B3M2C1 PDF - Bone Classification and Structure
Document Details
Uploaded by RadiantChalcedony5173
Tags
Summary
This document provides an overview of bone classification, structure, and functions. It details the different types of bones (long, short, flat, irregular) and the microscopic structure of compact and spongy bones, their components. The functions of bones, including calcium storage and support, are also discussed.
Full Transcript
T his cartilaginous zone between the BONES diaphysis and bony epiphysis is calledthe...
T his cartilaginous zone between the BONES diaphysis and bony epiphysis is calledthe CLASSIFICATION OF BONES epiphyseal cartilage plate Based on the shape or form ○ Long bones ○ Metaphysis Humerus Zone of spongy bone that connects the Radius epiphysis cartilage plate to the diaphysis Ulna Metaphysis and epiphyseal cartilage = Etc. add addtl notes growth apparatus of bone which is ○ Short bones responsiblefortheincreaseinthelengthof Carpal and tarsal bones bone ○ Flat bones In adult life, the epiphyseal cartilage plate Skull becomes replaced with bone andincrease Sternum in length is no longer possible (Closureof Ribs the epiphysis) Etc. ○ Irregular bones Bone Matrix Vertebrae and hip bones In adult bones, they are arranged in layers (bone Based on microscopic appearance lamellae)indicatingtherhythmicalmannerinwhichit ○ Spongy or cancellous bones is produced and deposited. Consistsofanastomosing,branchingplatesor Two Major Components: bars of various sizes and shapes ○ Organic matrix - comprises 35% of its dry weight In between the trabeculaeareseveralminute ○ Inorganic salts - comprises 65% of its dry weight inter-communicating spaces filled with bone Organic matrix: marrow ○ Composed of glycosaminoglycans: Spongy bone always lies internal to the chondroitin sulfate compact bone Keratan sulfate ○ Compact bone Hyaluronic acid Appears as a solid mass composed of Thestainingisacidophilicbecauseofthepresenceof regularly arranged bone lamella containing abundant closely packed collagen. microscopic spaces and canals Therearealsonon-collagenmatrixproteinswhichare It surrounds a single large marrow cavity vitamin K dependent proteins: add addtl notes in ○ Osteocalcin Functions of Bones goodnotes Constitutes 2% of the total matrix proteins Storageofcalciumwhichcanbemobilizedasneededto Function unknown maintain the concentration of calcium in the blood and ○ Osteopontin other tissue fluid Maybe involved in binding ofosteoblastor Serves as the internal support of the body osteoclast to bone Protection of thevitalorgansinthecranialandthoracic Both osteocalcin and osteopontin are products of cavities osteoblast and their synthesis is stimulated by 1,25 Provides attachment of muscles and tendons and the dihydroxycholecalciferol, the active metabolite of leverage for muscle action for locomotion. Vitamin D. Encloses the bone marrow (hemopoietic tissue) if Collagen Type I considered as organ ○ constitutes90%oftheorganicmatter,knownas ○ Responsible for hemopoiesis. osteocollagen. Organiccomponentisresponsibleforthestrengthand STRUCTURE OF A LONG BONE resilience of bone Inorganic matter Gross or Macroscopic Parts ○ responsible for hardness of bone It has a shaft and 2 ends. Components: ○ Diaphysis or shaft mainly calcium and phosphate Middle cylindrical part composed of compact add addtl notes lesser amount of magnesium, bone sodium, citrates and carbonates It has the bone marrow cavity As bone matures, the amount of organic materials remains relatively constant while the H20 content ○ Epiphysis decreases and the proportion of inorganic matter Broad end of long bones increases,attainingintheadultamaximumif65%of In the early development of bone, the fat free dry weight. epiphysis consists of fetal hyaline cartilage Thismaybedecreasedtoaslowas even if the diaphysis has already developed 35% in rickets or osteomalacia into bone ○ These individuals have poorly calcified bones. L ater, the cartilage is replaced with spongy bone, except for a narrow zone next to the diaphysis which persist throughout