Human Anatomy & Physiology

BIO 201 Joints Chapter 9 By A. Fellah, Ph.D.

9-1

Joints

• • •

Joints and their classification

– – –

bony joints fibrous joints cartilaginous joints Synovial joints Anatomy of selected diarthroses

– – – –

humeroscapular joint elbow joint coxal joint knee joint 9-2

Joints and Their Classification

• • • •

Arthrology = study of the joints Kinesiology = study of musculoskeletal movement Classified by freedom of movement

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diarthrosis (freely movable)

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amphiarthrosis (slightly movable)

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synarthrosis (little or no movement) Classified how adjacent bones are joined

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fibrous, cartilaginous, bony or synovial 9-3

Bony Joint (Synostosis)

•

Gap between two bones ossifies

–

frontal and mandibular bones in infants

–

cranial sutures in elderly

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attachment of first rib and sternum

•

Can occur in either fibrous or cartilaginous joint 9-4

Fibrous Joints (Synarthrosis)

•

Collagen fibers span the space between bones

–

sutures, gomphoses and syndesmoses 9-5

Fibrous Joint -- Sutures

• • • •

Immovable fibrous joints

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bind skull bones together Serrate - interlocking lines

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coronal, sagittal and lambdoid sutures Lap - overlapping beveled edges

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temporal and parietal bones Plane - straight, nonoverlapping edges

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palatine processes of the maxillae 9-6

Types of Sutures

9-7

Fibrous Joint -- Gomphoses

• • •

Attachment of a tooth to its socket Held in place by fibrous periodontal ligament

–

collagen fibers attach tooth to jawbone Some movement while chewing 9-8

Fibrous Joint -- Syndesmosis

• • •

Two bones bound by ligament only

–

interosseus membrane Most movable of fibrous joints Interosseus membranes unite radius to ulna and tibia to fibula 9-9

Cartilaginous Joint -- Synchondrosis

•

Bones are joined by hyaline cartilage

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rib attachment to sternum

–

epiphyseal plate in children binds epiphysis and diaphysis 9-10

Cartilaginous Joint -- Symphysis

• •

2 bones joined by fibrocartilage

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pubic symphysis and intervertebral discs Only slight amount of movement is possible 9-11

Synovial Joint

• •

Joint in which two bones are separated by a space called a joint cavity Most are freely movable 9-12

General Anatomy

• • • • • •

Articular capsule encloses joint cavity

– –

continuous with periosteum lined by synovial membrane Synovial fluid = slippery fluid; feeds cartilages Articular cartilage = hyaline cartilage covering the joint surfaces Articular discs and menisci

– –

jaw, wrist, sternoclavicular and knee joints absorbs shock, guides bone movements and distributes forces Tendon attaches muscle to bone Ligament attaches bone to bone 9-13

Tendon Sheaths and Bursae

• •

Bursa = saclike extension of joint capsule

–

between nearby structures so slide more easily past each other Tendon sheaths = cylinders of connective tissue lined with synovial membrane and wrapped around a tendo 9-14

Components of a Lever

• •

A lever is a rigid object that rotates around a fixed point called a fulcrum Rotation occurs when effort overcomes resistance

–

resistance arm and effort arm are described relative to fulcrum 9-15

Mechanical Advantage of a Lever

•

Two kinds of levers

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lever that helps increase output of force

•

human moving a heavy object with help of crowbar

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lever move object further and faster

•

movement of row boat with paddle

•

Types of levers produce either increase in speed or force 9-16

Mechanical Advantage

• •

Mechanical advantage is calculated from the length of the effort arm divided by the length of the resistance arm Contraction of the biceps muscle causes the hand to move fast and further (MA <1.0) 9-17

First-Class Lever

• •

Has fulcrum in the middle between effort and resistance Atlantooccipital joint lies between the muscles on the back of the neck and the weight of the face

–

loss of muscle tone occurs when you nod off in class 9-18

Second-Class Lever

• •

Resistance between fulcrum and effort Resistance from the muscle tone of the temporalis muscle lies between the jaw joint and the pull of the diagastric muscle on the chin as it opens the mouth quickly 9-19

Third-Class Lever

• •

Effort between the resistance and the fulcrum

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most joints of the body The effort applied by the biceps muscle is applied to the forearm between the elbow joint and the weight of the hand and the forearm 9-20

Range of Motion

• •

Degrees through which a joint can move Determined by

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structure of the articular surfaces

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strength and tautness of ligaments, tendons and capsule

• •

stretching of ligaments increases range of motion double-jointed people have long or slack ligaments

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action of the muscles and tendons

•

nervous system monitors joint position and muscle tone 9-21

Axes of Rotation

• •

Shoulder joint has 3 degrees of freedom = multiaxial joint Other joints – monoaxial or biaxial 9-22

Types of Synovial Joints

9-23

Ball-and-Socket Joints

•

Smooth hemispherical head fits within a cuplike depression

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head of humerus into glenoid cavity of scapula

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head of femur into acetabulum of hip bone

•

Multiaxial joint 9-24

Condyloid (ellipsoid) Joints

•

Oval convex surface on one bone fits into a similarly shaped depression on the next

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radiocarpal joint of the wrist

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metacarpophalangeal joints at the bases of the fingers

•

Biaxial joints 9-25

Saddle Joints

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Each articular surface is shaped like a saddle, concave in one direction and convex in the other

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trapeziometacarpal joint at the base of the thumb

•

Biaxial joint

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more movable than a condyloid or hinge joint forming the primate opposable thumb 9-26

