264 December 2005 1 CE Credit

Human embryonic

oocyte fertilizationmorula (4–16 cells)free blastocystattachmentto endometrium of blastocystimplantation embryoyolk • bilaminarwith sac primary trilaminar with embryo primitivechorionic streak villigastrulation • of notochordal • formationHensen’s process primitive node and and pit neurenteric • appearancenotochordplate, canal neuralofblood neural • foldsislands and appearancesomites ofgroove first• deep cranial • neuralelevation heartneural of tubes folds • beginningearly neural of offusionfolds optic • offormation sulci first •arches presencetwo pharyngeal heart• beginning beatembryo • curving of closureof neuropore of cranialoptic • vesiclesformationof oropharyngealmembrane • rupture of closureneuropore of caudalpharyngeal • formation4 • appearance archeslimb of buds 3formation and of and upper tail of bud oticappearance • vesiclelimb buds of separation lower • lensvesicle placode ofectoderm from otic • surface

Table 1:DevelopmentAge in(days) weeks 1 1–8 2–3 4 5–6 7–12 13–15 16 18 20 22 24 26 28

14 The Surgical Technologist DECEMBER 2005 Embryological Development of the Musculoskeletal System Bob Caruthers, cst, phd

n the first eight weeks of development, incred- Intraembryonic mesoderm ible changes take place that define the struc- The vast majority of the musculoskeletal system I ture of the human embryo (Table 1). This arti- derives from intraembryonic mesoderm, which cle will provide an overview of the development forms from the epiblast during the process of of the musculoskeletal system. gastrulation. Gastrulation is the process by Skeletal tissue derives from mesenchymal which the germ layers are formed through cell cells, originating in different regions of the movement. The three primary germ layers are body, and may form connective tissue, blood, the ectoderm (outer layer), mesoderm (middle bone and cartilage. One of the common features layer), and endoderm (inner layer).6 Shortly after of mesenchymal cells, precursors of skeletal for- formation, the mesenchymal cells spread later- mation, is their tendency to be displaced some ally as a continuous layer between the ectoderm distance from their point of origin. Mesenchy- and endoderm, dividing into three regions: mal cells differentiate into osteoblasts and chon- ● Paraxial mesoderm (somites)—paired seg- droblasts. Osteoblasts and chondroblasts pro- ments (somitomeres) lying along the primitive duce different extracellular macromolecules. node. At approximately 20 days, somitomeres The end result of this process is bone and car- begin to transform into somites (solid masses of tilage, two types of connective tissue that are paraxial mesoderm). These will further develop related but significantly different.1,2,3,6 into the vertebral column and muscles.6

Human embryonic oocyte fertilizationmorula (4–16 cells)free blastocystattachmentto endometrium of blastocystimplantation embryoyolk • bilaminarwith sac primary trilaminar with embryo primitivechorionic streak villigastrulation • of notochordal • formationHensen’s process primitive node and and pit neurenteric • appearancenotochordplate, canal neuralofblood neural • foldsislands and appearancesomites ofgroove first• deep cranial • neuralelevation heartneural of tubes folds • beginningearly neural of offusionfolds optic • offormation sulci first •arches presencetwo pharyngeal heart• beginning beatembryo • curving of closureof neuropore of cranialoptic • vesiclesformationof oropharyngealmembrane • rupture of closureneuropore of caudalpharyngeal • formation4 • appearance archeslimb of buds 3formation and of and upper tail of bud oticappearance • vesiclelimb buds of separation lower • lensvesicle placode ofectoderm from otic • surface

Table 1:DevelopmentAge in(days) weeks 1 1–8 2–3 4 5–6 7–12 13–15 16 18 20 22 24 26 28