theperiod of growth of the individual B3M2 Case 1 1of 22 Microscopic Appearance of Diaphysis (Compact Bone) osteogenetic layer or cambium layer Haversian system or osteon - structural and add addtl notes inner, more elastic,more cellular and functional unit of compact bone. looser layer ○ Parts or components: This contains bone forming cells but in Haversiancanal-orientedalongthelongaxis normal, fully formed bones, osteoblast of bone. This forms the central axis of the are not demonstrable but maybe Haversian system. It contains blood vessels, reactivated upon stimulation as in Lymphatics and nerves. fractures. HaversianLamellae-bonylamellaearranged Sharpey's fiber or perforating fibers of concentricallyaroundtheHaversiancanal.The Sharpey - These are coarse collagen collagen fibers in oneLamellaareorientedin fiber bundles coming from the one direction, but the orientation varies in periosteumandpenetratetheunderlying adjacent lamellae bone matrix serving to anchor the Osteocytes -distributedinroughlyconcentric periosteum to the bone layers. Theyarefoundintheperiosteallamellae They are lodged in the lacuna in and come in sets of interstitial lamellae between the Haversian Lamellae. They never occur in the Haversian From each lacuna radiates the minute add addtll notes systems or endosteal lamella. canaliculi Areas without periosteum: The canaliculi at the periphery loop area where tendon and ligaments back and do not communicate with where inserted the canaliculi of the other Haversian surface of patella system ends of long bones covered with It is through this canaliculi that articular cartilage nutrients and O2 from the blood subcapsularareasoftheneckofthe vessels in the Haversian canal reach femur and astragalus. the osteocytes in the lacuna. ○ Endosteum Lacunae and canaliculi are thinlayerofconnectivetissuewithosteogenic surrounded by a thin layer of special and hemopoietic potencies, that lines the ground substance different from the bone marrow cavities rest of organic matrix and forms the Itextendsasaliningintothecanalsystemof lacunar capsule. compact bone. Cementingline-thinbrightlinethatformsthe "Bone band" supplies fragmentsofbonein outer boundary of the Haversian system connective tissues not associated with bone. Its made up of ground substance. Interstitial Lamellae Calcium Mobilization from Bone ○ Fills up the spaces in between Haversian systems L ow level Ca → Stimulates parathyroid hormone ○ TheyareremnantsofHaversiansystemsthatwere secretion → Osteoblast is suppressed in their bone partially destroyed during the previous period of deposition and induces secretion of osteoclast - bone remodeling stimulating factor → Osteoclast resorbs → releaseof Circumferential or basic lamellae calcium → restores normal calcium level in blood. If calcium levels are high then the opposite will happen. ○ setsofbonelamellaearrangedinthecircumference ofthebone,i.e.externalandinternalsurfaceofthe Internal Reorganization of Bone bone. T he conversion of the primary network of trabeculae Periosteal Lamellae or outer circumferential laiddownduringintramembranousossificationisdueto Lamella the thickening of the trabecula and encroachment of Lying at the external surface of the bone on the perivascular spaces until these are bone, next to the periosteum obliterated The canaliculi on the outer lamella As this process continues, bone deposition is in open into the surface ill-defined layers and the collagen fibersarerandomly Endosteal Lamella oriented lines the bone marrow cavity lying But since they are surrounding the vascular channels next to the endosteum. Canaliculi they will now have a superficial resemblance to the open into the marrow cavity. Haversian systems so they are sometimes called Voltmann'scanal-orientedperpendiculartothelongaxis Primitive Haversian Systems of the bone. They should not be confused with the definitive ○ They interconnect Haversian systems, connect haversiansystemofadultboneswhichariseonlyinthe Haversian systems with the surface and bone courseoftheinternalreorganizationofprimarycompact