36 Questions
What is the primary function of joints in the human body?
To hold the skeletal bones together and allow for flexibility
How many joints are present in the human body?
230
What type of tissue holds bones together in fibrous joints?
Fibrous connective tissue
What is the term for slightly movable joints?
Amphiarthroses
What is the definition of a joint?
A site where two or more bones come together
Which type of joint is characterized by the presence of cartilage between the bones?
Cartilagenous joints
What happens to the angle of a joint when it undergoes flexion?
It decreases
What type of movement involves moving a part away from the midline?
Abduction
What is the term for rotation of the trunk, thigh, head, or arm?
Rotation
What is the term for moving a body part forward in a transverse or horizontal direction?
Protraction
What type of joint has articulating surfaces joined by fibrous tissue?
Fibrous joint
What is the term for extension beyond 180 degrees?
Hyperextension
What is the characteristic of immobile joints in the skull?
They have serrate and lap/squamous lines
What is the term for the joint where two bones are bound by a ligament only?
Syndesmosis
What type of cartilage is found in Synchondroses?
Hyaline cartilage
Where are Symphysis joints typically found?
Between vertebrae and pubic bone
What is the function of synovial fluid?
To reduce friction between the articular surfaces
What is the term for the thin layer of hyaline cartilage covering the articular surfaces of the bones?
Articular cartilage
What is the outer layer of the joint that protects the synovial membrane?
Joint capsule
What is the characteristic of synovial joints?
They are separated by a space
What type of joint allows for rotation as the only possible movement?
Pivot joints
What is the primary characteristic of Ball-and-socket joints?
They have a ball-shaped head that fits into a socket-like concavity
Which joint type is characterized by a concave and convex articular surface?
Saddle joints
What is an example of a Hinge joint?
Elbow joint
What type of joint allows for flexion, extension, abduction, and adduction, as well as a small amount of rotation?
Condyloid joints
Which joint type is characterized by two distinct convex surfaces that articulate with two concave surfaces?
Condyloid joints
What is the primary characteristic of Plane joints?
They are flat, allowing for gliding movements
What type of joint is the carpometacarpal joint of the thumb an example of?
Saddle joints
What is the characteristic of the bone surface in 6-Plane joints?
The bone surface is almost flat
What type of movement is impossible in Ellipsoid joints?
Rotation
What is the function of tendons in synovial joints?
Holding muscle to bone
Where are bursa commonly found in synovial joints?
Close to the joint where the skin rubs against underlying bony structures
What is the characteristic of a meniscus in synovial joints?
A crescent-shaped fibrocartilaginous structure
What type of disease is characterized by the storage of crystals of uric acid in the vicinity of a joint?
Gout
What is the result of inflammation of the synovial membrane?
Production of effusion into the articular cavity
What is the characteristic of the metacarpophalangeal joints?
They are good examples of synovial joints
Study Notes
Joint Structure and Function
- A joint is the junction between two or more bones; every bone in the body except the hyoid bone is connected to a joint.
- There are 230 joints in the body.
Functions of Joints
- Hold skeletal bones together
- Allow the skeleton some flexibility for gross movement
- Make bone growth possible
Classification of Joints
- Classification by structure:
- Fibrous joints (bones held together by fibrous connective tissue)
- Cartilagenous joints (bones held together by cartilage)
- Synovial joints (complex structure with cartilage and cavities)
- Classification by function:
- Synarthroses (immovable joints)
- Amphiarthroses (slightly movable joints)
- Diarthroses (freely movable joints)
Types of Joint Movements
- Flexion (decreases the angle of a joint)
- Extension (straightens and returns to the anatomical position)
- Hyperextension (extension beyond 180 degrees)
- Abduction (movement away from the midline)
- Adduction (movement towards the midline)
- Rotation (movement on a vertical axis)
- Medial rotation (turns the bone inwards)
- Lateral rotation (turns the bone outwards)
- Protraction (moving a body part forward)
- Retraction (posterior movement)
Fibrous Joints
- The articulating surfaces of the bones are joined by fibrous tissue
- Examples: sutures of the skull
- Immobile joints in the skull:
- Serrate (wavy lines, parietal/frontal bones)
- Lap/squamous (overlapping, temporal/parietal bones)
- Plane (non-overlapping, paired maxillary and palatine bones)
Cartilagenous Joints
- Synchondroses (bones joined by hyaline cartilage)
- Between the 1st rib and the manubrium sterni (only the first rib)
- Symphysis (bones joined by fibrous cartilage)
- Between vertebrae
- Pubic bone (pelvis)
Synovial Joints
- Synovial fluid is rich in albumin (blood protein) and hyaluronic acid produced by the synovial membrane
- The cavity of the joint is lined by synovial membrane
- Articular surfaces of the bones are covered by a thin layer of hyaline cartilage called articular cartilage
- Synovial membrane is protected on the outside by a tough fibrous membrane referred to as the capsule of the joint
Classification of Synovial Joints
- Ball-and-socket joints (hip and shoulder)
- Permit free movements, including flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction
- Hinge joints (elbow, knee, and ankle joints)
- Permit flexion and extension movements
- Pivot joints (atlantoaxial and superior radioulnar joints)
- Rotation is the only movement possible
- Saddle joints (carpometacarpal joint of the thumb)
- Permit flexion, extension, abduction, and adduction
- Condyloid joints (metacarpophalangeal joints)
- Permit flexion, extension, abduction, and adduction together with a small amount of rotation
- Plane joints (carpal bone, patella-femur)
- Permit bones to slide along each other
- Ellipsoid joints (wrist joint)
- Permit flexion, extension, abduction, and adduction, but rotation is impossible
Other Structures in Synovial Joints
- Tendons (collagen-based connective tissue that hold muscle to bone)
- Ligaments (collagen-based connective tissue that hold bone to bone)
- Labrum (a fibrocartilage ring around the bony cup)
- Bursa (fibrous "sac" that holds synovial fluid)
- Meniscus (a crescent-shaped fibrocartilaginous structure)
Joint Diseases
- Inflammatory illness of a joint (autoimmune, septic, or gout)
- Rheumatoid arthritis (an autoimmune disease)
- Osteoarthritis (bone degeneration due to old age)
- Synovitis (inflammation of the synovial membrane)
- Production of effusion into the articular cavity
Learn about the structure and function of joints in the human body, including their role in holding bones together, allowing flexibility, and enabling bone growth.
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