Chapter 9: Joints

general functions of a tendon sheath

-A tendon sheath is similar in structure to a bursa, but smaller -It is a connective tissue sac that surrounds a muscle tendon at places where the tendon crosses a joint -It contains a lubricating fluid that allows for smooth motions of the tendon during muscle contraction and joint movements

The three different types of fibrous joints?

-Sutures -Syndesmosis -Gomphosis

What are the three category of movements in a diarthrotic joint?

-Uniaxial -biaxial -multiaxial (triaxial or polyaxial)

glenohumeral joint

-ball and socket joint joint formed by the articulation between the head of the humerus and the glenoid cavity of the scapula -glenoid labrum (extends around the outer margin of the cavity) -coracohumeral ligament (running from the coracoid process of the scapula to the anterior humerus, and three ligaments, each called a glenohumeral ligament, located on the anterior side of the articular capsule. These ligaments help to strengthen the superior and anterior capsule walls) -

ball-and-socket

-multiaxial joint -flexion/extension -abduction/adduction -circumduction -medial/lateral rotation movements -Ex: *shoulder and hip joints

Hinge joint

-uniaxial joint -allows flexion and extension movements -Ex: *knee *elbow *ankle *interphalangeal joints of fingers and toes

What is bursitis?

Bursitis is the inflammation of the bursa sac near joint. It usually occurs when people overuse their joints usually happens on elbows, knees, shoulders, or hip joints.

General function of articular capsule?

The walls of this space are formed by the articular capsule, a fibrous connective tissue structure that is attached to each bone just outside the area of the bone's articulating surface. The bones of the joint articulate with each other within the joint cavity

What is an axis?

an axis in anatomy is described as the movementss in reference to the three anatomical planes: transverse, frontal, and sagittal.

Type of movement for synarthrosis, amphiarthrosis and diarthrosis?

synarthrosis: immobile amphiarthrosis: slightly more moveable darthrosis: completely mobile

general function of gomphosis

-aka peg and socket -Spanning between the bony walls of the socket and the root of the tooth are numerous short bands of dense connective tissue, each of which is called a periodontal ligament -Due to the immobility of a gomphosis, this type of joint is functionally classified as a synarthrosis

What would happen if there were to be damage to a syndesmotic joint?

results from a fracture of the bone with an accompanying tear of the interosseous membrane, will produce pain, loss of stability of the bones, and may damage the muscles attached to the interosseous membrane. If the fracture site is not properly immobilized with a cast or splint, contractile activity by these muscles can cause improper alignment of the broken bones during healing

Symphysis

-A cartilaginous joint where the bones are joined by fibrocartilage is called a symphysis ("growing together") -Fibrocartilage is very strong because it contains numerous bundles of thick collagen fibers, thus giving it a much greater ability to resist pulling and bending forces when compared with hyaline cartilage -The gap separating the bones at a symphysis may be narrow or wide -Examples in which the gap between the bones is narrow include the pubic symphysis and the manubriosternal joint -At the pubic symphysis, the pubic portions of the right and left hip bones of the pelvis are joined together by fibrocartilage across a narrow gap -at the manubriosternal joint, fibrocartilage unites the manubrium and body portions of the sternum -The intervertebral symphysis is a wide symphysis located between the bodies of adjacent vertebrae of the vertebral column. Here a thick pad of fibrocartilage called an intervertebral disc strongly unites the adjacent vertebrae by filling the gap between them -amphiarthrosis

general functions of an articular disc (miniscus)

-A few synovial joints of the body have a fibrocartilage structure located between the articulating bones. This is called an articular disc, which is generally small and oval-shaped, or a meniscus, which is larger and C-shaped -In some places, an articular disc may act to strongly unite the bones of the joint to each other. Examples of this include the articular discs found at the sternoclavicular joint or between the distal ends of the radius and ulna bones -At other synovial joints, the disc can provide shock absorption and cushioning between the bones, which is the function of each meniscus within the knee joint -Finally, an articular disc can serve to smooth the movements between the articulating bones, as seen at the temporomandibular joint. Some synovial joints also have a fat pad, which can serve as a cushion between the bones

What are joints and what are they designed for?

