A&P final #5

How do joints enable movement?

They link bones so muscles and tendons can exert force across them.

How do joints provide stability?

Some joints allow limited or no movement, protecting underlying structures (e.g., skull).

How do joints allow long bones to lengthen?

Through the epiphyseal plate, a temporary joint during skeletal development.

What is a synarthrosis?

A joint with no movement between articulating bones.

What is an amphiarthrosis?

A joint with a small amount of movement between articulating bones.

What is a diarthrosis?

A freely moveable joint allowing a wide variety of movements.

What are fibrous joints?

Joints fastened by dense regular collagenous connective tissue; no joint space; can be synarthroses or amphiarthroses.

What are cartilaginous joints?

Joints fastened by cartilage; no joint space; can be synarthroses or amphiarthroses.

What are synovial joints?

Diarthroses with hyaline cartilage on articulating surfaces and a fluid‑filled joint cavity.

What tissue holds fibrous joints together?

Dense regular collagenous connective tissue.

What is the function of collagen fibers in fibrous joints?

Provide stability but permit little or no motion.

What are the three types of fibrous joints?

Sutures, gomphoses, syndesmoses.

What are sutures?

Immovable joints between edges of cranial bones; very stable, protect brain.

What are gomphoses?

Immovable joints between teeth and bony sockets in jaw; linked by periodontal ligament.

What are syndesmoses?

Joints between tibia/fibula or ulna/radius; joined by interosseous membrane; allow small movement (amphiarthroses).

What tissue holds cartilaginous joints together?

Cartilage.

Do cartilaginous joints have a joint cavity?

No, they lack a joint cavity.

What are the two types of cartilaginous joints?

Synchondroses and symphyses.

What cartilage links bones in synchondroses?

Hyaline cartilage.

What is the functional classification of synchondroses?

Synarthroses (immovable).

What are examples of synchondroses?

Epiphyseal plates, first sternocostal joint, costochondral joints.

Why are epiphyseal plates considered synchondroses?

They connect diaphyses and epiphyses of developing long bones with hyaline cartilage.

What links bones in symphyses?

Fibrocartilaginous pad or plug.

What is the functional classification of symphyses?

Amphiarthroses (slightly moveable).

What is the structure‑function principle of symphyses?

Best suited to resist compression and tension while allowing slight motion.

What are examples of symphyses?

Intervertebral joints and pubic symphysis.

What is the joint cavity (synovial cavity)?

The space between articulating bones filled with synovial fluid.

What is the articular capsule?

A double‑layered structure enclosing the joint cavity.

What is the function of the outer fibrous layer of the capsule?

Keeps bones from being pulled apart and isolates the joint.

What is the synovial membrane?

Inner layer of capsule that secretes synovial fluid.

What principle does the synovial membrane illustrate?

Structure‑Function Core Principle — provides nutrients and waste removal for joint.

What are the three main functions of synovial fluid?

Lubrication, nutrient/waste transport, shock absorption.

Why is synovial fluid necessary?

Joints lack blood vessels, so fluid supplies nutrients and removes waste.

What type of cartilage covers articulating surfaces in synovial joints?

Hyaline cartilage.

What is the function of articular cartilage?

Provides smooth surface, reduces friction, absorbs stress.

Why is articular cartilage avascular?

It is isolated within the capsule and relies on synovial fluid for nutrients.

What additional structures are found in synovial joints?

Adipose tissue, nerves, and blood vessels.

Why do synovial joints need extra stabilization?

They allow more mobility but less stability than other joint types.

What is a ligament?

Dense regular collagenous connective tissue linking bone to bone; adds strength.

What is a tendon?

Dense regular collagenous connective tissue connecting muscle to bone.

How do tendons stabilize joints?

By crossing joints and tightening when muscles contract.

What is muscle tone?

Continuous low‑level muscle contraction providing stabilizing force.

What is a bursa?

Synovial fluid‑filled fibrous sac that reduces friction in high‑stress regions.

What is a tendon sheath?

Long bursa surrounding tendons to protect them as they slide across joints.

What is arthritis?

Inflammation of one or more joints causing pain and limited movement.

What is osteoarthritis?

Most common form; caused by wear and tear, injuries, or aging.

What is rheumatoid arthritis?

Autoimmune disease where immune system attacks synovial membrane.

What is gouty arthritis?

Joint damage from inflammatory reaction to uric acid crystal deposits.