marrow cavity bone that is referred to assecondary bone formation ○ They also conduct blood vessels, nerves and Incompactbones,theosteoblasticcrosionsofprimary lymphatics. bones result in formation of cavities (absorption ○ Periosteum cavities) which will enlarge to form long cylindrical Dense fibrous tissue covering of bone. cavities containing blood vessels andembryonicbone In young bones there are 2 layers: marrow. outer fibrous layer B3M2 Case 1 2of 22 W hen they reach a considerable length, bone o uter fibrous layer - contain blood vessels, destruction ceases and osteoclast give way to nerves and lymphatics. osteoblast and concentric bone lamellae are laid Growth (two types) downonthewallsofthecavityuntilitisfilledinform ○ Appositional/exogenous growth atypical haversian systems of lamellar bone increase in the size of a tissue or part by The lamellar bone starts to form from the age of 1. formation of new tissueon its surface. The outer limits of 2° haversian systems are This is from thechondrogeneticlayerwhere defined by distinctcement lines the innermost cells or fibroblasts are These are layers ofbonematrixformedwhenevera transformed into chondrocytes which lay period of resorption is followed by a new bone down a new matrix on the surface of the formation. They are poor in collagen and have no original cartilage plate. canaliculi. ○ Interstitial/endogenous growth Bone resorption and reconstruction continue increase in the size of tissue or part by throughout. mitosiswithin the tissue Bone Repair The chondrocytes divide and daughter cells Blood clot will form at the site of the fracture → laydownnewmatrixbetweenthemselvesas granulation tissue → condenses into a connective they move apart and in turn undergo cell tissue → fibrocartilaginous callus betweenthebone division fragments. Quiescent cells in the poriestan are This occurs in young, expansile cartilage. reactivated by the trauma → deposit new bone → Intheadult,continuedcelldivisionwillresult bony callus ( a mashwork of trabecula of woven in the formation of cellfamiliesbecausethe bone) → bridge the gap between fragments matrix is solid and very dense. Sameactivationofthecellsintheendostriumcallus Types of Cartilage whichisgraduallyreplacedbybone.Normalcontour Based on structure of the matrix: is restored by resorption of excess bone. Hyaline ○ homogeneous matrix, masked collagen fibers CARTILAGE Elastic A specialized type of fibrous connective tissue ○ abundant and obvious elastic fibers in matrix It is composed of cells and intercellular substance Fibrocartilage known a Matrix-solidbutflexibleandcontainstissue ○ obvious, coarse collagen fiber bundles. fibers It provides a kind of support to organs that combine Hyaline Cartilage rigidity with some degree of flexibility. The fundamental and most common type of cartilage Translucent, whitish but with bluish or pearly tint General Characteristics Degenerative Changes Cells ○ Calcification ○ chondrocytes with basophilic cytoplasm Most important and most common form. ○ largeandsphericalatthecenterbecomingoval→ Casaltsaredepositedinthematrixsothatit angular → small at the periphery. becomes hard and brittle. ○ Lodged in spaces known as lacuna/lenticular Infetalcartilage,itisnormalandpartofbone cavity formation ○ Occur singly or may form groups called cell Intheadult,itimpliesthelostofvitalityofthe family/cell territory. cartilage. Cartilage matrix ○ Amianthoid degeneration or asbestos formation ○ relatively abundant, solid but pliable, basophilic Characterized by the appearance of silky, and metachromatic glossy fibers resembling asbestos in the ○ it is made up of proteoglycans. The matrix glycosaminoglycans are chondroitin SO4 and This may lead to softening of the cartilage. keratan SO4 Has (3) subtypes: ○ They radiate in a bottle brush configuration. ○ Cartilagecapsule/capsularmatrix/territorialmatrix: 1. Adult Hyaline Cartilage more refractile and basophilic layer of the matrix O ccurrence: Respiratory passages (nose, larynx, It forms the wall of the lacuna. This