Joint Classification

Home , Acetabular labrum, Coracohumeral ligament, Fibrous joint, Hinge joint, Humeroradial joint, Pivot joint

Chapter 9 *Lecture PowerPoint Joints

*See separate FlexArt PowerPoint slides for all figures and tables preinserted into PowerPoint without notes.

• Joints link the bones of the skeletal system, permit effective movement, and protect the softer organs

• Joint anatomy and movements will provide a foundation for the study of muscle actions

9-2 Joints and Their Classification

• Expected Learning Outcomes – Explain what joints are, how they are named, and what functions they serve. – Name and describe the four major classes of joints. – Describe the three types of fibrous joints and give an example of each. – Distinguish between the three types of sutures. – Describe the two types of cartilaginous joints and give an example of each. – Name some joints that become synostoses as they age.

9-3 Joints and Their Classification

• Joint (articulation)— any point where two bones meet, whether or not the bones are movable at that interface

Figure 9.1 9-4 © Gerard Vandystadt/Photo Researchers, Inc. Joints and Their Classification

• Arthrology—science of joint structure, function, and dysfunction

• Kinesiology—the study of musculoskeletal movement – A branch of biomechanics, which deals with a broad variety of movements and mechanical processes in the body, including the physics of blood circulation, respiration, and hearing

9-5 Joints and Their Classification

• Joint name—typically derived from the names of the bones involved – Atlanto–occipital joint, glenohumeral joint, radioulnar joint

• Joints classified according to the manner in which the adjacent bones are bound to each other, with differences in how freely the bones can move

• Four major joint categories – Bony joints – Fibrous joints – Cartilaginous joints – Synovial joints

9-6 Bony Joints

• Bony joint, or synostosis—an immovable joint formed when the gap between two bones ossifies, and the bones become, in effect, a single bone – Frontal and mandibular bones in infants – Cranial sutures in elderly – Attachment of first rib and sternum with old age

• Can occur in either fibrous or cartilaginous joint

9-7 Fibrous Joints

• Fibrous joint, synarthrosis, or synarthrodial joint—a point at which adjacent bones are bound by collagen fibers that emerge from one bone, cross the space between them, and penetrate into the other

• Three kinds of fibrous joints – Sutures – Gomphoses – Syndesmoses

9-8 Sutures

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Sutures—immovable or slightly Fibrous connective tissue movable fibrous joints that closely bind the bones of the skull to each other

• Sutures can be classified as:

– Serrate: interlocking wavy lines • Coronal, sagittal, and lambdoid sutures

– Lap (squamous): overlapping beveled edges • Temporal and parietal bones

– Plane (butt): straight, nonoverlapping edges • Palatine processes of the maxillae Figure 9.2a 9-9 Sutures

Figure 9.3

Serrate suture Lap suture Plane suture

Bone

Wood

9-10 Dovetail joint Miter joint Butt joint Gomphoses

• Gomphosis (fibrous joint)— attachment of a tooth to its socket

• Held in place by fibrous periodontal ligament – Collagen fibers attach tooth to jawbone – Allows the tooth to move a little under the stress of chewing

Figure 9.2b (b) Gomphosis 9-11 Syndesmoses

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fibrous connective tissue • Syndesmosis—a fibrous joint at which two bones are bound Figure 9.2c by longer collagenous fibers than in a suture or gomphosis giving the bones more mobility – Interosseus membrane

• Most movable syndesmosis – Interosseus membranes unite radius to ulna allowing supination and pronation

• Less movable syndesmosis – Tibia to fibula 9-12 (c) Syndesmosis Cartilaginous Joints

• Cartilaginous joint, amphiarthrosis, or amphiarthrodial joint—two bones are linked by cartilage

• Two types of cartilaginous joints – Synchondroses – Symphyses

9-13 Synchondroses

cartilage Rib 1 Costal cartilage – Temporary joint in the epiphyseal plate in children (a) • Binds epiphysis and diaphysis – First rib attachment to sternum • Other costal cartilages are

Interpubic disc joined to sternum by (fibrocartilage)

Pubic symphysis synovial joints (b) Figure 9.4a,b 9-14 Symphyses

– Pubic symphysis in which right and left pubic bones joined by Intervertebral interpubic disc disc (fibrocartilage)

– Bodies of vertebrae and intervertebral discs • Only slight amount of Body of vertebra movement between (c) adjacent vertebrae • Collective effect of all

Interpubic disc 23 discs gives spine (fibrocartilage)

considerable flexibility Pubic symphysis (b) 9-15 Figure 9.4b,c Synovial Joints

• Expected Learning Outcomes – Identify the anatomical components of a typical synovial joint. – Classify any given joint action as a first-, second-, or third-class lever. – Explain how mechanical advantage relates to the power and speed of joint movement. – Discuss the factors that determine a joint’s range of motion.

