The Ankle Joint

The talocrural (ankle) joint includes two articulations— a medial joint between the tibia and talus and a lateral joint between the fibula and talus, both enclosed in one joint capsule (fig. 9.25). The malleoli of the tibia and fibula overhang the talus on each side like a cap and prevent most side-to-side motion (fig. 9.26). The ankle therefore has a more restricted range of motion than the wrist.

Chapter 9 Joints 317

The ligaments of the ankle include (1) anterior and posterior tibiofibular ligaments, which bind the tibia to the fibula; (2) a multipart deltoid ligament, which binds the tibia to the foot on the medial side; and (3) a multipart lateral collateral ligament, which binds the fibula to the foot on the lateral side. The calcaneal (Achilles) tendon extends from the calf muscles to the calcaneus. It enables plantar flexion and limits dorsiflexion of the joint. Plantar flexion is limited by extensor tendons on the anterior side of the ankle and by the anterior part of the joint capsule.

Sprains (torn ligaments and tendons) occur especially often at the ankle. Excessive eversion can tear the deltoid ligament, and excessive inversion often tears the anterior talofibular ligament and calcaneofibular ligament. These sprains are painful and usually accompanied by immediate swelling. They are best treated by immobilizing the joint and reducing swelling with an ice pack, but in extreme cases they may require a cast or surgery.

The synovial joints described in this section are summarized in table 9.2. A summary of some common joint disorders, including sprains, is presented in table 9.3.

Lateral

Fibula Tibia

Anterior and posterior tibiofibular ligaments

Calcaneal—f tendon

Calcaneus

Deltoid Ligament Sprain
Posterior talofibular ligament Calcaneofibular ligament Anterior talofibular ligament

Lateral collateral ligament

Calcaneal—f tendon

Calcaneus

Medial

Deltoid ligament Navicular Metatarsal I

Tendons of Metatarsal V

peroneus longus and brevis

Tendons of Metatarsal V

peroneus longus and brevis

-Tibia t*m

Deltoid Ligament Pain

Calcaneal tendon

Calcaneus

Calcaneus

Medial malleolus

Arcuate Ligament Calcaneus

Posterior tibiofibular ligament

Lateral malleolus

Posterior talofibular ligament

Calcaneofibular ligament

Posterior

Tibia

Fibula

Interosseous membrane

Medial malleolus

Posterior tibiofibular ligament

Lateral malleolus

Posterior talofibular ligament

Calcaneofibular ligament

Calcaneus

Tendons of tibialis anterior and posterior (b)

Figure 9.25 The Talocrural (ankle) Joint and Ligaments of the Right Foot. (a) Lateral view; (b) medial view; (c) posterior view.

Before You Go On

Answer the following questions to test your understanding of the preceding section:

  1. What keeps the mandibular condyle from slipping out of its fossa in a posterior direction?
  2. Explain how the biceps tendon braces the shoulder joint.
  3. What structure elsewhere in the skeletal system has a structure and function similar to the acetabular labrum of the os coxae?
  4. What keeps the femur from slipping backward off the tibia?
  5. What keeps the tibia from slipping sideways off the talus?

Table 9.2 Review of the Principal Diarthroses

Joint

Major Anatomical Features and Actions

Temporomandibular (fig. 9.18)

Type: condyloid, hinge, and gliding

Movements: elevation, depression, protraction, retraction, lateral and medial excursion Articulation: condyle of mandible, mandibular fossa of temporal bone Ligaments: temporomandibular, sphenomandibular Cartilage: articular disc

Humeroscapular (fig. 9.19)

Type: ball-and-socket

Movements: adduction, abduction, flexion, extension, circumduction, medial and lateral rotation

Articulation: head of humerus, glenoid fossa of scapula

Ligaments: coracohumeral, transverse humeral, three glenohumerals

Tendons: rotator cuff (tendons of subscapularis, supraspinatus, infraspinatus, teres minor), tendon of biceps brachii Bursae: subdeltoid, subacromial, subcoracoid, subscapular Cartilage: glenoid labrum

Elbow (fig. 9.20)

Type: hinge and pivot

Movements: flexion, extension, pronation, supination, rotation

Articulations: humeroulnar—trochlea of humerus, trochlear notch of ulna; humeroradial—capitulum of humerus, head of radius; radioulnar—head of radius, radial notch of ulna Ligaments: radial collateral, ulnar collateral, annular Bursa: olecranon

Coxal (fig. 9.21)

Type: ball-and-socket

Movements: adduction, abduction, flexion, extension, circumduction, medial and lateral rotation Articulations: head of femur, acetabulum of os coxae

Saladin: Anatomy & Physiology: The Unity of Form and Function, Third Edition

318 Part Two Support and Movement

Fibula Tibia-

Medial malleolus

Lateral malleolus

Trochlear surface of talus

Deltoid ligament

Calcaneofibular ligament

Anterior talofibular ligament

Dorsum of foot

318 Part Two Support and Movement

Trochlear Surface Talus
Figure 9.26 Photograph of the Talocrural Joint, Anterior View.