-A joint is an articulation in any place where adjacent bones or cartilage come together to form a connection -designed for stability and provide for little or no movement -most movement = least stable

Subcutaneous bursa?

-A subcutaneous bursa is located between the skin and an underlying bone. It allows skin to move smoothly over the bone. Examples include the prepatellar bursa located over the kneecap and the olecranon bursa at the tip of the elbow

submuscular bursa?

-A submuscular bursa is found between a muscle and an underlying bone, or between adjacent muscles. These prevent rubbing of the muscle during movements. A large submuscular bursa, the trochanteric bursa, is found at the lateral hip, between the greater trochanter of the femur and the overlying gluteus maximus muscle

subtendinous bursa?

-A subtendinous bursa is found between a tendon and a bone. Examples include the subacromial bursa that protects the tendon of shoulder muscle as it passes under the acromion of the scapula, and the suprapatellar bursa that separates the tendon of the large anterior thigh muscle from the distal femur just above the knee

general functions of bursa

-Additional structures located outside of a synovial joint serve to prevent friction between the bones of the joint and the overlying muscle tendons or skin. A bursa (plural = bursae) is a thin connective tissue sac filled with lubricating liquid -located in regions where skin, ligaments, muscles, or muscle tendons can rub against each other, usually near a body join -Bursae reduce friction by separating the adjacent structures, preventing them from rubbing directly against each other

General function of a fibrous joint? And what three categories underly fibrous joints?

-Adjacent bones are connected by fibrous connective tissue -Gap between bones may be narrow or wide -A SUTURE is the narrow fibrous joint found between most bones of the skull -At a SYNDESMOSIS joint, the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a ligament or a wide sheet of connective tissue called an interosseous membrane. This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg. -GOMPHOSIS is the narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits

suture and its examples (how do fontanelles help during birth?)

-All bones of the skull but mandible are joined to each other by this fibrous joint -The fibrous connective tissue found at a suture ("to bind or sew") strongly unites the adjacent skull bones and thus helps to protect the brain and form the face -. In adults, the skull bones are closely opposed and fibrous connective tissue fills the narrow gap between the bones. The suture is frequently convoluted, forming a tight union that prevents most movement between the bones -skull sutures are functionally classified as a synarthrosis, although some sutures may allow for slight movements between the cranial bones -In newborns and infants, the areas of connective tissue between the bones are much wider, especially in those areas on the top and sides of the skull that will become the sagittal, coronal, squamous, and lambdoid sutures -During birth, the fontanelles provide flexibility to the skull, allowing the bones to push closer together or to overlap slightly, thus aiding movement of the infant's head through the birth canal -Synarthrosis

What do diarthrosis joints provide?

-All synovial joints of the body providing the majority of body movements -Found mostly in the appendicular skeleton (upper and lower limbs)

cartilaginous joints

-adjacent bones are united by cartilage, a tough but flexible type of connective tissue -the bones that are joined together by either hyaline cartilage or fibrocartilage -A synchondrosis is a cartilaginous joint where the bones are joined by hyaline cartilage -The second type of cartilaginous joint is a symphysis, where the bones are joined by fibrocartilage

osteoarthritis

-Associated with aging and "wear and tear" of the articular cartilage -Risk factors that may lead to osteoarthritis later in life include injury to a joint; jobs that involve physical labor; sports with running, twisting, or throwing actions; and being overweight -These factors put stress on the articular cartilage that covers the surfaces of bones at synovial joints, causing the cartilage to gradually become thinner -The joint responds by increasing production of the lubricating synovial fluid, but this can lead to swelling of the joint cavity, causing pain and joint stiffness as the articular capsule is stretched. The bone tissue underlying the damaged articular cartilage also responds by thickening, producing irregularities and causing the articulating surface of the bone to become rough or bumpy -no cure

