Articulations

Synovial Joint: Structures

A synovial joint is composed of a variety of structures; namely: • Joint capsule • Articular cartilage • Ligaments • Menisci • Bursae

Condyloid Joints

Condyloid joints permit an up-and-down motion and side-to-side motion, but no rotational movement. In this type of joint, the end of one bone is oval or convex and fits into an elliptical or concave depression of the other bone. Examples of condyloid joints include: • Radiocarpal joint at the wrist • Joint between the metacarpals and phalanges

Diarthortic Joints

Diarthrotic joints are freely movable joints. Diarthrotic joints allow your body to move in different ways.

Fibrous Joints

Fibrous joints are characterized by the absence of a joint cavity and the presence of fibrous connective tissue surrounding the articulating bones.

Types of Fibrous Joints

Fibrous joints are synarthrotic joints because they are tightly woven by fibrous tissue; therefore, causing the joints to be rigid and immovable. There are three types of fibrous joints: • Sutures • Syndesmoses • Gomphoses

Functional Classification

Functional classification is determined by how much the bones are able to move.

Gliding Joints

Gliding joints permit side-to-side and back-and-forth movements with some slight rotational movement. Examples of gliding joints include: • Intercarpal joints • Intertarsal joints • Sternoclavicular joint

Gomphoses

Gomphoses are fibrous joints between the teeth and the supporting bones of the jaws. The gomphosis is located where the root of the tooth is attached to the periodontal ligament within the socket of the jawbones.

Hinges Joints

Hinge joints permit bending in only one plane. Just like a hinge on a door. In this type of joint, one bone is always concave and the other is convex. Examples of hinge joints include: • Knee joints • Humeroulnar articulation of elbows • Joints between phalanges

Unique Structures

In order to do these primary functions, a synovial joint is composed of a variety of unique structures, namely: • Joint capsule • Articular cartilage • Ligaments • Menisci • Bursae

Saddle Joints

Saddle joints permit a wide range of movement. In this type of joint, one bone is concave and the other is convex. It is called the saddle joint because one bone is shaped like a saddle and the other is shaped like a rider sitting in the saddle. An example of a saddle joint is: • Joint between the carpals and the first metacarpal bone. This allows your thumb to cross the palm of your hand.

Structural Classification

Structural classification is determined by how the bones connect to each other. There are two main considerations: • Whether there is a joint cavity or not. • What kind of supportive connective tissue surrounds the joint.

Sutures

Sutures bind the bones of the skull together. The bones do not fuse together until around 18 months or two years old in order to allow space for the infant's brain to grow. Then in early adulthood the fibrous connective tissue is replaced by bone.

Symphyses

Symphyses are cartilaginous joints where the articulating bones are separated by a pad of fibrocartilage. Examples of symphyses joints are the symphysis pubis and the intervertebral joints.

Synarthortic Joints

Synarthrotic joints are immovable joints. For example, the sutures that connect the bones of your skull are synarthrotic joints.

Interphalangeal Joint

The interphalangeal joint is your finger joint. The interphalangeal joint is formed in-between your phalanges. It is a hinge joint.

Joint Capsule

The joint capsule is a fibroelastic cavity that encloses two articulating bones. The joint capsule is filled with a fluid called synovial fluid. Synovial fluid helps to lubricate the joint.

Collateral Ligaments

The medial and lateral sides of the knee joint are protected by strong collateral ligaments. The names of these ligaments are: • The medial collateral ligament (MCL) • The lateral collateral ligament (LCL)

Metacarpophalangeal Joint

The metacarpophalangeal joint is your knuckle joint. The metacarpophalangeal joint is formed by the oval convex end of the metacarpals and the concave depression on the phalanges. It is a condyloid joint

Patellofemoral Joint

The patella does not articulate with the tibia or femur; rather, it is a free-floating bone. It helps to stabilize and protect the anterior side of the knee joint. It connects with the patellar ligament to form the patellofemoral joint; which is a gliding joint.

Popliteal Ligaments

The popliteal ligaments are superficial ligaments. There are two popliteal ligaments: • The broad oblique popliteal ligament • The arcuate popliteal ligament

Popliteal Region

The posterior side of the knee joint is known as the popliteal region. It has several supporting ligaments. Namely: • Popliteal ligaments • Cruciate ligaments

Posterior Talofibular Ligament

The posterior talofibular ligament is found on the lateral side of the ankle joint. It passes posteriorly from the lateral malleolus of the fibula to the talus.