Saladin: Anatomy & I 9. Joints I Text I I © The McGraw-Hill

Physiology: The Unity of Companies, 2003 Form and Function, Third Edition

Chapter 9 Joints 319

Table 9.2 Review of the Principal Diarthroses (continued)

Joint Major Anatomical Features and Actions

Ligaments: iliofemoral, pubofemoral, ischiofemoral, ligamentum teres, transverse acetabular Cartilage: acetabular labrum Knee (fig. 9.23) Type: primarily hinge

Movements: flexion, extension, slight rotation Articulations: tibiofemoral, patellofemoral

Ligaments: anterior—lateral patellar retinaculum, medial patellar retinaculum; popliteal intracapsular—anterior cruciate, posterior cruciate; popliteal extracapsular—oblique popliteal, arcuate popliteal, lateral collateral, medial collateral

Bursae: anterior—superficial infrapatellar, suprapatellar, prepatellar, deep infrapatellar; popliteal—popliteal, semimembranosus; medial and lateral—seven other bursae not named in this chapter Cartilages: lateral meniscus, medial meniscus (connected by transverse ligament) Ankle (fig. 9.25) Type: hinge

Movements: dorsiflexion, plantar flexion, extension, inversion, eversion Articulations: tibia-talus, fibula-talus, tibia-fibula Ligaments: anterior and posterior tibiofibular, deltoid, lateral collateral Tendon: calcaneal (Achilles)

Table 9.3 Some Common Joint Disorders

Strain

Painful overstretching of a tendon or muscle without serious tissue damage. Often results from inadequate warm-up before exercise.

Sprain

Torn ligament or tendon, sometimes with damage to a meniscus or other cartilage.

Synovitis

Inflammation of a joint capsule, often as a complication of a sprain.

Dislocation

Displacement of a bone from its normal position at a joint, usually accompanied by a sprain of the adjoining connective tissues. Most common at the fingers, thumb, shoulder, and knee.

Rheumatism

Broad term for any pain in the supportive and locomotory organs of the body, including bones, ligaments, tendons, and muscles.

Arthritis

Broad term embracing more than 100 types of joint rheumatism.

Osteoarthritis (OA)

The most common form of arthritis, also known as "wear-and-tear arthritis" because it is apparently a normal consequence of aging. Associated with softening and degeneration of the articular cartilage, exposure of the epiphyseal bone, and development of bony spurs in the joint cavity, causing pain and restricting movement.

Rheumatoid arthritis (RA)

A more severe form of arthritis resulting from an autoimmune attack against the joint tissues (failure of the immune system to recognize the tissues as one's own).

Gout

A hereditary disease, most common in men, in which uric acid crystals accumulate in the joints and irritate the articular cartilage and synovial membrane. Causes gouty arthritis, with swelling, pain, tissue degeneration, and sometimes fusion of the joint. Most commonly affects the great toe.

Bursitis

Inflammation of a bursa, usually due to overexertion of a joint.

Tendinitis

A form of bursitis in which a tendon sheath is inflamed.

Disorders described elsewhere

Arthritis p. 320

Knee injuries p. 316

Dislocation of hip p. 313

Rotator cuff injury p. 386

Dislocation of mandible p. 310

Sprains p. 317

Dislocation of shoulder p. 311

TMJ syndrome p. 310

Saladin: Anatomy & I 9. Joints I Text

Physiology: The Unity of Form and Function, Third Edition

320 Part Two Support and Movement

Insight 9.4 Clinical Application

Arthritis and Artificial Joints

Arthritis26 is a broad term for pain and inflammation of a joint and embraces more than a hundred different diseases of largely obscure or unknown causes. In all of its forms, it is the most common crippling disease in the United States; nearly everyone past middle age develops arthritis to some degree. Physicians who treat joint disorders are called rheumatologists.

The most common form of arthritis is osteoarthritis (OA), also called "wear-and-tear arthritis" because it is apparently a normal consequence of years of wear on the joints. As joints age, the articular cartilage softens and degenerates. As the cartilage becomes roughened by wear, joint movement may be accompanied by crunching or crackling sounds called crepitus. OA affects especially the fingers, intervertebral joints, hips, and knees. As the articular cartilage wears away, exposed bone tissue often develops spurs that grow into the joint cavity, restrict movement, and cause pain. OA rarely occurs before age 40, but it affects about 85% of people older than 70. It usually does not cripple, but in severe cases it can immobilize the hip.

