articular system and joints Flashcards
Name the 3 types of cartilage found in the body and give an example of where each type of cartilage can be found
The three types of cartilage are:
1. Hyaline cartilage - costal cartilage of ribs, articular cartilage in joints
2. Elastic cartilage - external ear
3. Fibrocartilage - intervertebral discs
Describe the structure and function of fibrous and cartilaginous joints
Fibrous Joints:
- Structure: Bones are united by dense connective tissue with no joint cavity.
- Function: Generally immovable or allow limited movement.
Cartilaginous Joints:
- Structure: Bones are united by hyaline or fibrocartilage, with no joint cavity.
- Function: Allow limited movement and provide strength and shock absorption.
Describe the general features of a synovial joint
- Articular cartilage: Hyaline cartilage covering the ends of bones, reducing friction.
- Joint cavity: A fluid-filled space between the bones, allowing movement.
- Synovial membrane: Lines the joint cavity and secretes synovial fluid for lubrication.
- Joint capsule: A fibrous capsule enclosing the joint, reinforced by ligaments.
- Ligaments: Connect bones and provide stability to the joint.
- Accessory structures: Include bursae, menisci, and fat pads, which help reduce friction and improve joint stability.
Describe the factors that affect joint mobility and stability
- Bone Structure/Shape: The shape of bones determines movement type and range. For example, ball-and-socket joints allow more mobility than hinge joints.
- Ligament Strength and Tension: Ligaments stabilize joints; more or tighter ligaments increase stability, though excessive tension can limit movement.
- Muscle Arrangement and Tension: Surrounding muscles control movement and support joints. Well-developed muscles improve stability, while imbalances affect motion.
- Soft Tissue Contact: Soft tissues (like muscles and fat pads) can restrict or enable movement by filling or expanding joint space.
- Hormones: Hormones like relaxin can increase joint flexibility, affecting mobility and stability, especially during pregnancy.
- Disuse: Lack of activity weakens muscles and ligaments, reducing both stability and mobility.
What components make up the articular system?
The articular system consists of joints, associated ligaments, and accessory structures.
What is a joint or articulation?
A joint or articulation is a point of contact between two bones, bones and cartilage, or bones and teeth.
How are joints classified structurally?
Joints are classified based on:
(1) The presence or absence of a synovial cavity (space between articulating bones).
(2) The type of connective tissue that binds the bones together (e.g., cartilage).
What type of tissue is cartilage, and where is it located?
Cartilage is a resilient, semirigid connective tissue found in parts of the skeleton
How is cartilage nourished, and why?
Cartilage is nourished via diffusion because it lacks blood vessels, lymphatic vessels, and nerves.
Why do younger people have more cartilage?
Younger people have more cartilage due to the process of endochondral ossification during bone development.
What is the role of articular cartilage?
Articular cartilage provides smooth surfaces for joints, facilitating movement.
What is the most common type of cartilage, and where is it found?
Hyaline cartilage is the most common type and covers bony articular surfaces.
What role does hyaline cartilage play in fetal development?
Hyaline cartilage serves as the model for the early fetal skeleton.
What is the primary structural component of hyaline cartilage?
Hyaline cartilage contains moderate amounts of collagen.
Which type of cartilage is highly flexible, and where is it found?
Elastic cartilage is highly flexible and is found in the external ear, auditory tube, and parts of the larynx.
What structural feature characterizes elastic cartilage?
Elastic cartilage contains bundles of elastic fibers.
Where is fibrocartilage found in the body?
Fibrocartilage is found in specialized joints such as discs, menisci, and labra, contributing to articular surfaces.
What structural component gives fibrocartilage its strength?
Fibrocartilage contains substantial amounts of collagen.
What is fibrocartilage composed of?
Fibrocartilage is a mix of fibrous tissue and hyaline cartilage.
What are the three main types of joints or articulations?
Synovial, fibrous, and cartilaginous joints.
What characterizes synovial joints?
Synovial joints are moveable, with bones united by a joint or articular cavity and often supported by associated structures.
How are bones united in fibrous joints, and how does this affect movement?
