Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 1 Chapter 8 Skeletal System

Slide 1Mosby items and derived items © 2007, 2003 by Mosby, Inc.

Chapter 8Chapter 8Skeletal SystemSkeletal System


IntroductionIntroduction

• Skeletal tissues form bones—the organs of Skeletal tissues form bones—the organs of the skeletal systemthe skeletal system

• The relationship of bones to each other and The relationship of bones to each other and to other body structures provides a basis for to other body structures provides a basis for understanding the function of other organ understanding the function of other organ systemssystems

• The adult skeleton is composed of 206 The adult skeleton is composed of 206 separate bonesseparate bones


Divisions of Skeleton Divisions of Skeleton (Figure 8-1; Table 8-1)(Figure 8-1; Table 8-1)

• Axial skeleton—the 80 bones of the head, Axial skeleton—the 80 bones of the head, neck, and torso; composed of 74 bones that neck, and torso; composed of 74 bones that form the upright axis of the body and six tiny form the upright axis of the body and six tiny middle ear bonesmiddle ear bones

• Appendicular skeleton—the 126 bones that Appendicular skeleton—the 126 bones that form the appendages to the axial skeleton; form the appendages to the axial skeleton; the upper and lower extremitiesthe upper and lower extremities


Axial SkeletonAxial Skeleton

• Skull—made up of 28 bones in two major divisions: Skull—made up of 28 bones in two major divisions: cranial bones and facial bones (Figures 8-2 to 8-7; cranial bones and facial bones (Figures 8-2 to 8-7; Table 8-3)Table 8-3)

Cranial bonesCranial bones

• Frontal bone (Figure 8-8, Frontal bone (Figure 8-8, CC))

Forms the forehead and anterior part of the top Forms the forehead and anterior part of the top of the craniumof the cranium

Contains the frontal sinusesContains the frontal sinuses

Forms the upper portion of the orbitsForms the upper portion of the orbits

Forms the coronal suture with the two parietal bonesForms the coronal suture with the two parietal bones



Cranial bones (cont.)Cranial bones (cont.)

• Parietal bones (Figure 8-8, A)Parietal bones (Figure 8-8, A)

Form the bulging top of the craniumForm the bulging top of the cranium

Form several sutures: lambdoidal suture with occipital Form several sutures: lambdoidal suture with occipital bone; squamous suture with temporal bone and part of bone; squamous suture with temporal bone and part of sphenoid; and coronal suture with frontal bonesphenoid; and coronal suture with frontal bone




• Temporal bones (Figure 8-8, B)Temporal bones (Figure 8-8, B)

Form the lower sides of the cranium and part Form the lower sides of the cranium and part of the cranial floorof the cranial floor

Contain the inner and middle earsContain the inner and middle ears




• Occipital bone (Figure 8-8, D)Occipital bone (Figure 8-8, D)

Forms the lower, posterior part of the skullForms the lower, posterior part of the skull

Forms immovable joints with three other cranial bones Forms immovable joints with three other cranial bones and a movable joint with the first cervical vertebraand a movable joint with the first cervical vertebra




• Sphenoid bone (Figure 8-8, E)Sphenoid bone (Figure 8-8, E)

A bat-shaped bone located in the central portion of the A bat-shaped bone located in the central portion of the cranial floorcranial floor

Anchors the frontal, parietal, occipital, and ethmoid bones Anchors the frontal, parietal, occipital, and ethmoid bones and forms part of the lateral wall of the cranium and part and forms part of the lateral wall of the cranium and part of the floor of each orbit (Figure 8-7)of the floor of each orbit (Figure 8-7)

Contains the sphenoid sinusesContains the sphenoid sinuses




• Ethmoid bone (Figure 8-8, F)Ethmoid bone (Figure 8-8, F)

A complicated, irregular bone that lies anterior to the A complicated, irregular bone that lies anterior to the sphenoid and posterior to the nasal bonessphenoid and posterior to the nasal bones

Forms the anterior cranial floor, medial orbit walls, upper Forms the anterior cranial floor, medial orbit walls, upper parts of the nasal septum, and sidewalls of the nasal cavityparts of the nasal septum, and sidewalls of the nasal cavity

The cribriform plate is located in the ethmoidThe cribriform plate is located in the ethmoid



Facial bones (Table 8-4)Facial bones (Table 8-4)

• Maxilla (upper jaw) (Figure 8-8, H)Maxilla (upper jaw) (Figure 8-8, H)

Two maxillae form the keystone of the faceTwo maxillae form the keystone of the face

Maxillae articulate with each other and with nasal, Maxillae articulate with each other and with nasal, zygomatic, inferior concha, and palatine boneszygomatic, inferior concha, and palatine bones

Forms parts of the orbital floors, roof of the mouth, and Forms parts of the orbital floors, roof of the mouth, and floor and sidewalls of the nosefloor and sidewalls of the nose

Contains maxillary sinusesContains maxillary sinuses



Facial bones (cont.)Facial bones (cont.)

