AP Ch 9: Articulations
How does the connective tissue in synchondroses and symphyses differ?
A synchondrosis is composed of hyaline cartilage but a symphysis is composed of hyaline cartilage and fibrocartilage
Name 6 Major Categories of Synovial Joint Movements
Plane Hinge Pivot Condyloid Saddle joint Ball-and-socket
Why should you warm up before exercise?
When a synovial joint is immobile for a time, the fluid becomes quite viscous, but as a joint movement increases, the fluid thins, becomes less viscous. warming up stimulates the production and secretion of synovial fluid, and more fluid means less stress on joints during exercise
What does a synovial joint cavity do?
allows the synovial joint to function as a diarthrosis
Define an articulation
area where two or more bones meet, or where bone and cartilage, or bone and teeth meet
Nutritional supplements that claim to aid joint movement by rebuilding knee cartilage are most likely referring to help with which component of the synovial joint?
articular cartilage
Where can gomphoses be found?
articulations between the roots of the teeth and the alveolar sockets in the maxillae and mandible
Why are condyloid and saddle joints important to many musicians?
condyloid joints are found in the wrists and saddle joints are found in the fingers
What is the functional classification of synovial joints?
diarthroses
Condyloid Joint Describe how the shape of this synovial joint determines the type of movement that can occur at the joint.
the convex oval-shaped projection of one bone fits into the oval-shaped depression of another bone permits movement around two axes (flexion-extension and abduction-adduction) permits limited circumduction (remember that circumduction is not an isolated movement). Examples of condyloid joints are the wrist and the metacarpophalangeal joints (between the metacarpals and phalanges) of the second through fifth fingers.
Which types of synovial joints allow movement around one axis, two axes, three axes, no axes?
1. HP 2. CS 3.B-S! 0. P one axis: hinge, pivot; two axes: condyloid, saddle; three axes: ball-and-socket; no axes: planar
On which anatomical characteristics do you base your classification of a joint?
based on 1. presence or absence of a synovial cavity 2. type of connective tissue binding the bones together
On what basis are joints classified?
based on either structure or function
As you may have noticed in the chapters on the skeleton, the ends of long bones are often rounded. What structures add stability to synovial joints and compensate for this anatomical phenomenon?
ligaments and articular menisci
How are bursae similar to and different from joint capsules? What is the function of bursae?
(a) they resemble joint capsules because their walls consist of connective tissue lined by a synovial membrane and they are also filled with synovial fluid; they are different from joint capsules because they are located outside joints; (b) cushion the movement of body parts over one another
Synovial Joint Cavity Describe the distinguishing structures Describe the accessory structures
Distinguishing structures: 1. articular hyaline cartilage on bone ends to absorb shock/reduce friction 2. articular capsule to hold everything in 3. synovial fluid to nourish Accessory structures: 1. Ligaments to connect bones 2. menisci to fill space and provide stability 3. bursae to help reduce friction 4. tendon sheaths 5. articular fat pad
Name the three structural types of joints
Fibrous joints: The bones are held together by dense connective tissue that is rich in collagen fibers, and there is no synovial cavity. Cartilaginous joints: The bones are held together by cartilage, and there is no synovial cavity. Synovial joints (syn- = together): The bones are united by the dense connective tissue of an articular capsule and often by accessory ligaments, and there is a synovial cavity.
Why do synovial joints move in diff ways?
Shapes of articulating surfaces within the joint capsule allow a variety of movement. The shape determines the movement
Synovial fluid consists of 1. ___________ acid secreted by ____________ in the __________ 2. _______filtered from blood plasma List 5 functions of Synovial Fluid
Synovial fluid consists of hyaluronic acid secreted by fibroblast-like cells in the synovial membrane and interstitial fluid filtered from blood plasma. 1. reduces friction by lubrication of the joint 2. absorbs shocks 3. supplies oxygen and nutrients 4. removes carbon dioxide and metabolic wastes from the articular cartilage. (Recall that cartilage is an avascular tissue, so it does not have blood vessels to perform the latter function.) 5. contains phagocytic cells that remove microbes and the debris that results from normal wear and tear in the joint.
