131, T6, Ch9 Joints _14

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Joints Chapter 9 IB 131

Instructor: Tom Carlson Department of Integrative Biology University of California Berkeley

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Joints

•  Rigid elements of the skeleton meet at joints or articulations

•  Greek root “arthro” means joint •  Structure of joints

– Enables resistance to crushing, tearing, and other forces

2

Functional Classification of Joints based on amount of movement

•  Synarthroses—immovable; common in axial skeleton

•  Amphiarthroses—slightly movable; common in axial skeleton

•  Diarthroses—freely movable; common in appendicular skeleton; all synovial joints are diarthoses

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Structural Classification of Joints

• Based on material that binds bones together

• Presence or absence of a joint cavity

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Structural Classifiction of Joints

• Fibrous • Cartilaginous • Synovial

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Classifications of Joints

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Fibrous Joints • Bones are connected by fibrous

dense regular connective tissue rich in collagen fibers

• Do not have a joint cavity • Most are immovable

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Types of Fibrous Joints • Sutures (short fibers) • Syndesmoses (longer fibers) • Gomphoses (periodontal

ligaments)

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Fibrous Joints: Sutures •  Bones are tightly bound by a minimal

amount of fibrous tissue with short fibers

•  Occur between the bones of the skull •  Allow bone growth so the skull can

expand with brain growth during childhood

•  Fibrous tissue ossifies in middle age to produce synostoses (= closed sutures)

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Fibrous Joints

Figure 9.1

Dense fibrous connective tissue

Suture line

Root of tooth

Socket of alveolar process

Periodontal ligament

Fibula Tibia

Ligament

(a) Suture Joint held together with very short, interconnecting fibers,

and bone edges interlock. Found only in the skull.

(b) Syndesmosis Joint held together by a

ligament. Fibrous tissue can vary in length but is longer

than in sutures.

(c) Gomphosis Peg-in-socket fibrous joint. Periodontal ligament holds

tooth in socket.

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Fibrous Joints: Syndesmoses •  Bones are connected exclusively by

ligaments, fibrous tissue with relatively long fibers

•  Amount of movement depends on length of fibers – Distal tibiofibular joint articulation—

synarthrosis with minimal or no movement – Interosseous membrane between radius

and ulna has quite long fibers which enables some movement between these bones

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Example of a Syndesmoses: Interosseous Membrane between

ulna and radius bones

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Fibrous Joints

Figure 9.1

Dense fibrous connective tissue

Suture line

Root of tooth

Socket of alveolar process


Fibula Tibia

Ligament

(a) Suture Joint held together with very short, interconnecting fibers,

and bone edges interlock. Found only in the skull.

(b) Syndesmosis Joint held together by a

ligament. Fibrous tissue can vary in length but is longer

than in sutures.

(c) Gomphosis Peg-in-socket fibrous joint. Periodontal ligament holds

tooth in socket.

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Fibrous Joints: Gomphoses

•  Tooth in a socket •  Connecting ligament—the periodontal

ligament •  Immobile

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Crown

Neck

Root

Enamel Dentin Dentinal tubules Pulp cavity (contains blood vessels and nerves)

Gingiva (gum)

Cementum

Root canal


Apical foramen

Bone

Tooth Structure •  Longitudinal

section of tooth in bone alveolus

•  Enamel •  Dentin •  Pulp cavity •  Root canal •  Cementum •  Apical foramen •  Periodontal

ligament

Figure 23.14 15

Cartilaginous Joints • Two types

– Synchondroses – Symphyses

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Cartilaginous Joints

•  Bones are united by cartilage •  Lack a joint cavity •  Immobile to slightly mobile •  Two types

– Synchondroses: hyaline cartilage, immobile

– Symphyses: fibrocartilage, slightly mobile

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Figure 9.2a

Cartilaginous Joints: Synchondroses

•  Hyaline cartilage unites bones – Epiphyseal plates – Joint between first rib and manubrium

Epiphyseal plate (temporary hyaline cartilage joint)

Sternum (manubrium)

Joint between first rib and sternum (immovable)