9-16 Synovial Joints

Cont. – Describe the primary axes of rotation that a bone can have and relate this to a joint’s degrees of freedom. – Name and describe six classes of synovial joints. – Use the correct standard terminology for various joint movements.

9-17 Synovial Joints

Proximal diarthrodial joint—joint phalanx in which two bones are separated by a space

Ligament called a joint cavity Joint cavity Articular containing cartilages synovial fluid • Most familiar type of joint Periosteum Fibrous capsule Joint Bone Synovial capsule • Most are freely movable membrane Middle • Most structurally complex phalanx type of joint Figure 9.5

9-18 Synovial Joints

• Most important joints for Proximal phalanx physical and occupational therapists, athletic coaches, nurses, Ligament Joint cavity Articular containing cartilages and fitness trainers synovial fluid Periosteum Fibrous capsule Joint Bone Synovial capsule • Their mobility makes membrane

them important to quality Middle phalanx of life Figure 9.5

9-19 General Anatomy • Articular cartilage—layer of hyaline cartilage that covers the facing surfaces of two bones – Usually 2 or 3 mm thick • Joint (articular) cavity—separates articular surfaces • Synovial fluid—slippery lubricant in joint cavity – Rich in albumin and hyaluronic acid – Gives it a viscous, slippery texture like raw egg whites – Nourishes articular cartilage and removes waste – Makes movement of synovial joints almost friction free

9-20 General Anatomy

• Joint (articular) capsule—connective tissue that encloses the cavity and retains the fluid – Outer fibrous capsule: continuous with periosteum of adjoining bones – Inner, cellular, synovial membrane: composed mainly of fibroblast-like cells that secrete synovial fluid and macrophages that remove debris from the joint cavity

9-21 General Anatomy

• In a few synovial joints, fibrocartilage grows inward from the joint capsule – Articular disc forms a pad between articulating bones that crosses the entire joint capsule • Temporomandibular joint, distal radioulnar joints, sternoclavicular and acromioclavicular joints – Meniscus: in the knee, two cartilages extend inward from the left and right but do not entirely cross the joint • These cartilages absorb shock and pressure • Guide bones across each other • Improve the fit between bones • Stabilize the joints, reducing the chance of dislocation

9-22 General Anatomy

• Accessory structures associated with synovial joints – Tendon: a strip or sheet of tough collagenous connective tissue that attaches muscle to bone • Most important structures in stabilizing a joint – Ligament: similar tissue that attaches one bone to another

9-23 General Anatomy

Cont. – Bursa: a fibrous sac filled with synovial fluid, located between adjacent muscles, where tendon passes over bone, or between bone and skin • Cushions muscles, helps tendons slide more easily over joints, modifies direction of tendon pull

– Tendon sheaths: elongated cylindrical bursae wrapped around a tendon • In hand and foot

Tendon of flexor carpi radialis Tendons of flexor digitorum superficialis Tendon of flexor pollicis longus and flexor digitorum profundus

Ulnar bursa (cut) Radial bursa (cut)

Flexor retinaculum (cut)

Lumbrical muscles

Tendons of flexor digitorum superficialis

Tendon sheaths Tendon sheath (opened)

Tendon of flexor digitorum superficialis

Tendon of flexor digitorum profundus Figure 9.6 9-25 Exercise and Articular Cartilage

• Exercise warms synovial fluid – Becomes less viscous and more easily absorbed by articular cartilage

• Cartilage then swells and provides a more effective cushion against compression – Warm-up period before vigorous exercise helps protect cartilage from undue wear and tear

9-26 Exercise and Articular Cartilage

• Repetitive compression of nonvascular cartilage during exercise squeezes fluid and metabolic waste out of the cartilage

• When weight removed, cartilage absorbs synovial fluid like a sponge taking in oxygen and nutrients to the chondrocytes

• Without exercise, cartilage deteriorates more rapidly from inadequate nutrition and waste removal

9-27 Joints and Lever Systems

• Long bones act as levers to enhance the speed or power of limb movements

• Lever—any elongated, rigid object that rotates around a fixed point called a fulcrum

• Rotation occurs when an effort applied overcomes resistance (load) at some other point – Resistance arm and effort arm are described relative to fulcrum

Effort

R E Figure 9.7

Resistance arm Effort arm F 9-28 Fulcrum Mechanical Advantage

• Advantage conferred by a lever can be of two kinds – To exert more force against a resisting object than the force applied to the lever • Human moving a heavy object with help of crowbar – To move the resisting object farther or faster than the effort arm is moved • Movement of rowing a boat • A single lever cannot confer both advantages – As one increases, the other decreases

9-29 Mechanical Advantage

LE 95 mm MA = = = 2.7 LR 35 mm

High mechanical advantage High power Low speed R LE 50 mm MA = = = 0.15 LR 330 mm F Temporalis muscle Low mechanical advantage Low power Coronoid process High speed R

Condyloid process

Biceps brachii F Figure 9.8

Radius E

Resistance arm (LR = 35 mm) Digastric muscle

(a) (b) Effort arm (LE = 95 mm) • MA > 1.0: lever produces more force, but less speed and distance, than force exerted on it

• MA < 1.0: lever produces more speed or distance, but less force, than input

• Contraction of biceps brachii muscle puts more power into lever than we get out of it, but hand moves faster and further (MA < 1.0) 9-30 Mechanical Advantage

• Mechanical advantage (MA) of a lever—the ratio of its output force to its input force

• MA is calculated from length of effort arm divided by length of resistance arm

9-31 Types of Levers

Effort Resistance R Effort

R E Resistance E

F F F Fulcrum Fulcrum (a) First-class lever Resistance Effort

Figure 9.9a • First-class lever – Has fulcrum in the middle between effort and resistance (EFR) – Atlanto–occipital 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

9-32 Types of Levers

Resistance

Resistance R Resistance R

E E F Fulcrum F Effort Effort F Fulcrum (b) Second-class lever Effort Figure 9.9b • Second-class lever – Resistance between fulcrum and effort (FRE) – Resistance from the muscle tone of the temporalis muscle lies between the jaw joint and the pull of the digastric muscle on the chin as it opens the mouth quickly

9-33 Types of Levers

Fulcrum F Resistance Effort

E E R Effort Resistance Effort F Fulcrum Resistance R (c) Third-class lever

F Figure 9.9c • Third-class lever – Effort between the resistance and the fulcrum (REF) – 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 9-34 Range of Motion

• Range of motion (ROM)—the degrees through which a joint can move – Aspect of joint performance – Physical assessment of a patient’s joint flexibility

• ROM determined by: – Structure of the articular surfaces • Elbow—olecranon of ulna fits into olecranon fossa of humerus – Strength and tautness of ligaments and joint capsules • Stretching of ligaments increases range of motion • Double-jointed people have long or slack ligaments – Action of the muscles and tendons • Nervous system monitors joint position and muscle tone • Muscle tone—state of tension maintained in resting muscles 9-35 Axes of Rotation

(a) Abduction of arm

Figure 9.10

(b) Flexion of arm

• A moving bone has a relatively stationary axis of rotation that passes through the bone in a direction perpendicular to the plane of movement • Multiaxial joint—shoulder joint has three degrees of freedom or axes of rotation

• Other joints—monoaxial or biaxial 9-36 Classes of Synovial Joints

Ball-and-socket joint Humerus Hinge joint (humeroscapular) Head of humerus (humeroulnar)

Scapula Ulna

Pivot joint Radius Plane joint (radioulnar) (intercarpal)

Ulna Carpal bones

Saddle joint Carpal bone Condylar joint (trapeziometacarpal) (metacarpophalangeal)

Metacarpal Metacarpal bone bone Phalanx

Figure 9.11 9-37 Classes of Synovial Joints

• Ball-and-socket joints – Smooth, hemispherical head fits within a cuplike socket – Shoulder joint: head of humerus into glenoid cavity of scapula – Hip joint: head of femur into acetabulum of hip bone

• Only multiaxial joints in the body

9-38 Classes of Synovial Joints

• Condylar (ellipsoid) joints – Oval convex surface on one bone fits into a complementary-shaped depression on the other – Radiocarpal joint of the wrist – Metacarpophalangeal joints at the bases of the fingers

• Biaxial joints—movement in two planes

9-39 Classes of Synovial Joints

• Saddle joints – Both bones have an articular surface that is shaped like a saddle, concave in one direction and convex in the other – Trapeziometacarpal joint at the base of the thumb – Sternoclavicular joint: clavicle articulates with sternum

• Biaxial joint – More movable than a condyloid or hinge joint forming the primate opposable thumb

9-40 Classes of Synovial Joints

• Plane (gliding) joints – Flat articular surfaces in which bones slide over each other with relatively limited movement

• Usually biaxial joint – Carpal bones of wrist – Tarsal bones of ankle – Articular processes of vertebrae

• Although any one joint moves only slightly, the combined action of the many joints in wrist, ankle, and vertebral column allows for considerable movement 9-41 Classes of Synovial Joints

• Hinge joints – One bone with convex surface that fits into a concave depression on other bone – Elbow joint: ulna and humerus – Knee joint: femur and tibia – Finger and toe joints