Bones in fibrous joints are united by fibrous tissue, and the degree of movement depends on the length of the fibers.
What is the main function of cartilaginous joints?
Cartilaginous joints provide strength and shock absorption.
What type of tissue unites bones in cartilaginous joints?
Bones in cartilaginous joints are united by hyaline cartilage or fibrocartilage.
What characterizes fibrous joints?
Fibrous joints are solid or immovable, lack a joint cavity, and are held together by dense irregular connective tissue.
What type of fibrous joint is found only in the skull?
Sutures are fibrous joints found only in the skull, where bones are connected by a thin layer of connective tissue called a sutural ligament.
What is a syndesmosis, and what determines its degree of movement?
A syndesmosis is a fibrous joint where two adjacent bones are linked by a ligament. The length of the ligament determines the degree of movement.
What type of fibrous joint is specific to teeth?
Gomphosis is a fibrous joint where short collagen fibers connect the root of a tooth to its bony socket.
Where are gomphoses found?
Gomphoses are found exclusively around the teeth.
What joins the bones in cartilaginous joints?
Bones in cartilaginous joints are joined by hyaline cartilage or fibrocartilage.
Do cartilaginous joints have a joint cavity, and how movable are they?
Cartilaginous joints lack a joint cavity and are generally solid and immovable.
What is a synchondrosis, and where is it found?
A synchondrosis (primary cartilaginous joint) consists of a bar or plate of hyaline cartilage located between two ossification centers of a developing bone
What is a symphysis, and where can it be found?
A symphysis (secondary cartilaginous joint) is where fibrocartilage connects two separate bones, such as in intervertebral discs and the pubic symphysis.
What type of movement is permitted by symphyses?
Symphyses permit limited movement.
What distinguishes synovial joints from other types of joints?
Synovial joints have two bones separated by a fluid-filled cavity, allowing a lot of movement.
What type of cartilage covers the articulating surfaces of bones in synovial joints?
Hyaline cartilage covers the articulating surfaces of bones in synovial joints.
What are the two layers of the joint capsule in synovial joints, and what are their functions?
The inner synovial membrane is highly vascular and produces synovial fluid, while the outer fibrous membrane is made of dense connective tissue and may thicken to form ligaments.
What role does the synovial membrane play in synovial joints?
The synovial membrane produces synovial fluid, which lubricates and nourishes the joint.
What are the accessory structures associated with synovial joints?
Accessory structures include ligaments, tendons, bursae, and menisci, which support and enhance joint function.
What is the space within a synovial joint called?
The space within a synovial joint is called the synovial cavity.
What is the function of the synovial membrane?
The synovial membrane secretes synovial fluid, which fills the synovial cavity, lubricating and nourishing the joint.
What does the synovial membrane line, and where does it not extend?
The synovial membrane lines the internal surface of the joint but does not extend over the articular cartilage.
What characteristic of the synovial membrane supports its function?
The synovial membrane has a rich blood supply, supporting its role in producing synovial fluid.
What is the primary function of the fibrous capsule in a synovial joint?
The fibrous capsule encloses the synovial joint, providing structural support and protection.
What are structures located inside the fibrous capsule called?
Structures located inside the fibrous capsule are called intracapsular.
What type of tissue makes up the fibrous capsule?
The fibrous capsule is made of dense connective tissue composed of collagen fibers.
How can the fibrous capsule be reinforced?
The fibrous capsule may be reinforced by ligaments or receive muscle attachments for additional strength and stability.
What type of movement do plane joints allow?
Plane joints allow sliding or gliding movements, where one bone moves across the surface of another.
Can you give examples of plane joints?
Examples of plane joints include intercarpal joints, intertarsal joints, and joints between the vertebrae.
What is the main characteristic of a plane joint?
A plane joint is characterized by flat or slightly curved articulating surfaces that allow limited gliding movements.
What type of movement do hinge joints allow?
Hinge joints allow movement at right angles to the joint, producing flexion and extension.
Can you provide examples of hinge joints?
Examples of hinge joints include the elbow joints and interphalangeal joints.
What is the primary motion produced by hinge joints?
Hinge joints primarily produce flexion and extension movements.
