Chapter 9 Joints

Explain how the structures associated with a synovial joint help to prevent injury

1. Collagen fibers of joint capsules and ligaments are interconnected and help each other hold joints together 2. The shapes of articulating surfaces and Menisci help limit range of motion and provide stability to prevent injury 3. Bones muscles and fat pads will also Iimit range of motion and increase stabiloty to help prevent injury 4. Tendons attached to articulating bones

joint

A place where two or more bones meet

Describe amphiarthrosis and give examples of two types of amphiarthrosis

Amphiarthrosis joints are more movable than a synarthrosis joint but still stronger than a diarthrosis joint. Amphiarthrosis joimts may be fibrous or cartilaginous. There are two types of amphiarthrosis: syndesmosis and symphysis. Syndesmosis is where bones are connected by a ligament more specifically a dense regular fibrous connective tissue. Symphysis is where bones are connected by fibrocartilages for example the pubic symphysis or intervertebral discs

Dorsiflexion and plantar flexion: explain the type of motions and give examples

Dorsiflexion is a flexion at the ankle joint and elevation of sole; lifting toes. Plantar flexion is a extension at the ankle joint and elevation of the heel; pointing toes (Think of a ballerina)

Explain why the word joint does not imply motion (using examples)

Joints are just where bones meet, it doesn't mean that movement can occur there. Joints are necessary for body movements, but Sometimes there are just two bones meeting and no movement can occur. A trade-off exists between strength and mobility; so the stronger and more stable a joint is, The lesser the mobility. For example a suture in the skull is very stable and strong, so there is no movement there.

Lateral flexion: Explain the type of motion and give an example

Lateral flexion is bending the vertebral column to the side. For example tilting your head left to right.

Identify the different planes of movement

Monaxial: 1 plane (e.g. the elbow) This is a joint that permits movement around one axis. Biaxial: 2 planes (e.g. the wrist) This is a joint that permits movement around to axes. Triaxial: 3 planes (e.g. the shoulder) This is a joint that permits movement around three axes.

Condylar joint: describe the joint structure, identify if the joint Is monaxial, biaxial, or triaxial and give examples

Condylar joints have an oval articular face nestled within a depression on the opposing surface. It is in angular movement and is biaxial. Examples include radiocarpal joint, metacarpophalangeal joints 2 to 5, metatarsophalangeal joints

Depression and elevation: explain the types of motion and give examples

Depression is moving a structure inferiorly; down. Elevation is moving a structure superiorly; up. For example, You depress your mandible when you open your mouth and you elevate your mandible as you close your mouth. Another example of elevation takes place when you shrug your shoulders.

Describe diarthrosis and give examples

Diarthrosis also called synovial joints are freely movable joints; most movable but least stable. They are found at the ends of the long bones and surrounded by a joint capsule (articular capsule) that has 2 layers: an outer fibrous layer and an inner cellular layer called a synovial membrane. The synovial membrane secretes synovial fluid. Articular cartilage (hyaline cartilage) covers the articulating surface so there is no grinding between the bones. Some examples include the knee and shoulder joint

Gliding movement: explain the type of motion and give examples

Gliding movement is whentwo flat surfaces like past each other. Example: between carpal bones, So the intercarpal joints which are classified as plane joints

Hinge joint: describe the joint structure, identify if the joint Is monaxial, biaxial, or triaxial and give examples

Hinge joints permit angular motion in a single plane, like the opening and closing of a door. The joint is Monaxial. Examples include the elbow joint, knee joint, ankle joint, interphalangeal joint

Ball and socket joint:describe the joint structure, identify if the joint Is monaxial, biaxial, or triaxial and give examples

In a ball and socket joint, the round head of one bone rests with in a cup shaped depression in another. It's types of movements include angular, circumduction and rotation. This joint is triaxial. Examples include the shoulder joint and the hip joint

Describe the structure of an intervertebral disc and what happens when that joint is damaged

In the intravertebral disc has two layers. The tough outer layer of fibrocartilage is called the anulus fibrosus, This attaches the disc to the vertebrae. The inner layer is a elastic, gelatinous core called the nucleus pulposus. The nucleus pulposus is a shock absorber. The vertebral inflates of cartilage cover the superior and inferior surfaces of the disc. When I enter vertebral disc is damage it can either be bulging or herniated. A bulging disc is a bulge in the anulus fibrosus, and it invades the vertebral canal. A herniated disc is When the nucleus pulposus breaks through the anulus fibrosus and compresses the spinal nerves.