December 2005 The Surgical Technologist 15 264 DecemBER 2005 1 CE credit

● Intermediate mesoderm—a small cord of but chondroblasts in the centers of chondrification cells lateral to the somites which forms about quickly begin to secrete an extracellular matrix day 22. These cells develop into the urogeni- that is characteristic of cartilage. The chondro- tal system and its related structures. blasts themselves are trapped in the matrix they ● Lateral mesoderm—differentiates into secrete. Once ensnared, they are called chondro- somatic (dorsal layer) and splanchnic (ven- cytes and begin to form cartilage.6 tral layer) mesoderm. The somatic meso- Mature cartilage growth occurs by two derm contributes to the musculature of the means: cell division within the cartilage and the body wall and the limbs. The splanchnic addition of newly differentiated cells onto the mesoderm develops into the mesentery and outer surface. The first type of growth is called walls of the digestive tract.1,3,6 interstitial growth, and it is essential to the growth in length and width of bones. The second Somites develop through a transformation pro- type is called appositional growth. cess in which blocks of segmented cells with mes- Osteogenesis occurs through a different enchymal morphology are changed into a sphere process. Mesenchymal cells differentiate into of epithelial cells. This sphere of epithelial cells osteoblasts. Osteoblasts secrete an extracellular remains within the paraxial mesoderm. This pro- organic matrix, called osteoid, that is later min- cess is initiated by a signal from the overlying eralized into bone. Osteoblasts, like chondro- ectoderm. The epithelial somites divide into two blasts, become entrapped in the secretion prod- structures. The ventral half becomes the sclero- ucts and are called osteocytes.6 tome and the dorsal half, the dermomyotome. The sclerotome forms the vertebral bodies and Intramembranous versus their associated connective tissue elements. The endochondral ossification dermomyotome further splits into two layers, the Bones are formed through two processes: Intra- myotome and the dermatome, which form the membranous ossification and endochondral dermis, connective tissues and skeletal muscles. A ossification. Intramembranous ossification is majority of the axial musculoskeletal system arises the process by which most of the flat bones of the from the sclerotomes, and the rest of the musculo- jaw and skull (excluding the base) are formed. skeletal system develops from the limb bud mes- Intramembranous ossification requires no pre- enchymal cells and lateral somatic mesoderm.6 existing cartilage. These bones form from and replace an embryonic membrane of connective Chondrogenesis and osteogenesis tissue. A periosteum develops in the surface of Chondrogenesis refers to the development of this bone, forming osteoblasts which continue cartilage, and osteogenesis to the development the ossification process. There is a close associa- of bone. Cartilage formation begins with the tion with blood vessels in this process.3,6,7,8 appearance of centers of chondrification of the While these bones are not commonly of con- axial skeleton and limb buds. The initial change cern in orthopedic surgery, a brief outline of the appears as an area of mesenchymal condensation process follows:

Age (days) 32 33 37 41 44

16 The Surgical Technologist DECEMBER 2005 m

h j b e e e a a a g g k c c d d f f l c g

b g

a. Cartilage f. Medullary cavity j. Growth plate j b. Mesenchyme g. Proliferating chondrocytes k. Bone marrow h c. Hypertrophic chondrocytes h. Uncalcified cartilage l. Compact bone d. Osteoblasts (bone) i. Secondary ossification m. Epiphyseal cartilage e. Blood vessel center i

● Condensation of mesenchymal cells occur final size, at which time the osteoblasts revert Figure 1: 3,6,7,8 in close association with blood cells. Osteo- to osteoprogenitor cells. During progenitor cells differentiate into osteoblasts, and the osteoblasts secrete osteoid. Endochondral ossification requires the pres- endochrondal ● The osteoid is rapidly mineralized, and spic- ence of preexisting cartilage which is utilized as ossification, ules of bone begin to grow around the blood a temporary structure. The cartilage is partial- vessels. ly degraded prior to bone formation. This type existing cartilage ● The growing spicules merge creating large of ossification accounts for the formation of the provides a spongy networks of trabeculae which contain long bones of the extremities, vertebral column, bone lamellae and entrapped osteocytes. bones of the pelvis and the bones forming the framework for ● The trabeculae thicken with the addition of base of the skull. These bones are sometimes developing bone. new layers of bone on the outer surface. referred to as cartilage bones, because cartilagi- ● Osteoprogenitor cells on the outer surface nous models appear in the embryo. The process continue this cycle until the bone reaches its of endochondral ossification will be presented in

- -

formationoptic of cup lens and vesicle,development nasal pitshand platesurogenital of • primaryprominent sinusevidence • nasalhemispheres of pits cerebral • development plates •pigment of visible footof retinal auricular• developmentformation hillocks of upper•appearance liprays • rapid ofment finger head • sixhillocks enlargeauricularnasolacrimal • formation appearanceofgroove and elbow ofbeginning toe regions raysof eyelids of • distinctformation • tipnipples of • presence nose of elongationstraightening andbeginning of of midgut trunk of cordherniation • into umbilical bending elbows of armswebbed • distinct at appearance fingers butcular • plexusoftion scalp of • italanaldegenera-vas membranes and urogen-longerdistinct and freetoes but fingers • webbed indifferentexternal • genitalia longerbetter and free eyelidsdevelopment toes •and externalmore of roundedfusion ear of head eyelids •

Age (days) 32 33 37 41 44 48 51 52 54 57

Adapted from Carlson BM. Human Embryology and Developmental Biology, 2nd ed. St Louis: Mosby; 1999.

