Lecture 2 - Joints of the Human Body Flashcards
classification of joints based on their movement
- Synarthroses (immovable)
- > joints of the skull and pelvic joints - Amphiarthrosis (semi-movable)
- > intervertebral joints and public symphysis - Diaorthosis (fully movable)
- > knee, elbow, hip
classification of joints based on structure
- Fibrous joints
- > immovable, no joint space (i.e. suture of skull) - Cartilaginous Joints
- > band of thick cartilage in joint space, some movm, lots of stability - Synovial joints
- > have joint capsules that contain synovial fluid, supported by ligaments
types of synovial joints
- Plane joint
- Hinge joint
- Condyloid joint
- Saddle joint
- Pivot joint
- Ball and socket
what are DoFs, what types, how many?
Degrees of Freedom
- > the number of independently variable factors affecting the range of states in which a system may exist, particular the direction in which independent motion can occur
1. 3 Translational DoFs
2. 3 Rotational Dofs
what are the 3 translational DoFs
- > a body segment may move or translate
1. Forward/backward (ant/post)
2. Left/right (med/lat)
3. Up/down (sup/inf)
3 rotational DoFs
- > a body segment may rotate:
1. about the sagittal axis
2. about a frontal axis
3. about a transverse axis
what are the DoFs of a plane joint
only allows for sliding/gliding between bones
- > 2 translational (up/down and fwd/back) and 1 rotational (gen rotation) (although often restricted)
- > intercarpal and acromioclavicular joints
Dofs of a hinge joint
surfaces are molded into each other such that they only allow for 1 rotational DoF
- > elbow, ankle and knee
dofs of a saddle joint
bones are molded to each other to allow rotation about 2 axis (2 DoFs) with no trans DoF
- > flex/extend
- > abd/add
- > carpometacarpal joint of the thumb
what are the dofs of condyloid joints
- > 2 rot and 0 trans Dofs
bones are molded to each other (like saddle joints) to allow rotation about 2 axis however the shape of the contact area allows for circumduction - > flex/extend and abd/add and circumduction as a combo of both
- > wrist and metacarpalphalangeal joints
dofs of Pivot joints
1 rot DoF
- > joint that allows for one rot dof where a bone wraps around a process or rounded surface
- > prox and distal radioulnar joints, alantro-axial joint
ball and socket joint DoF
- > 3 rot DoF
- > a rounded head of a bone fits into a convex socket that allows for 3 rot dofs and a combined action (circumduction)
- > flex/ext, abd/add, circum, med/lat rotation
- > glenohumeral joint, hip joint
why does the human body have such variation in the design of the skeletal joints
joints require differents amounts of mobility and stability depending on the joint
- > mobility and stability are inversely correlated
joint stability vs joint mobility
stability
- > refers to the resistance to motion that joint is able to provide
mobility
- > is the amount of movement that a joint is capable of moving through before being restricted by surrounding tissues
how do we measure joint angle
using goniometers