trachea, bronchi), ventral end of ribs represents the youngest layer of the matrix Structure: At thecenteroftheplate,chondrocytesare produces by the chondrocytes. large and more or less spherical, with dark-staining ○ Interterritorial matrix: is the matrix in-between. nucleus and finely granular basophilic cytoplasm ○ Connective tissue fibers (collagen or elastic) are ○ It has abundant and large cell families (2-10). embedded in the matrix. Dominant collagen is Towardstheperiphery,thecellsaremoreovaland type Il, minor collagens are IX, X, XI. smaller and more flattened just beneath the Perichondrium perichondrium. ○ dense fibrous tissue covering; in the young cartilage, there are two layers in the perichondrium. chondrogenetic layer - inner cellular layer B3M2 Case 1 3of 22 ○ T hematrixisrelativelyabundant,basophilicand Fibrocartilage contains a network of fine collagenous fibers O ccurs mainly in the interventricular disc, symphysis embedded in the matrix. It appears pubis, sternoclavicular joint and other joints where homogeneous because collagen fibers are numerous fibrous bands are required to unite bones. masked. This is considered a transitionaltypebetweenhyaline ○ The perichondrium covers the cartilage plate cartilageanddensefibrousconnectivetissuethatforms entirely, there is no chondrogeneticlayer. tendons and ligaments. Avascular Structure: Chondrocytes are fewer and smaller.They ○ Nerve and lymphatics are absent. are oval or flattened, occurring singly or in rows ○ N utrients and O2 reach the chondrocyte by between the collagen fiber bundles. diffusion through the matrix from the blood ○ Cell families are smaller and rare. vessels in the perichondrium and surrounding ○ Matrixcontainsadensenetworkofcollagenfibers tissue fluid. whichmaybeinterlactinginanirregularpatternor maybe arranged in parallel, wavy bundles. 2. Fetal Hyaline Cartilage ○ No perichondrium. This forms the temporary skeleton in the embryo Degeneration- no tendency to undergo; if it does, that provides the model in which most bones similar as in hyaline. develop, except the flat bones of the skull. Structure ○ This is the most cellular of all the Regeneration in Cartilage subtypes. he defect is filled up with new connective tissue T ○ Chondrocytes are small, flattened and from the perichondrium and surrounding areolar irregularly arranged. tissue. The fibroblasts become chondrocytes and ○ They are scattered singly, cell families start to produce new matrix are rare. Large defects are filled by permanent fibrous tissue. ○ The matrix contains a network of fine collagenous fibers and is less basophilic. ○ The perichondrium has a chondrogenic layer and an outer fibrous layer. 3. Articular Cartilage T hiscoversthearticulatingsurfacesofsomebones.It isresilient and elastic. Structure: Chondrocytes are small, flattened or oval. Theyarescatteredsingly.Inthedeeperportion,cells arearrangedinrows.Fewandsmallcellfamiliesmay be present. Matrix same as the adult type. Perichondrium is absent in the surface that is in contact with the bone as well asonthesurfacethat faces the other bones that make-up the joint. It is presentonlyonthesidesandblendswiththefibrous tissue that makes up the capsule of the joint. Elastic Cartilage O ccurrence: External ear, eustachean tube, larynx (comiculate, cuneiform, tips of arytenoids) Appearance: yellowish, more opaque and flexible. Structure: chondrocytes are bigger than in hyaline. ○ cell families are smaller and fewer. ○ matrix containsanetworkofelasticfiberswhich maybe so abundant and closely packed as to obscure the ground substance ○ Collagen fibers are present but not seen. : perichondrium same as adult hyaline. Degenerative Changes: ○ Fatty degeneration chondrocytes appear to be capable to synthesize and store fat, so that they resemble fat cells Theareaofdegenerationlookslikeadipose tissue. ○ Calcification and asbestos formation are not as common as fatty generation. B3M2 Case 1 4of 22 Cranial Bones Special Features of the Skull Feature Description Sutures: Immovable joints between skull bones ine