gouty arthritis

-Gout is a form of arthritis that results from the deposition of uric acid crystals within a body joint. Usually only one or a few joints are affected, such as the big toe, knee, or ankle -Gout occurs when the body makes too much uric acid or the kidneys do not properly excrete it. A diet with excessive fructose has been implicated in raising the chances of a susceptible individual developing gout

rheumatoid arthrisis

-In rheumatoid arthritis, the joint capsule and synovial membrane become inflamed. As the disease progresses, the articular cartilage is severely damaged or destroyed, resulting in joint deformation, loss of movement, and severe disability -The most commonly involved joints are the hands, feet, and cervical spine -no known cure

plane

-Multiaxial joint -inversion and eversion of foot - flexion, extension -lateral flexion of the vertebral column -Ex: *Intertarsal joints of foot * superior-inferior articular process articulations between vertebrae

What do amphiarthrosis joints provide?

-One example is the cartilaginous joint that unites the bodies of adjacent vertebrae. Filling the gap between the vertebrae is a thick pad of fibrocartilage called an intervertebral disc. Each intervertebral disc strongly unites the vertebrae but also allows for limited amount of movement -Another example is the pubic symphysis of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage. This joint normally has very little mobility. The strength of the pubic symphysis is important in conferring weight-bearing stability to the pelvis

General function of ligaments and the different types of ligaments

-Outside of their articulating surfaces, the bones are connected together by ligaments, which are strong bands of fibrous connective tissue -These strengthen and support the joint by anchoring the bones together and preventing their separation -Ligaments allow for normal movements at a joint, but limit the range of these motions, thus preventing excessive or abnormal joint movements -Ligaments are classified based on their relationship to the fibrous articular capsule - An extrinsic ligament is located outside of the articular capsule -an intrinsic ligament is fused to or incorporated into the wall of the articular capsule - an intracapsular ligament is located inside of the articular capsule

The two different types of cartilaginous joints?

-Synchondrosis -Symphoses

sprains

-The ankle is the most frequently injured joint in the body, with the most common injury being an inversion ankle sprain -A sprain is the stretching or tearing of the supporting ligaments -Excess inversion causes the talus bone to tilt laterally, thus damaging the ligaments on the lateral side of the ankle

What is synostosis? Provide an example

-The connective tissue will ossify and be converted into bone, causing the adjacent bones to fuse to each other (two bones that begin as seperate bones but eventually fuse as one) -Between cranial bones early and later in life -e. At the time of birth, the frontal and maxillary bones consist of right and left halves joined together by sutures, which disappear by the eighth year as the halves fuse together to form a single bone -Late in life, the sagittal, coronal, and lambdoid sutures of the skull will begin to ossify and fuse, causing the suture line to gradually disappear

why is the width of the intervertebral symphysis important? What does the intervertebral disc provide?

-The width of the intervertebral symphysis is important because it allows for small movements between the adjacent vertebrae. In addition, the thick intervertebral disc provides cushioning between the vertebrae, which is important when carrying heavy objects or during high-impact activities such as running or jumping

Syndesmosis and its examples

-Two parallel bones are united to each other by fibrous connective tissue -The gap between the bones may be narrow, with the bones joined by ligaments, or the gap may be wide and filled in by a broad sheet of connective tissue called an interosseous membrane -In the forearm and leg, the wide gap between the shaft portions of the radius and ulna (and tibia and fibula) bones are strongly united by an interosseous membrane -distal tibiofibular joint, the articulating surfaces of the bones lack cartilage and the narrow gap between the bones is anchored by fibrous connective tissue and ligaments on both the anterior and posterior aspects of the joint. Together, the interosseous membrane and these ligaments form the tibiofibular syndesmosis

Describe the three axial movements

-Uniaxial (movement in one plane): The elbow joint which only allows for bending and straightening -Biaxial (movement in two planes) : metacarpophalangeal joint (knuckle joint) *One axis: bending and straightening *Second axis: spreading of the fingers away from each other and bringing them together -Multiaxial (movement in all three anatomical planes): The shoulder and hip joint *allow upper and lower limb to move in an anterior-posterior *medial-lateral *rotation so that f the limb so that its anterior surface is moved either toward or away from the midline of the body

What do synarthrosis joints provide?

