A & P ch 8: Joints

arthroscope

narrow, flexible fiberoptic scope containing a tiny camera used to look into a joint •can be used for arthroscopic surgery; flexible intruments inserted that permit surgery inside joint within view of the arthroscope. •Cannot show soft tissue details outside the joint cavity; instead Magnetic resonance imaging (MRI-cost effective and non invasive) is used to view without injury •Repeated arthroscopy eventually leads to formation of scar tissue and other joint problems

Nursemaid's elbow

dislocation of radial head from annular ligament caused by an upward, twisting pull on elbow joint

Abduction and adduction

•Always refers to movements of appendicular skeleton, not axial •ADDUCTION- movements are toward longitudinal axis of body in frontal plane (midline) •ABDUCTION- away from body midline •For fingers or toes, movements are spreading digits apart (abduction) or bringing them together (adduction) at the central digit (middle finger)

knee joint

•Consists of three joints: two between the femur and tibia (medial to medial condyle, lateral to lateral condyle) and one between the patela and the patellar surface. •Joints permit flexion, extension, and limited rotation •fibula not part of knee joint •tendons from quadriceps muscle pass over the anterior surface of the joint and enclose the patella •the patellar ligament attaches to the anterior surface of tibia, this and adjacent ligamentous bands supports the anterior surface of the knee joint •the POPLITEAL LIGAMENTS and several muscles that originate/insert on femoral or tibial epiphyses reinforce the posterior surface of joint; two popliteal ligaments extend between femur and heads of tibia and fibula •FIBULAR COLLATERAL LIGAMENT (or lateral collateral ligament), provides lateral support from femur to fibula •TIBIAL COLLATERAL LIGAMENT (medial collateral ligament)- provides medial support •MEDIAL and LATERAL MENISCI- are fibrocartilage pads, lie between the femoral and tibia to act as a cushion and provide lateral stability to joint •ANTERIOR CRUCIATE LIGAMENT and POSTERIOR CRUCIATE LIGAMENT- attach the intercondylar area of tibia to the condyles of the femur; they limit the anterior and posterior movement of the tibia, maintain alignment of the femoral and tibial condyles.

What is a dislocation? and why?

•Displacement of a bones from a joint, usually from excessive force applied (extreme stress) •Displacement can damage the articular cartilage, tear ligaments, or distort the joint capsule. •Dislocations are very painful even though inside of joint has no pain receptors, can feel it because sensitive nerves monitor the joint capsule, ligaments and tendons. •Joint cannot be highly mobile and very strong, so the greater the range of motion then the weaker it is.

Gomphosis

•GOMPHOSIS- is a synarthrosis that binds the teeth to bony sockets in the maxillae and mandible. The fibrous connection between a tooth and its socket is a periodontal ligament

Rotation

•Head and trunk rotation is described as RIGHT OR LEFT ROTATION •Limb rotation can be described as MEDIAL OR LATERAL ROTATION; medial rotation is also known as internal rotation or inward rotation, anterior surface of a limb turns toward midline of body; lateral rotation is also called outward rotation or external rotation •rotation is also described with reference to a figure in anatomical position •special terms for rotation in the forearm, proximal joint between radius and ulna (proximal radio ulna joint) permits rotation of the head of radius. PRONATION, turns wrist and hand from palm facing front to palm facing back; SUSPINATION- opposite movement, palm is turned anteriorly

Appendicular skeleton joints

•Joint at appendicular skeleton has extensive range of motion but are often weaker than axial joints •The sternoclavicular joint, the only articulation between the axial skeleton and the pectoral girdle and upper limb •Shoulder joint •the sacro iliac joint, which firmly attaches the sacrum of the axial skeleton to the pelvic girdle of the appendicular skeleton •elbow joint •proximal and distal radio ulnar joints •wrist joint •joints of the hand and fingers •hip joint •knee joint

Synovial fluid functions

•Looks clear, straw colored, viscous fluid;Originates in the areolar tissue of the synovial membrane. •LUBRICATION- when articular cartilage is compressed during movement, synovial fluid squeezes out of cartilage into the space between the opposing surfaces creating a thin layer of fluid that reduces friction between the moving surfaces •NUTRIENT DISTRIBUTION- synovial fluid in a joint must circulate continuously to provide nutrients and dispose of waste for the chondrocutes in the articular cartilage; circulates whenever joint moves and compression and reexpansion of the articular cartilage pump synovial fluid into and out of cartilage matrix •SHOCK ABSORPTION- synovial fluid cushions shocks in joints that are subjected to sudden compression or impact. Cushioning effect occurs because the viscosity of synovial fluid increases with increasing pressure.

