CHAPTER 9

Fibrous joints

Joints where the bones are connected by fibrous tissue, such as the sacroiliac joint and the pubic symphysis. No joint cavity is present.

Sutures

Joints where the bones are tightly bound by a minimal amount of fibrous tissue, found only between bones of the skull.

Syndesmoses

Joints where the bones are connected exclusively by ligaments, with the amount of movement allowed depending on the length of the connecting fibers.

Gomphoses

Peg-in-socket fibrous joints, with the only example being the articulation of a tooth with its socket.

Functional classification of joints

Classifying joints based on the amount of movement allowed, including synarthroses (immovable joints), amphiarthroses (slightly movable joints), and diarthroses (freely movable joints).

Structural classification of joints

Classifying joints based on the material that binds the bones together and the presence or absence of a joint cavity, including fibrous, cartilaginous, and synovial joints.

Synchondroses

Joints where the bones are united by hyaline cartilage, such as the epiphyseal plates.

Symphyses

Joints where the bones are united by fibrocartilage, such as the intervertebral discs and the pubic symphysis of the pelvis.

Synovial joints

The most movable joints of the body, containing a fluid-filled joint cavity, and classified as diarthroses.

Synovial fluid

The viscous liquid inside the joint cavity that resembles raw egg white and acts as a lubricant for joint movement.

Reinforcing ligaments

Bandlike ligaments that strengthen and reinforce synovial joints, often thickened parts of the fibrous layer of the articular capsule.

Articular cartilage

Hyaline cartilage that covers the ends of opposing bones in a synovial joint, providing cushioning and absorbing compressive forces.

Joint (articular) cavity

A potential space within synovial joints that holds a small amount of synovial fluid.

Articular capsule

A two-layered structure that encloses the joint cavity, consisting of an outer fibrous layer and an inner synovial membrane.

Exracapsular ligaments

Ligaments located just outside the articular capsule of a synovial joint.

Intracapsular ligaments

Ligaments located inside the articular capsule of a synovial joint, covered by a synovial membrane.

Nerves and vessels

Sensory nerve fibers and blood vessels that supply synovial joints, detecting pain and monitoring joint stretching.

Joint cavity

The space between the articulating bones in a joint.

Synovial fluid

A lubricating fluid found in the joint cavity that reduces friction between the articulating bones.

Subacromial bursa

A fluid-filled sac located between the acromion of the scapula and the rotator cuff tendons, reducing friction during shoulder movement.

Tendon of long head of biceps brachii muscle

The tendon that attaches the long head of the biceps brachii muscle to the shoulder joint.

Articular disc

A disc of fibrocartilage found in certain synovial joints, such as the temporomandibular joint and knee joint, that improves the fit between articulating bones and distributes the load more evenly. It divides the synovial cavity into superior and inferior compartments, allowing distinct kinds of movement.

Bursae

Flattened fibrous sacs lined by a synovial membrane that contain synovial fluid and reduce friction between body elements that move over one another.

Tendon sheaths

Elongated bursae that wrap around tendons to decrease friction, particularly in tendons that travel through joint cavities or narrow canals.

Gliding

Sliding the flat surfaces of two bones across each other.

Angular movements

Movements that increase or decrease the angle between two bones, including flexion, extension, abduction, adduction, and circumduction.

Rotation

Turning a bone around its longitudinal axis.

Medial rotation

Rotating toward the median plane.

Lateral rotation

Rotating away from the median plane.

Pronation

Rotating the forearm so that the palm faces posteriorly.

Supination

Rotating the forearm so that the palm faces anteriorly.

Dorsiflexion

Lifting the foot so that its superior surface approaches the shin.

Plantar flexion

Depressing the foot, elevating the heel.

Inversion

Turning the sole of the foot medially.

Eversion

Turning the sole of the foot laterally.

Protraction

Moving a body part in the anterior direction.

Retraction

Moving a body part in the posterior direction.

Elevation

Lifting a body part superiorly.

Depression

Moving a body part inferiorly.

Opposition

Moving the thumb to touch the tips of the other fingers.

Joints

The points where two bones meet and allow for movement.

Thumb

The digit on the hand that is opposable to the other fingers, allowing for grasping and manipulation of objects.

Inversion

Turning the sole of the foot medially.

Eversion

Turning the sole of the foot laterally.

Dorsiflexion

Lifting the foot so that its superior surface approaches the shin.

Plantar Flexion

Depressing the foot or elevating the heel, pointing the toes.

