JOINTS & ARTICULATION/BIOMECHANICS Flashcards
Joints
Locations where bones, or bones and cartilage meet for movement and allow bones to slide smoothly against one another
Joints that provide little to no movement:
Some bones are joined to one another by connective tissue (cartilage) that are designed for stability and will provide little to no movement
How many bones in human body
There are 206 bones in the adult human body and all except one will connect to at least one other bone at specialized structures called JOINTS
Structural classification of joints (GENERAL)
Consider whether the bones are strongly anchored to each other by connective tissue or whether they articulate within a fluid-filled space called joint cavity
Functional classification of joints (GENERAL)
Describe the degree or range of movement ranging from immobile to slightly moveable, to freely moveable
3 classifications of structural (4)
- Based on structural components surrounding articulating surfaces
- Fibrous joint
- Cartilaginous joint
- Synovial joint:
Fibrous joint
Fibrous joint has bones united by fibrous connective tissue
Cartilaginous joint
Bones joined by hyaline cartilage or fibrocartilage at cartilaginous joint
Synovial joint
Articulating surfaces of bones are not directly connected but come into contact within fluid-filled cavity
3 classifications of functional (4)
- Based on amount of movement allowed between articulating bones
- Synarthrosis
- Amphiarthrosis
- Diarthrosis
Synarthrosis
Immobile/nearly immobile that could be fibrous or cartilaginous. Provides a strong union between articulating bones, especially important at locations where the bone provides protection for internal organs
Examples of synarthrosis (4)
Sutures, fibrous joints between bones of skull, manubriosternal joint, cartilaginous joint that unites manubrium and body of sternum for protection of heart
Amphiarthrosis
Joint with limited mobility
Joints of adjacent vertebrae
Contains an amphiarthrosis joint made of cartilaginous joint that unites the bodies of adjacent vertebrae and contains a thick pad of fibrocartilage called INTERVERTEBRAL DISC that fills in between each gap
Joints of pubic symphysis
Contains an amphiarthrosis joint made of cartilaginous joint in which the pubic regions of right and left hip bones and strongly anchored to each other via fibrocartilage
Diarthrosis
Freely moveable joint and encompasses all synovial joints
Examples of diarthrosis (3)
All synovial joints of body providing most body movements, common in appendicular skeleton giving the limbs a wide range of motion, shoulder/hip joints providing multiaxial movement (3 types movement)
Fibrous joints
Bones joined by fibrous tissue (dense fibrous connective tissue) and does not contain any cavity between, gap filled with fibrous connective tissue may be narrow or wide
3 types of fibrous joints:
- Suture
- Syndesmosis
- Gomphosis
Suture
Type of fibrous joint that connects all the bones of the skull, except for the mandible. It helps to protect brain and form face
Suture functional classification
Classified as synarthrosis as the suture is frequently convoluted, forming a tight union
Adult skull bone
Skull bones are closely joined, and the narrow gap between them is filled with connective tissue
Syndesmosis
Type of fibrous joint that has two parallel bones united by fibrous connective tissue
Syndesmosis functional classification
Classified as amphiarthroses because they provide some movement
Examples of syndesmosis
Syndesmosis joints can be found between the radius and ulna, where an interosseous membrane fills gap between bones. The shafts of tibia and fibula are also connected by interosseous membrane
Structural specifics of distal tibiofibular joint
Articulating surfaces of those bones lack cartilage; the narrow gap is anchored by fibrous connective tissue and ligaments