of articulation along top curved edge of L Squamous temporal bone Coronal Joint between parietal bones and frontal bone oint between parietal bones and occipital J Lambdoidal bone Sagittal Joint between right and left parietal bones “ Soft spots” where ossification is incomplete at birth; allow some compression of skull during Fontanels: birth; also important in determining position of head before delivery; six such areas located at angles of parietal bones t intersection of sagittal and coronal sutures A rontal (or F (juncture of parietal bones and frontal bone); anterior) diamond-shaped; largest of fontanels; usually closed by 1 ½ years of age t intersection of sagittal and lambdoidal A ccipital (or O sutures (juncture of parietal bones and posterior) occipital bone); triangular; usually closed by second month phenoid (or S t juncture of frontal, parietal, temporal, and A anterolateral) sphenoid bones astoid (or M t juncture of parietal, occipital, and temporal A posterolateral) bones; usually closed b second year paces or cavities within bones; those that S communicate with nose calledparanasal sinuses(frontal, sphenoid, ethmoidal, and Air Sinuses maxillary); mastoid cells communicate with middle ear rather than nose, therefore not included among paranasal sinuses Orbits formed by: Frontal Roof of orbit Ethmoid Medial wall Lacrimal Medial wall Sphenoid Lateral wall Zygomatic Lateral wall Maxillary Floor Palatine Floor Nasal Septum artition in midline of nasal cavity; Separates P cavity into right and left halves Formed by: erpendicular P plate of ethmoid Forms upper part of septum bone Vomer bone Forms lower, posterior part Cartilage Forms anterior part Wormian Bones Small islets of bone i sutures iny bones, referred to asauditory ossicles, in T alleus, Incus, M middle ear cavity in temporal bones; Stapes resemble, respectively, miniature hammer, anvil, and stirrup B3M2 Case 1 5of 22 B3M2 Case 1 6of 22 B3M2 Case 1 7of 22 B3M2 Case 1 8of 22 B3M2 Case 1 9of 22 SCALP Around the Mouth Levator Labii Superioris Alaque nasi Definition ○ Dilate the nares, expresses sadness soft structure that covers the vault of the cranium Levator Labii Superioris from the temporal line to the other, extending from ○ Proper elevator of the lips in sadness the eyebrows anteriorly to the superior Nuchal line Levator Anguli Oris posteriorly. ○ Elevate the angle of the mouth Layers Zygomaticus major Skin ○ Smiling muscle, laughing, draws ○ the dermis and epidermis of typical skin, the angle of the mouth thicker, provided with hairs and sebaceous Zygomaticus minor glands ○ Elevates the lateral half of the upper lip Connective tissue Risorius ○ a dense layer closely adherent to the ○ Draws the angle of the underlying aponeurosis, act as a support for mouth, laterally a blood vessels and nerves. grinning-sardonic smile Aponeurotic layer Depressor anguli oris (triangularis) ○ Epicranium - consisting of the occipito- frontalis ○ Expresses grief, disgust, depresses muscles united by the galea aponeurotica or the angle of the mouth,draws it epicranial laterally. Loose areolar connective tissue or subaponeurotic Depressor labii inferioris ○ very vascular but loosely attached to the layers ○ Terror, irony draws lower lip downward and above. laterally. ○ This layer is traversed by important emissary Mentalis veins that communicate with the dural ○ Pouting, doubt, elevates chin, raises & lower lip sinuses. Orbicularis oris ○ This layer is considered the dangerous area of ○ Chief intrinsic muscle of the lip, the scalp, because of the presence of emissary closing, twisting, protruding, veins may complicate dural sinuses. pressing against the teeth. Pericranium Blood supply: ○ external periosteum ○ Facial artery ○ Motor nerve supply- facial nerve MUSCLES OF FACIAL EXPRESSION Around the eyes Orbicularis oculi ○ Palpebral part Origin: Medial palpebral ligament Insertion: Lateral palpebral raphe Nerve supply: Facial nerve Action: Closes eyelids and dilates lacrimal sac ○ Orbital part Origin: Medial palpebral ligament and adjoining bone