Inversion and Eversion: explain the type of motion and give examples

Inversion twists sole of foot medially. Eversion twists sole of the foot laterally. And example of Inversion is tilting a foot toward midline. An example of eversion is tilting a foot away from midline.

Opposition and reposition: explain the type of motions and give examples

Opposition is the movement of the thumb toward palm or other fingers. For example grasping in the holding objects between your thumb and palm. Reposition is the opposite of opposition; it's the movement that returns the thumb and fingers from opposition. For example letting go of the grasped object.

Pivot joint:describe the joint structure, identify if the joint Is monaxial, biaxial, or triaxial and give examples

Pivot joints only permit rotation. It is monaxial. Examples include atlantoaxial joint, proximal radial-ulnar joint

Plane (gliding) joint: describe the joint structure, identify if the joint Is monaxial, biaxial, or triaxial and give examples

Plane joints, or gliding joints, have flattened or slightly curved surfaces that slide across one another, but the amount of movement is very slight. It's limited gliding motion; slight non-axial. Examples include intercarpal joints, acromioclavicular and claviculosternal joints, Vertebrocostal joints, sacroiliac joints

Pronation and supination: explain the type of motions and give examples

Pronation and supination are a type of rotational movement. Pronation rotates forearm so that radius rolls across Ulna result in palm facing posteriorly. Supination turns palm anteriorly and forearm is supinated in anatomical position.

Protraction and retraction: explain the types of motions and give examples

Protraction is an anterior movement in the horizontal plane; the movement forward. Retraction is the opposite of protraction; pulling back. For example you protract your jaw when you jut your chin forward and you retract your jaw when you return it to it's normal position.

Explain what is meant by range of motion

Range of motion is movements at synovial joints. The movements are described in terms that reflect the plane or direction of movement and the relationship between structures

Rotation: Explain the type of motion and give examples

Rotational movement is Rotation in reference to anatomical position. Limb rotation is relative to longitudinal axis of body; medial rotation (internal rotation toward long axis) and lateral rotation (external rotation away from body). Example of rotational movement is left or right rotation of head.

Saddle joint:describe the joint structure, identify if the joint Is monaxial, biaxial, or triaxial and give examples

Saddle joints have articular faces and fit together like a rudder in a saddle. Each face is concave along one axis and convex along the other. It's an angular motion and biaxial. The first carpometacarpal joint is an example; the joint between the metacarpal bone of thumb and trapezium.

Describe synarthrosis and give examples of the four different types of synarthrotic joints

Synarthrosis has no movement, it's very strong; high stability, no mobility. Edges of bones here may touch or interlock. It may be fibrous or cartilaginous. There are four types of synarthrotic joints: suture, gomphosis, Synchondrosis, Synostosis. Sutures are a fibrous joint, they are found only between bones of the skull and where edges of bones interlock. They are bound by dense fibrous connective tissue. Gomphosis is a fibrous joint, they bind teeth to bony sockets, so they're not where two bones meet. They have a fibrous connection (periodontal ligament) and are slightly mobile. Synchondrosis is a cartilaginous joint; A rigid cartilaginous bridge between two bones. They are found between vertebrosternal ribs and the sternum or The epiphyse Cartliage of growing long bones. Synostosis is a bony joint; least mobile, most stable(no movement) They are created when two bones fuse. For example metopic suture of frontal bone, and Epiphyseal lines of mature long bones.

Describe and give examples of synostoses

Synostosis is a bony joint; it's the least mobile and most stable so there is no movement. It's created when two bones fuse for example the metopic suture of frontal bone and the epiphyseal lines of mature long bones.

Describe the consistency and composition of synovial fluid and use that to explain the functions of synovial fluid

Synovial fluid has the consistency of raw egg whites or heavy molasses; The consistency changes as the temperature changes. Synovial fluid contains a lot of proteoglycans; proteins with sugar. Lots of hyaluronan. The primary functions of synovial fluid include: lubrication which helps reduce friction, nutrient distribution since articular cartilage is avascular, and shock absorption which cushions against compressive forces.