The epiphyseal plate in a young child is an example of which type of joint? When the epiphyseal plate ossifies, which kind of joint does it become?
(a) synchondroses; (b) synostosis
What does synovial fluid form and where? Functions?
1. forms a thin film over the surface of articular joint structures within the capsule Functions: 1. reduce friction by lubrication 2. shock absorber as if joint is floating in bag of water 3. supply oxygen and nutrients to avascular articular cartilage tissue of a joint 4. remove waste 5. phagocytic cells (wandering microphages) remove microbes and debris from normal wear and tear of joint
What happens at a fibrous joint? Name 3 types of fibrous joints: Say what type of tissue composes each one: Give ex locations:
2 articulating bones are held together very closely by dense (usually fibrous) connective tissue and permit little to no movement Suture - btw skull bones, play a role in shock absorption -thin layer of dense connective tissue Syndesmosis - btw tibia and fibula at distal tibiofibular joint; btw tooth and socket (gomphosis) -dense connective tissue typically arranged as a tendon Interosseous membrane - btw the diaphyses of tibia an diaphyses (may be classified as amphiarthrosis but doesn't move much) -substantial sheet of dense irregular connective tissue
Ball-and-Socket Describe how the shape of this synovial joint determines the type of movement that can occur at the joint.
A ball-and-socket joint consists of the ball-like surface of one bone fitting into a cuplike depression of another bone Such joints permit movement around three axes (flexion-extension, abduction-adduction, and rotation). Examples of ball-and-socket joints are the shoulder and hip joints. At the shoulder joint the head of the humerus fits into the glenoid cavity of the scapula. At the hip joint the head of the femur fits into the acetabulum of the hip bone.
Tendon sheaths: What are they made of? Location? Purpose?
Accessory structure of a synovial joint tube like bursae wrapped around muscle tendons where they pass through synovial cavities Purpose: prevent friction
What are ligaments in relation to synovial joint? What are they made of? Location? Purpose?
Accessory structure of synovial joint Made of: Parallel bundles of dense reg connective tissue Location: inside or outside the articular capsule Purpose: Resist strain and hold bones close together EXAMPLES: ex of accessory ligaments outside articular capsule: fibular and tibial collateral ligaments of knee ex of inside ones: anterior and posterior cruciate ligaments of knee
Bursae What are they made of? Location? Purpose?
Accessory structure of synovial joint Made of: connective tissue lined by synovial membrane and filled with fluid similar to synovial fluid (this makes them resemble joint capsules) Location: can be btw skin/bones, tendons/bones, muscles/bones, ligaments/bones Purpose : cushion adjacent body parts at certain joints and alleviate friction between them
Articular Menisci What are they made of? Location? Purpose?
Accessory structure of synovial joint Made of: fibrocartilage Location: between articular surfaces of bones, and are attached to the fibrous membranes Purpose: laterally stabilize the joint and redirect the flow of synovial fluid to areas of greatest friction -can modify shape of joint surfaces of articulating bones so they fit together more snugly. -usually subdivide the synovial cavity into two separate spaces which allows separate movements to happen in each space.
Skip is asked by his instructor if he knows what a pivot joint is and he vigorously shakes his head side-to-side, indicating "no." His instructor responds "Good job. Nice example." Skip is confused—why is the instructor happy?
Answer: because the movement between the atlas and axis is allowed by the atlantoaxial joint which is a pivot joint
What happens at a cartilaginous joint? Name 2 types: Say the type of tissue: Give ex locations
Articulating bones are tightly connected by hyaline or fibrocartilage tissue 1. synchondrosis (connected by hyaline) ex: epiphyseal plates (diarthrosis) 2. symphysis (bone ends covered with articular cartilage but a broad flat disc of fibrocartilage connects the bones) ex: pubic symphysis , sternal angle, junction of the manubrium and body of the sternum, intervertebral joints, (ampharthroses)
What does the functional classification of joints relate to? Classify each functional classification
The functional classification of joints relates to the degree of movement they permit. Functionally, joints are classified as one of the following types: Synarthrosis: An immovable joint. Amphiarthrosis (amphi- = on both sides): A slightly movable joint. Diarthrosis: A freely movable joint. All diarthroses are synovial joints. They have a variety of shapes and permit several different types of movements.