Insertion: Loops return to origin Nerve supply: Facial nerve Action: Throws skin around orbit into folds to protect eyeball ○ Corrugator supercilli Origin: Superciliary arch Insertion: Skin of the eyebrow Nerve supply: Facial nerve Action: Vertical wrinkles of forehead as in frowning Around the Nose Procerus ○ Wrinkles skin over the bridge of the nose Naris ○ Compressor - composed of mobile nasal cartilage Dilator ○ Pulls the ala laterally - widening the nasal aperture Depressor septi ○ Constricts the nostrils B3M2 Case 1 10of 22 the thyrohyoid muscles. NECK Itcontainstheinternaljugularvein,common Surface Landmarks of the Neck carotid artery (distal part), internal and Thyroid cartilage externalcarotidarteries(proximalportions), ○ is positionedintheanteriorneck,inferiortothe superior thyroid, lingual, andfacialarteries hyoidbone,towhichitisattachedbythethyroid (proximal portions), vagusandhypoglossal membrane. nerves. ○ It is composed of two quarnagular plates, or laminae, joined in the anterior midline. Muscular triangle ○ The Thyroid cartilage forms the main ○ Is bounded by the anterior border of the anterior attachment for the inferior sternocleidomastoid, the superior belly of the constrictor muscle. omohyoid, and the anterior midline of the neck. ○ It forms the laryngeal prominence or adam's ○ Hasafloorbythesternohyoidandsternothyroid apple. muscles. It contains the anterior jugular vein. Cricoid cartilage Posterior triangle ○ positioned inferior to the thyroid cartilage, is ○ It is bounded by the anterior border of the shaped like a signet ring, with a broad trapezius, the posterior border of the cartilaginous plate facing posteriorly. sternocleidomastoid, and the superior borderof ○ It forms the mainanteroinferiorattachmentfor the clavicle. cricopharyngeus muscle and provides ○ This triangle can be subdivided by the inferior attachment for the cricothyroideus muscles. belly of the omohyoid muscle into occipitaland External Jugular Vein subclavian triangles ○ superficial obliquely placed vein atthelateral ○ The roof is formed by the superficial layer of side of the neck. deep cervical fascia (investing layer). ○ Prominent among persons like singers, ○ Thefloorisformedbythesuperiorlytoinferiorly speakers or persons who speak with effort. by the splenius capitis, levator scapulae, scalenus posterior, and scalenus medius, all Triangles of the Neck covered by the prevertebral fascia. The side of the neck is divided into two main ○ ContaintheAccessorynervedescendingonthe triangles by the sternocleidomastoid muscle surfaceofthelevatorscapulae,rootsandtrunks ○ Anterior ofthebrachialplexus,subclavianarterycrossing ○ Posterior thefirstrib,supraclavicularnerve,suprascapular nerve, dorsal scapular andlongthoracicnerves The Anterior Triangle emerging through the scalenus mediusmuscle, The anterior triangle is bounded by the anterior nervetothelevatorscapulae,transversecervical midline, by the anterior border of the and suprascapular arteries sternocleidomastoid, and the superiorborderofthe clavicle. It is subdivided bythedigastricmuscleandsuperior belly of the omohyoid muscle into submandibular, submental, carotid and muscular triangle. ○ Submandibular triangle or digastric is bounded by the inferior border of the mandible and the anterior and posterior bellies of the digastric. Floor formed by the mylohyoid and hyoglossus muscles. It contains the Submandibular salivary gland, facial vein, facial artery, submandibular lymph nodes. ○ Submental triangle Isanunpairedtrianglelyingabovethe hyoid bone and between the anterior bellies of the digastric muscles. The floor is formed by the mylohyoid muscles. It contains the submental lymph nodesandbeginningsoftheanterior jugular veins. ○ Carotid triangle Is bounded by the anterior border of the sternocleidomastoid, the superior belly of theomohyoid,andtheposteriorbellyofthe digastric muscles. TheFloorformedbypartsofthemiddleand inferior pharyngealconstrictormusclesand B3M2 Case 1 11of 22 TERMS T here are no definitive studies that demonstrate that using