Part 5 Joints

Selected Synovial Joints Shoulder (Glenohumeral) joint The most freely movable joint lacks stability Articular capsule is thin and loose Muscle tendons contribute to joint stability Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Glenohumeral Joint Figure 9.8a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Rotator cuff injuries are common shoulder injuries Glenohumeral Joint The rotator cuff is made up of four muscles and their associated tendons Subscapularis Supraspinatus Infraspinatus Teres minor Rotator cuff injuries are common shoulder injuries Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The shoulder joint Figure 9.8b, c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Shoulder Joint Figure 9.8d, e Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Selected Synovial Joints Elbow joint Allows flexion and extension The humerus’ articulation with the trochlear notch of the ulna forms the hinge Tendons of biceps and triceps brachii provide stability Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Elbow Joint Figure 9.9a, b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Elbow Joint Figure 9.9c, d Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Stabilized by numerous ligaments Wrist Joint Stabilized by numerous ligaments Composed of radiocarpal and intercarpal joint Radiocarpal joint – joint between the radius and proximal carpals (the scaphoid and lunate) Allows for flexion, extension, adduction, abduction, and circumduction Intercarpal joint – joint between the proximal and distal rows or carpals Allows for gliding movement Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Wrist Joint Figure 9.10a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Wrist Joint Figure 9.10b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Wrist Joint Figure 9.10c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Selected Synovial Joints Hip joint A ball-and-socket structure Movements occur in all axes Limited by ligaments and acetabulum Head of femur articulates with acetabulum Stability comes chiefly from acetabulum and capsular ligaments Muscle tendons contribute somewhat to stability PLAY Movement at the hip joint: An overview Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Frontal Section and Anterior View of the Hip Joint Figure 9.11a, b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Posterior View of the Hip Joint Figure 9.11c, d Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Selected Synovial Joints Knee joint The largest and most complex joint Primarily acts as a hinge joint Has some capacity for rotation when leg is flexed Structurally considered compound and bicondyloid Two fibrocartilage menisci occur within the joint cavity Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sagittal Section and Superior View of Knee Joint Figure 9.12a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sagittal Section and Superior View of Knee Joint Figure 9.12b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Knee Joint Capsule of knee joint Covers posterior and lateral aspects of the knee Covers tibial and femoral condyles Does not cover the anterior aspect of the knee Anteriorly covered by three ligaments Patellar, medial, and lateral retinacula Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anterior View of Knee Figure 9.12c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Ligaments of the knee joint Become taut when knee is extended These extracapsular ligaments are Fibular and tibial collateral ligament Oblique popliteal ligament Arcuate popliteal ligament Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Posterior View of Knee Joint Figure 9.12d Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intracapsular ligaments Knee Joint Intracapsular ligaments Cruciate ligaments Cross each other like an “X” Each cruciate ligament runs from the proximal tibia to the distal femur Anterior cruciate ligament Posterior cruciate ligament Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anterior View of Flexed Knee Figure 9.12e, f Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Knee Joint Cruciate ligaments Prevent undesirable movements at the knee joint Figure 9.13a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Selected Synovial Joint Ankle Joint A hinge joint between United inferior ends of tibia and fibula The talus of the foot Allows the movements Dorsiflexion and plantar flexion only Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Ankle Joint Medially and laterally stabilized by ligaments Medial (deltoid) ligament Lateral ligament Inferior ends of tibia and fibula are joined by ligaments Anterior and posterior tibiofibular ligaments Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Ankle Joint Figure 9.15a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Ligaments of the Ankle Joint Figure 9.15b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Ligaments of the Ankle Joint Figure 9.15c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Ligaments of the Ankle Joint Figure 9.15d Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Selected Synovial Joints Temporomandibular joint (TMJ) Lies anterior to the ear Head of the mandible articulates with the mandibular fossa Two surfaces of the articular disc allow two kinds of movement Hinge-like movement Superior surface of disc glides anteriorly Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Temporomandibular Joint Figure 9.16a, b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Selected Synovial Joints Sternoclavicular Joint Is a saddle joint Muscles and ligaments contribute to joint stability Unique joint shape allows for multiple complex movements Another example of a saddle joint Joint between trapezium and metacarpal 1 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sternoclavicular Joint Figure 9.17a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sternoclavicular Joint Figure 9.17b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Structure of joints makes them prone to traumatic stress Disorders of Joints Structure of joints makes them prone to traumatic stress Function of joints makes them subject to friction and wear Affected by inflammatory and degenerative processes Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sprains – ligaments of a reinforcing joint are stretched or torn Joint Injuries Sprains – ligaments of a reinforcing joint are stretched or torn Dislocation – occurs when the bones of a joint are forced out of alignment Torn cartilage – common injury to meniscus of knee joint Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Inflammatory and Degenerative Conditions Bursitis – inflammation of a bursa do to injury or friction Tendonitis – inflammation of a tendon sheath Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Inflammatory and Degenerative Conditions Arthritis – describes over 100 kinds of joint-damaging diseases Osteoarthritis – most common type “wear and tear” arthritis Rheumatoid arthritis – a chronic inflammatory disorder Gouty arthritis (gout) – uric acid build-up causes pain in joints Lyme disease – inflammatory disease often resulting in joint pain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Joints Throughout Life Synovial joints develop from mesenchyme By week 8 of fetal development, joints resemble adult joints Outer region of mesenchyme becomes fibrous joint capsule Inner region becomes the joint cavity Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Joints Throughout Life During youth – injury may tear an epiphysis off a bone shaft Advancing age – osteoarthritis becomes more common Exercise – helps maintain joint health Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings