chapter 19: the skeleton

Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 19: The Skeleton


Chapter Objectives Axial skeleton and appendicular skeleton. Formation of bone tissue. The structure of a long bone. Suture, symphysis and synovial joint. Roots pertaining to the skeleton. Main disorders that affect the skeleton and joints. Common methods to diagnose & treat disorders of the

skeleton. Abbreviations used in relation to the skeleton.


Key TermsNormal Structure and Function

acetabulum The bony socket in the hip bone that holds the head of the femur (from the Latin word for vinegar because it resembles the base of a vinegar cruet)

articulation A joint (adjective: articular)

atlas The first cervical vertebra (root: atlant/o)

axis The second cervical vertebra

bone A calcified form of dense connective tissue; osseous tissue; also an individual unit of the skeleton made of such tissue (root: oste/o)

bone marrow The soft material that fills the cavities of bones. Yellow marrow fills the central cavity of the long bones; blood cells are formed in red bone marrow, which is located in spongy bone tissue (root: myel/o)

bursa A fluid-filled sac that reduces friction near a joint (root: burs/o)

cartilage A type of dense connective tissue that is found in the skeleton, larynx, trachea, and bronchi. It is the precursor to most bone tissue (root: chondr/o)


Key TermsNormal Structure and Function (cont’d)

diarthrosis A freely movable joint; also called a synovial join; adjective: diarthrotic

diaphysis The shaft of a long bone

epiphyseal plate The growth region of a long bone; located in the metaphysis, between the diaphysis and epiphysis. When bone growth ceases, this area appears as the epiphyseal line

epiphysis The irregularly shaped end of a long bone

ilium The large, flared, superior portion of the pelvic bone; adjective: iliac; (root: ili/o)

joint The junction between two bones; articulation (root: arthr/o)

ligament A strong band of connective tissue that joins one bone to another

metaphysis The region of a long bone between the diaphysis (shaft) and epiphysis (end); during development, the growing region of a long bone



ossification The formation of bone tissue (from Latin os, meaning “bone”)

osteoblast A cell that produces bone tissue

osteoclast A cell that destroys bone tissue

osteocyte A mature bone cell that nourishes and maintains bone tissue

pelvis The large ring of bone at the inferior trunk. Formed of the two hip bones (os coxae) joined to the sacrum and coccyx (plural: pelves). Each os coxae is formed of three bones, the superior, flared ilium (IL-ē-um), ischium (IS-kē-um), and pubis (PŪ-bis).

periosteum The fibrous membrane that covers the surface of a bone

resorption Removal of bone by breakdown and absorption into the circulation



skeleton The bony framework of the body, consisting of 206 bones. The axial portion (80 bones) is composed of the skull, spinal column, ribs, and sternum. The appendicular skeleton (126 bones) contains the bones of the arms and legs, shoulder girdle, and pelvis.

suture An immovable joint, such as the joints between the skull bones

symphysis A slightly movable joint

synovial fluids The fluid contained in a freely movable (diarthrotic) joint; synovia (root: synov/i)

synovial joint A freely movable joint; has a joint cavity containing synovial fluid; a diarthrosis

tendon A fibrous band of connective tissue that attaches a muscle to a bone

thorax The upper part of the trunk between the neck and the abdomen; formed by the 12 pairs of ribs and sternum


Key TermsDisorders

ankylosing spondylitis

A chronic, progressive inflammatory disease involving the joints of the spine and surrounding soft tissue, most common in young males; also called rheumatoid spondylitis

ankylosis Immobility and fixation of a joint

arthritis Inflammation of a joint

chondrosarcoma A malignant tumor of cartilage

curvature of the spine

An exaggerated spinal curve, such as scoliosis, lordosis, or kyphosis

degenerative joint disease (DJD)

Osteoarthritis

fracture A break in a bone. In a closed or simple fracture, the broken bone does not penetrate the skin; in an open fracture, there is an accompanying wound in the skin


