Puzzle Piece 8: Joints

Joint

A joint, also known as articulation, is the place where bones join together.

Cartilage

Cartilage provides a smooth surface for articulation, acts as a shock absorber, and reduces friction during movement.

Ligaments

Ligaments help stabilize the joint and prevent excessive movement or dislocation.

Classification based on connective tissue

Classification of joints according to what is found between the bones joining together.

Classification based on mobility

Classification of joints based on how much they move.

Fibrous Joints

Dense fibrous connective tissue connects the bones and are characterized by minimal or no movement.

Suture fibrous joints

Narrow band of fibrous connective tissue between cranial bones that does not allow movement.

Syndesmosis fibrous joints

Wide band of fibrous connective tissue between shafts of bones that allows for slight movement.

Gomphosis fibrous joints

Type of fibrous joint where a peg-like structure fits into a socket.

Cartilaginous Joints

Cartilage connective tissue connects the bones.

Synchondrosis cartilaginous joints

Cartilaginous joints containing hyaline cartilage.

Symphysis cartilaginous joints

Cartilaginous joints containing fibrocartilage.

Synovial Joints

Characterized by the presence of a cavity filled with synovial fluid.

Planar synovial joints

Type of synovial joint that allows for sliding movements.

Hinge synovial joints

Type of synovial joint that allows for bending and straightening motions.

Pivot synovial joints

Type of synovial joint that allows for rotational movement.

Condyloid synovial joints

Type of synovial joint that allows for movement in two planes.

Saddle synovial joints

Type of synovial joint that allows for movement in two planes with a greater range of motion.

Ball-and-Socket synovial joints

Type of synovial joint that allows for movement in multiple directions.

Articular capsule

The structure that firmly connects the articulating bones together in a synovial joint.

Synovial membrane

The membrane that produces synovial fluid and is vascular.

Dense irregular connective tissue

Characterized by fibers running in all directions, providing strength in multiple directions.

Interosseous membrane

A membrane between bones.

Gomphosis

A type of joint found snugly between the teeth and their bony sockets.

Movement in cartilaginous joints

More movement than fibrous joints but less movement than synovial joints.

Fibrocartilage

The toughest type of cartilage.

Hyaline cartilage

The most abundant type of cartilage in the body, tough but somewhat flexible.

Elastic cartilage

The most elastic type of cartilage, found in the foldable outer ear.

Synchondrosis

A type of cartilaginous joint composed of hyaline cartilage that allows for slight movement.

Examples of synchondrosis

Epiphyseal plate (growth plate) and the joint between the ribs and the sternum.

Symphysis

A type of cartilaginous joint composed of fibrocartilage that allows for slight movement.

Epiphyseal plate

The growth plate made of hyaline cartilage that allows bones to grow in length.

Epiphyseal line

The line that forms when the epiphyseal plate becomes ossified.

Endochondral ossification

The bone formation that occurs within a cartilage model.

Vertebrochondral ribs

Ribs 8 to 10, which have cartilage that allows slight movement.

Sternum

The bone to which the ribs are connected via hyaline cartilage.

Types of cartilaginous joints

Synchondrosis and symphysis.

Movement in symphyses

Symphysis allows for slight movement.

Pubic Symphysis

A symphysis joint between the pubic bones, allowing slight movement.

Intervertebral Symphysis

A symphysis joint between the vertebrae, allowing slight movement.

Synovial Fluid

A slippery fluid that lubricates joints and delivers nutrients and oxygen to articular cartilage.

Articular Cartilage

Hyaline cartilage covering the epiphysis of long bones, which is avascular.

Types of Synovial Joints

There are 6 types: planar, hinge, pivot, condyloid, saddle, ball and socket.

Ball and Socket Synovial Joints

Joints that allow movement in multiple axes, including rotation.

Movement Types

Describes the types of movement: uniaxial, biaxial, multiaxial.

Uniaxial Movement

Movement in one single axis, such as side-to-side or back-and-forth.

Biaxial Movement

Movement in two axes, such as side-to-side and back-and-forth.

Multiaxial Movement

Movements in multiple axes, including slight rotation.

Intertarsal Joints

Joints between tarsal bones that allow gliding movements.

Intercarpal Joint

Joint between carpal bones that allows gliding movements.

Sternoclavicular Joint

A joint between the sternum and clavicle that allows gliding movements.

