Mechanics of movement of joints

Frolich, Human Anatomy, Mechanics of Movement

MECHANICS OF MOVEMENT Tissues and Structures Involved

Muscle Nerve Bone Cartilage

What are Tendons? Role of Joints Mechanics of Joints Making it all work


Bone and Cartilage

Bone as tissue Bones as structures

formed from bone, cartilage and other tissues

Location of cartilage in skeleton and relation to joints

Fig. 6.1, M&M


HOW MOVEMENT HAPPENS: Muscles Pull on Tendons to Move Bones at Connections called Joints or Articulations


Tendon Generally regular

connective tissue Musculo-skeletal

connections Muscle to bone Muscle to muscle Bone to bone

Fig. 4.15f, M&M


Tendons Tendons are structures that

connect bone to muscle and are made up of tendon tissue

Can have various shapes Typical is cord-like tendon of

biceps Sheeths are

common--”aponeuroses” e.g. acromiotrapezius origin from thoracic vertebral spines

Fig. 10.3, M&M


• Ligaments connect bone-to-bone or reinforce joints--they are made up of tendinous tissue as well

•E.g. knee ligaments

Ligaments

Fig. 9.12, M&M


Joints or Articulations

Connections between bonesUsually, but not always allow for

movementFormed from various connective tissues

Fibrous Cartilaginous Synovial (most complex--typical limb joints)


Fibrous joints Suture

Bones tightly bound by minimal fiber

Only found in skull Syndemoses

Bones connected by ligaments

E.g. tibiofibular ligament, interosseous membrane of radius/ulna

Gomphoses Peg in socket joint Only found in teeth/alveoli

Fig. 9.1 a, M&M







Gomphoses Peg in socket joint Only found in teeth/alveoli Fig. 8.4, M&M

Fig. 9.1 b, M&M







Gomphoses Peg in socket joint Only found in

teeth/alveoliFig. 9.1 c, M&M


Cartilaginous Joints Synchondrosis

Hyaline cartilage unites bones

Epiphyseal growth plates Costal cartilage-sternum

Symphyses Fibrocartilage unites bones Pubic symphysis Intervertebral disc

Fig. 9.2, M&M


Synovial JointsMost common joints in bodyMost mobile jointsHave

Articular surfaces on bone with hyaline cartilage

Completely enclosed joint capsule formed from ligamentous connective tissue

Synovial fluid within capsule lubricates joint Some have meniscus or articular disc(e.g.

knee, jaw joint)


Also see Fig. 9.3, M&M




Synovial Joint Shape Types

Plane joints--intercarpal joints Hinge joints--elbow,ankle, interj-phalangeal Pivot joints--radio-ulnar joint Condyloid joints (egg into oval)--metacarpo-

phalangeal Saddle joints--carpo-metacarpal joint of thumb Ball-and-socket--hip, shoulder

The type of joint, in part, determines the range and direction of movement


Fig. 9.9, M&M








X-ray of hand affected by arthritis

Arthritis Arthritis = inflammation of the joints. Term

also used by lay people to describe pain in soft tissues.

Over 200 forms of arthritis.

About 30% of adults have arthritis.

Major symptom = in or around jointsPAIN

ARTHRITIS OSTEOARTHRITIS: common in older people.

The articular cartilage begins to break down, and bone spurs start to grow.

RHEUMATOID ARTHRITIS: It’s an autoimmune disease where body attacks and destroys the cartilage in synovial joints. It is NOT known for having spurs, like osteoarthritis.

GOUTY ARTHRITIS (gout). Caused by eating too much red meat or protein. The breakdown product is urea, and acid, which causes uric acid crystals in the cooler areas of the body, especially big toes.

Risk Factors for ArthritisAge > 40 years Women > men ObesityPrevious joint injuryEthnic background

Osteoarthritis Your mother, who is overweight, has pain in

both knees whenever she walks too far. Her knees are stiff in the morning and hurt before it rains. The pain gets better when she rests or takes acetaminophen, ibuprofen, or naprosyn over the counter. Her knees are big, bony, and sometimes swollen, but don’t get red or warm.