Gliding Joints

• • •

Flat articular surfaces in which bones slide over each other Limited monoaxial joint Considered amphiarthroses 9-27

Hinge Joints

•

One bone with convex surface that fits into a concave depression on other bone

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ulna and humerus at elbow joint

–

femur and tibia at knee joint

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finger and toe joints

•

Monoaxial joint 9-28

Pivot Joints

• •

One bone has a projection that fits into a ringlike ligament of another First bone rotates on its longitudinal axis relative to the other

–

atlantoaxial joint (dens and atlas)

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proximal radioulnar joint allows the radius during pronation and supination 9-29

Flexion, Extension and Hyperextension

• • •

Flexion decreases the angle of a joint Extension straightens and returns to the anatomical position Hyperextension = extension beyond 180 degrees 9-30

Flexion, Extension and Hyperextension 9-31

Abduction and Adduction

• •

Abduction is movement of a part away from the midline

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hyperabduction – raise arm over back or front of head Adduction is movement towards the midline

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hyperadduction – crossing fingers 9-32

Elevation and Depression

• •

Elevation is a movement that raises a bone vertically

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mandibles are elevated during biting and clavicles during a shrug Depression is lowering the mandible or the shoulders 9-33

Protraction and Retraction

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Protraction = movement anteriorly on horizontal plane

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thrusting the jaw forward, shoulders or pelvis forward

•

Retraction is movement posteriorly 9-34

Circumduction

• •

Movement in which one end of an appendage remains stationary while the other end makes a circular motion Sequence of flexion, abduction, extension and adduction movements

–

baseball player winding up for a pitch 9-35

Rotation

• •

Movement on longitudinal axis

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rotation of trunk, thigh, head or arm

•

Medial rotation turns the bone inwards Lateral rotation turns the bone outwards 9-36

Supination and Pronation

• • •

In the forearm and foot Supination

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rotation of forearm so that the palm faces forward

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inversion and abduction of foot (raising the medial edge of the foot) Pronation

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rotation of forearm so the palm faces to the rear

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eversion and abduction of foot (raising the lateral edge of the 9-37 foot)

Movements of Head and Trunk

•

Flexion, hyperextension and lateral flexion of vertebral column 9-38

Rotation of Trunk and Head

•

Right rotation of trunk; rotation of head 9-39

Movements of Mandible

• • •

Lateral excursion = sideways movement Medial excursion = movement back to the midline

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side-to-side grinding during chewing Protraction – retraction of mandible 9-40

Movement of Hand and Digits

• • • •

Radial and ulnar flexion Abduction of fingers and thumb Opposition is movement of the thumb to approach or touch the fingertips Reposition is movement back to the anatomical position 9-41

Movements of the Foot

• • • •

Dorsiflexion is raising of the toes as when you swing the foot forward to take a step (heel strike) Plantarflexion is extension of the foot so that the toes point downward as in standing on tiptoe Inversion is a movement in which the soles are turned medially Eversion is a turning of the soles to face laterally 9-42

The Humeroscapular Joint

• • • •

Most freely movable joint in the body

–

shallowness and looseness

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deepened by glenoid labrum Supported by ligaments and tendons

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3 glenohumeral, coracohumeral, transverse humeral and biceps tendon are important joint stabilizer Supported by rotator cuff musculature

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tendons fuse to joint capsule and strengthens it

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supraspinatus, infraspinatus, teres minor and subscapularis, 4 Bursae associated with shoulder joint 9-43

Stabilizers of the Shoulder Joint 9-44

Tendons of Rotator Cuff Muscles 9-45

Dissection of Shoulder Joint

9-46

The Elbow Joint

• • •

Single joint capsule enclosing the humeroulnar and humeroradial joints Humeroulnar joint is supported by collateral ligaments.

Radioulnar joint is head of radius held in place by the anular ligament encircling the head 9-47

Elbow Joint

9-48

The Coaxal (hip) Joint

• • •

Head of femur articulates with acetabulum Socket deepened by acetabular labrum Blood supply to head of femur found in ligament of the head of the femur Joint capsule strengthened by ligaments 9-49

Hip Joint

•

Joint capsule strengthened by ligaments

– – –

pubofemoral ischiofemoral iliofemoral 9-50

Dissection of Hip Joint

9-51

The Knee Joint

• • •

Most complex diarthrosis

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patellofemoral = gliding joint

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tibiofemoral = gliding with slight rotation and gliding possible in flexed position Joint capsule anteriorly consists of patella and extensions of quadriceps femoris tendon Capsule strengthened by extracapsular and intracapsular ligaments 9-52

Knee Joint – Sagittal Section

9-53

Knee Joint – Anterior and Posterior Views

• •

Anterior and lateral cruciate ligaments limit anterior and posterior sliding movements Medial and lateral collateral ligaments prevent rotation of extended knee 9-54

Knee Joint – Superior View

•

Medial and lateral meniscus absorb shock and shape joint 9-55

Dissection of Knee Joint

9-56

Arthritis

• •

Arthritis is a broad term for pain and inflammation Osteoarthritis results from years of joint wear

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articular cartilage softens and degenerates

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accompanied by crackling sounds called crepitus

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bone spurs develop on exposed bone tissue causing pain 9-57

Arthritis and Artificial Joints

• •

Rheumatoid arthritis is autoimmune attack on joint

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antibodies attack synovial membrane, enzymes in synovial fluid degrade the cartilage, bones ossify

–

remissions occur, steroids and aspirin control inflammation Arthroplasty is replacement of diseased joint with artificial device called prosthesis 9-58

Rheumatoid Arthritis

9-59

Joint Prostheses

9-60