Principle Joints

The principal joints in the body include: • Temporomandibular joint • Sternoclavicular joint • Glenohumeral joint • Elbow joint • Metacarpophalangeal joints • Interphalangeal joints • Coxal joint • Tibiofemoral joint • Talocrural joint

Ligament

A ligament is connective tissue that connects a bone to another bone. Ligaments provide support to the articulating bones as well as span the joint. They may either be within the joint capsule or on the outside of the capsule

Sprain

A sprain is a tearing of the ligaments that surround a joint. In the "Muscular Issues" lesson, you learned that a muscle strain is when you overstretch or tear the muscle fibers within a muscle or the attached tendon. One tip to help you keep them straight "sTrain" is a tear of a muscle or Tendon; whereas, "sprain" is a tear of a ligament. A sprain and a strain do have very similar symptoms, namely; • You may feel or hear a "pop" • Sudden onset of pain • Soreness • Stiffness • Weakness • Swelling • Bruising • Limited range of motion In a sprain, the swelling is located inside the joint capsule which is known as synovitis. Sprains are very common. A sprain is caused when a joint is knocked out of position causing excessive force on the supporting ligaments. This can occur due to a direct blow to the joint or indirectly. An example of an indirect cause would be falling on an out-stretched hand or rolling your ankle. This type of injury can occur to individuals in the general population, as well as, elite athletes For example, ankle sprains are most commonly caused by an excessive inversion of the foot causing damage to the anterior talofibular ligament, calcaneofibular ligament, and/or the posterior talofibular ligament. For mild or moderate sprains, you may treat it at home using the R.I.C.E. method: • R: Rest. Allow your body time to recover on its own by trying not to use that muscle. As pain begins to decrease, slowly increase range of motion again. • I: Ice. Ice the muscle by either using an ice pack or by taking an ice bath. Ice for 15 minutes several times a day for best results. • C: Compression. To reduce swelling, apply compression by wrapping the injured muscle with an elastic bandage. Be careful not to wrap too tightly which could cut off blood circulation. • E: Elevate. If possible, elevate the injured muscle above your heart. This will also help the swelling to decrease. You may also want to take a nonsteroidal anti-inflammatory drug (NSAID) like aspirin or ibuprofen. Sprains may also be severe. For example, knee sprains can damage the articular cartilages and menisci that support the knee joint. If the knee sprain is severe, as with an anterior cruciate ligament (ACL) tear, it may require surgery You can prevent muscle sprains by doing the following: • Warm-up before you exercise. • Use good posture throughout the day, and proper form while you exercise. • When beginning a new exercise program, start slowly. • Listen to your body to ensure you don't overdo it. • Wear appropriate protective equipment when playing sports

Patella Retinacula

Also on the anterior side, is two supportive bands formed by the quadriceps femoris know as the patellar retinacula. • From the vastus lateralis, the lateral patellar retinacula is created. • From the vastus medialis, the medial patellar retinacula is creat

Amphiarthortic Joints

Amphiarthrotic joints are slightly movable joints. For example, the disc between the vertebrae of your spine forms an amphiarthrotic joint.

Articular Cartilage

Articular cartilage is found at the ends of articulating bones of a synovial joint. It provides a smooth surface and exchanges waste products and nutrients with the surrounding synovial fluid.

Articulations

Articulations, or joints, are where two or more bones meet. Generally, the primary function of articulations is to allow movement between bones. However, the structure of some joints does not enable movement. There are two types of classifications for joints: 1. Functional classification 2. Structural classification

Ball-and-Socket Joints

Ball-and-socket joints permit the greatest range of movement. In this type of joint, the end of one bone is rounded and the other bone is convex and creates a cup-like cavity. Examples of ball-and-socket joints include: • Hip joint • Shoulder joint

Bursae

Bursae are flattened, pouchlike sacs that are filled with synovial fluid. Bursae are located between muscles or where a tendon passes over a bone. A tendon sheath is a type of bursa that wraps around and lubricates the tendons of certain muscles, especially those that cross the wrist and ankle joints. The knee joint also has several bursae: • 4 on the anterior side • 2 on the posterior side • 7 on the lateral and medial sides