(a) Synchondroses

Bones united by hyaline cartilage

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Cartilaginous Joints: Symphyses •  Fibrocartilage unites bones •  Fibrocartilage resists tension & compression

stresses and can act as a shock absorber •  Slightly movable joints that provide strength

with flexibility – intervertebral discs – pubic symphysis

•  Hyaline cartilage is also present as articular cartilage on the bony surfaces to reduce friction between bones during movement

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Cartilaginous Joints: Symphyses Bones United by Fibrocartilage

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Axial bone locations of different structural joint types

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Upper extremity locations of different structural joint types

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Lower extremity locations of different structural joint types

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Synovial joints

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Synovial Joints •  Most movable type of joint •  All are diarthroses (movable joints)

and contain a fluid-filled joint cavity •  Adjoining bones are covered with

articular cartilage and are separated by a joint cavity

•  Joint cavity is enclosed within an articular capsule with the inner layer lined with synovial membrane

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Periosteum

Ligament

Fibrous capsule Synovial membrane

Joint cavity (contains synovial fluid) Articular (hyaline) cartilage

Articular capsule

(a) A typical synovial joint

General Structure of Synovial Joints

Figure 9.3a 26


•  Articular cartilage – Ends of opposing bones are covered with

hyaline cartilage – Absorbs compression

•  Joint cavity (synovial cavity) – Unique to synovial joints – Cavity is a space that contains synovial fluid

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Periosteum

Ligament



Articular capsule



Figure 9.3a 28

Ligaments

•  Ligaments extend over the outer surface of the articular capsule and contribute to joint stability

•  Ligaments are anchored in periosteum of adjacent bones

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Articular Capsule of Synovial Joints is enclosed in a two-layered capsule

•  Fibrous capsule—dense irregular connective tissue is continuous with periosteal layer of adjoining bones; strengthens joint

•  Synovial membrane—loose connective tissue

• Lines inner layer of joint capsule and covers internal joint surfaces not covered by cartilage

• Functions to make synovial fluid 30

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Synovial membrane •  Rich blood supply to synovial membrane

forms extensive capillary beds that provide blood filtrate which forms synovial fluid

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Synovial Fluid •  Produced by synovial membrane •  Present in joint cavity •  Is a viscous fluid with consistency similar

to raw egg white •  Contains glycoprotein molecules

secreted by fibroblasts

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How Synovial Joints Function •  Synovial joints—lubricating devices •  Friction could overheat and destroy joint

tissue •  As synovial joints are subjected to

compressive forces • Fluid is squeezed out as opposing

cartilages touch • Cartilages ride on the slippery film

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Periosteum

Ligament



Articular capsule



Figure 9.3a 34

Sensory Fibers Richly Innervate Synovial Joints

•  Detect pain •  Most monitor how much the capsule is

being stretched

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Three Basic Movements of Synovial Joints

•  Gliding—one bone across the surface of another

•  Angular movement—movements change the angle between bones

•  Rotation—movement around a bone's long axis

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Synovial Joint Types •  Plane is nonaxial: intercarpal & intertarsal •  Hinge is uniaxial: elbow, ankle & interphalangeal •  Pivot is uniaxial: proximal radio-ulnar and

between atlas (C1) and dens of axis (C2) which allows the skull to rotate on the neck’s axis

•  Chondyloid is biaxial: metatarsophalangeal, metacarpophalangeal & wrist

•  Saddle is > biaxial: sternoclavicular & 1st carpometacarpal

•  Ball & Socket is multiaxial: shoulder & hip 37

Plane joints

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Synovial Joints Classified by Shape: Plane joint

•  Articular surfaces are flat planes •  Short gliding movements are allowed

• Intertarsal and intercarpal joints • Movements are nonaxial • Gliding does not involve rotation

around any axis

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Plane Joint

Figure 9.8a

(a) Plane joint

Gliding

Metacarpals

Carpals

Nonaxial movement

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Hinge joints

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Synovial Joints Classified by Shape: Hinge Joints

