Human Anatomy and Physiology Chapter 8 (Pages 248-274) Joints Human Anatomy and Physiology Chapter 8 (Pages 248-274)

Joints (Articulations) Articulation - site where two or more bones meet Functions of joints: Give skeleton mobility Hold skeleton together

Classification of Joints Structural Based on material binding bones together and whether or not a joint cavity is present Fibrous Cartilaginous Synovial Functional Based on movement allowed Synarthroses - immovable Amphiarthroses - slightly movable Diarthroses - freely movable

Fibrous Joints Bones joined by dense fibrous connective tissue No joint cavity Most are synarthrotic (immovable) Three types: Sutures: Syndesmoses: Gomphoses:

Fibrous Joints: Sutures Dense fibrous connective tissue Suture line Rigid, joints containing short connective tissue Allow for growth during youth Found only in skull Figure 8.1a

Fibrous Joints: Syndesmoses Tibia Ligament Syndesmosis Bones connected by ligaments Movement varies from immovable to slightly movable Figure 8.1b

Fibrous Joints: Gomphoses Root of tooth Socket of alveolar process Periodontal ligament Gomphosis Peg-in-socket joints of teeth in alveolar sockets Fibrous connection is the periodontal ligament Figure 8.1c

Cartilaginous Joints Bones united by cartilage No joint cavity Two types: Synchondroses A bar or plate of hyaline cartilage unites the bones Symphyses Hyaline cartilage covers the articulating surfaces and is fused to an intervening pad of fibrocartilage

Synchondroses Bones united by hyaline cartilage Sternum (manubrium) Epiphyseal plate (temporary hyaline cartilage joint) Joint between first rib and sternum (immovable) Joint between 1st rib and sternum Figure 8.2a

Symphyses Bones united by fibrocartilage Body of vertebra Fibrocartilaginous intervertebral disc Hyaline cartilage Pubic symphysis Figure 8.2b

STRUCTURAL TYPES & THE FUNCTIONAL TYPES KNOW STRUCTURAL TYPES & THE FUNCTIONAL TYPES FROM THESE TABLES Table 8.2 (1 of 4)

Table 8.2 (2 of 4)

Table 8.2 (3 of 4)

Table 8.2 (4 of 4)

Synovial Joints Ligament Joint cavity (contains synovial fluid) Periosteum Ligament Fibrous capsule Synovial membrane Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Articular Figure 8.3

Synovial Joints All are diarthrotic Include all limb joints; most joints of the body Distinguishing features (there are 6): Articular cartilage: hyaline cartilage Joint (synovial) cavity: small potential space Articular (joint) capsule: Outer fibrous capsule of dense irregular connective tissue Inner synovial membrane of loose connective tissue

Synovial Joints Distinguishing features (continued): Synovial fluid: Viscous slippery filtrate of plasma + hyaluronic acid Lubricates and nourishes articular cartilage Three possible types of reinforcing ligaments: Capsular (intrinsic)—part of the fibrous capsule Extracapsular—outside the capsule Intracapsular—deep to capsule; covered by synovial membrane

Synovial Joints Distinguishing features: 6. Rich nerve and blood vessel supply: Nerve fibers detect pain, monitor joint position and stretch Capillary beds produce filtrate for synovial fluid

Movements at Synovial Joints Gliding Angular movements: Flexion, extension, hyperextension Abduction, adduction Circumduction Rotation Medial and lateral rotation Special movements Supination, pronation Dorsiflexion, plantar flexion of the foot Inversion, eversion Protraction, retraction Elevation, depression Opposition

1. Gliding Movements One flat bone surface glides or slips over another similar surface Examples: Intercarpal joints Intertarsal joints Between articular processes of vertebrae

(a) Gliding movements at the wrist Figure 8.5a

2. Angular Movements Increase or decrease angle between 2 bones: Flexion - decreases the angle of the joint Extension - increases the angle of the joint Hyperextension - excessive extension beyond normal range of motion

Angular movements: flexion, extension, and hyperextension of the neck Figure 8.5b

Angular movements: flexion and extension at the shoulder and knee Figure 8.5d

3. Angular Movements Movements that occur along the frontal plane: Abduction - movement away from the midline Adduction - movement toward the midline Circumduction - flexion + abduction + extension + adduction of a limb so as to describe a cone in space

Abduction Circumduction Adduction Angular movements: abduction, adduction, and circumduction of the upper limb at the shoulder Figure 8.5e

4. Rotation The turning of a bone around its own long axis Examples: Between C1 and C2 vertebrae Rotation of humerus and femur

Rotation of the head, neck, and lower limb Lateral rotation Medial rotation Rotation of the head, neck, and lower limb Figure 8.5f

5. Special Movements Movements of radius around ulna: Supination (turning hand backward) Pronation (turning hand forward)

Pronation (P) and supination (S) (radius rotates over ulna) Supination (radius and ulna are parallel) Pronation (P) and supination (S) Figure 8.6a

5. Special Movements Movements of the foot: Dorsiflexion (upward movement) Plantar flexion (downward movement)

Dorsiflexion and plantar flexion Figure 8.6b

5. Special Movements Movements of the foot: Inversion (turn sole medially) Eversion (turn sole laterally)

Inversion and eversion Figure 8.6c

5. Special Movements Movements in a transverse plane: Protraction (anterior movement) Retraction (posterior movement)

Protraction and retraction of mandible Retraction of mandible Protraction and retraction Figure 8.6d

5. Special Movements Elevation (lifting a body part superiorly) Depression (moving a body part inferiorly)

Elevation and depression of mandible Depression of mandible Elevation and depression Figure 8.6e