Key TermsDisorders (cont’d)

gout A form of acute arthritis, usually beginning in the knee or foot, caused by deposit of uric acid salts in the joints

herniated disk Protrusion of the center (nucleus pulposus) of an intervertebral disk into the spinal canal; ruptured or “slipped” disk

kyphosis An exaggerated curve of the spine in the thoracic region; hunchback, humpback

lordosis An exaggerated curve of the spine in the lumbar region; swayback

osteoarthritis (OA) Progressive deterioration of joint cartilage with growth of new bone and soft tissue in and around the joint; the most common form of arthritis; results from wear and tear, injury, or disease; also called degenerative joint disease (DJD)

osteogenic sarcoma A malignant bone tumor; osteosarcoma

osteomalacia A softening and weakening of the bones due to vitamin D deficiency or other disease



osteomyelitis Inflammation of bone and bone marrow caused by infection, usually bacterial

osteopenia A lower-than-average bone density, which may foreshadow osteoporosis

osteoporosis A condition characterized by reduction in bone density, most common in white women past menopause; predisposing factors include poor diet, inactivity, and low estrogen levels

Paget disease Skeletal disease of the elderly characterized by bone thickening and distortion with bowing of long bones; osteitis deformans

Pott disease Inflammation of the vertebrae, usually caused by tuberculosis

rheumatoid arthritis A chronic autoimmune disease of unknown origin resulting in inflammation of peripheral joints and related structures; more common in women than in men



rheumatoid factor A group of antibodies found in the blood in cases of rheumatoid arthritis and other systemic diseases

rickets Faulty bone formation in children, usually caused by a deficiency of vitamin D

sciatica Severe pain in the leg along the course of the sciatic nerve, usually related to spinal nerve root irritation

scoliosis A sideways curvature of the spine in any region

spondylolisthesis A forward displacement of one vertebra over another (-listhesis means “a slipping”)

spondylolysis Degeneration of the articulating portions of a vertebra allowing for spinal distortion, specifically in the lumbar region


Key TermsTreatment

alkaline phosphatase An enzyme needed in the formation of bone; serum activity of this enzyme is useful in diagnosis

arthrocentesis Aspiration of fluid from a joint by needle puncture

arthrodesis Surgical immobilization (fusion) of a joint; artificial ankylosis

arthroplasty Partial or total replacement of a joint with a prosthesis

arthroscopy Use of an endoscope to examine the interior of a joint or to perform surgery on the joint; the instrument used is an arthroscope

diskectomy Surgical removal of a herniated intervertebral disk; also spelled discectomy

orthopedics The study and treatment of disorders of the skeleton, muscles, and associated structures; literally “straight” (ortho) “child” (ped); also spelled orthopaedics

reduction of a fracture

Return of a fractured bone to a normal position; may be closed (not requiring surgery) or open (requiring surgery)

traction The process of drawing or pulling, such as traction of the head in the treatment of injuries to the cervical vertebrae


Key TermsDrugs

antiinflammatory agent Drug that reduces inflammation; includes steroids, such as cortisone, and nonsteroidal antiinflammatory drugs (NSAIDs)

bisphosphonate Agent used to prevent and treat osteoporosis; increases bone mass by decreasing bone turnover. Examples are alendronate (Fosamax) and risedronate (Actonel)

nonsteroidal antiinflammatory drug (NSAID)

Drug that reduces inflammation but is not a steroid; examples include aspirin and ibuprofen and other inhibitors of prostaglandins, naturally produced substances that promote inflammation

selective estrogen receptor modulator (SERM)

Drug that acts on estrogen receptors. Raloxifene (Avista) is used to prevent bone loss after menopause. Other SERMs are used to prevent and treat estrogen-sensitive breast cancer