Bursitis & Tendonitis

Bursitis is inflammation (or swelling) of the flattened, pouch-like sacs that are filled with synovial fluid associated with a joint. Bursitis can occur to any bursa, but the most commonly injured ones include: • Shoulder • Elbow • Hip • Knee • Heel • Big toe Tendonitis is inflammation (or swelling) of the connective tissue that connects a muscle to a bone. Tendonitis can occur in any tendon. Some of the common names for tendonitis include: • Tennis elbow • Golfer's elbow • Pitcher's shoulder • Swimmer's shoulder • Jumper's knee The symptoms of bursitis and tendonitis include: • Swelling • Redness • Bruising • Pain when touched or moved • Sharp, shooting pain Risk factors associated with bursitis and tendonitis are the following: • Age- both are more common the older you get. • Job, hobby, or sport with repetitive motions. • Systemic diseases such as arthritis, gout, and diabetes are also risk factors for bursitis. Bursitis and tendonitis are first treated using the R.I.C.E. method just like sprains. If pain persists then more intensive treatment methods may be used such as: • Physical therapy • Corticosteroid injections • Surgery The following tips can help you prevent bursitis: • Wear kneepads when kneeling for extended amounts of time. • Use a wheelbarrow rather than carrying heavy items. • Take frequent breaks when doing repetitive motions. • Maintain a healthy weight. • Warm-up before strenuous exercise. Follow this advice to help you prevent tendonitis: • Add variety to your workouts and your exercise program. • Be sure to allow your body to rest after strenuous work. • Don't forget to include a warm-up before you exercise. • Be aware of your posture while at work.

Types Cartilaginous Joints

Cartilaginous joints are amphiarthrotic joints because the joints can move slightly in response to twisting and compression. There are two types of cartilaginous joints: • Symphyses • Synchondroses

Cartilaginous Joints

Cartilaginous joints are characterized by the absence of a joint cavity and the presence of cartilage binding the articulating bones together.

Joint Dislocation

Joint dislocation, or luxation, is the misalignment of the articulating bones. Common joints that suffer from dislocations: • Shoulder • Hip • Knee • Elbow A joint dislocation can be a complete separation or a partial misalignment. A partial dislocation is known as a subluxation The shoulder (glenohumeral) joint is the most freely moveable joint in your body. In order to achieve this mobility, it had to sacrifice stability. This is why shoulder dislocations are common. A subluxation of the shoulder joint is when the head of the humerus is partially out of the joint capsule. A complete dislocation is when the head of the humerus is all the way out of the joint capsule. Symptoms include: • Swelling • Numbness • Weakness • Bruising A doctor will put the head of the humerus back into the joint capsule. It is important that you do not try to do this yourself because there are several nerve endings and blood vessels that you could damage if not done properly In order to prevent shoulder dislocations follow these guidelines: • Exercise regularly to build strength and improve range of motion. • Take precautions to avoid falling. • Wear appropriate gear when playing sports

Menisci

Menisci are tough, fibrous, cartilaginous pads found in the joint capsule of some synovial joints. Menisci have two purposes: • To guide the articulating bones. • To cushion the contact between the articulating bones.

Pivot Joints

Pivot joints permit rotation about a central axis. In this type of joint, one bone is rounded and fits into a depression of the other bone. Examples of pivot joints include: • Proximal articulation between the radius and ulna. This allows you to turn a doorknob. • Articulation between atlas and axis. This allows you to rotate your head.

Synchodroses

Synchondroses are cartilaginous joints where the articulating bones have hyaline cartilage in between them. Examples of synchondroses joints are some of the bones of the skull and the joint between the ribs and the sternum. Another example of synchondroses joints is the epiphyseal plates between the diaphysis and epiphysis of growing bones. The epiphyseal plates are temporary, but then with time they will solidify and become bone. At this point, the synchondrosis no longer exists.

Syndesmoses

Syndesmoses are fibrous joints found in the forearm and leg. In the forearm, the syndesmosis joint is between the distal end of the radius and the ulna. In the leg, the syndesmosis joint is between the distal end of the tibia and the fibula. This synarthrotic joint allows slight movement when these joints are rotated

Synovial Joints

Synovial joints are characterized by the presence of a joint cavity and the presence of ligaments that provide support for the articulating bones. A ligament is connective tissue that connects a bone to another bone. Synovial joints are diarthrotic joints because they are freely moveable joints Synovial joints have two primary functions: • To carry out smooth movements. • To provide stability, strength, and sometimes rigidity

Synovial Joints: Primary Function

Synovial joints have two primary functions: • To carry out smooth movements. • To provide stability, strength, and sometimes rigidity

Anterior Talofibular Ligament

The anterior talofibular ligament is found on the lateral side of the ankle joint. It passes anteriorly from the lateral malleolus of the fibula to the talus.

Calceneofibular Ligament

The calcaneofibular ligament is found on the lateral side of the ankle joint. It passes inferiorly from the lateral malleolus of the fibula to the calcaneus

Coxal Joint

The coxal joint is your hip joint. The coxal joint is formed by th head of the femur and the acetabulum of the os coxae. It is a ball-and-socket joint. It is much stronger and more stable than the shoulder joint because it must bear the weight of the body.