What are nonaxial joints?

Joints that allow motion in one or more planes without rotation around an axis.

What are uniaxial joints?

Joints that allow motion around only one axis.

What are biaxial joints?

Joints that allow motion around two axes.

What are multiaxial (triaxial) joints?

Joints that allow motion around three axes.

What type of joint is the elbow?

Uniaxial hinge joint; allows flexion and extension.

What type of joint are metacarpophalangeal joints?

Biaxial; allow flexion/extension and abduction/adduction.

What type of joint is the shoulder?

Multiaxial ball‑and‑socket joint; allows flexion/extension, abduction/adduction, rotation.

What are gliding movements?

Sliding motion between articulating surfaces; nonaxial.

What are angular movements?

Movements that increase or decrease the angle between bones.

What is flexion?

Decreases angle between bones (e.g., bending elbow).

What is extension?

Increases angle between bones (straightening).

What is hyperextension?

Extension beyond anatomical position.

What is abduction?

Movement away from midline.

What is adduction?

Movement toward midline.

What is circumduction?

Cone‑shaped motion combining flexion/extension and abduction/adduction.

What is rotation?

Nonangular motion where bone rotates around its longitudinal axis.

What is opposition?

Thumb moves across palm to touch fingers.

What is reposition?

Thumb returns to anatomical position.

What is depression?

Moves body part inferiorly.

What is elevation?

Moves body part superiorly.

What is protraction?

Moves body part anteriorly.

What is retraction?

Moves body part posteriorly.

What is inversion?

Plantar surface of foot rotates medially.

What is eversion?

Plantar surface of foot rotates laterally.

What is dorsiflexion?

Angle between foot and leg decreases (toes up).

What is plantarflexion?

Angle between foot and leg increases (toes down).

What is supination?

Rotational movement turning palm upward.

What is pronation?

Rotational movement turning palm downward.

What is range of motion?

The amount of movement a joint is capable of under normal circumstances.

Which joints have the smallest range of motion?

Uniaxial joints (e.g., knee).

Which joints have the greatest range of motion?

Multiaxial joints (e.g., shoulder).

What is a plane (gliding) joint?

Simplest synovial joint; articulation between flat surfaces of bones; allows gliding motion.

What is a hinge joint?

Convex surface of one bone fits into concave depression of another; uniaxial movement (flexion/extension).

What is a pivot joint?

Rounded surface of one bone fits into groove of another; uniaxial rotation.

What is a condylar (ellipsoid) joint?

Oval convex surface fits into shallow concave surface; biaxial movement.

What is a saddle joint?

Each surface has concave and convex regions; biaxial with greater motion (e.g., thumb joint).

What is a ball‑and‑socket joint?

Spherical surface fits into cup‑shaped depression; multiaxial, widest range of motion.

What type of joint is the elbow?

Stable hinge joint.

What are the two articulations of the elbow?

Humeroulnar (trochlea of humerus with trochlear notch of ulna) and humeroradial (capitulum of humerus with head of radius).

What ligaments stabilize the elbow?

Radial collateral ligament, ulnar collateral ligament, anular ligament.

What are the two articulations of the knee?

Tibiofemoral (femoral condyles with tibial condyles) and patellofemoral (patella with femur).

What is the patellar ligament?

Continuation of quadriceps tendon; connects patella to tibia.

What are the menisci?

Medial and lateral fibrocartilaginous pads between femur and tibia; absorb shock and stabilize.

What is the tibial collateral ligament?

Connects femur, medial meniscus, and tibia; prevents lateral shift of tibia.

What type of joint is the shoulder (glenohumeral)?

Multiaxial ball‑and‑socket joint.

What is the glenoid labrum?

Fibrocartilaginous ring that deepens glenoid cavity for stability.

What tendon helps stabilize the shoulder joint?

Biceps brachii tendon.

What muscles form the rotator cuff?

Supraspinatus, infraspinatus, subscapularis, teres minor.

What type of joint is the hip (coxal)?

Stable multiaxial ball‑and‑socket joint.

What is the acetabular labrum?

Fibrocartilaginous ring stabilizing femur head in acetabulum.

What are retinacular fibers?

Intracapsular ligaments reinforcing joint capsule around femur neck.

What are the three extracapsular ligaments of the hip?

Iliofemoral, ischiofemoral, pubofemoral ligaments.