•  Cylindrical end of one bone fits into a trough on another bone

•  Angular movement is allowed in one plane •  Elbow, ankle, and interphalangeal joints •  Movement is uniaxial—allows movement

around one axis only

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Hinge Joint

Figure 9.8b

(b) Hinge joint

Medial/ lateral axis

Flexion and extension

Humerus

Ulna

Uniaxial movement

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Trochlea of distal humerus articulates with trochlear notch of olecronon process of proximal ulna

Figure 8.3c, d

Coronoid fossa

Radius

Radial tuberosity

Head of radius

Capitulum

Trochlea

(c) Anterior view at the elbow region

Humerus

Medial epicondyle

Coronoid process of ulna

Ulna Radial notch

Olecranon fossa

Ulna

Olecranon process

Medial epicondyle

(d) Posterior view of extended elbow

Humerus

Lateral epicondyle

Head

Radius

Neck

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Elbow joint •  The trochlea of the distal humerus articulates

with the trochlear notch of the proximal ulna to form a hinge

•  Allows flexion and extension •  Tendons of biceps brachii, triceps brachii,

and brachialis provide stability •  Anular ligament helps stabilize proximal

radius and ulna bones

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Tendon of biceps brachii contributes to stability of elbow joint

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Tendon of triceps brachii contributes to stability of elbow joint

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Brachialis muscle attached to humerus and ulna helps

stabilize the elbow Anterior view

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Trochlea of distal humerus articulates with trochlear notch of olecronon process of proximal ulna

Figure 8.4a, b

Radial notch of the ulna

Olecranon process

Trochlear notch

Coronoid process Proximal radioulnar joint

Distal radioulnar joint

Ulnar notch of the radius Head of ulna

Styloid process of ulna

Interosseous membrane Ulna

Head Neck Radial tuberosity

Radius

Styloid process of radius

(a) Anterior view

Olecranon process

Styloid process of radius

Radius

Neck of radius

Head of radius

Ulnar notch of the radius

Head of ulna

Styloid process of ulna

Interosseous membrane Ulna

(b) Posterior view

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Elbow Joint

Figure 9.12a, b

Articular capsule

Synovial membrane

Synovial cavity

Articular cartilage

Coronoid process

Tendon of brachialis muscle

Ulna

Humerus

Fat pad

Tendon of triceps muscle Bursa

Trochlea

Articular cartilage of the trochlear notch (a) Mid-sagittal section through right elbow (lateral view)

Humerus

Lateral epicondyle

Articular capsule Radial collateral ligament

Olecranon process

(b) Lateral view of right elbow joint

Anular ligament

Radius

Ulna

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Elbow Joint is stabilized by different types of ligaments

Figure 9.12c, d

Articular capsule Anular ligament

Coronoid process

(d) Medial view of right elbow

Radius

Humerus

Medial epicondyle Ulnar collateral ligament

Ulna

Anular ligament

Humerus

Medial epicondyle

Ulnar collateral ligament

Ulna

Articular capsule

Radius


(c) Cadaver photo of medial view of right elbow

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Ankle joint

•  A hinge joint between the united distal ends of tibia and fibula and the talus bone of the foot

•  This hinge joint allows dorsiflexion and plantar flexion only

•  Intertarsal joints are plane joints

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Medial cuneiform

Phalanges

Metatarsals

Tarsals

Navicular

Intermediate cuneiform

Talus

Calcaneus

(a) Superior view

Cuboid

Lateral cuneiform

Proximal Middle Distal

Trochlea of talus

5 4 3 2 1

Superior view of trochlea of talus

Figure 8.12a 53

Medial view of talus

Figure 8.12b

Facet for medial malleolus

Calcaneal tuberosity (b) Medial view

Intermediate cuneiform

Sustentaculum tali (talar shelf) Talus

Navicular

First metatarsal

Medial cuneiform

Calcaneus

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Ligaments of the Ankle Joint stabilize the joint

Figure 9.18b

Medial malleolus

Calcaneus

Sustentaculum tali

Medial (deltoid) ligament

Talus

Navicular

Tibia

1st metatarsal

(b) Right ankle, medial view

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Ligaments of the Ankle Joint •  Medial (deltoid) ligament attached to tibia •  Lateral ligaments: talofibular ligaments &

calcaneofibular ligaments •  Distal ends of tibia and fibula are joined by

anterior and posterior tibiofibular ligaments

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Ligaments of the Ankle Joint & foot