DECEMBER 2005 The Surgical Technologist 17 steps, but many of the steps temporarily coexist liferate toward the ends of the bone, enlarging with other steps.3,6,7,8 the marrow cavity. The bony collar increases by The formation of a cartilage model initiates the process of appositional growth. the process of endochondral ossification. This At the ends of the bones, the cartilage con- cartilage model provides a type of framework for tinues to proliferate, hypertrophy, and degener- the developing bone. (Figure 1) ate resulting in calcified cartilage. This cartilage An area of cartilage, called the perichondri- changes into bony spicules, leading to the forma- um, is surrounded by a dense connective tissue tion of spongy (cancellous) bone. New vascular capsule. The inner layer of the perichondrium buds may secondarily invade the epiphyses, there- contains a layer of chondroblasts that secretes car- by reinitiating the cycle of cartilage degeneration, tilage matrix, entraps and become chondrocytes. ossification and spongy bone formation.3,6,7,8 In the diaphyseal region of the cartilage model, It is important to remember that carti- the perichondrium differentiates into a layer of lage remains at the epiphyseal plate in children osteoprogenitor cells which become osteoblasts with growing bones. The cycle of proliferation, and secrete osteoid around the cartilage model. hypertrophy, degeneration and cartilage calci- The osteoid calcifies quickly forming a kind of fication continues in children and adolescents. collar around the cartilage model. The cells in the (The epiphyseal plate becomes inactive and ossi- center of the cartilage model hypertrophy and fies when adult stature has been reached.) Carti- then degenerate. This action leaves a cavity in the lage remains on the articular surfaces of bones center of the developing bone.6,7,8 throughout life. A vascular bud, assisted by osteoclasts, makes An inactive and closed epiphyseal place does a hole in the bony collar and invades the cavity not preclude all bone growth, however. Growth formed by the degeneration of the central cells of in length is prohibited but growth in diame- the cartilage model. The cavity is rapidly filled by ter can continue through the process of apposi- hematopoietic stem and osteoprogenitor cells, tional growth. Surface bone can be modified by both of which are derived from mesenchymal new bone formation, spongy bone can change in cells. This action establishes a marrow cavity response to several factors, and bones can respond inside the growing bone. The blood vessels pro- to fractures.3,6,

Figure 2: Stage 1 Stage 2 Development of Amniotic sac Embryonic the notochord. ectoderm Embryonic mesoderm Yolk sac Notochordal plate Notochordal Notochordal canal process Embryonic opening into yolk sac endoderm

Stage 3 Stage 4 Paraxial mesoderm

Notochordal plate infolding Lateral Intermediate Notochord to form the notochord mesoderm mesoderm