Rheumatoid arthritis (RA), which is far more severe than osteoarthritis, results from an autoimmune attack against the joint tissues. It begins when the body produces antibodies to fight an infection. Failing to recognize the body's own tissues, a misguided antibody known as rheumatoid factor also attacks the synovial membranes. Inflammatory cells accumulate in the synovial fluid and produce enzymes that degrade the articular cartilage. The synovial membrane thickens and adheres to the articular cartilage, fluid accumulates in the joint capsule, and the capsule is invaded by fibrous connective tissue. As articular cartilage degenerates, the joint begins to ossify, and sometimes the bones become solidly fused and immobilized, a condition called ankylosis27 (fig. 9.27). The disease tends to develop symmetrically—if the right wrist or hip develops RA, so does the left.

Rheumatoid arthritis is named for the fact that symptoms tend to flare up and subside (go into remission) periodically.28 It affects women far more often than men, and because RA typically begins between the ages of 30 and 40, it can cause decades of pain and disability. There is no cure, but joint damage can be slowed with hydrocortisone or other steroids. Because long-term use of steroids weakens the bone, however, aspirin is the treatment of first choice to control the inflammation. Physical therapy is also used to preserve the joint's range of motion and the patient's functional ability.

Arthroplasty29 a treatment of last resort, is the replacement of a diseased joint with an artificial device called a prosthesis.30 Joint prostheses were first developed to treat injuries in World War II and the Korean War. Total hip replacement (THR), first performed in 1963 by English orthopedic surgeon Sir John Charnley, is now the most common orthopedic procedure for the elderly. The first knee replacements were performed in the 1970s. Joint prostheses are now available for finger, shoulder, and elbow joints, as well as for hip and knee joints. Arthroplasty is performed on over 250,000 patients per year in the United States, primarily to relieve pain and restore function in elderly people with OA or RA.

Arthroplasty presents ongoing challenges for biomedical engineering. An effective prosthesis must be strong, nontoxic, and corrosion-resistant. In addition, it must bond firmly to the patient's bones and enable a normal range of motion with a minimum of friction. The heads of long bones are usually replaced with prostheses made of a

Physiology Health

Figure 9.27 Rheumatoid Arthritis (RA). (a) A severe case with ankylosis of the joints. (b) X ray of a hand with RA.

Figure 9.27 Rheumatoid Arthritis (RA). (a) A severe case with ankylosis of the joints. (b) X ray of a hand with RA.

metal alloy such as cobalt-chrome, titanium alloy, or stainless steel. Joint sockets are made of polyethylene (fig. 9.28). Prostheses are bonded to the patient's bone with screws or bone cement.

About 80% to 90% of hip replacements and at least 60% of ankle replacements are still functional 2 to 10 years later. The most common form of failure is detachment of the prosthesis from the bone. This problem has been reduced by using porous-coated prostheses, which become infiltrated by the patient's own bone and create a firmer bond. A prosthesis is not as strong as a natural joint, however, and is not an option for many young, active patients.

Arthroplasty has been greatly improved by computer-assisted design and manufacture (CAD/CAM). A computer scans X rays from the patient and presents several design possibilities for review. Once a design is selected, the computer generates a program to operate the machinery that produces the prosthesis. CAD/CAM has reduced the waiting period for a prosthesis from about 12 weeks to about 2 weeks and has lowered the cost dramatically.

26 arthr = joint + itis = inflammation

27ankyl = bent, crooked + osis = condition

28rheumat = tending to change

29arthro = joint + plasty = surgical repair

30prosthe = something added

Saladin: Anatomy & I 9. Joints I Text I I © The McGraw-Hill

Physiology: The Unity of Companies, 2003 Form and Function, Third Edition

Chapter 9 Joints 321

Figure 9.28 Joint Prostheses. (a) An artificial femoral head inserted into the femur. (b) An artificial knee joint bonded to a natural femur and tibia. (c) A porous-coated hip prosthesis. The caplike portion replaces the acetabulum of the os coxae, and the ball and shaft shown below are bonded to the proximal end of the femur. (d) X ray of a patient with a total hip replacement.

Artificial Joint Cad

Figure 9.28 Joint Prostheses. (a) An artificial femoral head inserted into the femur. (b) An artificial knee joint bonded to a natural femur and tibia. (c) A porous-coated hip prosthesis. The caplike portion replaces the acetabulum of the os coxae, and the ball and shaft shown below are bonded to the proximal end of the femur. (d) X ray of a patient with a total hip replacement.

Saladin: Anatomy & I 9. Joints I Text I I © The McGraw-Hill

Physiology: The Unity of Companies, 2003 Form and Function, Third Edition

322 Part Two Support and Movement

Was this article helpful?

+1 0
Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • malcolm
    What keeps the femur from slipping backward off the tibia?
    7 years ago
  • CAILIN YOUNG
    What keeps the tibia from slipping sideways off the talus?
    7 years ago
  • SABINE
    What keeps the mandibular condyle from slipping out of its fossa in a posterior direction?
    7 years ago
  • Abel
    What keeps the tibia from sliding off the talus?
    4 years ago

Post a comment