• Monoaxial joint—move freely in one plane

9-42 Classes of Synovial Joints

• Pivot joints – One bone has a projection that is held in place by a ringlike ligament

• Bone spins on its longitudinal axis – Atlantoaxial joint (dens of axis and atlas) • Transverse ligament – Proximal radioulnar joint allows the radius to rotate during pronation and supination • Anular ligament

• Monoaxial joint

9-43 Movement of Synovial Joints

• Vocabulary of movements of synovial joints used in kinesiology, physical therapy, and other medical fields – Many presented in pairs with opposite or contrasting meanings – Need to understand anatomical planes and directional terms

• Zero position—the position of a joint when a person is in the standard anatomical position – Joint movements are described as deviating from the zero position or returning to it

9-44 Flexion and Extension

• Extension—movement that Extension straightens a joint and generally returns a body part (a) to the zero position © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Figure 9.12a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Hyperextension—further Hyperextension extension of a joint beyond the zero position

– Flexion and extension occur at Extension nearly all diarthroses, Figure 9.12b hyperextension is limited to a few

Flexion 9-45 (b) © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Flexion and Extension

Flexion

Hip flexion

Hyperextension (c) © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Figure 9.12c Knee flexion

Extension Figure 9.12d (d) 9-46 © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Abduction and Adduction

Figure 9.13a,b (a) Abduction (b) Adduction © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer • Abduction—movement of a body part in the frontal plane away from the midline of the body – Hyperabduction: raise arm over back or front of head

• Adduction—movement in the frontal plane back toward the midline – Hyperadduction: crossing fingers, crossing ankles 9-47 Elevation and Depression

(a) Elevation (b) Depression © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Figure 9.14a,b

• Elevation—movement that raises a body part vertically in the frontal plane • Depression—movement that lowers a body part in the same plane 9-48 Protraction and Retraction

• Protraction—the anterior movement of a body part in the transverse (horizontal) plane (a) Protraction

• Retraction—posterior movement

Figure 9.15a,b (b) Retraction 9-49 © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Circumduction

• Sequence of flexion, abduction, extension, and adduction movements – Baseball player winding up for a pitch

• Rotation— Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. movement in which a bone spins on its longitudinal axis – Rotation of trunk, thigh, head, or arm

• Medial (internal) rotation turns the bone inward

• Lateral (external) rotation turns the (a) Medial (internal) rotation (b) Lateral (external) rotation bone outward © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Figure 9.17a,b 9-51 Supination and Pronation

• Primarily forearm movements Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Supination—forearm movement that turns palm to face anteriorly or upward – Forearm supinated in anatomical position – Radius is parallel to the ulna • Pronation—forearm movement that turns palm to face either posteriorly or downward – Radius spins on capitulum of humerus – Disc spins in radial notch of ulna (a) Supination (b) Pronation – Radius crosses stationary © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Figure 9.18a,b ulna like an X 9-52 Special Movements of Head and Trunk

(a) Flexion (b) Hyperextension (c) Lateral flexion

© The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Figure 9.19a,b,c • Flexion—forward-bending movements at the waist • Extension—straightens trunk or neck • Hyperextension—bending over backward • Lateral flexion—tilting the head or trunk to the right or left at the midline 9-53 Special Movements of Head and Trunk

Figure 9.19d,e

(a) Protraction (b) Retraction

Figure 9.20 (c) Lateral excursion (d) Medial excursion © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer

• Lateral excursion—right or left movement from the zero position • Medial excursion—movement back to the median, zero position – Side-to-side grinding during chewing • Protraction–retraction • Elevation–depression 9-55 Special Movements of Hand and Digits

• Radial flexion—tilts the hand toward the thumb

(a) Radial flexion (b) Ulnar flexion (c) Abduction of fingers • Flexion of fingers— curling them

• Extension of fingers—

straightening them (d) Palmar abduction of thumb (e) Opposition of thumb © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer Figure 9.21 9-56 Special Movements of Hand and Digits

• Abduction of the fingers—spreads them apart

• Adduction of the fingers—brings them together again

• Flexion of thumb—tip of thumb directed toward palm

• Extension of thumb—straightening the thumb

9-57 Special Movements of Hand and Digits

• Radial abduction—moves thumb away from index finger 90°

• Palmar abduction—moves thumb away from hand and points it anteriorly

• Adduction of thumb—moves it to the zero position

• Opposition—moves thumb to touch tips of any of the fingers

• Reposition—returns thumb to the zero position 9-58 Special Movements of the Foot

Dorsiflexion

Zero position

(b) Inversion (c) Eversion

Plantar flexion Figure 9.22

(a) Flexion of ankle © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer • Dorsiflexion—elevation of toes as you do while swinging foot forward to take a step (heel strike)

• Plantar flexion—extension of foot so that toes point downward as in standing on tiptoe (toe-off)

• Inversion—movement in which the soles are turned medially

9-59 Special Movements of the Foot

• Eversion—movement in which the soles are turned laterally

• Supination of foot—complex combination of plantar flexion, inversion, and adduction

• Pronation of foot—complex combination of dorsiflexion, eversion, and abduction

9-60 Anatomy of Selected Diarthroses

• Expected Learning Outcomes – Identify the major anatomical features of the jaw, shoulder, elbow, hip, knee, and ankle joints. – Explain how the anatomical differences between these joints are related to differences in function.