Special movements of joints

•OPPOSITION- movement of thumb toward surface of the palm or the pads of other fingers, this helps you to grasp and hold objects between thumb and palm. Involves movement of the first carpometacarpal and metacarpophalangeal joints •PROTRACTION and RETRACTION- protraction is moving a part of the body anteriorly in the horizontal plate; retraction is the reverse movement. (jaw and clavicles) •INVERSION and EVERSION- inversion is a twisting motion of the foot that turns the sole inward; eversion is the opposite movement •DEPRESSION and ELEVATION- depression takes place when a body part moves inferiorly; elevation is lifting a body structure superiorly

Vertebral ligaments

•Paired LIGAMENTA FLAVA connect the laminae of the adjacent vertebrae •POSTERIOR LONGITUDINAL LIGAMENT parallels the anterior longitudinal ligament and connects the posterior surfaces of the adjacent vertebral bodies closest to the vertebral foramen •ANTERIOR LONGITUDINAL LIGAMENT connects the anterior surfaces of the adjacent vertebral bodies •INTERSPINOUS LIGAMENT connects the spinous processes of adjacent vertebrae •SUPRASPINOUS LIGAMENT interconnects the tips of the spinous processes from the sacrum to vertebra C7. The ligamentum nuchae extends from vertebra C7 to the base of the skull

arthritis

•RHEUMATISM- general term that indicates pain and stiffness affecting musculoskeletal system •ARTHRITIS- encompasses all rheumatic diseases that affect synovial joints; involves damage to the articular cartilage •OSTEOARTHRITIS (degenerative arthritis)- is the most common form of arthritis, generally affects 60+ years (25% woman 15% men), and is a result from wear and tear at joint surfaces or genetic factors affecting collagen formation. •two other less common types are the GOUTY ARTHRITIS and RHEUMATIOD ARTHRITIS. •normal joint shows articular cartilage with a smooth, slick surface while arthritic joint shows articular cartilage with a rough feltwork of bristly collagen fibers (which increases friction and results in further degeneration)

Fibrous Suture

•SUTURE- is a synarthrotic joint located only between the bones of the skull. The edges of the bones are interlocked and bound together at the suture by dense fibrous connective tissue

Cartilaginous Symphysis

•SYMPHYSIS- the articulating bones are separated by a wedge or pad of fibrocartilage. The joint between the two pubic bones is an example of symphysis

Cartilaginous Synchondrosis

•SYNCHONDROSIS- is a rigid, cartilaginous bridge between two articulating bones. The cartilaginous connection between the ends of the first pair of ribs and the sternum is a synchondrosis

Fibrous Syndesmosis

•SYNDESMOSIS- bones are connected by a ligament. One example is the distal joint between the tibia and fibula

Bony Synostosis

•SYNOSTOSIS- is a totally rigid, immovable joint formed when two bones fuse and the boundary between them disappears. The frontal surface of the frontal bone and the epiphyseal lines of mature long bones are synostoses