Gomphosis
Also known as peg-and-socket joint. Specialized fibrous joint that anchors root of tooth into bony socket within maxillary bone (upper jaw) or mandible bone (lower jaw) of skull
Gomphosis structure
Contains numerous short bands of dense connective tissue called a periodontal ligament
Gomphosis functional classification
Classified as synarthrosis due to the immobility
Cartilaginous joint
No joint cavity, adjacent bones are joined together by either hyaline cartilage of fibrocartilage
2 types of cartilaginous joint:
- Synchondrosis
- Symphysis
Synchondrosis
When bones are joined together by hyaline cartilage and may be temporary or permanent and classified as a synarthrosis due to lack of movement between bone and cartilage
Temporary synchondrosis
Formed by epiphyseal plate of growing long bone which is eventually lost when epiphyseal plate ossifies as bone reaches maturity
Permanent synchondrosis
Does not ossify with age; it retains its hyaline cartilage
Symphysis
Fibrocartiliginous fusion between 2 bones, found in intervertebral disc and is amphiarthrosis
Fibrocartilage strength
Very strong because it contains numerous bundles of thick collagen fibers
Gaps separating bones at symphysis structure
Narrow like pubic symphysis and manubriosternal joint
Intervertebral disc
Wide symphysis between bodies of adjacent vertebrae
Synovial joint
Most common type of joint in body and possesses a fluid filled joint cavity. Bones are not directly connected with connective tissue, allowing for smoother movements and increased joint mobility making them DIARTHROTIC
Fluid filled space of synovial joint
Where the articulating surfaces of bones contact each other
articular capsule
Forms walls of joint cavity, which is a fibrous connective tissue structure attached to each bone
Articular cartilage function and structure
Prevents friction between bones at synovial joint made of a thin layer of hyaline cartilage that covers the entire articulating surface of each bone
Synovial membrane function
Lines inner surface of articular capsule. The cells of this membrane secrete synovial fluid
Synovial fluid
Thick, slimy fluid that provides lubrication to further reduce friction and provides nourishment to articular cartilage that doesn’t contain blood vessels
Diarthrosis
Freedom of joint movement (classification of each synovial joint)
Ligaments
Strong bands of fibrous connective tissue that strengthen and support the joint, found outside of articulating surfaces and connect bones
Tendons
Dense connective tissue structure that attaches muscle to bone. Provides additional support at synovial joints
Articular disc
Small, oval shaped plate of fibrocartilage present in several joints to separate synovial cavities
Meniscus
Larger, C-Shape plate of fibrocartilage present in several joints to separate synovial cavities
Bursa
Thin connective tissue sac filled with lubricating liquid that reduces friction, located where skin, ligaments, muscles, or muscle tendons rub against each other
6 types of synovial joints:
- Pivot joint
- Hinge joint
- Saddle joint
- Plane joint
- Condyloid joint
- Ball and socket joint
Pivot joint (3)
- Rounded portion of one bone rotates in depression in another bone
- ROTATION around single axis (uniaxial)
- atlandoaxial joint/proximal radioulnar joint
Hinge joint (3)
- Surface of one articulating bone is concave and the other is convex
- FLEXION/EXTENSION Bending and straightening around single axis (uniaxial)
- Elbow joint/knee/ankle joint/between phalanges
Saddle joint (3)
- Ends of both bones are saddle shaped and fit together
- FLEXION/EXTENSION, ABDUCTION/ADDUCTION, CIRCUMDUCTION Movement in sagittal and frontal planes (biaxial)
- carpometacarpal joint/sternoclavicular joint
Plane joint (gliding point) (3)
- Articulating surfaces are flat and slightly curved.