9-61 The Jaw Joint

• Temporomandibular (jaw) joint (TMJ)—articulation of the condyle of the mandible with the mandibular fossa of the temporal bone – Combines elements of condylar, hinge, and plane joints – Synovial cavity of the TMJ is divided into superior and inferior chambers by an articular disc

9-62 The Jaw Joint

– Two ligaments support joint • Lateral ligament—prevents posterior displacement of mandible • Sphenomandibular ligament—on the medial side

– Deep yawn or strenuous depression can dislocate the TMJ • Condyles pop out of fossa and slip forward • Relocated by pressing down on molar teeth while pushing the jaw backward

9-63 The Jaw Joint

Lateral ligament Joint capsule

External acoustic meatus

Styloid process

Stylomandibular ligament Figure 9.23 (a) Lateral view

Sphenoid sinus Mandibular fossa of temporal bone Occipital bone Superior joint cavity Articular disc Sphenomandibular Inferior joint cavity ligament Mandibular condyle Styloid process Synovial membrane Stylomandibular Joint capsule ligament

9-64 (b) Medial view (c) Sagittal section TMJ Syndrome

Sphenomandibular ligament

Lateral • Temporomandibular joint (TMJ) ligament syndrome Joint capsule External – May affect as many as 75 million acoustic meatus Americans Styloid process Stylomandibular ligament

– Can cause moderate intermittent Mandibular fossa facial pain of temporal bone Superior joint cavity – Clicking sounds in the jaw Articular disc – Limitation of jaw movement Inferior joint cavity Mandibular condyle

– Often severe headaches, vertigo Synovial membrane (dizziness), tinnitus (ringing in the Joint capsule ears) – Pain radiating from jaw down the neck, shoulders, and back

• Cause of syndrome – Caused by combination of psychological tension and malocclusion (misalignment of teeth)

• Treatment – Psychological management, physical therapy, analgesic and anti-inflammatory drugs, corrective dental appliances to align teeth properly

9-66 The Shoulder Joint

• Glenohumeral Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (humeroscapular) joint— hemispherical head of Acromion Supraspinatus tendon Subdeltoid humerus articulates with bursa Capsular ligament Glenoid labrum glenoid cavity of scapula Deltoid muscle Synovial – Most freely movable joint in membrane

body Glenoid cavity of scapula – Shallow glenoid cavity and Glenoid labrum loose shoulder joint capsule Humerus sacrifice joint stability for freedom of movement – Glenoid labrum: fibrocartilage (c) Frontal section ring that deepens glenoid Figure 9.24c cavity

9-67 The Shoulder Joint

• Shoulder supported by

biceps brachii tendon Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anteriorly and also rotator cuff tendons Acromion Supraspinatus tendon Subdeltoid – Tendons fuse to joint capsule bursa Capsular ligament Glenoid labrum and strengthen it Deltoid muscle Synovial – Supraspinatus, infraspinatus, membrane

teres minor, and Glenoid cavity subscapularis of scapula

Glenoid labrum Humerus

9-68 The Shoulder Joint

– Three are called the Acromion Supraspinatus tendon glenohumeral ligaments Subdeltoid bursa Capsular ligament

– Coracohumeral ligament Glenoid labrum Deltoid muscle – Transverse humeral Synovial ligament membrane Glenoid cavity of scapula

Glenoid labrum • Four bursa occur at the Humerus shoulder – Subdeltoid, subacromial, subcoracoid, and (c) Frontal section subscapular bursae Figure 9.24c

9-69 The Shoulder Joint

Subacromial Coraco- bursa clavicular ligament Supraspinatus tendon Coraco- Coracohumeral acromial ligament ligament Subdeltoid bursa Coracoid process Subscapularis tendon Transverse Subcoracoid humeral bursa ligament Subscapular Tendon sheath bursa

Biceps brachii tendon (long head) Glenohumeral Humerus ligaments

(b) Anterior view Figure 9.24b 9-70 The Shoulder Joint

Acromion Coracoid process Supraspinatus tendon Coracohumeral ligament Subdeltoid Superior glenohumeral bursa ligament Infraspinatus Biceps brachii tendon tendon (long head) Glenoid cavity Subscapular bursa (articular cartilage) Subscapularis tendon