Figure 9.18c

Anterior tibiofibular ligament

Anterior talofibular ligament

Calcaneus

Metatarsals

Lateral malleolus

Posterior tibiofibular ligament

Posterior talofibular ligament Calcaneofibular ligament

Tibia

Talus

Cuboid

Fibula

(c) Right ankle, lateral view

Lateral ligament

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Ligaments of the Ankle Joint

Figure 9.18d

Talus

Posterior talofibular ligament

Posterior tibiofibular ligament

Interosseous membrane

Calcaneofibular ligament

Fibula Tibia

Medial (deltoid) ligament

Calcaneus

(d) Right ankle, posterior view 58

Pivot joints

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Synovial Joints by Shape Pivot Joints

•  Classified as uniaxial – rotating bone only turns around its long axis

•  Examples • Proximal radioulnar joint where

the head of the radius rotates within a ring-like anular ligament secured by the ulna bone

• Joint between atlas (C1) and dens of axis (C2) which allows the skull to rotate on the neck’s axis

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Pivot Joint Proximal radioulnar joint

Figure 9.8c

(c) Pivot joint

Ulna

Vertical axis

Rotation Radius

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Anular filament around proximal radioulnar joint

Figure 9.12c, d

Articular capsule Anular ligament

Coronoid process

(d) Medial view of right elbow

Radius

Humerus

Medial epicondyle Ulnar collateral ligament

Ulna

Anular ligament

Humerus

Medial epicondyle


Ulna

Articular capsule

Radius


(c) Cadaver photo of medial view of right elbow

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Dens of axis Transverse ligament of atlas C1 (atlas) C2 (axis) C3

Bifid spinous process

Transverse processes

C7 (vertebra prominens)

(a) Cervical vertebrae

Inferior articular process

Dens of axis allows rotation of head

Figure 7.22a 63

Pivot Joint Joint between atlas and axis

•  Dens (odontoid process “tooth”) is a knoblike structure which projects superiorly from the body of C2 (axis) and is cradled in the anterior arch of C1 atlas

•  Dens acts as a pivot for rotation of the atlas and skull

•  Dens participates in rotating the head from side to side

•  The name axis for C2 is appropriate since its dens allows the skull to rotate on the neck’s axis

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Maxilla (palatine process)

Hard palate

Zygomatic bone

Incisive fossa

Median palatine suture Intermaxillary suture

Infraorbital foramen Maxilla Sphenoid bone (greater wing)

Foramen ovale Pterygoid process

Foramen lacerum Carotid canal External acoustic meatus Stylomastoid foramen Jugular foramen

Foramen magnum

Occipital condyle Inferior nuchal line Superior nuchal line

Temporal bone (zygomatic process)

Mandibular fossa

Vomer

Styloid process

External occipital crest External occipital protuberance (a) Inferior view of the skull (mandible removed)

Mastoid process Temporal bone (petrous part) Basilar part of the occipital bone Occipital bone

Palatine bone (horizontal plate)

Foramen spinosum

Inferior Aspect of the Skull

Figure 7.7a 65

Condyloid joints

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Synovial Joints by Shape Condyloid Joints

•  Classified as biaxial—movement occurs along two axes

•  Examples: – Metacarpophalangeal joints – Metatarsophalangeal joints – Wrist joint •  Allow moving bone to travel

• Side to side—abduction-adduction • Back and forth—flexion-extension

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Condyloid Joint

Figure 9.8d

(d) Condyloid joint


Adduction and abduction


Metacarpals

Phalanges

Anterior/ posterior axis

Biaxial movement

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Wrist Joint •  Stabilized by numerous ligaments •  Composed of radiocarpal and intercarpal

joints – Radiocarpal joint—condyloid joint between the

radius and proximal carpals (the scaphoid and lunate) • Allows for flexion, extension, adduction,