-GLIDING Flat bones slide over each other (uniaxial/biaxial/multiaxial), - intercarpal joint/intertarsal joint/acromioclavicular joint/ygapophysial joint
Where are plane joints found specifically (4)
- Intercarpal joints
- Intertarsal joints
- Acromioclavicular joint
- Zygapophysial joint
Condyloid joint (3)
- Convex oval shape of one bone fits into concave oval depression in another bone
- FLEXION/EXTENSION, ABDUCTION/ADDUTION, CIRCUMDUCTION Forward backward and side movements (biaxial)
- knucle joint/radiocarpal joint of wrist
Ball and socket joint (3)
- Rounded ball at the end of one bone articulates with rounded depression of another
- FLEXION/EXTENSION, ABDUCTION/ADDUCTION, CIRCUMDUCTION, ROTATION, Bone moving in depression on another bone (multiaxial)
- hip joint/shoulder joint
Circumduction
Where distal end of the bone moves in a circle while the proximal end remains relatively stationary
Specific examples of ball and socket joint movement (2)
- Hip joint: Head of femur articulates with hip bone
- Shoulder joint: Head of humerus articulates with scapula
Biomechanics
The interplay between bones of skeleton, the muscles that contract to move them, and the tendons that connect the two together that allow us to examine biomechanics of body movement
When a skeletal muscle contracts, where is the tension exerted
When a skeletal muscle contracts, the tension is usually exerted on tendons that attach to the moveable bones of body
Origin of muscle
Part where muscle is attached to a fixed part of a bone and doesn’t move during contraction
Insertion of muscle
Part of the bone that moves when the muscle contracts
Prime mover/agonist
Term for the principal muscle that is used for movement in a certain body part (muscle that is contracting)
Synergist
Any muscle that assists the agonist
Fixator
A synergist that stabilizes the origin
Antagonist
A muscle with the opposite action of the prime mover. It maintains body or limb position and control rapid movement and check motion of a limb (muscle that is relaxing or lengthening)
Example of agonist and antagonist usage in biceps branchii and triceps branchii
The bicep branchii is agonist and works to flex the forearm, while the tricep branchii is an antagonist and extends the forearm
Examples of agonist and antagonist usage in hamstrings and quadriceps femoris
The hamstrings is agonist and works to flex the leg, while the quadriceps femoris is the antagonist and extends the leg
Examples of agonist and antagonist usage in flexor digitorum superficialis & profundus and extensor digitorum
The flexor digitorum superficialis & profundus is the agonist and works to flex the fingers and hand at the wrist, while the extensor digitorum is the antagonist and works to extend fingers and hand at wrist
Muscles without attachment to skeleton (2):
- Muscles that produce facial expressions have their insertions and origins on the skin
- Diaphragm contracts and relaxes to change volume of pleural cavities without moving skeleton
Lever systems
Illustrate how muscles and bones interact to move body parts
Principal components of lever systems (3):
- Lever
- Fulcrum effort
- Load/resistance
Lever
Bone or body part being moved
Fulcrum
Fixed point to which a force is applied
Effort
Applies force and the result of skeletal muscle contraction
Load/resistance
Weight of the body part bring moved or any resistance encountered in moving the body part (eg. Weight of holding something in hand)
What component mostly makes up for how a lever system operates
Mainly determined by the forces applied and their distances from the fulcrum
Effort arm
Distance from the fulcrum to the skeletal muscle insertion point
Load/resistance arm
Distance from the fulcrum to the bulk of the load/resistance
What is needed for movement to occur
The effort produced MUST overcome the load/resistance
Balanced lever system
No movement is occurring and the amount of effort being applied is just enough to balance out the efforts of load/resistance (effort x effort arm = load/resistance x load/resistance arm)
Basic formula to calculate relationships between forces and distances in given lever system
effort x effort arm = load/resistance x load/resistance arm
Power levers
Lever systems that can move heavy loads over short distances using comparatively little effort
Speed levers
Lever systems that can move light loads over large distances using a comparatively large amount of energy
What determines whether we have a power lever or a speed lever
It is dependant on the location of the insertion point relative to the load/resistance location
First class lever (2)
- Simplest type of lever where the two forces (effort and resistance) are applied on opposite sides of fulcrum
- Eg. Raising head –> Posterior neck muscles produce effort, the facial skeleton is resistance, and the atlanto-occipital joint is fulcrum
Second class lever (3):
- Has resistance between the effort and fulcrum, making effort closer to resistance than fulcrum
- Allows larger resistance to be moved by a small amount of effort (power lever), but this also means that the resistance will be moved at a relatively slow pace and can only be moved a short distance
- Eg. Standing up on toes –> Weight of body is resistance, calf muscles produce effort, and joints in the balls of feet are fulcrums
Third class lever (2):
- Most common type with the effort applied between fulcrum and resistance, allowing resistance to be moved relatively quicker over larger distances (speed lever)
- Eg. Lifting hand by flexing bice; branchii –> Elbow joint acts as fulcrum, the biceps branchii produces effort, and the weight of hand is the resistance being lifted