Osteoarthritis 21 million Americans have osteoarthritis

Breakdown in cartilage and new bone formation

Increased risk with older age, obesity, overuse or previous injury to joints

Osteoarthritis Common spots of osteoarthritis

hips knees hands, especially base of thumb base of great toe spine

What is not osteoarthritis? Red, hot joints


OsteoarthritisTreatment

weight reduction exercise physical and occupational therapy joint protection pain relief

over the counter medications, esp. acetaminophen prescription medications joint injections

joint replacement

Gout

Your brother, who has high blood pressure, woke up in the middle of the night with excruciating pain in his right great toe. It hurt so bad he could not stand to have the sheet rest on his foot last night; he couldn’t sleep. The joint at the base of the toe is red, hot, swollen and very tender. His other joints are OK. He had an episode just like this 5 months ago, and it went away by itself, over 5-7 days.

Gout Gout is caused by too much uric acid in the body.

Crystals of uric acid form inside a joint and cause inflammation, which makes the joint red, hot, swollen and painful.runs in families more common in men, women after menopause, and African

Americans. Other risk factors include

obesityhigh blood pressuredrinking too much alcoholkidney failurewater pills

Gout Treatment: See a doctor for evaluation and

medicine to reduce inflammation and pain. May need to medicine to prevent future attacks.

Can develop into chronic arthritis and cause joint destruction.

TendonitisYour son just spent two weeks painting

his house. Now, his shoulders hurt whenever he reaches overhead, even to put on a shirt. He has never had any shoulder pain before and his other joints are fine.


Tendonitis

Diagnosis = shoulder tendonitis. Tendonitis = inflammation of a tendon. A tendon is a tissue cord that holds a muscle onto a bone.

Treatments reduce/stop doing whatever caused it non-steroidal anti-inflammatory agents steroid injections physical therapy – splinting, heat, ice

BursitisBursitis = inflammation of a bursa. A bursa

is a closed fluid-filled sac that functions as a gliding surface to reduce friction between tissues of the body.

Common sites of bursitis outer shoulder area outer hip area elbow over and below the knee cap


Rheumatoid arthritis


-chronic, progressive chronic, progressive inflammatory disorder which inflammatory disorder which attacks the smaller synovial attacks the smaller synovial joints of the hands and feet and joints of the hands and feet and can cause can cause synositissynositis and erosion and erosion of the cartilage of the joints. of the cartilage of the joints. - Sometimes bigger joints like Sometimes bigger joints like the shoulder and knees can also the shoulder and knees can also get involved. get involved. - This inflammatory process can This inflammatory process can also extend to the lungs, heart, also extend to the lungs, heart, skin and the eyes.skin and the eyes.


•Typical feature in RA is early morning stiffness •Rheumatoid Arthritis Pain which later is relieved by movements. • This pain and stiffness typically also This pain and stiffness typically also appears after a period of inactivity appears after a period of inactivity being again relieved by movements.being again relieved by movements.

•This is a differentiating point This is a differentiating point with with Osteoarthritis where the Osteoarthritis where the pain is aggravated by pain is aggravated by movement and only one of the movement and only one of the larger joint is involved. larger joint is involved. • The tendons, the cartilage and The tendons, the cartilage and the bone surfaces of the joint the bone surfaces of the joint get eroded leading to get eroded leading to limitations of movement and limitations of movement and deformity of the joint. deformity of the joint. •It becomes increasingly It becomes increasingly difficult to perform daily minor difficult to perform daily minor tasks like holding a glass or a tasks like holding a glass or a spoon.spoon.

TYPES OF FRACTURES

COMMINUTED: The most serious; bone shatters into many small pieces. Bone graft might be needed.

SPIRAL: Bone was twisted. GREENSTICK: most common in children COMPRESSION: bone is crushed, like the vertebrae in

osteoporosis. STRESS: least serious, get tiny, almost invisible breaks. COMPOUND FRACTURES: Bone breaks and goes through skin.

Increased chance of infections, which can be life-threatening. SIMPLE FRACTURES: Skin is not broken. PATHOLOGICAL FRACTURE: When the bone (especially the

hip bone of someone with osteoporosis) breaks first, then the patient falls.

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Mechanics of movement of joints

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