abduction, and circumduction –  Intercarpal joints— plane joint between the

proximal and distal rows or carpals • Allows for gliding movement

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Wrist Joint

Figure 9.13a

Radius Ulna

Lunate

Triquetrum

Pisiform

Hamate Capitate

Scaphoid

Trapezoid

Trapezium

Thumb

Radiocarpal joint

(a) Right wrist, anterior (palmar) view

Wrist bones

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Wrist Joint

Figure 9.13b

Distal radioulnar joint


Articular disc Radial

collateral ligament

Radiocarpal joint

Intercarpal joint

(b) Wrist joints, coronal section

Radiocarpal joint is condyloid Intercarpal joints are planar

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Ligaments of Wrist Joints

Figure 9.13c

Hamate

Carpo- metacarpal ligaments

Pisiform

Lunate

Radius Ulna


Radial collateral ligament

Palmar radiocarpal ligament

Intercarpal ligaments

Trapezium

Capitate

Scaphoid

(c) Ligaments of the wrist, anterior (palmar) view 72

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Wrist Joint stabilized by numerous ligaments

•  Radiocarpal ligaments •  Intercarpal ligaments •  Carpometacarpal ligaments •  Collateral ligaments

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Saddle joints

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Synovial Joints by Shape Saddle Joints

•  Each articular surface has concave and convex surfaces

•  Essentially the same as condyloid joints •  Often classified as biaxial joints, however have

the ability to move in more than two axes •  1st carpometacarpal joint is a good example

as it allows opposition of the thumb in addition to flexion and extension

•  Sternoclavicular joint is another example 75

Saddle joint 1st carpometacarpal joint

Figure 9.8e

(e) Saddle joint

Anterior/ posterior axis


Adduction and abduction

Metacarpal 1

Trapezium Flexion and extension

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Saddle joint Sternoclavicular joint

•  Is a saddle joint •  Performs multiple complex movements •  Four ligaments surround the joint

• Anterior and posterior sternoclavicular ligaments

• Interclavicular ligament • Costoclavicular ligament

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Sternoclavicular Joint with articular disc (meniscus)

Figure 9.9

Anterior sternoclavicular ligament and joint capsule

Interclavicular ligament

Articular disc

Manubrium of sternum

Costal cartilage of 1st rib

Costoclavicular ligament

Clavicle

(a) Sternoclavicular joint, anterior view

Depression Protraction

Elevation Retraction Posterior rotation

(b) Sternoclavicular movements

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Ball-in socket joints

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Synovial Joints by Shape Ball-and-socket joints

•  Spherical head of one bone fits into round socket of another

•  Classified as multiaxial—allow movement in many axes

•  Flexion and extension •  Abduction and adduction •  Rotation •  Shoulder and hip joints are examples

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Ball-and-Socket Joint

Figure 9.8f

PLAY Movement of the glenohumeral joint (a)

(f) Ball-and-socket joint

Medial/lateral axis

Anterior/posterior axis Vertical

axis

Rotation Adduction and abduction


Scapula

Humerus

Multiaxial movement

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Hip Joint •  A ball-and-socket structure •  Movements occur in all axes •  Movements 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 82

Frontal Section and Anterior View of the Hip Joint

Figure 9.14a, b

Articular cartilage Coxal (hip) bone Ligament of the head of the femur (ligamentum teres)

Synovial cavity Articular capsule

Acetabular labrum

Femur

(a) Frontal section through the right hip joint

Acetabular labrum

Synovial membrane

Ligament of the head of the femur (ligamentum teres)

Head of femur

Articular capsule (cut)

(b) Photo of the interior of the hip joint, lateral view

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Anterior inferior iliac spine

Iliofemoral ligament

Pubofemoral ligament

Greater trochanter

(d) Anterior view of right hip joint, capsule in place

Hip joint is stabilized by iliofemoral, isheofemoral, and pubofemoral ligaments

Figure 9.14c, d

Ischium

Iliofemoral ligament

Ischiofemoral ligament

Greater trochanter of femur

(c) Posterior view of right hip joint, capsule in place

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Shoulder (glenohumeral) joint •  The most freely movable joint is less stable

than other joints •  Articular capsule is thin and loose •  Synovial cavity of glenoid cavity •  Glenoid labrum: rim of fibrocartilage

around glenoid cavity

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The Shoulder Joint

Figure 9.11d, e

Acromion

Coracoid process Articular capsule Glenoid cavity Glenoid labrum

Tendon of long head of biceps brachii muscle Glenohumeral ligaments Tendon of the subscapularis muscle Scapula