Identify the articulations present in elbow and knee

The Humero-ulnar joint Is the largest and strongest joint at the elbow. It is found between the Trochlea of the humerus and the trochlear notch of the ulna. There is limited movement here (flexion and extension) due to the shape of the bones. The humeroradial joint is the smaller joint of the elbow. It's articulation is between the capitulum of the humerus and the head of the radius (supination). The knee joint is a complex hinge joint that transfers weight from the femur to the tibia(shock absorbers). It has three articulations: two femur- tibia articulations at the medial and lateral condyles, and one articulation between the patella and Patellar surface of the femur.

Identify the different structures that gives stability to a joint and explain how they provide that activity and give their location

The accessory structures that help stabilize synovial joints include cartilages, fat pads, ligaments, tendons, and bursae. Cartilages include meniscus which is a fibrocartilage pad between opposing bones. They sometimes separate the synovial cavity to control the flow of synovial fluid, or they allow for variability between the shapes of the opposing surfaces. Fat pads are typically a superficial structure and they are adipose tissue and is covered by the synovial membrane. They fill in spaces as the joint moves to help protect articular cartilage. Ligaments support and strengthen joints, they can be intracapsular or extracapsular and are found at knee, ankle, shoulder, and other joints. Tendons attach to muscles around the joints; they help to attach muscles to bones. They are found at the end of muscles. Per se are small pockets of synovial fluid that are shock absorbers; they cushion areas where tendons or ligaments rub against other tissues. Bursae are found near tendons and ligaments that need extra cushion.

Identify the synovial joints associated with the vertebrae

The first two cervical vertebrae are joined by A synovial joint, More specifically the pivot joint. Synovial joints also live between in Jason articular processes.

Describe the type of joints present at the shoulder and revisit the concept of joint motion vs. joint stability

The glenohumeral joint is a ball and socket diarthrosis joint found between the head of the humerus and the glenoid cavity of the scapula. This joint has the greatest range of motion and is the most frequently dislocated joint. Remember the more mobile a joint is, the least stable it is. This joint is supported by skeletal muscles, tendons, and ligaments.

Describe the structure of the hip joint

The hip joint is found between the head of the femur and the acetabulum of the hip bone. It's a stronger ball and socket diarthrosis joint than the shoulder joint because of the muscles helping stabilize it. The hip joint has a wide range of motion. The hip has an acetabular labrum which is a rim of fibrocartilage and helps increase the depth of the joint cavity and seals in synovial fluid.

Explain the relationship between joint mobility and joint stability

The more mobile a joint is, The least stable the joint will be.

Identify the types of motion made possible by the vertebrae

The types of vertebral movements made possible by the vertebrae include flexion, extension, lateral flexion, rotation. As vertebral column moves the nucleus proposes compresses; this is the shock absorption. The disc shape conforms to the motion and enter vertebral ligaments help bind the vertebrae together to stabilize the vertebral column.

Describe the different joint classifications

There are two classifications for joints, structural (anatomy) and functional (range of motion). Joint structure determines function; form makes function. Structural classifications are based upon what holds the bones together; fibrous C.T., cartilaginous, bony, synovial. Functional classifications are based upon immovable joints to freely moveable joints; synarthrosis (immovable joint/high stability), Amphiarthrosis (slightly movable joint), Diarthrosis (freely movable joint/Low stability and more likely to get damaged)

Adduction and abduction: explain the type of motion and give examples

This is a type of angular movement; abduction and adduction are movements in the frontal plane. Abduction is movement away from longitudinal axis; away from midline. Adduction is movement toward longitudinal axis; toward midline. An example of abduction is jumping jacks or spreading of fingers. An example of adduction is moving fingers together or bringing your arms/legs in from jumping jacks.

Flexion and extension and hyperextension: give examples and explain the types of motion

This is a type of angular movement; movements are in the anterior posterior plane and is based relative to anatomic position. Flexion decreases angle between articulating bones (moving away from anatomical position); extension increases angle between articulating bones (moving back towards anatomical position); hyperextension is an extension past anatomical position. Flexing your arm or moving your leg forward is an example of flexion; kicking or lifting weights. Moving your arm or leg back in to anatomical position is an example of extension. Looking at the stars or the ceiling Is an example of hyperextension; moving your head or leg past anatomical position.

Circumduction: explain the type of motion and give examples

This is another type of angular movement; circumduction is a complete circular movement without rotation. Circumduction is a combination of flexion extension adduction and abduction. For example moving your arm in a loop as when you draw a large circle on a whiteboard.