antibiotics or antiseptic solutions inhibits Concussion infection or improves healing. ○ Severeblowtotheheadjostlesbrain,causingit Scalp Avulsion to strike the skull; results in temporary neural typically includes all layers of the scalp, sparingthe dysfunction underlying periosteum. Contusion If avulsion is small, closure can be accomplished ○ results from more severe blow thatbruisesthe primarily. brainanddisruptsneuralfunction:composedof If the denuded area is large, the wound may be areasofbruisedtissueinwhichtheblood-brain covered with a single layer of fine mesh gauze barrier may have lost its integrity, creating a A large dressing is placed on thegauge,andafirm heterogeneous region of injured cerebral circumferential dressing is applied to exert even parenchyma mixed with extravasated blood; pressure over the area. may coalesce to form intracerebral Delayed closure can be performed several days later. hematoma. Largescalpwoundscanberepairedbymicrosurgical Laceration techniques, includingvascularanastomosis,provided ○ disruption in the continuity of skin theavulsedscalphasbeenpreservedandsurgeryis Hematoma undertaken soon after injury. ○ accumulation of blood on a specific part of the Skull fractures body Are classified according to Epidural hematoma - accumulation of ○ whether the skin overlying the fracture isintact blood betweentheduramaterandskull; (closed) or disrupted (open or compound) commonly results from laceration of the ○ whether there is single fracture line (linear), middle meningeal artery during skull several fracture fracture. radiating from a central point (stellate), or Subdural hematoma - accumulation of fragmentationorbone(comminuted)and/or blood between dura and arachnoid; whethertheedgesofthefracturelinehave venous bleeding that forms slowly; been driven inward below the level of the maybe acute, subacute, or chronic surrounding bone (depressed) or not Subarachnoid hematoma (nondepressed) -bleeding in subarachnoid Simpleskullfractures(linear,stellateorcomminuted space nondepressed) require no specific treatment, Intracerebralhematoma-accumulationof ○ They are however potentially serious if they blood within the cerebrum cross vascular channels in the skull, such as DIAGNOSTICS PROCEDURES USED IN middle meningeal artery or dural venous sinuses. MUSCULOSKELETAL PROBLEMS ○ If these structures are torn, an epidural or R adiograms subdural hematoma may form. CT-Scan ○ A simple skull fracture that extends into the Magnetic Resonance Imaging accessory nasal sinuses or mastoid air cells is considered open, since it is in communication with air. MANAGEMENT Depressed skull fractures of ten require surgical Scalp Laceration treatment to elevate the depressed bone fragments. Scalp injurymaycausehemorrhageandsubsequent ○ Iftherearenountowardneurologicsignsandthe shock if not promptly treated fracture is closed, repair may be done electively Bleeding can usually be controlled by a pressure ○ Intraoperatively, the dura should be inspected dressing or by clamps applied to the galea and repaired. aponeurotica Open skull fractures also require surgical intervention. Scalp wounds should be closed as soon as possible ○ Linear or stellate, nondepressed openfractures Lacerations that overlie a depressed fracture or can be treated by simple closure of the scalp penetrating wound of the skull require debridement after thorough cleansing. and closure in the operating room. ○ Open fractures with severe comminution of Simple scalp lacerations should be debrided underlying bone should be treated in the removing all devitalized tissue, taking care not to operating room, where thorough debridement excise viable tissue. can be carried out. The wound copiously irrigated with saline,removing Facial Fractures foreign bodies that may lead to infection or leave Facial fracturesaremostfrequentlycausedbymotor unsightly tattoos, then the wound can be closed vehicle accidents and physical assaults. primarily, taking care to approximatebothgaleaand Although the specifics of facial fractures treatment skin. have