Supplementary TermsNormal Structure and Function

annulus fibrosus The outer ringlike portion of an intervertebral disk

calvaria The domelike upper portion of the skull

coxa Hip

cruciate ligaments Ligaments that cross in the knee joint to connect the tibia and fibula. They are the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). Cruciate means “shaped like a cross”

genu The knee

glenoid cavity The bony socket in the scapula that articulates with the head of the humerus

hallux The great toe


Supplementary TermsNormal Structure and Function (cont’d)

malleolus The projection of the tibia or fibula on either side of the ankle

meniscus Crescent-shaped disk of cartilage found in certain joints, such as the knee joint. In the knee, the medial meniscus and the lateral meniscus separate the tibia and femur. (plural: menisci (me-NIS-kī); meniscus means “crescent”)

olecranon The process of the ulna that forms the elbow

os Bone (plural: ossa)

osseous Pertaining to bone

symphysis pubis The anterior pelvic joint, formed by the union of the two pubic bones; also called pubic symphysis


Supplementary TermsSymptoms and Conditions

achondroplasia Decreased growth of cartilage in the growth plate of long bones resulting in dwarfism; a genetic disorder

Baker cyst Mass formed at the knee joint by distention of a bursa with excess synovial fluid resulting from chronic irritation

bunion Inflammation and enlargement of the metatarsal joint of the great toe, usually with displacement of the great toe toward the other toes

bursitis Inflammation of a bursa, a small fluid-filled sac near a joint; causes include injury, irritation, and joint disease; the shoulder, hip, elbow, and knee are common sites

carpal tunnel syndrome Numbness and weakness of the hand caused by pressure on the median nerve as it passes through a tunnel formed by carpal bones

chondroma A benign tumor of cartilage


Supplementary TermsSymptoms and Conditions (cont’d)

Ewing tumor A bone tumor that usually appears in children 5 to 15 years of age. It begins in the shaft of a bone and spreads readily to other bones. It may respond to radiation therapy, but then returns. Also called Ewing sarcoma

exostosis A bony outgrowth from the surface of a bone

giant cell tumor A bone tumor that usually appears in children and young adults. The ends of the bones are destroyed, commonly at the knee, by a large mass that does not metastasize

hammertoe Change in position of the toe joints so that the toe takes on a claw-like appearance and the first joint protrudes upward, causing irritation and pain on walking

hallux valgus Painful condition involving lateral displacement of the great toe at the metatarsal joint. There is also enlargement of the metatarsal head and bunion formation



Heberden nodes Small, hard nodules formed in the cartilage of the distal joints of the fingers in osteoarthritis

hemarthrosis Bleeding into a joint cavity

Legg–Calvé–Perthes disease

Degeneration (osteochondrosis) of the proximal growth center of the femur. The bone is eventually restored, but there may be deformity and weakness. Most common in young boys. Also called coxa plana

multiple myeloma A cancer of blood-forming cells in bone marrow (see Chapter 10)

neurogenic arthropathy

Degenerative disease of joints caused by impaired nervous stimulation; most common cause is diabetes mellitus; Charcot arthropathy

Osgood-Schlatter disease

Degeneration (osteochondrosis) of the proximal growth center of the tibia causing pain and tendinitis at the knee

osteochondroma A benign tumor consisting of cartilage and bone



osteochondrosis Disease of a bone's growth center in children; degeneration of the tissue is followed by recalcification

osteodystrophy Abnormal bone development

osteogenesis imperfecta (OI)

A hereditary disease resulting in the formation of brittle bones that fracture easily. There is faulty synthesis of collagen, the main structural protein in connective tissue.

osteoma A benign bone tumor that usually remains small and localized

Reiter syndrome Chronic polyarthritis that usually affects young men; occurs after a bacterial infection and is common in those infected with HIV; may also involve the eyes and genitourinary tract

spondylosis Degeneration and ankylosis of the vertebrae resulting in pressure on the spinal cord and nerve roots; often applied to any degenerative lesion of the spine



sprain Trauma to a joint involving the ligaments

subluxation A partial dislocation

talipes A deformity of the foot, especially one occurring congenitally; clubfoot

valgus Bent outward

varus Bent inward

von Recklinghausen disease

Loss of bone tissue caused by increased parathyroid hormone; bones become decalcified and deformed, and fracture easily