-a strong union between the adjacent bones -important at locations where bones provide protection for internal organs -Ex: sutures (the fibrous joints btwn the bones of skull that surround and protect the brain

general functions of a tendon

-additional support is provided by the muscles and their tendons that act across the joint -a tendon is the dense connective tissue structure that attaches a muscle to bone -As forces acting on a joint increase, the body will automatically increase the overall strength of contraction of the muscles crossing that joint, thus allowing the muscle and its tendon to serve as a "dynamic ligament" to resist forces and support the joint -This type of indirect support by muscles is very important at the shoulder joint, for example, where the ligaments are relatively weak

Atlantoaxial joint

-between the atlas and axis consists of 3 articulations -The paired superior articular processes of the axis articulate with the inferior articular processes of the atlas -These articulating surfaces are relatively flat and oriented horizontally -The third articulation is the pivot joint formed between the dens, which projects upward from the body of the axis, and the inner aspect of the anterior arch of the atlas -A strong ligament passes posterior to the dens to hold it in position against the anterior arch. These articulations allow the atlas to rotate on top of the axis, moving the head toward the right or left, as when shaking your head "no."

Condyloid

-biaxial joint -flexion/extension -abbduction/adduction -and circumduction movements -Ex: *Metacarpophalangeal (knuckle) joints of fingers * radiocarpal joint of wrist *metatarsophalangeal joints for toes

Saddle

-biaxial joint -flexion/extension -abduction/adduction -and circumduction movements -Ex: *First carpometacarpal joint of the thumb *sternoclavicular joint

How do synovial joints function like levers? (fulcrum, resistance, effort)

-bones being stiff levers and the articular endings of the bones—encased in synovial joints—acting as fulcrums. The load would be an object being lifted or any resistance to a movement (your head is a load when you are lifting it), and the effort, or applied force, comes from contracting skeletal muscle

general functions of synchondrosis

-hyaline cartilage -may be temporary or permanent -A temporary synchondrosis is the epiphyseal plate (growth plate) of a growing long bone. The epiphyseal plate is the region of growing hyaline cartilage that unites the diaphysis (shaft) of the bone to the epiphysis (end of the bone). -Examples of permanent synchondroses are found in the thoracic cage. One example is the first sternocostal joint, where the first rib is anchored to the manubrium by its costal cartilage (The articulations of the remaining costal cartilages to the sternum are all synovial plane joints) -Unlike the temporary synchondroses of the epiphyseal plate, these permanent synchondroses retain their hyaline cartilage and thus do not ossify with age -Due to the lack of movement between the bone and cartilage, both temporary and permanent synchondroses are functionally classified as a synarthrosis

Temporalmandibular joint

-joint that allows for opening (mandibular depression) and closing (mandibular elevation) of the mouth as well as side-to-side and protraction/retraction motions of the lower jaw -This joint involves the articulation between the mandibular fossa and articular tubercle of the temporal bone, with the condyle (head) of the mandible -Located between these bony structures, filling the gap between the skull and mandible, is a flexible articular disc. This disc serves to smooth the movements between the temporal bone and mandibular condyle -Movement at the TMJ during opening and closing of the mouth involves both gliding and hinge motions of the mandible. With the mouth closed, the mandibular condyle and articular disc are located within the mandibular fossa of the temporal bone. During opening of the mouth, the mandible hinges downward and at the same time is pulled anteriorly, causing both the condyle and the articular disc to glide forward from the mandibular fossa onto the downward projecting articular tubercle

acetabulofemoral joint

-multiaxial ball-and-socket joint between the head of the femur and the acetabulum of the hip bone -The hip carries the weight of the body and thus requires strength and stability during standing and walking. For these reasons, its range of motion is more limited than at the shoulder joint -The acetabulum is further deepened by the acetabular labrum (fibrocartilage lip attached to the outer margin of the acetabulum) -The surrounding articular capsule is strong, with several thickened areas forming intrinsic ligaments. These ligaments arise from the hip bone, at the margins of the acetabulum, and attach to the femur at the base of the neck. The ligaments are the iliofemoral ligament, pubofemoral ligament, and ischiofemoral ligament

general functions of sydesmosis and what type of movement does it provide?

-the forearm and leg serve to unite parallel bones and prevent their separation -In the leg, the syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint. This provides strength and stability to the leg and ankle, which are important during weight bearing -In the forearm, the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements. Thus in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the antebrachial interosseous membrane allows for the much greater mobility of the forearm -The interosseous membranes of the leg and forearm also provide areas for muscle attachment -amphiarthosis

What is a synovial joint?

-the most common type of joint in the body -A key structural characteristic for a synovial joint that is not seen at fibrous or cartilaginous joints is the presence of a joint cavity -This fluid-filled space is the site at which the articulating surfaces of the bones contact each other -Also unlike fibrous or cartilaginous joints, the articulating, bone surfaces at a synovial joint are not directly connected to each other with fibrous connective tissue or cartilage -This gives the bones of a synovial joint the ability to move smoothly against each other, allowing for increased joint mobility

Pivot joint

-uniaxial diarthrosis joint -allows rotational movement -Ex: *Atlantoaxial joint (C1 + C2 vertebrae articulation) *proximal radioulnar joint

arthrisis

Arthritis is a common disorder of synovial joints that involves inflammation of the joint. This often results in significant joint pain, along with swelling, stiffness, and reduced joint mobility. There are more than 100 different forms of arthritis. Arthritis may arise from aging, damage to the articular cartilage, autoimmune diseases, bacterial or viral infections, or unknown (probably genetic) causes

Why is the epiphyseal plate considered to be a temporary synchondrosis?

Bone lengthening involves growth of the epiphyseal plate cartilage and its replacement by bone, which adds to the diaphysis. For many years during childhood growth, the rates of cartilage growth and bone formation are equal and thus the epiphyseal plate does not change in overall thickness as the bone lengthens. During the late teens and early 20s, growth of the cartilage slows and eventually stops. The epiphyseal plate is then completely replaced by bone, and the diaphysis and epiphysis portions of the bone fuse together to form a single adult bone. This fusion of the diaphysis and epiphysis is a synostosis. Once this occurs, bone lengthening ceases. For this reason, the epiphyseal plate is considered to be a temporary synchondrosis

pott fracture

Forcible eversion of the foot, for example, with an awkward landing from a jump or when a football player has a foot planted and is hit on the lateral ankle, can result in a Pott's fracture and dislocation of the ankle joint

General function of articular cartilage?

Friction between the bones at a synovial joint is prevented by the presence of the articular cartilage, a thin layer of hyaline cartilage that covers the entire articulating surface of each bone. However, unlike at a cartilaginous joint, the articular cartilages of each bone are not continuous with each other. Instead, the articular cartilage acts like a Teflon® coating over the bone surface, allowing the articulating bones to move smoothly against each other without damaging the underlying bone tissue

General function of synovial membrane?

Lining the inner surface of the articular capsule is a thin synovial membrane. The cells of this membrane secrete synovial fluid (synovia = "a thick fluid"), a thick, slimy fluid that provides lubrication to further reduce friction between the bones of the joint. This fluid also provides nourishment to the articular cartilage, which does not contain blood vessels. The ability of the bones to move smoothly against each other within the joint cavity, and the freedom of joint movement this provides, means that each synovial joint is functionally classified as a diarthrosis