Posterior Anterior (d) Lateral view of socket of right shoulder joint, humerus removed

(e) Posterior view of an opened left shoulder joint

Head of humerus

Muscle of rotator cuff (cut)

Acromion (cut)

Glenoid cavity of scapula Capsule of shoulder joint (opened)

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Bursae and Tendon Sheaths •  Bursae and tendon sheaths are not

within synovial joints, but rather are closed bags of lubricant which reduce friction between body structures e.g., between a bone and a ligament

•  Bursa—a flattened fibrous sac lined with a synovial membrane and containing synovial fluid

•  Tendon sheath—an elongated bursa that wraps around a tendon

87

Subacromial and subscapular bursa and tendon sheath

Figure 9.5a, b

Acromion of scapula

Joint cavity containing synovial fluid

Synovial membrane Fibrous capsule

Humerus

Hyaline cartilage

Coracoacromial ligament Subacromial bursa Fibrous articular capsule

Tendon sheath

Tendon of long head of biceps brachii muscle (a) Frontal section through the right shoulder joint

Coracoacromial ligament Subacromial bursa

Cavity in bursa containing synovial fluid

(b) Enlargement of (a), showing how a bursa eliminates friction where a ligament (or other structure) would rub against a bone

Humerus resting

Humerus moving

Bursa rolls and lessens friction.

Humerus head rolls medially as arm abducts.

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Multiple ligaments and muscle tendons contribute to stability

Figure 9.11c

Acromion Coracoacromial ligament Subacromial bursa Coracohumeral ligament Greater tubercle of humerus Transverse humeral ligament Tendon sheath Tendon of long head of biceps brachii muscle

Articular capsule reinforced by glenohumeral ligaments

Subscapular bursa Tendon of the subscapularis muscle Scapula

Coracoid process

(c) Anterior view of right shoulder joint capsule 89

Rotator Cuff muscles •  Group of muscles and their tendons which

act to stabilize the shoulder (glenohumeral) joint

•  Muscles rise from the scapula and connect to the tuberosities of the head of the humerus, forming a cuff at the shoulder joint which helps hold the humerus head into the glenoid fossa of the scapula

90

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Glenohumeral (Shoulder) Joint •  The rotator cuff is made up of four

muscles and their associated tendons – Subscapularis – Supraspinatus – Infraspinatus – Teres minor

•  All four of these tendons contribute to the stability of the joint

•  Rotator cuff injuries are common shoulder injuries

91

Rotator cuff muscles: - Supraspinatus muscle - Infraspinatus muscle - Teres minor muscle - Subscapularis muscle(

92

Subscapularis muscle attached to humerus Anterior view

93

Knee joint

94

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 (both femur and tibia have two chondylar surfaces)

•  Chondyles of the femur roll along the almost flat chondyles of the tibia

95

Neck Fovea capitis Greater

trochanter

Inter- trochanteric crest

Lateral condyle Lateral epicondyle

Head

Intertrochanteric line

Lesser trochanter

Gluteal tuberosity

Linea aspera

Intercondylar fossa

Medial and lateral supra- condylar lines

Medial condyle

Medial epicondyle

Adductor tubercle

Anterior view Posterior view (b) Femur (thigh bone)

Lateral epicondyle

Patellar surface

Structures of the Femur

Figure 8.10b 96

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Structures of the Tibia and Fibula

Figure 8.11a, b 97

Knee Joint •  Many supporting ligaments •  At least 12 bursae including suprapatellar

bursa, prepatellar bursa, and deep infrapatellar bursa

•  Two fibrocartilage menisci (articular discs) occur within the joint cavity---the medial & lateral menisci

