Learning Plan 4--Ch. 8 Joints Pages 248-253, 255-260, 262-269 Michael Aprill Lakeshore Technical College

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

Functional Classification of Joints Based on amount of movement allowed by the joint Three functional classifications: Synarthroses—immovable Amphiarthroses—slightly movable Diarthroses—freely movable

Structural Classification of Joints Based on material binding bones together and whether or not a joint cavity is present Three structural classifications: Fibrous Cartilaginous Synovial

Bones held together by fibrous CT. No joint cavity Fibrous Joints Bones held together by fibrous CT. No joint cavity Most are synarthrotic (immovable) Some are amphiathrotic Three types: Sutures Syndesmoses Gomphoses

Fibrous Joints: Sutures (Fig. 8.1A) Unites bones of skull. Allow for growth during youth In middle age, sutures ossify and are called synostoses Synarthrotic (completely immovable)

Fibrous Joints: Syndesmoses (Fig. 8.1B) Bones connected by ligaments (bands of fibrous tissue) Movement varies from immovable to slightly movable Examples: Synarthrotic distal tibiofibular joint Diarthrotic interosseous connection between radius and ulna

Fibrous Joints: Gomphoses Peg-in-socket joints of teeth in alveolar sockets Fibrous connection is the periodontal ligament

Bones united by cartilage No joint cavity Two types: Cartilaginous Joints Bones united by cartilage No joint cavity Two types: Synchondroses Symphyses

Cartilaginous Joints: Synchondrose (Fig. 8.2A)s A bar or plate of hyaline cartilage unites the bones All are synarthrotic Ex. Epiphyseal plate Ex. Joint between ribs/sternum

Cartilaginous Joints: Symphyses (Fig. 6.2B) No synovial cavity. Connected by disc of fibrocartilage. Ex. Intervertebral discs. Ex. Pubic Symphysis

Include all limb joints; most joints of the body Synovial Joints All are diarthrotic Include all limb joints; most joints of the body Distinguishing features: Articular cartilage: hyaline cartilage->absorbs compression placed on joint, preventing bone form being crushed. Joint (synovial) cavity: small potential space Articular (joint) capsule: Outer fibrous capsule of dense irregular connective tissue

Distinguishing features: Synovial Joints Distinguishing features: Synovial fluid: Lubricates & nourishes articular cartilage Reinforcing ligaments Rich nerve & blood vessel supply

Synovial Joints: Friction-Reducing Structures (Fig. 8.4A) Bursae: Flattened, fibrous sacs lined with synovial membranes Commonly act as “ball bearings” where ligaments, muscles, skin, tendons, or bones rub together

Synovial Joints: Friction-Reducing Structures Tendon sheath: Elongated bursa that wraps completely around a tendon

Synovial Joints: Range of Motion Nonaxial—slipping movements only Uniaxial—movement in one plane Biaxial—movement in two planes Multiaxial—movement in or around all three planes

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

Angular Movements Movements that occur along the sagittal plane: Flexion—decreases the angle of the joint Extension— increases the angle of the joint Hyperextension—excessive extension beyond normal range of motion

Hyperextension Extension Flexion

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

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

Movements of radius around ulna: Special Movements Movements of radius around ulna: Supination (SEE DIAGRAM) Pronation (SEE DIAGRAM)

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

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

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

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

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

Classification of Synovial Joints Six types, based on shape of articular surfaces: Plane Hinge Pivot Condyloid Saddle Ball and socket

Flat articular surfaces Short gliding movements Plane Joints Nonaxial joints Flat articular surfaces Short gliding movements Ex. Intercarpal & Intertarsal Ex. Sternoclavicular Ex. Vertebrocostal

Motion along a single plane Flexion and extension only Hinge Joints Uniaxial joints Motion along a single plane Flexion and extension only Ex. Knee, elbow, ankle, interphalangeal

Uniaxial movement only Pivot Joints Rounded end of one bone conforms to a “sleeve,” or ring of another bone Uniaxial movement only Ex. Radioulnar

Condyloid (Ellipsoidal) Joints Biaxial joints Both articular surfaces are oval Permit all angular movements Ex. Carpals over digits 3-5 & radius

Saddle Joints Biaxial Allow greater freedom of movement than condyloid joints Each articular surface has both concave and convex areas Ex. Metacarpal of thumb with carpal

Ball-and-Socket Joints Multiaxial joints The most freely moving synovial joints Ex. Shoulder & Hip

Knee Joint Largest, most complex joint of body Three joints surrounded by a single joint cavity:

(c) Anterior view of right knee Quadriceps femoris muscle Tendon of quadriceps femoris muscle Patella Medial patellar retinaculum Lateral patellar retinaculum Tibial collateral ligament Fibular collateral ligament Patellar ligament Fibula Tibia (c) Anterior view of right knee Figure 8.8c

(d) Posterior view of the joint capsule, including ligaments Femur Tendon of adductor magnus Articular capsule Oblique popliteal ligament Medial head of gastrocnemius muscle Lateral head of gastrocnemius muscle Popliteus muscle (cut) Bursa Fibular collateral ligament Tibial collateral ligament Arcuate popliteal ligament Tendon of semimembranosus muscle Tibia (d) Posterior view of the joint capsule, including ligaments Figure 8.8d

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 (e) Anterior view of flexed knee, showing the cruciate ligaments (articular capsule removed, and quadriceps tendon cut and reflected distally) Figure 8.8e

Shoulder (Glenohumeral) Joint Ball-and-socket joint: head of humerus and glenoid fossa of the scapula Stability is sacrificed for greater freedom of movement

(c) Anterior view of right shoulder joint capsule Acromion Coracoid process Coracoacromial ligament Articular capsule reinforced by glenohumeral ligaments Subacromial bursa Coracohumeral ligament Subscapular bursa Greater tubercle of humerus Tendon of the subscapularis muscle Transverse humeral ligament Scapula Tendon sheath Tendon of long head of biceps brachii muscle (c) Anterior view of right shoulder joint capsule Figure 8.10c

Elbow Joint Radius and ulna articulate with the humerus Hinge joint formed mainly by trochlear notch of ulna and trochlea of humerus Flexion and extension only

Anular ligament—surrounds head of radius Elbow Joint Anular ligament—surrounds head of radius Two capsular ligaments restrict side-to-side movement: Ulnar collateral ligament Radial collateral ligament

(b) Lateral view of right elbow joint Humerus Anular ligament Radius Lateral epicondyle Articular capsule Radial collateral ligament Olecranon process Ulna (b) Lateral view of right elbow joint Figure 8.11b

(d) Medial view of right elbow Articular capsule Anular ligament Humerus Coronoid process Medial epicondyle Ulnar collateral ligament Radius Ulna (d) Medial view of right elbow Figure 8.11d

Hip (Coxal) Joint Ball-and-socket joint Head of the femur articulates with the acetabulum Good range of motion, but limited by the deep socket

Temporomandibular Joint (TMJ) Two types of movement Hinge—depression and elevation of mandible Gliding—e.g. side-to-side (lateral excursion) grinding of teeth Most easily dislocated joint in the body

(a) Location of the joint in the skull Mandibular fossa Articular tubercle Zygomatic process Infratemporal fossa External acoustic meatus Lateral ligament Articular capsule Ramus of mandible (a) Location of the joint in the skull Figure 8.13a