Complex Synovial Joint accessories

•Tendons of the quadriceps muscles attaches to th base of the patella, not part of the joint, but tendons passing across or around a joint can limit the joints range of motion and provide mechanical support for it •BURSA- small, thin, fluid filled pocket that forms in connective tissue outside a joint capsule. Contains synovial fluid and lined by a synovial membrane. Bursae often form where a tendon or ligament rubs against other tissues (most synovia joints), to reduce friction and act as shock absorbers •FAT PADS- localized masses of adipose tissue covered by a layer of synovial membrane. Commonly superficial to joint capsule. They protect the articular cartilage and act as packing material for the joint, as bones move, the fat pads fill spaces created as joint cavity changes shape •MENISCUS- a pad of fibrocartilage between opposing bones within a synovial joint. Menisci are like articular discs that subdivide a synovial cavity, channel flow of synovial fluid, or allow for variations in the shapes of the articular surfaces. •ACESSORY LIGAMENTS- support, strengthen, and reinforce synovial joints; CAPSULAR LIGAMENTS or intrinsic ligaments, are localized thickenings of joint capsule; EXTRINSIC LIGAMENTS are separate from joint capsule, may pass outside or inside joint capsule and are called extracapsular or intracapsular ligaments. •PATELLAR LIGAMENT (extracapsular ligament)- extends from the apex of the patella to the tibial tuberosity •CRUCIATE LIGAMENTS (intracapsular ligaments)- run through the interior of the knee

Vertebral column joints

•Three types of joints: SYNDESMOSES, SYNCHONDROSES, and SYNOVIAL •SYNDESMOSES OF VERTEBRAL COLUMN- made up of fibrous joints uniting vertebrae, including vertebral ligaments •SYNCHONDROSES OF VERTEBRAL COLUMN- made up of intervertebral discs that contain the intervertebral joints combined with the vertebral bodies and fibrocartilage •VERTEBRAL SYNOVIAL JOINTS- made up of numerous joints between bony processes of adjoining vertebrae

elbow joint

•a complex hinge joint that involves the humerus, radius, and ulna. •extremely stable because the bony surfaces of the humerus and ulna interlock, a single thick articular capsule surrounds both the humero ulnar and proximal radio ulnar joint, and the articular capsule is reinforced by strong ligaments •proximal radio ulnar joint is not part of the elbow joint but the capsule and ligaments associated with this joint help with the connection between the articular capsule •HUMERORADIAL JOINT forms when the capitulum of the humerus articulates with the head of radius •HUMERO ULNAR JOINT is a larger articulation of the elbow, it is where the trochlea of the articulates with the trochlear notch of the ulna. •physical limitations imposed on movement; shape of trochlear notch of ulna determines plane of movement and shape of olecranon fossa and olecranon determine degree of extension •Muscles that extend elbow attach to the rough surface of the olecranon. These muscles are primarily controlled by the radial nerve ( which pass along radial groove of humerus) •RADIAL COLLLATERAL LIGAMENT- stabilizes the lateral surface of the elbow joint •ANNULAR LIGAMENT- binds the head of radius to the ulna •ULNAR COLLATERAL LIGAMENT- stabilizes the medial surface of the elbow joint. Extends from the medial epicondyle of the humerus anteriorly to the coronoid process of the ulna and posteriorly to the olecranon •tendons of the large biceps brachii muscle attaches to the radius at the radial tuberosity. Contracting the biceps brachii muscle produces supination of the forearm and flexion at the elbow

intervertebral discs

•account for 1/4 the length of the vertebral column superior to the sacrum •older we get, water from nucleus pulposus decreases, making it less effective as a cushion and increasing vertebral injury; water loss can cause shortening of vertebral column •ANULUS FIBROSUS- tough outer ring in the intervertebral disc made of fibrocartilage; collagen fibers of this layer attach the disc to the bodies of adjacent vertebrae •NUCLEUS PULPOSUS- surrounded by anulus fibrosus; is a soft, elastic, gelatinous core; gives the disc resilience and enables it to absorb shocks

Hip Joint (anterior and posterior view)

•articular capsule of hip joint extends from the lateral and inferior surfaces of the pelvic girdle to the intertrochanteric line and intertrochanteric crest of the femur, enclosing both neck and head of femur. •3 remaining ligaments reinforce the articular capsule: PUBOFEMORAL LIGAMENT, ILIOFEMORAL LIGAMENT, ISCHIOFEMORAL LIGAMENT •Hip fractures are more common than hip dislocations because the ball and socket joint is not directly aligned with the weight distribution of the shaft.