•  Femoropatellar joint—shares the joint cavity • Allows patella to glide across the distal

femur 98

Sagittal Section of Knee Joint

Figure 9.15a (a) Sagittal section through the right knee joint

Femur

Tendon of quadriceps femoris

Suprapatellar bursa

Patella Subcutaneous prepatellar bursa

Synovial cavity Lateral meniscus

Posterior cruciate ligament

Infrapatellar fat pad Deep infrapatellar bursa Patellar ligament

Articular capsule

Lateral meniscus Anterior cruciate ligament

Tibia

99

Synovial Joints with Articular Disc (= meniscus)

•  Some synovial joints contain an articular disc (meniscus) made of fibrocartilage

•  Articular disc is present in knee joint, temporomandibular joint, and sternoclavicular joint

100

Medial and Lateral Meniscus in Superior View of Knee Joint

Figure 9.15b

(b) Superior view of the right tibia in the knee joint, showing the menisci and cruciate ligaments

Medial meniscus

Articular cartilage on medial tibial condyle

Anterior

Anterior cruciate ligament

Articular cartilage on lateral tibial condyle

Lateral meniscus


101

Articular Disc (= meniscus) •  Consists of fibrocartilage •  Cushion compressive forces and help

articulate bone ends of different shapes •  Permits a more even distribution of forces

between the articulating surfaces of bones •  Aids in directing the flow of synovial fluid to

areas of the articular cartilage that experience the most friction

•  Increases the stability of the joint 102

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Medial and Lateral Meniscus in Anterior View of Flexed Knee

103

Important Factors Influencing Stability of Synovial Joints

including the knee joint •  Ligaments •  Retinacula •  Muscle tone •  Muscle tendons

104

Factors Influencing Stability of Synovial Joints:

Ligaments

•  Capsules and ligaments prevent excessive motions

•  On the medial or inferior side of a joint: prevent excessive abduction

•  On the lateral or superior side—resist adduction

105

Anterior View of Knee

Figure 9.15c

Quadriceps femoris muscle Tendon of quadriceps femoris muscle

Patella Lateral patellar retinaculum

Medial patellar retinaculum

Tibial collateral ligament

Tibia

Fibular collateral ligament

Fibula

(c) Anterior view of right knee

Patellar ligament

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Retinacula •  Any of several fibrous bands of fascia that

pass over or under tendons to help keep the tendons in place

•  Groups of tendons from separate muscles may pass under a retinaculum (band of connective tissue)

•  Lateral & medial retinacula around the knee are anterior and attach to tibia

107


Muscle Tone & Muscle Tendons •  Muscle tone helps stabilize joints by

keeping tension on tendons •  Is important in reinforcing knee joint as

well also shoulder joint and joints in foot arches

108

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Knee Joint ligaments

•  Extracapsular ligaments: located outside the capsule

•  Capsular ligaments: attached to the capsule

•  Intracapsular ligaments: located internal to the capsule

109

Knee Joint ligaments relationship to joint capsules

EXTRACAPSULAR LIGAMENTS: •  Patellar ligament is anterior and attaches to tibia •  Fibular (lateral) collateral ligament •  Tibular (medial) collateral ligament CAPSULAR LIGAMENTS: •  Oblique popliteal ligament crosses posterior aspect of

capsule •  Arcuate popliteal ligament from posterior capsule to fibula INTRACAPSULAR LIGAMENTS: •  Anterior cruciate ligament internal to capsule •  Posterior cruciate ligament internal to capsule

110

Anterior View of Knee

Figure 9.15c

Quadriceps femoris muscle Tendon of quadriceps femoris muscle

Patella Lateral patellar retinaculum

Medial patellar retinaculum


Tibia


Fibula

(c) Anterior view of right knee

Patellar ligament

111

Anterior view of flexed knee

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Posterior View of Knee Joint

Figure 9.15d

Articular capsule

Oblique popliteal ligament

Lateral head of gastrocnemius muscle


Arcuate popliteal ligament

Tibia

Femur

Medial head of gastrocnemius muscle

Tendon of semimembranosus muscle

(d) Posterior view of the joint capsule, including ligaments

Popliteus muscle (cut)

Tendon of adductor magnus

Bursa


113

Knee Joint ligaments that become taut with knee extension

•  Fibular collateral ligaments on lateral side •  Tibular collateral ligament on medial side •  Oblique popliteal ligament crosses posterior

aspect of capsule •  Arcuate popliteal ligament from posterior capsule

to fibula •  Anterior cruciate ligament internal to capsule •  Posterior cruciate ligament internal to capsule