5. Special Movements Opposition of the thumb Movement in the saddle joint so that the thumb touches the tips of the other fingers

Opposition Opposition Figure 8.6f

Classification of Synovial Joints 6 types, based on shape of articular surfaces: Plane Hinge Pivot Condyloid Saddle Ball and socket **what is an articular surface?**

Plane Joints Flat articular surfaces Short gliding movements Plane joint (intercarpal joint) Figure 8.7a

Hinge Joints Motion along a single plane Flexion and extension only ) Figure 8.7b

Pivot Joints Rounded end of one bone conforms to a “sleeve,” or ring of another bone Pivot joint Figure 8.7c

Condyloid Joints Both articular surfaces are oval Permit all angular movements Condyloid joint Figure 8.7d

Saddle Joints Allow greater freedom of movement than condyloid joints Each articular surface has both concave and convex areas Saddle joint Figure 8.7e

Ball-and-Socket Joints The most freely moving synovial joints Ball-and-socket joint Figure 8.7f

Knee Joint Largest, most complex joint of body Three joints surrounded by a single joint cavity: Femoropatellar joint Lateral and medial tibiofemoral joints between the femoral condyles and the C-shaped lateral and medial menisci (semilunar cartilages) of the tibia

Sagittal section through the right knee joint Tendon of quadriceps femoris Femur Articular capsule Patella Posterior cruciate ligament Synovial cavity Lateral meniscus Lateral meniscus Infrapatellar fat pad Anterior cruciate ligament Tibia Patellar ligament Sagittal section through the right knee joint Figure 8.8a

Animation: Rotatable knee Posterior cruciate ligament Fibular collateral ligament Medial condyle Tibial collateral ligament Lateral condyle of femur Anterior cruciate ligament Lateral meniscus Medial meniscus Tibia Patellar ligament Fibula Patella Quadriceps tendon Anterior view of flexed knee, showing the cruciate ligaments (articular capsule removed, and quadriceps tendon cut) PLAY Animation: Rotatable knee Figure 8.8e

Lateral Medial Patella (outline) Hockey puck Tibial collateral ligament (torn) Medial meniscus (torn) Anterior cruciate ligament (torn) Figure 8.9

Temporomandibular Joint (TMJ) Mandibular condyle articulates with the temporal bone Two types of movement Hinge - depression and elevation of mandible Gliding - side-to-side grinding of teeth Most easily dislocated joint in the body

Location of the joint in the skull Mandibular fossa Zygomatic process Infratemporal fossa External acoustic meatus Lateral ligament Location of the joint in the skull Figure 8.13a

Common Joint Injuries Sprains Cartilage tears The ligaments are stretched or torn Partial tears slowly repair themselves Complete ruptures require prompt surgical repair Cartilage tears Due to compression and shear stress Fragments may cause joint to lock or bind Cartilage rarely repairs itself Repaired with arthroscopic surgery

Common Joint Injuries Dislocations Occur when bones are forced out of alignment Accompanied by sprains, inflammation, and joint immobilization Caused by serious falls or playing sports

Inflammatory Joint Conditions Tendonitis Inflammation of tendon sheaths typically caused by overuse Treated with rest and ice and, if severe, anti-inflammatory drugs

Arthritis >100 different types of inflammatory or degenerative diseases that damage joints Most widespread crippling disease in the U.S. Symptoms; pain, stiffness, and swelling of a joint Acute forms: caused by bacteria, treated with antibiotics Chronic forms: osteoarthritis, rheumatoid arthritis, and gouty arthritis

Osteoarthritis (OA) Irreversible, degenerative (“wear-and-tear”) More cartilage is destroyed than replaced in badly aligned or overworked joints Exposed bone ends thicken, enlarge, form bone spurs, and restrict movement Treatment: moderate activity, mild pain relievers, capsaicin creams, glucosamine and chondroitin sulfate

Rheumatoid Arthritis (RA) Chronic, inflammatory, autoimmune disease of unknown cause Usually arises between age 40 and 50, but may occur at any age Signs and symptoms include joint pain and swelling (usually bilateral), anemia, osteoporosis, muscle weakness, and cardiovascular problems

Rheumatoid Arthritis RA begins with inflammation of the affected joint Inflammatory blood cells migrate to the joint, release inflammatory chemicals Inflamed membrane thickens Membrane erodes cartilage, scar tissue forms, articulating bone ends connect (ankylosis)

Figure 8.15

Rheumatoid Arthritis: Treatment Conservative therapy: aspirin, long-term use of antibiotics, and physical therapy Progressive treatment: anti-inflammatory drugs or immunosuppressants New biological response modifier drugs neutralize inflammatory chemicals

Gouty Arthritis Deposition of uric acid crystals in joints and soft tissues, followed by inflammation Typically affects the joint at the base of the great toe In untreated gouty arthritis, the bone ends fuse and immobilize the joint Treatment: drugs, plenty of water, avoidance of alcohol

Lyme Disease Caused by bacteria transmitted by the bites of ticks Symptoms: skin rash, flu-like symptoms, and foggy thinking May lead to joint pain and arthritis Treatment: antibiotics

Developmental Aspects of Joints By embryonic week 8, synovial joints resemble adult joints A joint’s size, shape, and flexibility are modified by use Advancing years take their toll on joints: Ligaments and tendons shorten and weaken Intervertebral discs become more likely to herniate Most people in their 70s have some degree of OA Exercise that coaxes joints through their full range of motion is key to postponing joint problems