Joints

What are the three functional classifications of joints

Synarthroses, amphiarthroses, and diarthroses.

What is a synarthrosis

An immovable joint; found mainly in axial skeleton (e.g., skull sutures

What is an amphiarthrosis

A slightly movable joint; found in the axial skeleton (e.g., intervertebral discs

What is a diarthrosis

: A freely movable joint; found mostly in the appendicular skeleton (e.g., shoulder, hip

What are the three types of fibrous joints

Sutures, syndesmoses, and gomphoses

Describe sutures structurally and functionally

Short collagen fibers, immobile; found only in the skull

Describe syndesmoses structurally and functionally

Connected by ligaments; movement depends on fiber length (e.g., tibia/fibula = no movement, radius/ulna = movable

What is a gomphosis?

A peg-in-socket joint (e.g., tooth in socket) held by periodontal ligament

What are the two types of cartilaginous joints

Synchondroses and symphyses

What is a synchondrosis

Bones joined by hyaline cartilage; immovable (e.g., epiphyseal plate, rib 1 to sternum

What is a symphysis

Bones joined by fibrocartilage; slightly movable (e.g., pubic symphysis, intervertebral discs

What makes a joint synovial

Has a fluid-filled joint cavity and is diarthrotic (freely movable

What is articular cartilage

Hyaline cartilage on the ends of bones to absorb shock and reduce friction

What is the joint capsule

Two-layered capsule: outer fibrous capsule (dense irregular CT) and inner synovial membrane (secretes synovial fluid

What is synovial fluid

Lubricating, nutrient-rich fluid derived from blood plasma; reduces friction and nourishes cartilage

Do synovial joints have nerves and blood vessels

Yes, they are richly innervated and vascularized

What are reinforcing ligaments

Ligaments that stabilize joints; may be part of the capsule (capsular), outside (extracapsular), or inside (intracapsular

What is flexion

Decreases the angle between two bones

What is extension

Increases the angle between two bones

What is abduction?

Moves a limb away from the body's midline

What is adduction

Moves a limb toward the body's midline

What is circumduction

Circular movement combining flexion, extension, abduction, and adduction

What is rotation

Movement around the longitudinal axis of a bone; e.g., shaking head 'no

What is medial rotation

Limb rotates toward the midline

What is lateral rotation

Limb rotates away from the midline

What is elevation? / What is depression?

Lifting a body part superiorly (e.g., shrugging shoulders). / Lowering a body part (e.g., opening mouth

What is protraction? / What is retraction

Moving a body part forward (e.g., jutting jaw). / Moving a body part backward (e.g., pulling jaw in

What is supination? / What is pronation

Palm rotates to face anteriorly (radius and ulna are parallel). / Palm rotates to face posteriorly (radius crosses over ulna

What is opposition? / What is inversion

Thumb moves across palm to touch fingers. / Turning the sole of the foot medially

What is eversion? / What is dorsiflexion

Turning the sole of the foot laterally. / Lifting foot so the top moves toward the shin

What is plantar flexion? / What is a sprain

Pointing the foot downward (e.g., tiptoeing). / Stretched or torn ligament from twist or blow.

What is a dislocation? / What is arthritis

Bones are forced out of normal alignment. / General term for over 100 types of inflammatory joint disorders.

What is osteoarthritis? / What is rheumatoid arthritis

Most common type; wear and tear causes cartilage breakdown. / Autoimmune disorder that attacks joint lining, causing chronic inflammation

What is gouty arthritis? / What is Lyme disease

Uric acid crystal buildup in joints, causing severe pain. / Bacterial infection from tick bite that can cause joint swelling and pain

How are bones connected in fibrous joints? / Do fibrous joints contain nerves and blood vessels

By dense regular connective tissue; no joint cavity. / Yes, but fewer than synovial joints; minimal innervation for stability

Where are sutures found and how do they function? / Where are syndesmoses found and how do they move?

In the skull; immobile and eventually ossify (become synostoses). / In distal tibia-fibula (immobile) and radius-ulna (movable); connected by ligaments or interosseous membrane

What holds a gomphosis joint together? / How are bones connected in cartilaginous joints?

Periodontal ligament; located between tooth and socket. / By cartilage (hyaline or fibrocartilage); no joint cavity.

Do cartilaginous joints have nerves and blood vessels? / Where are synchondroses located and what connects them?

They are less vascularized and innervated compared to synovial joints. / Epiphyseal plates and first rib to sternum; connected by hyaline cartilage.

Where are symphyses located and what connects them? / How are bones connected in synovial joints?

Intervertebral discs and pubic symphysis; connected by fibrocartilage with hyaline at articular surfaces. / They are not directly connected; separated by a synovial cavity and stabilized by capsule and ligaments.

Where are synovial joints found? / Do synovial joints have nerves and blood vessels?

In all freely movable joints, especially limbs (shoulder, elbow, knee, hip). / Yes, richly innervated and vascularized to monitor joint stretch and provide nutrients to the synovial membrane.

What are the structural features of a synovial joint? / How are bones connected in fibrous joints?

Articular cartilage, joint cavity, articular capsule (fibrous + synovial membrane), synovial fluid, nerves, and vessels. / By dense regular connective tissue with no joint cavity.

What type of movement is allowed in fibrous joints? / Do fibrous joints have nerves and blood vessels?

Mostly immovable (synarthroses) or slightly movable (amphiarthroses). / Minimal; low mobility means low innervation and vascular supply.

Where are sutures found and what do they do? / What are syndesmoses and where are they found?

Only in the skull; tightly bind bones and allow for brain growth in childhood. / Bones connected by ligaments; found between radius-ulna and tibia-fibula.

What are gomphoses? / How are bones connected in cartilaginous joints?

Peg-in-socket joints found between teeth and their sockets; stabilized by periodontal ligament. / By cartilage (hyaline or fibrocartilage); no joint cavity.

What is the vascular and nerve supply like in cartilaginous joints? / What are synchondroses and where are they found?

Limited; there is no joint cavity to support rich innervation. / Immovable joints joined by hyaline cartilage (e.g., epiphyseal plate, rib 1 to sternum).

What are symphyses and where are they found? / What function do symphyses serve?

Bones joined by fibrocartilage with hyaline at surfaces; e.g., intervertebral discs, pubic symphysis. / Provide strength with flexibility and act as shock absorbers.

How are bones connected in synovial joints? / Where are synovial joints typically found?

They are not directly joined; bones are enclosed in a capsule and separated by a fluid-filled cavity. / In freely movable limb joints like shoulder, elbow, hip, and knee.

Do synovial joints have nerves and blood vessels? / What are the main features of a synovial joint?

Yes; richly innervated and vascularized. Nerves monitor stretch, vessels nourish tissues. / Articular cartilage, synovial cavity, joint capsule, synovial fluid, reinforcing ligaments, nerves, and blood vessels.

What is the articular capsule composed of? / What does synovial fluid do?

An outer fibrous layer and an inner synovial membrane that secretes fluid. / Reduces friction, nourishes cartilage, and lubricates joint surfaces.