Cruciate Ligaments

The cruciate ligaments are deep ligaments that cross each other to help stabilize the knee joint. There are two cruciate ligaments: • The anterior cruciate ligament (ACL) • The posterior cruciate ligament (PCL)

Deltoid Ligament

The deltoid ligament is found on the medial side and creates a triangle shape. It extends from the medial malleolus of the tibia, to the talus, calcaneus, and another tarsal bone.

Elbow Joint

The elbow joint is formed by two separate articulations: • The trochlea of the humerus and the tochlear notch of the ulna. • The capitulum of the humerus and the head of the radius. Yet, the elbow joint still only has one joint capsule. Within this joint capsule, there is a large olecranon bursa to aid in lubrication of the joint. The elbow joint is a hinge joint.

Glenohumeral Joint

The glenohumeral joint is your shoulder joint. It is formed by the head of the humerus and the glenoid fossa of the scapula. It is a ball-and-socket joint. The glenohumeral joint is also the most freely moveable joint in your body. In order to achieve this mobility, it had to sacrifice stability. This is why shoulder dislocations are common. A shoulder dislocation is when the head of the humerus comes out of the joint capsule.

Sternoclavicular Joint

The sternoclavicular joint is formed by the clavicle and the manubrium of the sternum. It is a gliding joint with a good range of motion because it has an articular disc within the joint capsule

Talocrural Joint

The talocrural joint is your ankle joint. It is formed by two separate articulations: • The medial malleolus of the tibia and the talus • The lateral malleolus of the fibula and the talus The talocrural joint has one joint capsule and is a hinge joint.

Temporomandibular Joint

The temporomandibular joint is formed by the mandibular condyle of the mandible and the mandibular fossa of the temporal bone. It is the only synovial joint in the skull. It is a unique combination of a hinge joint and a gliding joint. The hinge joint of the temporomandibular joint allows the mouth to lower and rise. The gliding joint of the temporomandibular joints allows the jaw to protract and retract. It is also able to do lateral rotations.

Functional Classes

The three functional classes of joints are: • Synarthrotic joints • Amphiarthrotic joints • Diarthrotic joints

Structural Classes

The three structural classes of joints are: • Fibrous joints • Cartilaginous joints • Synovial joints

Tibiofemoral Joint

The tibiofemoral joint is your knee joint. The tibiofemoral joint is formed by the femur and the tibia. It is the largest joint in the body. It is also the most vulnerable joint in the body and so in order to protect it, it is very complex. So we will take a closer look at this important joint. The tibiofemoral joint is a complex hinge joint. Therefore, in addition to flexion and extension, it also allows a limited rolling and gliding movement The tibiofemoral has many structures that surround it to help protect it. Anterior • Patella and patellar ligament • Patellar retinacula Posterior • Popliteal ligaments • Cruciate ligaments Medial/lateral • Collateral ligaments

Correlation of Classifications

The two types of classifications are correlated with one another. • Most fibrous joints are synarthrotic joints. • Most cartilaginous joints are amphiarthrotic joints. • Most synovial joints are diarthrotic joints.

Ligaments that Support the Ankle

There are four ligaments that support the ankle outside the joint capsule. • Deltoid ligament • Anterior talofibular ligament • Posterior talofibular ligament • Calcaneofibular ligament

Types of Synovial Joints

There are six types of synovial joints. They are classified by their structure and the kinds of movements they permit. The six types of synovial joints are: • Gliding • Hinge • Pivot • Condyloid • Saddle • Ball-and-Socket

Menisci: Knee Joint

There are two menisci in the knee joint: the lateral meniscus and the medial meniscus. • The medial collateral ligament is attached to the medial meniscus. • The lateral collateral ligament is not attached to the lateral meniscus though.

Joint Classifications

There are two types of classifications for joints: • Functional classification • Structural classification The three functional classes of joints are: • Synarthrotic joints • Amphiarthrotic joints • Diarthrotic joints The three structural classes of joints are: • Fibrous joints • Cartilaginous joints • Synovial joints

Joint Mobility

There is a wide variety of joint mobility among all different people. Most often this is the result of body conditioning. The range of motion also varies according to the specific joint. The factors that determine a synovial joint's range of motion include: • The structure and shape of the articulating bones. • The strength and tautness of the specific ligaments, tendons, and joint capsule. • The size, arrangement, and action of the muscles that span the joint.