Supplementary TermsDiagnosis and Treatment

allograft Graft of tissue between individuals of the same species but different genetic makeup; homograft, allogenic graft (see autograft)

arthroclasia Surgical breaking of an ankylosed joint to provide movement

aspiration Removal by suction, as removal of fluid from a body cavity; also inhalation, such as accidental inhalation of material into the respiratory tract

autograft Graft of tissue taken from a site on or in the body of the person receiving the graft; autologous graft (see allograft)

calcitonin A hormone from the thyroid gland that decreases resorption (loss) of bone tissue; used in the treatment of Paget disease and osteoporosis; also called thyrocalcitonin

chondroitin A complex polysaccharide found in connective tissue; used as a dietary supplement, usually with glucosamine, for treatment of joint pain

glucosamine A dietary supplement used in the treatment of joint pain


Supplementary TermsDiagnosis and Treatment (cont’d)

goniometer A device used to measure joint angles and movements (root goni/o means “angle”)

iontophoresis Introduction into the tissue by means of electric current, using the ions of a given drug; used in the treatment of musculoskeletal disorders

laminectomy Excision of the posterior arch (lamina) of a vertebra

meniscectomy Removal of the crescent-shaped cartilage (meniscus) of the knee joint

myelogram Radiograph of the spinal canal after injection of a radiopaque dye; used to evaluate a herniated disk

osteoplasty Scraping and removal of damaged bone from a joint

prosthesis An artificial organ or part, such as an artificial limb


Abbreviations

ACL Anterior cruciate ligament

AE Above the elbow

AK Above the knee

ASF Anterior spinal fusion

BE Below the elbow

BK Below the knee

BMD Bone mineral density

C Cervical vertebra; numbered C1 to C7

Co Coccyx; coccygeal


Abbreviations (cont’d)DEXA Dual-energy x-ray absorptiometry (scan)

DIP Distal interphalangeal (joint)

DJD Degenerative joint disease

Fx Fracture

HNP Herniated nucleus pulposus

IM Intramedullary

L Lumbar vertebra; numbered L1 to L5

MCP Metacarpophalangeal (joint)

MTP Metatarsophalangeal (joint)


Abbreviations (cont’d)

NSAID(s) Nonsteroidal antiinflammatory drug(s)

OA Osteoarthritis

OI Osteogenesis imperfecta

ORIF Open reduction internal fixation

ortho, ORTH Orthopedics

PCL Posterior cruciate ligament

PIP Proximal interphalangeal (joint)

PSF Posterior spinal fusion


Abbreviations (cont’d)RA Rheumatoid arthritis

S Sacrum; sacral

SERM Selective estrogen receptor modulator

T Thoracic vertebra; numbered T1 to T12

THA Total hip arthroplasty

TKA Total knee arthroplasty

TMJ Temporomandibular joint

Tx Traction


The Skeletal System

Axial Skeleton

SkullSpinal column

Thorax

Appendicular skeleton

Shoulder girdleArmsHands

Pelvic girdleLegsFeet


Axial Skeleton• Consists of:

– Skull• Cranial bones (8)• Facial bones (14)

– Spinal column• Cervical vertebrae (7)• Thoracic vertebrae (12)• Lumbar vertebrae (5)• Sacrum vertebrae (5 fused into 1)• Coccyx vertebrae (4 or 5 fused into 1)


Axial Skeleton (cont’d)– Thorax

• Ribs (12 pair)• True ribs (pairs 1-7)• False ribs (pairs 8-12)• Floating ribs (pairs 11 & 12)

• Sternum


Appendicular Skeleton

• Attached to axial skeleton• Consists of:

– Shoulder girdle• Clavicle• Scapula


Appendicular Skeleton (cont’d)

– Arm bones•Humerus•Radius•Ulna•Carpals•Metacarpals•Phalanges


Appendicular Skeleton (cont’d)– Pelvis

• 2 pelvic bones• Formed of 3 fused bones

Ilium Ischium pubis


Appendicular Skeleton (cont’d)– Leg bones

• Femur• Patella• Tibia• Fibula• Tarsals• Metatarsals• Phalanges


Skeleton Illustrated


Skull


Vertebral Column


Pelvic Bones


Roots for the Skeleton

Root Meaning Example Definition of Examplecrani/o skull, cranium craniometry measurement of the cranium

spondyl/o vertebra spondylolysis destruction and separation of a vertebra

vertebr/o vertebra, spinal column

paravertebral near the vertebrae or spinal column

rachi/o spine rachischisis fissure (-schisis) of the spine; spina bifida

cost/o rib costochondral pertaining to a rib and its cartilage


Roots for the Skeleton (cont’d)

Root Meaning Example Definition of Examplesacr/o sacrum presacral in front of the sacrum

coccy, coccyg/o coccyx coccygeal* pertaining to the coccyx

pelvi/o pelvis pelviscope endoscope for examining the pelvis

ili/o ilium iliopelvic pertaining to the ilium and pelvis

* Note spelling.


Bone Formation• Bones formed from cartilage• Ossification begins at birth and continues through adulthood• Three types of bone cells

– Osteoblasts = cells that produce bone– Osteocytes = mature bone cells– Osteoclasts = involved in breakdown of bone tissue

• Resorption = process of destroying bone for absorption into circulation


Structure of Long Bone• Diaphysis = shaft of compact bone tissue

– Yellow bone marrow located inside medullary cavity• Epiphysis = ends of spongy bone tissue

– Contains red bone marrow– Covered by thin layer of cartilage


Structure of Long Bone (cont’d)• Metaphysis = region between diaphysis and epiphysis

– Contains epiphyseal plate (growth region)• Periosteum = thin layer of fibrous tissue covering outside

of bone– Nourishes and protects bone– Generates new bone cells for growth and repair


Structure of a Long Bone


Roots for Bones and JointsRoot Meaning Example Definition of Exampleoste/o bone osteopenia deficiency of bone tissue

myel/o bone marrow; also, spinal cord

myeloid pertaining to or resembling bone marrow

chondr/o cartilage chondroblast a cartilage-forming cell

arthr/o joint arthrosis joint; condition affecting a joint

synov/i synovial fluid, joint, or membrane

asynovia lack of synovial fluid

burs/o bursa peribursal around a bursa


Joints• Known as articulations• Classified by amount of movement they allow

– Suture = immoveable joint• Held together by fibrous connective tissue

– Symphysis = slightly moveable joint• Connected by fibrous cartilage

• Synovial joint = freely moveable joint– Allow for wide range of movements


Joints (cont’d)• Synovial fluid contained within diarthrotic cavity

– Protects joint by cushioning and lubricating– Produced by synovial membrane

• Ligaments connect articulating bones– Stabilize and strengthen synovial joints


Clinical Aspects of the Skeleton

• Orthopedics = study of diseases of skeletal and muscular systems

• Detection: radiographs, CT, MRI, changes in blood levels of calcium and alkaline phosphatase


Clinical Aspects of the Skeleton (cont’d)

• Infections– Osteomyelitis = inflammation of bone

• Caused by pus-forming bacteria– Tuberculosis

• May spread to bone, especially long bones, wrist, and ankle bones

• If in spine, called Pott disease


Clinical Aspects of the Skeleton (cont’d)• Fractures

– Break in bone• Usually caused by trauma

– Effects depend on:• Location• Severity

• Closed fracture (skin not broken)• Open fracture (accompanied by skin wound)