Teres minor tendon Middle glenohumeral Synovial membrane ligament (cut) Inferior glenohumeral ligament

(d) Lateral view , humerus removed Figure 9.24d 9-71 Shoulder Dislocation

Acromion

Supraspinatus tendon • Downward displacement of the Subdeltoid bursa Capsular ligament

humerus is the most common Glenoid labrum Deltoid muscle shoulder dislocation Synovial – Rotator cuff protects the joint in membrane Glenoid cavity all directions but inferiorly of scapula

– Joint protected from above by Glenoid labrum coracoid process, acromion, Humerus and clavicle

9-72 Shoulder Dislocation

• Dislocations most often occur when the arm is abducted and then receives a blow from above

• Children especially prone to dislocation

Acromioclavicular joint Acromion of scapula Clavicle Head of humerus

Coracobrachialis muscle Deltoid muscle (cut and folded back) Pectoralis major muscle

Biceps brachii muscle: Short head Long head

Figure 9.24a (a) Anterior dissection 9-74 © The McGraw-Hill Companies, Inc./Timothy L. Vacula, photographer The Elbow Joint

Humerus Coronoid process • Elbow is a hinge joint Trochlea Olecranon bursa composed of two Radius articulations Articular cartilage Olecranon – Humeroulnar joint: Ulna where the trochlea of the (b) Sagittal section Figure 9.25b humerus joins the Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

trochlear notch of the ulna Humerus • Hinge joint Anular ligament

Tendon of biceps Joint capsule brachii (cut)

Radius Tendon of triceps brachii

Ulnar collateral Coronoid process ligament

Olecranon bursa Ulna 9-75 Figure 9.25c (c) Medial view The Elbow Joint

Cont. – Humeroradial joint: where the capitulum of the humerus meets the head of the radius • Pivot joint • Edge of the disclike head of the radius fits into the radial notch of the ulna • Anular ligament holds the head in place • Radial head rotates like a wheel against the ulna as the forearm is supinated and pronated

• Both enclosed in a single joint capsule

9-76 The Elbow Joint

• Olecranon bursa—on posterior side of the elbow – Eases movement of the tendons over the joint

• Side-to-side motion of the elbow is restricted by a pair of ligaments – Radial (lateral) collateral ligament – Ulnar (medial) collateral ligament

9-77 The Elbow Joint

Humerus

Lateral Medial epicondyle epicondyle

Humerus Anular Anular ligament ligament Joint capsule Tendon of biceps brachii Lateral Tendon of (cut) epicondyle biceps brachii Ulna (cut) Radius Radial Radius collateral (a) Anterior view ligament Joint capsule Figure 9.25a

Ulna Olecranon

(d) Lateral view Figure 9.25d 9-78 The Hip Joint

Round which the head of femur ligament (cut) Fovea inserts into the Acetabulum capitis Head of femur acetabulum of the hip Labrum Greater trochanter bone

Ischial tuberosity • Bears much more weight, Obturator Femur membrane Transverse have deeper sockets, acetabular ligament more stable than shoulder (b) Lateral view, femur retracted Figure 9.26b

9-79 The Hip Joint

• Acetabular labrum—horseshoe-shaped ring of fibrocartilage that deepens socket – Dislocations rare: congenital dislocations in infants

• Ligaments supporting hip joint – Iliofemoral and pubofemoral—on anterior – Ischiofemoral ligament—on posterior – When standing, the ligaments become twisted and pull head of femur tightly into the acetabulum – Transverse acetabular ligament bridges gap on inferior margin of acetabular labrum

9-80 The Hip Joint

• Fovea capitis—pit on head of femur – Round ligament, or ligamentum teres—arises from here and attaches to lower margin of acetabulum – Contains artery that supplies blood to the head of the femur

9-81 The Hip Joint

Ilium Iliofemoral ligament

Ischiofemoral Pubofemoral ligament ligament

Iliofemoral Pubis ligament Greater trochanter Greater trochanter

Ischial tuberosity Femur

Lesser trochanter Femur

9-82 The Hip Joint

Acetabular labrum

Acetabulum

Head of femur

Greater trochanter

Round ligament

Shaft of femur Figure 9.26a

• Dislocation of the hips is rare • Some infants suffer congenital dislocation – Acetabulum is not deep enough to hold the head of the femur in place • Harness, worn for 2 to 4 months can assist with proper positioning

Figure 9.27 9-84 The Knee Joint

• Tibiofemoral (knee) Quadriceps femoris

joint—largest and most Femur Quadriceps femoris tendon

complex diarthrosis of Suprapatellar Bursa under lateral head of gastrocnemius bursa the body Prepatellar bursa Joint capsule Patella Articular cartilage Synovial membrane