evolved since the advent of craniofacial A good galeal closure provides excellent hemostasis. technique in the 1980s, the principle remains the When complete removal of devitalized tissue or same. foreign bodies cannot be assured, or when the The patient with facial fracture is often a multiple woundisheavilycontaminatedwithbacteria,itcan trauma patient a n d requires thorough evaluation. be left open and closed secondarily. B3M2 Case 1 12of 22 T he depression in the lateral face may also be a Physical Examination significant distortion in appearance. E xamination for facial trauma must besystematicand Non Comminutedzygomaticarcfracturessometimes complete. Proceeding from superior to inferior, the maybeelevatedbyslidinganinstrumentbeneaththe forehead and supraorbital ridge is palpated for any arch via an incision in the temporal scalp. fracture.Therimsarealsoevaluatedforanystepoffor Comminutedzygomaticarchfracturesusuallyrequire irregularity. The ophthalmologic examination includes plating via bicoronal incision papillary responses, extraocular muscle function, and Zygomaticomaxillary complex fractures result in a visual acuity. Any enophthalmos, inferiordisplacement depressed malar eminence and infraorbital rim. oftheglobe,orlimitationinextraocularmusclefunction The fracture lines are typically along the zygomatic is a sign of orbital fracture. frontalsuture,zygomaticarch,andinfraorbitalrimand Anypatientwithsignsofdirectinjurytotheocularglobe floor of the orbit, through the infraorbital foramen. or an orbital fracture should have a formal Thesepatientstypicallypresentwithaninferiorlyand ophthalmologic examination. laterallydisplacedeye,enopthlamos,andparesthesia The nose is examined for any gross deformity, the of the infraorbital nerve. septum is examined for hematoma, and patency of Malocclusion can result if thefractureextendsalong airway is ascertained. the anterior wall of the maxilla into the dental arch. The zygomatic arches are palpated for fractures. These fractures require open reduction and internal Depressed fracture of the zygomatic arches can fixationofthefracturefragmentsand,ifanysignificant impinge on the temporalis muscle. defect exists, reconstruction of the orbital floor. Itisimportanttonotewhetherthereispainassociated Antibioticsarealwaysusedinopenfractures.Grade1 with movement of the mandible or any limitation of and 2 open fractures with minimal contamination or mandibular excursion. straightforward roadcontaminationaretreatedwitha Fractures of the maxilla frequently run through the first generation cephalosporinsfor48hoursafterthe infraorbitalforamen,andthesepatientsfrequentlyhave first and subsequent procedures. paresthesia of the upper lip and teeth. GradeIIIwoundswithmorecontaminationaretreated Midface stability is assessed by grasping the upper with first generation Cephalosporin to cover incisorsandalveolarridgewithonehandandpalpating staphylococci, an aminoglycoside to cover the gram the nasofrontal junction and anterior maxilla with the negative organisms, and penicillin tocoverthegram other. positive rods. An attempt is then made to gently rock the alveolar Thisantibioticregimeniscontinuedfor72hoursafter ridge anteriorly and posteriorly each surgical procedure. Occlusionisnotedandpatientisaskedifhisteeth"fit FRACTURES together" as usual. F racture is defined as a linear deformation or The mandible is palpated for any tenderness or fracture. discontinuity ofboneproducedbyforcesthatexceed the ultimate strength of the material. Radiologic Examination deformationwithoutfracturecanoccurwithloadsthat Theradiologicexaminationisguidedbythehistoryand exceedtheelasticlimitofthebonebutnotitsultimate physical examination. strength.Thisisreferredtoasplasticdeformationand Mostpatientswillneedclearviewsofthecervicalspine, is more common in children. including odontoid, posteroanterior, and lateral to Pathologic fractures occur when the strength of the include the first thoracic vertebrae. bone is below normal, as in infections, tumors or The standard facial bone series includes