Axial skeleton joints

•axial joints have less range of motion than appendicular joints •Sutures of the skull •Temporomandibular joint (temporal bone and mandible) •Atlanto-occipital joint (occipital bone and atlas) and the atlanto axial joint (C1-C2) •Joints of the thoracic cage •Intervertebral joints •Lumbosacral joint, between the last lumbar vertebra and the sacrum •The sacrococcygeal and intercoccygeal joints, which structurally resemble simplified intervertebral joints

What is a joint?

•bones of the skeleton are relatively inflexible, movements occur only at joints, or articulations, where two bones connect •anatomical structure of a joint determines the type and amount of movement the joint can execute •Range of Motion (ROM)- amount of movement at a joint; categorized by ROM and anatomical structure •Functional categories are: Synarthrosis (no movement)- the bony edges are close together and may interlock; Amphiarthrosis (little movement)- permits more movement than a synarthrosis but is much stronger than a freely movable joint. Articulating bones are connected by collagen fibers or cartilage; Diarthrosis (free movement)- permits the widest range of movement •Synarthrosis types include: Fibrous suture, gomphosis, cartilaginous synchondrosis, and bony synostosis Amphiarthrosis type include: Fibrous syndesmosis and cartilaginous symphysis •Diarthrosis include: Synovial

Shoulder joint or glenohumeral joint

•has greatest range of motion of any joint but also most frequently dislocated joint; if dislocated, all or some ligaments may be injured which can affect the shoulder joint or a separation which can involve the acromioclavicular joint. •ACROMIOCLAVICULAR JOINT- is where the clavicle articulates with the scapula •Shoulder joint is a BALL AND SOCKET diarthrosis (freely moveable joint), formed by articulation of the head of the humerus with the glenoid cavity of the scapula •glenoid cavity is increased by a fibrocartilage glenoid labrum, which continues beyond the bony reim and depeens the socket •five major ligaments help stabilize shoulder joint: CORACOCLAVICULAR LIGAMENTS- connecting the clavicle with the coracoid process, ACROMIOCLAVICULAR LIGAMENT- connecting the clavicle with the acromion, CORACO ACROMIAL LIGAMENT- connecting the coracoid process with the acromion, CORACOHUMERAL LIGAMENT- connecting the coracoid process the the humerus, GLENOHUMERAL LIGAMENTS- connecting the scapula and the humerus •bursae at the shoulder reduces friction where large muscles and tendons pass across joint capsule •a tendon of the biceps brachii muscle runs through shoulder joint, passing through the articular capsule and surrounded by a tubular bursa •Articular capsule is oversized (from scapula to neck of humerus to permit extensive range of motion

Synovial joint breakdown

•have the greatest range of motion compared to other joints. They are typically located at the ends of long bones, such as those of upper and lower limbs •LIGAMENT- helps reinforce and hold together the joint; located in the joint capsule •JOINT CAPSULE/ARTICULAR MEMBRANE- a sac that encloses the articulating ends of the bones in the joint, made up of an outer fibrous layer (ligaments) and an inner synovial membrane. May be reinforced with accessory structures such as tendons or ligaments •SYNOVIAL MEMBRANE- lines interior of the joint capsule and secretes synovial fluid into joint cavity •JOINT CAVITY- contains synovial fluid, which lubricates, cushions shocks, prevents abrasion, and supports the chondrocytes of articular cartilages. Even when pressure is applied across joint, the articular cartilages do not touch each other because the synovial fluid creates a thin film. In a large joint such as the knee, the total volume of synovial fluid in a joint is normally less than 3 mL. •ARTICULAR CARTILAGE- covers bones surface at a joint, like hyaline cartilage but without perichondrium and its matrix contains more water than other cartilages. Articular cartilages alone can reduce friction during movement at joint •Periosteum of each bone is continuous with the capsule of the joint, this integration adds strength and mobility to the joint •Inside periosteum contains the layer of compact bone, then spongy bone of epiphysis and throughout remaining bone, and medullary cavity is in the middle of bone that stores red bone marrow or yellow bone marrow

hip joint (lateral view)

