LEVEL 3 DIPLOMA IN AROMATHERAPY MODULE 10 KNOWLEDGE OF ANATOMY, PHYSIOLOGY & PATHOLOGY FOR COMPLEMENTARY THERAPIES THE ARTICULAR SYSTEM COURSE MANUAL CHRISTINA LYNE christina@aromalyne.com 1
THE ARTICULAR SYSTEM A joint or articulation is formed wherever one bone or cartilage meets another. The bones of the skeleton are too rigid to bend without damage so the many separate bones are held together at joints by flexible connective tissue to allow for movement. Joints are classified into three groups according to the degree of movement possible between the articulating surfaces: 1. Fixed or fibrous joints (no movement possible) These are immovable joints they are very strong and no movement is possible. The articular surfaces of these joints are held together by fibrous connective tissue and there is no synovial cavity between them. Often the bones are dovetailed into one another and usually protect an organ, e.g. sutures of the skull, pelvic girdle bones. 2. Cartilaginous joints (slight movement possible) These are slightly moveable joints - a pad of white fibrocartilage lies between the bone ends. The pad acts as a shock absorber and there is a fibrous capsule to hold the bones and cartilage in place. Slight movement is made possible by compression of the pad of cartilage. The symphysis pubis is one example of a cartilaginous joint - it softens during pregnancy and allows greater movement at childbirth. Another example is the spine. 3. Synovial joints (freely moveable) These are the freely moveable joints. Synovial joints are the most common type of joint in the body. These are movable, highly versatile, lubricated joints. Cartilage covers and protects the bone ends, ligaments help provide stability, tendons link the skeletal muscles to the bones and synovial fluid fills the space between the ends of the bones. There are five types of synovial joint, but they all share the following features: A synovial cavity this is the space that is found between the articulating bones. Articular cartilage the articulating bones are covered by hyaline cartilage. This helps to reduce friction and absorb shock. Synovial capsule this surrounds the entire joint, enclosing the synovial cavity and joins the two bone ends. This capsule is composed of two layers: the outer layer, the fibrous capsule is made of dense, irregular connective tissue lending strength and flexibility. The inner layer is the synovial membrane is made of areolar connective tissue with elastic fibres and adipose tissue. It is this membrane that secretes synovial fluid. 2
Functions of synovial fluid Lubricating the joints Reducing friction in the joints Supplying nutrients to the joints Removing metabolic wastes Removing microbes and debris via phagocytic cells There are six different types: 1. Ball and socket - the end of one bone is rounded and fits into a hollow in the other bone and movement in nearly all directions is possible. 2. Hinge - these bones can move up and down, but not from side to side. 3. Gliding - the bone surfaces are practically flat and move by sliding over each other. 4. Pivot - one bone rotates inside a space formed by another. 5. Saddle - a joint that allows movement in two directions i.e. backwards and forwards and from side to side. 6. Condyloid - a smooth rounded projection on a bone sits within a cup-like depression on the other bone. 3
Name of Joint Ball and Socket Hinge Gliding Pivot Saddle Condyloid Examples Hip and shoulder joint Elbow, knee, ankle, wrist Interphalangeal joints (joints between phalanges of fingers & toes) Patellofemoral joint at knee Intercarpal joints Intertarsal joints Sacro-iliac joint Radius & ulna Atlas and axis (first two cervical vertebrae) Joint at the base of the thumb, between the trapezium and the 1st metacarpal Wrist joint Metacarpophalangeal joint 4
Ball & Socket Joint: the most moveable joint of all Movements: flexion, extension, adduction, abduction, rotation, circumduction Joints: Hip and shoulder Hinge Joint: movement in one direction only (like a hinged door) Movements: flexion, extension Joints: Elbow, knee, ankle, and joints between the phalanges of fingers and toes Gliding Joint: the bones glide over each other Movement: the least moveable of joints Joints: between the tarsals and carpals Pivot Joint: a projection from one bone turns within a ring-shaped socket of another bone. Movement: allows the head to rotate Joints: First two cervical vertebrae (atlas and axis) Saddle Joint: movement around two axes (like ball & socket). The bones can rock back and forth and from side to side. Movements: flexion, extension, adduction, abduction, circumduction and opposition of the thumb i.e. the ability to touch each of the fingertips on the same hand. Joints: at the base of the thumb, between the trapezium of the wrist and the 1st metacarpal bone. Condyloid Joint: a smooth rounded projection on a bone sits within a cup-like depression on the other bone Movements: flexion, extension, adduction, abduction, circumduction Joints: joint at the mandible and temporal bone, joints between the metacarpals and phalanges and joints between the metatarsals and phalanges. 5
MOVEMENTS POSSIBLE AT SYNOVIAL JOINTS FLEXION - A bending movement usually forward but occasionally backwards, e.g. knee joint. EXTENSION - Straightening or bending backwards movement. ABDUCTION - Movement of a bone away from the mid line of the body. ADDUCTION - Movement of a bone towards the mid line of the body. ROTATION - Movement around the long axis of a bone - can be medial or lateral. CIRCUMDUCTION - A combination of flexion, extension, abduction and adduction. PRONATION - Turning the palm of the hand down. SUPINATION - Turning the palm of the hand up. INVERSION - Turning the sole of the foot inwards at the ankle joint. EVERSION - Turning the sole of the foot outwards at the ankle joint. DORSIFLEXION - Turning the foot upwards towards the shin. PLANTAR FEXION - Pointing the foot downwards. 6