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Intracapsular knee joints

•  Anterior cruciate ligament: attaches to anterior part of tibia and passes posteriorly to attach to the femur at the medial side of the lateral condyle

•  Posterior cruciate ligament: attaches to posterior part of tibia and passes anteriorly to attach to the femur at the lateral side of the medial condyle

115

Anterior view of flexed knee

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Anterior View of Flexed Knee

Figure 9.15e, f



Medial condyle



Medial meniscus

Patellar ligament

Patella

Quadriceps tendon

Lateral condyle of femur

Lateral meniscus

Fibula

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

Tibia

Medial femoral condyle


Medial meniscus on medial tibial condyle

Patella

(f) Photograph of an opened knee joint; view similar to (e)

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Superior View of Knee Joint

Figure 9.15b

(b) Superior view of the right tibia in the knee joint, showing the menisci and cruciate ligaments

Medial meniscus

Articular cartilage on medial tibial condyle

Anterior


Articular cartilage on lateral tibial condyle

Lateral meniscus


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Intracapsular knee cruciate ligaments

•  Cross each other like an “X” •  Stabilize knee joint and prevent undesirable

movements of the knee joint •  Anterior cruciate ligament helps prevent anterior

sliding of the tibia •  Posterior cruciate ligament helps prevent posterior

sliding of the tibia and forward sliding of the femur •  When the knee is fully extended, both cruciate

ligaments are taut and the knee is ‘locked’

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Stabilizing function of cruciate ligaments During movement of the knee the anterior cruciate prevents anterior sliding of the tibia; the posterior cruciate prevents posterior sliding of the tibia.


(a)


Quadriceps muscle Femur Patella

Lateral meniscus

Tibia

Medial condyle

(b)



When the knee is fully extended, both cruciate ligaments are taut and the knee is locked.

1 2

Figure 9.16a, b 120

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Copyright © 2011 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

Ruptured ACL, ruptured tibial collateral ligament, torn meniscus

Lateral Medial Patella (outline)

Tibial collateral ligament (torn)

Anterior view

Medial meniscus (torn) Anterior cruciate ligament (torn)

Lateral force

Joint injuries and inflammation

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Joint Injuries •  Torn cartilage—common injury to meniscus

of knee joint; meniscus (= articular disc) is a disc of fibrocartilage which extends internally from the joint capsule

•  Sprain—ligaments of a reinforcing joint are stretched or torn

•  Strain—an stretch or tear to either a muscle or a tendon

•  Dislocation—occurs when the bones of a joint are forced out of alignment

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Inflammatory Conditions: Bursitis & tendonitis

•  Bursitis—inflammation of a bursa due to injury or friction

•  Tendonitis—inflammation of a tendon sheath

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Inflammatory and degenerative arthritis conditions which damage joints

•  Osteoarthritis—most common type of “wear and tear” arthritis

•  Rheumatoid arthritis—a chronic autoimmune inflammatory disorder

•  Gouty arthritis (gout)—uric acid build-up causes pain in joints

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Osteoarthritis of fingers

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Copyright © 2011 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

Figure 9.21 A hand deformed by rheumatoid arthritis.

Rheumatoid arthritis of hand Rheumatoid arthritis of the hand

128

Cavitation produces sounds when knuckles are ‘cracked’ or spinal manipulation is performed •  When a spinal manipulation is performed or when someone

‘cracks’ their knuckles, the applied force separates the articular surfaces of a fully encapsulated synovial joint, which creates a reduction in pressure within the joint cavity.

•  In this low-pressure environment within the joint cavity, some of the gases that are dissolved in the synovial fluid leave the solution, making a bubble, or cavity, which rapidly collapses upon itself, resulting in a "clicking" sound.

•  The contents of the resultant gas bubble are thought to be mainly carbon dioxide.

•  This process is known as cavitation. •  Mirsky, Steve (December 2009). "Crack Research: Good

News about Knuckle Cracking.” Scientific American. 129

131, T6, Ch9 Joints _14

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