Patellofemoral Joint

Joint between the patella and femur, one of the two joints forming the knee joint.

Condyloid (Ellipsoid) Synovial Joints

Smooth rounded surface (condyle) articulating with an elliptical shallow socket. Permit flexion, extension, abduction, adduction and circumduction. Examples: Radiocarpal joint, metacarpophalangeal joint, temporomandibular joint. Movement type: Biaxial.

Planar Synovial Joint

Introduces us to three different types of movement: Uniaxial, Biaxial, Multiaxial.

Joint Classification Based on the Degree of Movement

Includes Synarthrotic (immobile), Amphiarthrotic (slightly movable), and Diarthrotic (freely movable) joints.

Synarthrotic Joints

Immobile joints (joints that do not move at all). Examples: Sutures and gomphoses.

Amphiarthrotic Joints

Slightly movable joints. Examples: Syndesmoses and symphyses.

Diarthrotic Joints

Freely movable joints.

Witty Mnemonic for Synovial Joints

"Please Help Pivot Condoms Sails Back" helps remember the types of synovial joints.

Movement Type: Uniaxial

Movement that occurs around one axis. Examples: Hinge and pivot joints.

Movement Type: Biaxial

Movement that occurs around two axes. Examples: Condyloid and saddle joints.

Movement Type: Multiaxial

Movement that occurs around multiple axes. Example: Ball and socket joints.

Root 'arthro'

Means joints or articulations, related to the disease arthritis.

Root 'amphi'

Means both, like an amphibian that can live in both water and soil.

Sutures

Fibrous joint based on connective tissue classification, part of synarthrotic joints.

Gomphoses

Fibrous joint based on connective tissue classification, part of synarthrotic joints.

Syndesmoses

Fibrous joint based on connective tissue classification, part of amphiarthrotic joints.

Symphyses

Cartilaginous joint based on connective tissue classification, part of amphiarthrotic joints.

Anatomical Position

Body standing upright, facing forward, with arms at the sides and palms facing anteriorly.

Longitudinal Axis

A line running along the length of the body from head to toe, similar to the midsagittal plane.

Abduction

Limb moves away from the midline (longitudinal axis); for example, opening your upper limbs like a letter 'T'.

Adduction

Limb moves back, closer to the midline; for example, lowering your upper limbs back to the resting position from the letter 'T' position.

Flexion

Angle between the bones in the articulation decreases; for example, at the elbow joint when you move the forearm anteriorly.

Extension

Moving the forearm back to the resting position at the elbow joint.

Hyperextension

Extension beyond the anatomical position; for example, bending your head backward.

Flexion at the Hip Joint

Folding at the hip joint.

Extension at the Hip Joint

Bringing the leg back to the midline.

Hyperextension at the Hip Joint

Moving the leg further back than the midline.

Flexion at the Knee Joint

Folding at the knee.

Extension at the Knee Joint

Coming back to the imaginary line.

Flexion at the Intervertebral Joints

Folding the body, similar to performing a bow movement.

Extension at the Intervertebral Joints

Returning from flexion.

Hyperextension at the Intervertebral Joints

Moving backward beyond the midline.

Flexion at the Neck

Folding (bending) the neck forward.

Extension at the Neck

Straightening the neck.

Hyperextension at the Neck

Moving the neck backward beyond the midline.

Lateral Flexion

Moving the imaginary line laterally with the body, performing a side bend while standing upright.

Flexion at the wrist

Folding (bending) the wrist forward.

Extension at the wrist

Straightening the wrist.

Hyperextension at the wrist

Moving the wrist backward beyond the midline.

Flexion at the metacarpophalangeal joint

Folding (bending) the fingers.

Extension at the metacarpophalangeal joint

Straightening the fingers.

Lateral Rotation (External Rotation)

Rotation away from the midline, such as rotating the arm outward.

Medial Rotation (Internal Rotation)

Rotation toward the midline of the body.

Circumduction

Circular movement involving flexion, abduction, extension, and adduction.

Depression

Movement in a downward direction, such as opening the mouth.

Elevation

Movement in an upward direction, such as closing the mouth.

Protraction

The anterior movement of a body part, such as the forward movement of the mandible.

Retraction

The posterior movement of a body part, such as the backward movement of the mandible.

Supination

Rotating the forearm to turn the palm anteriorly.