Meniscus Joint cavity • Primarily a hinge joint Infrapatellar fat pad Superficial – Capable of slight infrapatellar bursa Tibia Patellar ligament rotation and lateral Deep gliding when knee is infrapatellar bursa (c) Sagittal section flexed Figure 9.29c – Patellofemoral joint— gliding joint

9-85

The Knee Joint

• Joint capsule encloses only the lateral and posterior aspects of the knee, not the anterior – Anterior covered by patellar ligament and lateral and medial retinacula • All are extensions of the tendon of quadriceps femoris muscle

• Knee stabilized – Quadriceps tendon in front – Tendon of semimembranosus muscle on rear of thigh

9-86 The Knee Joint

Quadriceps • Joint cavity contains two femoris Femur Quadriceps C-shaped cartilages femoris tendon Suprapatellar Bursa under lateral head of gastrocnemius bursa Prepatellar bursa – Lateral meniscus and Joint capsule Patella medial meniscus Articular cartilage Synovial membrane – Joined by transverse Meniscus Joint cavity ligament Infrapatellar fat pad Superficial • Absorbs shock on the infrapatellar bursa Tibia Patellar ligament knee Deep • Prevents femur from infrapatellar bursa rocking side-to-side on (c) Sagittal section the tibia Figure 9.29c

9-87 The Knee Joint

• Popliteal region of knee Quadriceps femoris

Femur Quadriceps – Supported by a complex femoris tendon

Suprapatellar array of extracapsular Bursa under lateral head of gastrocnemius bursa Prepatellar bursa ligaments external to Joint capsule Patella Articular cartilage joint capsule Synovial membrane Meniscus Joint cavity • Prevent knee from Infrapatellar fat pad Superficial rotating when joint is infrapatellar bursa

Tibia Patellar ligament extended Deep infrapatellar bursa

• Fibular (lateral) (c) Sagittal section collateral ligament Figure 9.29c • Tibial (medial) collateral ligament

9-88 The Knee Joint

Quadriceps femoris

Femur Quadriceps femoris tendon

• Two intracapsular Suprapatellar Bursa under lateral head of gastrocnemius bursa ligaments deep within Prepatellar bursa Joint capsule Patella Articular cartilage joint capsule Synovial membrane

Meniscus Joint cavity – Synovial membrane folds Infrapatellar fat pad Superficial around them, so they are infrapatellar bursa

Tibia Patellar ligament excluded from the fluid- Deep infrapatellar bursa

filled synovial cavity (c) Sagittal section – Ligaments cross each Figure 9.29c other to form an X

9-89 The Knee Joint

• Anterior cruciate ligament (ACL) – Prevents hyperextension of knee when ACL is pulled tight – Common site of knee injury

• Posterior cruciate ligament (PCL) – Prevents femur from sliding off tibia – Prevents tibia from being displaced backward – Untwists the ligaments

9-90 The Knee Joint

Quadriceps femoris

Femur Quadriceps • Ability to “lock” the knees femoris tendon

Suprapatellar Bursa under lateral – Important aspect of head of gastrocnemius bursa Prepatellar bursa human bipedalism Joint capsule Patella Articular cartilage – When knee is extended Synovial membrane Meniscus Joint cavity to the fullest degree Infrapatellar fat pad Superficial allowed by ACL infrapatellar bursa

Tibia Patellar ligament • Femur rotates medially Deep infrapatellar bursa on the tibia (c) Sagittal section • Locks knee, and all Figure 9.29c major knee ligaments are twisted and taut

9-91 The Knee Joint

• “Unlock” knee—popliteus muscle rotates the femur laterally and untwists the ligaments

• Knee joint has at least 13 bursae

• Four anterior: superficial infrapatellar, suprapatellar, prepatellar, and deep infrapatellar

9-92 The Knee Joint

Quadriceps femoris

Femur Quadriceps femoris tendon

Suprapatellar Bursa under lateral head of gastrocnemius bursa Prepatellar bursa Joint capsule Patella Articular cartilage Synovial membrane

Meniscus Joint cavity Infrapatellar fat pad

Superficial infrapatellar bursa

Tibia Patellar ligament Deep infrapatellar bursa

(c) Sagittal section Figure 9.29c • Popliteal region: popliteal bursa and semimembranosus bursa • Seven more bursae on lateral and medial sides of knee joint 9-93 The Knee Joint

Femur Femur

Medial Patellar surface condyle

Lateral Medial condyle Tibial Anterior cruciate condyle ligament Posterior cruciate collateral ligament Fibular ligament Fibular collateral collateral Anterior cruciate ligament Medial ligament ligament meniscus Lateral meniscus Lateral Medial meniscus meniscus Articular cartilage Tibial collateral Posterior of tibia Transverse ligament cruciate ligament ligament Patellar ligament (cut) Fibula Fibula Tibia Tibia

