___________ acid, lubricin, proteinase and collagenase. Functions: reduce __________, ________ absorption, nutrient and waste ___________.
Yellow Alkaline 0.5 Hyaluronic Friction Shock Transport
Describe the blood supply to synovial joints.
It is via a periarticular arterial plexus.
The articular cartilage is avascular, and the fibrous capsule and ligaments have a poor blood supply, whereas the synovial membrane has a rich supply.
When thinking about the nerve supply of joints, it may be useful to apply Hilton’s law, what is it?
Nerve supplying the joint capsule also supply the muscles moving the joint and the skin overlying their insertions.
Synovial joints may be classed based on their shape, what are the different types? (6)
Planar joint, hinge joint, pivot, condyloid/ellipsoidal, saddle and ball and socket.
Which type of joint is monoaxial, pulley shaped - convex surface of one bone fits into the concave surface of another? Give some examples.
Hinge joint e.g. Ulnohumeral, ankle and knee.
Which type of joint had a surface that is flat/slightly curved for gliding/sliding movements, which are non axial? Give some examples.
Palmar joints e.g. Sternoclavicular, acromioclavicular and inter carpal joints.
Which type of joint is monoaxial, with a rounded/pointed surface of one bone articulating with a ring formed by the concavity of another and a fibrous ligament? Give examples.
Pivot joint e.g. Proximal radioulnar joint and the atlantoaxial joint.
What is a condyloid/ellipsoidal joint, which movements does it perform and what are some examples?
A condylar joint is biaxial, with the oval shaped condyle of a bone resting in the elliptical cavity of another.
Movements: flexion, extension, abduction and addiction (circumduction) e.g. Metacarpal-pharyngeal joints, radiocarpal joints and the atlanto-occipital joint.