18 The Surgical Technologist DECEMBER 2005 Axial skeleton The term axial skeleton refers to the skeletal elements that develop along the long axis of the embryo. These elements are the vertebral col- Humerus umn, ribs, sternum and skull. The notochord, the first component of the axial skeleton to form (about 3.5 weeks), extends cephalad to the pro- chordal plate (Figure 2).6 The notochord repre- IV sents those components that will develop into the vertebral column and base of the skull.1 V As stated, most of the skull and facial bones develop by intramembraneous ossification. Radius Ulna Humerus Somites soon appear followed by rapid cell divi- II sion. Each somite forms a cavity known as a myocoele. Cells in the sclerotomal portion of III Humerus the somite migrate away from the myocoele and disperse around the notochord and neural tube. IV The vertebral bodies develop from the somite V sclerotome. Cells migrate cephalad and caudad Ulna to form a specific vertebral body. The notochord degenerates where the vertebral bodies form but II I 1,6 Radius remains in the gaps between the vertebrae. Phalanx Mesenchymal cells migrate dorsally and lat- III erally away from the vertebral bodies to form Scapula rudimentary vertebral arches and costal processes. Both the vertebral processes and the motor nerves retain a segmented arrangement. IV Carpus Ulna Sensory nerves passing to the skin are also seg- V mented and produce the characteristic derma- Metacarpus 1 tomes used in neurological evaluation. Adaptedfrom Carlson BM. Human Embryology andDevelopmental Biology, 3rded. Philadelphia: Mosby; 2004: 223. Somites contribute to the intercostal muscles and the muscles that flex and extend the verte- ● Lumbar vertebrae form large vertebral bodies in Figure 3: bral column. Intervertebral disks derive from order to withstand the forces of weight bearing. Formation of the rostral half of the sclerotome in the somites. ● The costal processes of the sacral vertebrae The spaces between vertebral bodies are packed fuse.1,3 the skeleton in with mesenchymal cells that differentiate into the mammalian fibroblasts and chondrocytes. These cells ulti- Appendicular skeleton mately form the annulus fibrosus, while noto- The bones of the upper and lower limbs are forelimb. chordal cells become the nucleus pulposus.1,6 referred to as the appendicular skeleton. The Four developmental variations occur in the appendicular skeleton develops from mesen- vertebrae that are important functionally and, at chymal elements in the limb buds. Limb buds times, clinically: have three components: a core of mesenchyme, ● The first cervical vertebra has an unusually a cover of ectoderm, and a cap called the distal large central foramen to accommodate the spi- apical ectodermal ridge. The apical ectodermal nal cord emerging from the foramen magnum. ridge has the ability to induce differentiation.1,5 ● Thoracic vertebrae have large costal process- The limb buds form in a somatic mesoderm es that form the ribs. at four weeks. Forelimb buds appear first and

DECEMBER 2005 The Surgical Technologist 19 develop faster than hindlimb buds. The bones models in the limb bud contain mesenchymal of the appendicular skeleton are formed by the cells that lie between the areas of cartilage. These process of endochondral ossification. By the fifth mesenchymal cells differentiate into joint cap- week, the forelimb buds have elongated slight- sule fibroblasts. Spaces appear between the mes- ly and soon divide into arm, forearm and hand enchymal cells and join to form a cavity in the components (Figure 3). Hands with partially joint. The cartilage models, themselves, under- separated fingers are evident by the beginning go ossification, except at an area on the articu- of the seventh week. Individual fingers and toes lar surfaces, where a sheet of hyaline cartilage are visible by the eighth week. Digital separa- remains throughout life. The fibroblasts around tion occurs through a process of controlled cell the joint differentiate into synoviocytes at death. Long bone development occurs by the approximately the same time that the surround- process previously described.1,5,6 ing mesenchymal cells change into blood vessels, ligaments, and layers of synovial cells that Joints line the joint cavity.1 Joint development must be accounted for in two major categories based on mobility. The joints Muscle development—skeletal muscle with limited mobility, called synarthroses, There are three types of muscle: smooth, car- are formed from mesenchymal cells that arise diac, and skeletal (Table 2). Some mesenchymal between developing bones and differentiate into cells differentiate into myoblasts, the precursors connective tissue.1 of muscle cells. Myoblasts aggregate and fuse to Diarthroses (ie synovial joints with consider- form myotubes, which are multinucleated mass- able mobility) are typically found in the appen- es of primitive skeletal muscle. As the myoblasts dicular skeleton, but occur in the axial skeleton fuse, a complex series of changes occur in the (eg the temporomandibular joint). Cartilage cytoarchitecture, involving the production of

Table 2: Major Types of Muscle - Embryologic Origins Muscle Origin Innervation Extrinsic eye muscles (most) Somitomeres 1-3 & prechordal plate Cranial nerves 3 & 4 Muscles that close the jaw Somitomere 4 Cranial nerves 5 Lateral rectus of eye Somitomere 5 Cranial nerves 6 Muscles that open the jaw Somitomere 6 Cranial nerves 7 Third-arch branchial muscles Somitomere 7 Cranial nerves 9 Intrinsic laryngeal muscles & Somites 1 & 2 Cranial nerves 10 pharyngeal muscles Muscles of tongue, larynx & neck Occipital somites Cranial nerves 11 & 12; spinal nerves Trunk, and limb muscles & Trunk somites Spinal nerves diaphragm Cardiac muscles Splanchnic mesoderm Autonomic Smooth muscles of gut & respiratory Splanchnic mesoderm Autonomic tract Other smooth muscles Local mesenchyme Autonomic

Adapted from Carlson BM. Patten’s foundations of embryology, ed 6. New York: McGraw-Hill; 1996.