What type of movement do pivot joints allow?
Pivot joints allow movement along the longitudinal axis of the bones, producing rotation.
Can you provide examples of pivot joints?
Examples of pivot joints include the proximal radioulnar joints and the atlantoaxial joint.
What is the axis of movement for pivot joints?
Pivot joints allow uniaxial movement around a vertical axis.
What are the components of a pivot joint?
A pivot joint consists of a sleeve (bone and ligament) and an axle (rounded bone)
What type of movement do condylar joints allow?
Condylar joints allow movement around two axes at right angles, producing flexion, extension, adduction, and abduction.
Can you provide examples of condylar joints?
Examples of condylar joints include the metacarpophalangeal (knuckle) joints and the wrist joints.
What are the main movements produced by condylar joints?
Condylar joints produce flexion, extension, adduction, and abduction movements.
What type of movement do saddle joints allow?
Saddle joints allow movement around two axes at right angles, producing flexion, extension, adduction, and abduction.
Can you provide an example of a saddle joint?
An example of a saddle joint is the carpometacarpal joint of the thumb.
What is a distinctive feature of the bones in a saddle joint?
The bones in a saddle joint are saddle-shaped, which allows for the unique range of movement.
What type of movement do ball-and-socket joints allow?
Ball-and-socket joints allow movement around multiple axes, producing flexion, extension, adduction, abduction, circumduction, and rotation.
Can you provide examples of ball-and-socket joints?
Examples of ball-and-socket joints include the shoulder joints and hip joints.
What is the shape of the bones in a ball-and-socket joint?
The bones in a ball-and-socket joint are shaped like a “ball” and a “socket,” allowing for a wide range of movement.
How does bone fit affect joint stability?
Well-fitting bones provide more stability, like the elbow compared to the knee.
How does the joint capsule contribute to stability?
A tight, strong capsule adds support and prevents excessive movement.
A tight, strong capsule adds support and prevents excessive movement.
Ligaments, such as the cruciate ligaments in the knee, stabilize the joint by limiting movement.
How do muscles stabilize joints?
Muscles, like the rotator cuff in the shoulder, control movement and provide support.
How does the shoulder’s stability compare to the hip?
The shoulder is less stable than the hip, relying on muscles for support, while the hip has a deeper socket and stronger ligaments.
What are articular discs and menisci made of?
Articular discs and menisci are made of fibrocartilage.
What role do articular discs and menisci play in joint stability?
They help absorb compression forces, contributing to joint stability.
What is the function of articular discs and menisci in joints?
They extend inward from the articular capsule and divide it, allowing separate movements to occur on each side of the partition.
How do articular discs and menisci affect joint movement?
They allow separate movements to occur simultaneously on each side of the partition.
What is the labrum made of?
The labrum is a fibrocartilage lip.
Where is the labrum located?
The labrum extends from the edge of the joint socket.
What is the function of the labrum in joints?
The labrum deepens the joint socket and increases the area of contact between bones.
In which type of joints is the labrum most prominent?
The labrum is most prominent in ball-and-socket joints.
What is the function of fat pads in joints?
Fat pads act as space fillers in joints.
Where are fat pads located in relation to the joint capsule?
Fat pads are intracapsular but extrasynovial.
How do fat pads assist in joint function?
They help spread synovial fluid within the joint.
What is the function of bursae and tendon sheaths?
Bursae and tendon sheaths reduce friction, working like ‘ball bearings.’
What are bursae and tendon sheaths filled with?
They are flattened fibrous sacs lined with synovial fluid.
Where are bursae and tendon sheaths more numerous?
They are more numerous in joints with greater mobility.
What determines the range of motion (ROM) in a synovial joint?
The articular surfaces of synovial joints contact one another, determining the type and range of motion.
What are the six factors that affect the ROM of a joint?
The six factors are:
1. Structure/shape of articulating bones
2. Strength and tension of joint ligaments
3. Arrangement and tension of muscles
4. Contact of soft parts
5. Hormones
6. Disuse
How is range of motion (ROM) measured?
ROM is measured in degrees of a circle (360°), indicating how far bones of a joint can move.