•is a sturdy BALL AND SOCKET diarthrosis that allows flexion and extension, adduction and abduction, circumduction and rotation •in lateral view, within the acetabulum, an articular cartilage pad extends like a horseshoe to either side of the acetabular notch. •2 of 5 ligaments can be seen this way •TRANSVERSE ACETABULAR LIGAMENT crosses the acetabular notch, filling in the gap in the inferior border of the acetabulum •LIGAMENT OF THE FEMORAL HEAD or LIGAMENTUM TERES originates along the transverse acetabular ligament and attaches to the fovea capitis, a small pit at the center of the femoral head •ACETABULAR LABRUM- a projecting rim of rubbery fibrocartilage, increases the depth of the joint cavity and helps seal in synovial fluid

Artificial joints

•last resort when regular exercise, physical therapy, and anti inflammatory drugs fail to slow progress of arthritis •restores mobility and relieves pain •has lifelong restrictions due to joint replacement surgery

Osteoporosis and osteopenia in older adults

•osteoporosis is a condition in which the body's bones become weaker and thinner; break easily. •Bones become weaker due to aging process. Inadequate ossification is called osteopenia. Reduction of bone mass begins between 30-40 years due to osteoblast activity declining and osteoclast activity continuing normally. When reduction in bone mass is sufficient it can compromise normal function. •combination of osteopenia or osteoporosis and reduced cushioning properties of intervertebral discs leads to vertebral fractures becoming common •women lose roughly 8 percent of skeletal mass every decade •men lose 3 percent per decade

intervertebral disc disease (IVDD)

•painful condition associated with disc degeneration that affects spinal nerves. Causes bulging disc or herniated disc. Bulging disc- if posterior longitudinal ligament weakens the nucleus pulposus may distort the anulus fibrosus making it partway into vertebral canal where the spinal cord and nerves are •Herniated disc- if nucleus pulposus breaks though anulus fibrosus, may protrude into the vertebral canal; compressing spinal nerves which may cause pain and nerve damage that can lead to paralysis

types of Synovial Joints based on movement

•types of axial movements include: GLIDING, ANGULAR MOTION, CIRCUMDUCTION, and ROTATION (partial rotation) •Joint that permits movement around one axis is called MONOAXIAL; a joint permits movement around two axes is called BIAXIAL; and one that permits movement around three axes is called TRIAXIAL •PLANE JOINT- also known as gliding joints, have flattened or slightly curved surfaces that slide across one another, movement is very slight; movement is gliding and slight monaxia; examples include the acromioclavicular and sternoclavicular joints, intercarpal joints, vertebrocostal joints, sacro iliac joints •HINGE JOINT- permit angular motion in a single plane, like opening and closing a door; movement is angular and monaxial; examples include elbow joints, knee joints, ankle joints, interphalangeal joints •PIVOT JOINT- permit only one rotation; movement is rotation and monaxial; examples include atlanto axial joint, proximal radio ulnar joints •CONDYLAR JOINT- have an oval articular face nestled within a depression on the opposing surface; movement is rotation and monaxial; examples include radiocarpal joints, metacarpophalangeal joints II-V, Metatarsophalangeal joints •SADDLE JOINT- have articular faces that fit together like a rider i a saddle. Each face is concave along one axis and convex along the other; movement is angular and biaxial; example is first carpometacarpal joints •BALL AND SOCKET JOINT- the round head of one bone rests within a cup-shaped depression in another; movement is angular, circumduction, rotation and triaxial; examples include shoulder joints and hip joints

Flexion and Extension

•usually to describe movements at hinge joints but can also describe movements of the axil skeleton. •FLEXION- movement in anterior to posterior (sagittal) plane that decreases angle between the articulating bone EXTENSION- occurs in the same plane as flexion but it increases angle between the articulating bones. When person is in anatomical position, all major joints of axial and appendicular skeletons (except ankle) are at full extension •HYPEREXTENSION- extension past the anatomical position •Lateral Flexion- occurs when vertebral column bends to the side, most pronounced in cervical and thoracic regions •Dorsiflexion (ankle flexion)- upward movement of foot or toes, •Plantar flexion (ankle extension)- opposite movement, extends the ankle joint and bends the foot or toes