Types of Fractures


Fracture Treatment• Reduction of fracture

– Realignment of broken bone– Closed - no surgery required– Open - requires surgery for proper positioning

• Healing phase– Splint or cast often needed– Bone immobilized– Traction


Metabolic Bone Diseases• Osteoporosis = loss of bone mass

– Weakens bones– Most susceptible: Women over 50– Possible prevention

• Adequate calcium intake• Weight-bearing exercises

– Diagnosed and monitored with DEXA scan


Metabolic Bone Diseases (cont’d)• Osteomalacia = softening of bone tissue

– Possible causes:• Deficiency of vitamin D• Renal disorders• Liver disease• Certain intestinal disorders


Metabolic Bone Diseases (cont’d)

• Paget disease (osteitis deformans)– Disorder of aging– Bones overgrown and thicker– Usually involves bones of axial skeleton


Neoplasms• Osteogenic sarcoma = highly malignant tumor

– Most commonly occurs in growing region– Often requires amputation

• Chondrosarcoma = cartilage tumor– May require amputation

• Signs of bone tumors– Pain– Easy fracture– Increases in serum calcium and alkaline phosphatase


Arthritis

• Joint inflammation– Most common form is osteoarthritis

• Joint cavity narrows• Bone thickens• Cartilage may crack and break loose

• Treatment– Analgesics– Antiinflammatory agents– Physical therapy


Rheumatoid Arthritis• Systemic inflammatory disease of joints

– Cause may involve immunologic reactions– Overgrowth of synovial membrane– Synovial fluid accumulates, causes joint swelling– Degeneration of bone eventually causes ankylosis

• Treatment– Rest– Physical therapy– Analgesics– Antiinflammatory drugs


Gout• Increased uric acid in blood causes salt deposits in joints • May result from

– Metabolic disturbance– Secondary effect of another disease

• Treatment– Drugs

• Suppress formation of uric acid• Increase elimination of uric acid


Joint Repair

• Arthroscopy = examination of joint interior and perform surgical repairs

• Arthroplasty = reconstruction or replacement of joint• Arthrodesis = fusion of joint


Disorders of the Spine• Ankylosing spondylitis

– Disease of spine mainly in males– Joint cartilage destroyed– Eventually disks between vertebrae calcify– Bones fuse– Starts “low” and progresses upward


Disorders of the Spine (cont’d)

• Spondylolisthesis– Forward sliding of vertebrae over vertebrae below

• Spondylolysis = degeneration of joint structures that stabilize vertebrae


Herniated Disk• Central mass of intervertebral disk protrudes into spinal

column• Commonly occurs:

– Lumbosacral region– Cervical regions

• Results from injury or heavy lifting• Severe cases may require diskectomy


Herniated Disk


Curvatures of the Spine

• Kyphosis = exaggerated curve in thoracic region, “hunchback”

• Lordosis = exaggerated curve in lumbar region, “swayback”

• Scoliosis = lateral curvature of spine in any region


Pretest1. The root oste/o means:

(a) cartilage (b) fat (c) bone (d) heart


Pretest

2. The root myel/o refers to the spinal cord. Used in reference to bones it means:

(a) bone marrow (b) joint (c) bone shaft (d) membrane


Pretest

3. A bone of the spinal column is a:(a) cortex (b) ventricle (c) labyrinth (d) vertebra


Pretest

4. The large, flared superior bone of the pelvis is the:(a) duodenum (b) ilium (c) thorax (d) phalange


Pretest

5. The bones of the wrist are the:(a) ribs (b) cervices (c) carpals (d) digits


Pretest

6. The bone of the thigh is the:(a) patella (b) umbilicus (c) cranium (d) femur


Pretest

7. A general term for inflammation of a joint is: (a) arthritis (b) conjunctivitis (c) epididymitis (d) myocarditis


Pretest

8. Chondrosarcoma is a tumor that originates in: (a) adipose tissue(b) bone (c) cartilage (d) muscle

chapter 19: the skeleton

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