Synovial Joint Movement Terminology Name the categories
These terms indicate the direction of movement or the relationships of body parts during movement 1. Gliding movements (ex gliding btw intercarpals of wrist) 2. Angular movements 3. Rotation 4 Special movements
Rotation
Type of Movement at Synovial Joint -involves a bone revolving around its own longitudinal axis defined relative to midline Medial rotation: anterior surface of a bone of the limb is turned toward the midline Lateral rotation: the anterior surface of a bone of the limb is turned away from midline EX: shaking your head no,
Angular
Type of Movement at Synovial Joint Occurs when the angle between articulating bones increases or decreases, with respect to the body in anatomical position. usually occurs on the sagittal plane, but can be a side bend Principle movements: -Flexion, extension, lateral flexion, hyper extension, abduction, adduction, circumduction EX: bending head toward chest @ atlanto-occipital joint btw the atlas and occipital bone, intervertebral joints btw c-spine vertebrae, and inververtebral joints that let you bend over and touch your toes, moving humerus fwd at shoulder joint (swinging arms to walk), moving forearm at elbow joint, femur/hip bone when walking,
Gliding
Type of Movement at Synovial Joint Simple movement that occurs where flat bones surfaces move back and forth or side to side No significant alteration of the angles between the bones Limited range of motion because of the structure of the articular capsule and associated ligaments/bones. EX: gliding between intercarpals
What does synovial fluid consist of?
hyaluronic acid secreted by fibroblast-like cells in the synovial membrane and and interstitial fluid filtered from blood plasma
What are the functions of synovial fluid?
reducing friction by lubrication of the joint, absorbing shocks, supplying oxygen and nutrients to and removing carbon dioxide and metabolic wastes from the chondrocytes within articular cartilage, and supplying phagocytic cells that remove microbes and debris which result from normal wear and tear in the joint
Articular Capsule of Synovial Joint Describe the 2 Layers
surrounds synovial joint encloses synovial cavity unites articulating bones Composed of 2 Layers 1. Outer Layer = Fibrous membrane -dense connective tissue that is mostly collagen fibers -attaches to periosteum of articulating bones -its flexibility permits considerable movement at a joint -tensile strength helps prevent bones from dislocating -fibers of some fibrous membranes are arranged in parallel bundles that are highly adapted for resisting strains (aka ligaments) 2. Inner synovial membrane -composed of areolar connective tissue
Saddle Joint Describe how the shape of this synovial joint determines the type of movement that can occur at the joint.
the articular surface of one bone is saddle-shaped (the concave surface); the articular surface of the other bone fits into the "saddle" like a rider sitting on a horse permit movement around three axes: side to side, up and down, and rotation. Like a condyloid joint, movements at a saddle joint are around two axes (flexion-extension and abduction-adduction) plus limited circumduction. Example of a saddle joint is the carpometacarpal joint between the trapezium of the wrist and metacarpal of the thumb.
Hinge Joint Describe how the shape of this synovial joint determines the type of movement that can occur at the joint.
the convex surface of one bone fits into the concave surface of another bone. As the name implies, hinge joints produce an angular, opening-and-closing motion like that of a hinged door. In most joint movements, one bone remains in a fixed position while the other moves around an axis. Hinge joints allow motion along a single axis. Hinge joints permit only flexion and extension. Examples of hinge joints are the knee, elbow, ankle, and interphalangeal joints (between the phalanges of the fingers and toes).
Pivot Joint Describe how the shape of this synovial joint determines the type of movement that can occur at the joint.
the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by a ligament. A pivot joint allows rotation only around its own axis. Examples of pivot joints: -atlanto-axial joint, in which the atlas rotates around the axis and permits the head to turn from side to side as when you shake your head "no" -radioulnar joints that enable the palms to turn anteriorly and posteriorly as the head of the radius pivots around its axis in the radial notch of the ulna (