(a) Anterior view (b) Posterior view Figure 9.29a,b 9-94 The Knee Joint

Lateral meniscus Posterior cruciate ligament

Medial meniscus

Synovial membrane Medial condyle of tibia

Figure 9.29d Lateral condyle Anterior cruciate of tibia ligament

(d) Superior view of tibia and menisci

• Medial and lateral meniscus absorb shock and shape joint 9-95 The Knee Joint

Lateral Medial

Femur: Shaft Patellar surface Medial condyle Lateral condyle

Joint capsule Joint cavity: Anterior cruciate ligament Medial meniscus Lateral meniscus

Tibia: Lateral condyle Medial condyle Tuberosity

Patellar ligament Figure 9.28 Patella (posterior surface)

Articular facets

Quadriceps tendon (reflected) 9-96

• Highly vulnerable to rotational and horizontal stress Twisting motion

• Most common injuries are to Foot fixed the meniscus and anterior cruciate ligament (ACL)

• Heal slowly due to scanty Anterior cruciate blood flow ligament (torn) Tibial collateral ligament (torn)

Medial meniscus (torn)

Patellar ligament Figure 9.30 9-97 Knee Injuries and Arthroscopic Surgery

• Arthroscopy—procedure in which the interior of the joint is viewed with a pencil-thin arthroscope inserted through a small incision – Less tissue damage than conventional surgery – Recover more quickly – Arthroscopic ACL repair: about 9 months for healing to be complete

9-98 The Ankle Joint

• Talocrural (ankle) joint—includes two articulations: – Medial joint: between tibia and talus – Lateral joint: between fibula and talus – Both enclosed by one joint capsule – Malleoli of tibia and fibula overhang the talus on either side and prevent side-to-side motion – More restricted range of motion than the wrist

9-99 The Ankle Joint

• Ankle ligaments – Anterior and posterior tibiofibular ligaments: bind the tibia to fibula – Multipart medial (deltoid) ligament: binds the tibia to the foot on the medial side – Multipart lateral (collateral) ligament: binds fibula to the foot on the lateral side – Calcaneal (Achilles) tendon: extends from the calf muscle to the calcaneus • Plantarflexes the foot and limits dorsiflexion – Sprains (torn ligaments and tendons) are common at the ankle • Pain and immediate swelling

9- 100 The Ankle Joint

Fibula Tibia Lateral ligament: Anterior and posterior tibiofibular Posterior talofibular ligament ligaments Calcaneofibular ligament Anterior talofibular ligament

Calcaneal tendon

Calcaneus

Tendons of Metatarsal v fibularis longus (a) Lateral view and brevis Tibia

Fibula

Interosseous membrane Medial ligament Tibia

Medial Posterior tibiofibular Navicular malleolus ligament Lateral malleolus Metatarsal I Calcaneal Posterior talofibular tendon ligament

Calcaneofibular ligament

Calcaneus Tendons of tibialis anterior and posterior Calcaneus

Calcaneofibular ligament Anterior talofibular ligament

(b) Lateral dissection

Figure 9.31b 9- 102 Arthritis and Artificial Joints

• Arthritis—a broad term for pain and inflammation of a joint

• Most common crippling disease in the United States

• Rheumatologists—physicians who treat arthritis and other joint disorders

• Osteoarthritis (OA)—most common form of arthritis – ―Wear-and-tear arthritis‖ – Results from years of joint wear – Articular cartilage softens and degenerates – Accompanied by crackling sounds called crepitus – Bone spurs develop on exposed bone tissue causing pain

9- 103 Arthritis and Artificial Joints

• Rheumatoid arthritis (RA)—autoimmune attack against the joint tissues – Misguided antibodies (rheumatoid factor) attack synovial membrane, enzymes in synovial fluid degrade the articular cartilage, joint begins to ossify – Ankylosis: solidly fused, immobilized joint – Remissions occur, steroids and aspirin control inflammation

• Arthroplasty—replacement of diseased joint with artificial device called prosthesis 9- 104 Rheumatoid Arthritis

Figure 9.32a,b

9- 105 Joint Prostheses

Artificial acetabulum

Artificial Femur femoral head

Prosthesis

(a) (c)

Femur

Tibia

Fibula

(b) (d) a: © SIU/Visuals Unlimited; b: © Ron Mensching/Phototake; c: © SIU/Peter Arnold, Inc.; d: © Mehau Kulyk/SPL/Photo Researchers, Inc. 9- Figure 9.33a,b Figure 9.33c,d 106