20 The Surgical Technologist DECEMBER 2005 tissue-specific proteins and modifications in the Table 3: Causes of Congenital Malformations structure of the cell.1 The changes can be sum- Genetic factors Abnormal chromosome numbers marized as: ● Proteins of the contractile apparatus accumu- Abnormal chromosome structure late and change the cell structure (actin, α-actin, Genetic mutation myosin, tropomyosin, and troponin complex). Actin and myosin filaments form sarcomeres, Environmental factors Maternal infections the basic contractile units in striated muscle. Chemical teratogens ● Sarcomere formation results in structural – folic acid antagonists changes in the cell: nuclei are forced to the – androgenic hormones periphery; endoplasmic reticulum becomes – anticonvulsants sarcoplasmic reticulum; and mitochondria – sedatives / tranquilizers are elongated and oriented along the long – antineoplastic agents 1 axis of the sarcomeres. – alcohol – vitamin A Congenital abnormalities – antibiotics Embryonic development is a complicated pro- – other drugs cess. The vast majority of the time the process produces its intended product, a healthy fetus. Physical factors Ionizing radiation However, there are many congenital problems Others (data often inconclusive) that result in negative outcomes in a continuum Maternal factors Diabetes from very mild to severe to death. Approximately 2%–3% of all newborns are found to have at least Smoking one recognizable congenital defect, although the figure rises to 6% when all diagnoses for the first few years of life are totaled. Table 4: Problems in the Developmental A paradoxical situation currently exists. With Process Resulting in Malformations the decline in infant mortality rates secondary to infection and malnutrition, an increase in birth Duplication of anatomical structure defects is seen. As many as 30% of the infants Reversal of anatomical structure admitted to neonatology or pediatric units are Faulty inductive tissue interactions diagnosed with a disease or problem that is congenital in origin.1 A basic list of causative factors Absence of normal cell death for congenital malformation is found in Table 3. Failure of tube formation The developmental process itself can go awry. Problems in the developmental process are sum- Failure of tissue resorption 1,4,5 marized in Table 4. Failure of migration One cause of congenital problems is the effect of teratogens on embryonic development. Table Persistence of an earlier stage of development 5 lists some common teratogens, the critical Failure of fusion period of their activity, and common fetal mal- Hypoplasia and Hyperplasia formations. Other molecular failures or variances About the author Bob Caruthers, cst, phd, served as former AST deputy director and director of professional development. He was responsible for leading

DECEMBER 2005 The Surgical Technologist 21 Table 5: Common Teratogens and Resultant Malformations Teratogen Critical period (gestational days) Malformations Rubella virus 0–60 Cataract; heart malformations 0–120 Deafness Thalidomide 21–40 Reduction defects of limbs Androgenic steroids < 90 Clitoral hypertrophy; labial fusion > 90 Clitoral hypertrophy only Coumadin type anticoagulants < 100 Nasal hypoplasia > 100 Mental retardation Radioiodine therapy > 65 Fetal thyroid deficiency Tetracycline > 120 Primary teeth, stained dental enamel > 250 Permanent teeth, stained crowns

Adapted from Carlson BM. Human Embryology and Developmental Biology, 2nd ed. St Louis: Mosby; 1999.

many significant educational efforts: becoming 7. Histology Lab Manual. Bone. Health Sci- executive editor of the first edition of Surgical ences Center at Brooklyn State University of Technology for the Surgical Technologist: A Posi- New York. Suny Downstate Medical Center. tive Care Approach; launching a program of edu- http://ect.downstate.edu/courseware/histomanual/ cational CD-ROMs; and initiating the develop- bone.html. Accessed 10/26/05. ment of advance practice forums. 8. Osteogenesis: Formation and development of In January 2000, Bob was diagnosed with glio- bone taking place in connective tissue or in car- blastoma multiforme and faced his illness with tilage. College of Agricultural Consumer and strength and determination. In 2002, he lost the Environmental Sciences. University of Illinois battle and is still missed. This article was excerpt- at Urbana-Champaign. http://classes.aces.uiuc.edu/ ed from the beginning of his manuscript related AnSci312/Bone/Bonelect.htm. Accessed 10/26/05. to an orthopedic advanced practice manual. 9. Notochordal Process and Notochord. Com- puter Assisted Teaching System. University References of Vermont College of Medicine. http://cats. 1. Carlson BM. Human Embryology and Develop- med.uvm.edu/cats_teachingmod/embryology/1_3/ mental Biology. 2nd ed. St. Louis: Mosby; 1999. week_3/notochordal.html. Accessed 10/26/05. 2. Guyton AC. Textbook of Medical Physiology. 10. Carlson BM. Patten’s Foundations of Embry- 8th ed. Philadelphia: W.B. Saunders; 1991. ology. 6th ed. New York: McGraw-Hill; 1996 3. Johnson KE. Human Developmental Anato- my. Malvern, PA: Harwal Publishing Com- Bibliography pany; 1988. 1. Moore KL. The Developing Human: Clinical- 4. O’Rahilly R, Muller F. Human Embryology & ly Oriented Embryology. 4th ed. Philadelphia: Teratology. New York: John Wiley & Sons; 1992 W.B. Saunders; 1988. 5. Thorogood P. Embryos, Genes, and Birth 2. Sadler TW. Langman’s Medical Embryology. Defects. New York: John Wiley & Sons; 1997. 6th ed. Baltimore: Williams & Wilkins; 1990. 6. Carlson BM. Human Embryology and Devel- 3. Solomon EP, Schmidt RR, Adragna PI. Human opmental Biology. Updated 3rd edition. Phil- Anatomy & Physiology. 2nd ed. Ft Worth, TX: adelphia: Mosby; 2004. Saunders College Publishing; 1990.