Nonaxial

Adjoining bones do not move around a specific axis.

Uniaxial

Movement occurs around a single axis.

Biaxial

Movement can occur around two axes, enabling motion along both the frontal and sagittal planes.

Multiaxial

Movement can occur around all three axes and along all three body planes:frontal, sagittal, and transverse.

Plane joint

A synovial joint with flat articular surfaces that allow for gliding movements.

Hinge joint

A synovial joint that allows for movement in only one axis, like a door hinge.

Pivot joint

A synovial joint that allows for rotational movement around a single axis.

Condylar joint

A synovial joint with oval articular surfaces that allow for flexion, extension, adduction, and abduction.

Saddle joint

A synovial joint that allows for biaxial movement, similar to the movement of a rider on a saddle.

Ball-and-socket joint

A synovial joint that allows for multiaxial movement, with a spherical head fitting into a cup-like socket.

Stability of synovial joints

The ability of a joint to resist dislocation and maintain proper alignment.

Articular surfaces

The surfaces of the bones in a joint that fit together in a complementary manner.

Ligaments

Connective tissues that help stabilize joints by connecting bones together.

Muscle tone

The state of partial contraction in muscles that helps stabilize joints and maintain posture.

Abduction

Movement of a limb away from the body midline.

Adduction

Movement of a limb toward the body midline.

Circumduction

Moving a limb or finger in a circular motion.

Rotation

Turning movement of a bone around its longitudinal axis.

Elevation

Lifting a body part superiorly.

Depression

Moving a body part inferiorly.

Protraction

Moving a body part in the anterior direction.

Retraction

Moving a body part in the posterior direction.

Supination

Rotation of the forearm so that the palm faces anteriorly.

Pronation

Rotation of the forearm so that the palm faces posteriorly.

Double-jointed

A term used to describe individuals who have looser and more stretchable joint ligaments and capsules than most people.

Joint stability

The ability of a joint to resist excessive or undesirable motions.

Joint capsule

A fibrous structure that surrounds a synovial joint and helps hold the bones together.

Synovial joint

A type of joint that has a joint cavity, articular cartilages, articular capsules, and synovial membranes.

Deep socket

A joint surface that has a deep indentation or groove, providing stability to the joint.

Ligament failure

When ligaments are stretched beyond their normal length and lose their ability to hold bones together.

Joint sockets

The hollow areas in bones where other bones fit in to form a joint.

Abduction

Movement of a body part away from the midline of the body.

Adduction

Movement of a body part towards the midline of the body.

Extension

Straightening of a joint, increasing the angle between two bones.

Flexion

Bending of a joint, decreasing the angle between two bones.

Rotation

Movement of a bone around its own axis.

Pronation

Rotation of the forearm so that the palm faces downwards.

Supination

Rotation of the forearm so that the palm faces upwards.

Temporomandibular joint

The joint between the temporal bone of the skull and the mandible.

Sternoclavicular joint

The joint between the sternum and the clavicle.

Glenohumeral joint

The ball-and-socket joint between the scapula and the humerus.

Temporomandibular Joint (TMJ)

The joint located just anterior to the ear where the condylar process of the mandible articulates with the inferior surface of the squamous temporal bone.

Fibrocartilage

The unique type of cartilage that covers the articular surfaces of the TMJ.

Hinge-like movement

The familiar movement of depressing and elevating the mandible, facilitated by the concave inferior surface of the TMJ.

Anterior gliding

The movement of the superior surface of the TMJ disc when the mouth is opened wide, allowing the condylar process to glide anteriorly.

Articular Tubercle

A dense knob on the anterior part of the articular surface of the temporal bone, against which the condylar process braces during anterior movement of the TMJ.

Mandibular Fossa

The concave posterior part of the articular surface of the temporal bone that receives the condylar process of the mandible.

Synovial Joints

Joints that have a synovial cavity and are surrounded by an articular capsule, allowing for a wide range of movements.

Cartilaginous Joints

Joints that are connected by cartilage, such as the pubic bones and the tibia and fibula.

Synarthrotic

Joints that are immovable.

Diarthrotic

Joints that are freely movable.

Ball and Socket Joint

A type of synovial joint, such as the hip joint, that allows for multiaxial movements.

Hinge Joint

A type of synovial joint, such as the knee joint, that allows for flexion and extension movements.

Gliding Joint

A type of synovial joint, such as the intertarsal joint, that allows for gliding movements.