22 The Surgical Technologist DECEMBER 2005 1. The process by which germ layers form 6. Which is not a component of a limb bud? through cell movement is: a. core of mesenchyme a. osteogenesis b. rod of fibroblasts CEE264 DecemxamBER 2005 1 CE credit b. gastrulation c. apical ectodermal ridge c. differentiation d. cover of ectoderm d. chondrogenesis 7. Controlled cell death begins after ____ to 2. Which region further divides into somatic separate individual fingers and toes. and splanchnic mesoderm? a. week 5 Embryological a. paraxial mesoderm b. week 6 b. intermediate mesoderm c. week 7 development of the c. lateral mesoderm d. week 8 d. none of the above musculoskeletal system 8. Joints with limited ability to move are: 3. Which is mismatched? a. synovial Earn CE credits at home a. interstitial growth: cell division within cartilage b. synarthroses You will be awarded continuing education (CE) credit(s) for b. osteoblasts: differentiated from c. diarthroses recertification after reading the designated article and com- mesenchymal cells d. axial pleting the exam with a score of 70% or better. c. appositional growth: addition of cells on the If you are a current AST member and are certified, credit outer surface 9. The embryonic origins of cardiac earned through completion of the CE exam will automatically d. osteocytes: secrete osteoid muscles are: be recorded in your file—you do not have to submit a CE report- a. the prechordal plate ing form. A printout of all the CE credits you have earned, includ- 4. Which process requires the prior existence b. trunk somites ing Journal CE credits, will be mailed to you in the first quarter of cartilage? c. somitomeres 1–3 following the end of the calendar year. You may check the status a. intramembranous ossification d. splanchnic mesoderm of your CE record with AST at any time. b. osteogenesis If you are not an AST member or not certified, you will be c. endochondral ossification 10. Myotubes are multinucleated masses notified by mail when Journal credits are submitted, but your d. chondrification of ____ muscle. credits will not be recorded in AST’s files. a. smooth Detach or photocopy the answer block, include your check or 5. The vertebral column, ribs, sternum and b. cardiac money order made payable to AST and send it to the Accounting skull are all elements of the: c. skeletal Department, AST, 6 West Dry Creek Circle, Suite 200, Littleton, CO a. axial skeleton d. synovial 80120-8031. b. notochord c. myocoele Members: $6 per CE, nonmembers: $10 per CE d. appendicular skeleton

264 December 2005 1 CE credit Embryological development a b c d a b c d

❑ Certified Member ❑ Certified Nonmember 1 ❑ ❑ ❑ ❑ 6 ❑ ❑ ❑ ❑

Certification No______2 ❑ ❑ ❑ ❑ 7 ❑ ❑ ❑ ❑

Name______3 ❑ ❑ ❑ ❑ 8 ❑ ❑ ❑ ❑

Address______4 ❑ ❑ ❑ ❑ 9 ❑ ❑ ❑ ❑

City______State______ZIP______5 ❑ ❑ ❑ ❑ 10 ❑ ❑ ❑ ❑

Telephone______Mark one box next to each number. Only one correct or best answer can be selected for each question. DECEMBER 2005 The Surgical Technologist 23