• Mandible (lower jaw) (Figure 8-8, M)Mandible (lower jaw) (Figure 8-8, M)

Largest, strongest bone of the faceLargest, strongest bone of the face

Forms the only movable joint of the skull with the temporal Forms the only movable joint of the skull with the temporal bonebone

• Zygomatic bone (Figure 8-8, I)Zygomatic bone (Figure 8-8, I)

Shapes the cheek and forms the outer margin of the orbitShapes the cheek and forms the outer margin of the orbit

Forms the zygomatic arch with the zygomatic process of Forms the zygomatic arch with the zygomatic process of the temporal bonesthe temporal bones




• Nasal bone (Figures 8-8, L, and 8-10)Nasal bone (Figures 8-8, L, and 8-10)

Both nasal bones form the upper part of the bridge of the Both nasal bones form the upper part of the bridge of the nose, whereas cartilage forms the lower partnose, whereas cartilage forms the lower part

Articulates with the ethmoid bone, nasal septum, frontal Articulates with the ethmoid bone, nasal septum, frontal bone, maxillae, and the other nasal bonebone, maxillae, and the other nasal bone




• Lacrimal bone (Figure 8-8, K)Lacrimal bone (Figure 8-8, K)

Paper-thin bone that lies just posterior and lateral Paper-thin bone that lies just posterior and lateral to each nasal boneto each nasal bone

Forms the nasal cavity and medial wall of the orbitForms the nasal cavity and medial wall of the orbit

Contains groove for the nasolacrimal (tear) ductContains groove for the nasolacrimal (tear) duct

Articulates with the maxilla and the frontal Articulates with the maxilla and the frontal and ethmoid bonesand ethmoid bones




• Palatine bone (Figure 8-8, J)Palatine bone (Figure 8-8, J)

Two bones form the posterior part of the hard palateTwo bones form the posterior part of the hard palate

Vertical portion forms the lateral wall of the posterior part Vertical portion forms the lateral wall of the posterior part of each nasal cavityof each nasal cavity

Articulates with the maxillae and the sphenoid boneArticulates with the maxillae and the sphenoid bone




• Inferior nasal conchae (turbinates)Inferior nasal conchae (turbinates)

Form lower edge projecting into the nasal cavity and form Form lower edge projecting into the nasal cavity and form the nasal meatithe nasal meati

Articulate with ethmoid, lacrimal, maxillary, and palatine Articulate with ethmoid, lacrimal, maxillary, and palatine bonesbones

• Vomer bone (Figure 8-8, G)Vomer bone (Figure 8-8, G)

Forms posterior portion of the nasal septumForms posterior portion of the nasal septum

Articulates with the sphenoid, ethmoid, and palatine Articulates with the sphenoid, ethmoid, and palatine bones and maxillaebones and maxillae



• Eye orbits (Figure 8-7)Eye orbits (Figure 8-7)

Right and left eye orbitsRight and left eye orbits

• Contain eyes, associated eye muscles, lacrimal Contain eyes, associated eye muscles, lacrimal apparatus, blood vessels, and nervesapparatus, blood vessels, and nerves

• Thin and fragile orbital walls separate orbital structures Thin and fragile orbital walls separate orbital structures from cranial and nasal cavities and paranasal sinusesfrom cranial and nasal cavities and paranasal sinuses

• Traumatic injuries may result in “blowout fractures” Traumatic injuries may result in “blowout fractures” (Figure 8-7, C)(Figure 8-7, C)

• ““Raccoon eyes”—clinical sign of blowout fracture Raccoon eyes”—clinical sign of blowout fracture (Figure 8-7, D)(Figure 8-7, D)



• Fetal skull (Figure 8-11)Fetal skull (Figure 8-11)

Characterized by unique anatomic features not Characterized by unique anatomic features not seen in adult skullseen in adult skull

Fontanels or “soft spots” (4) allow skull to “mold” Fontanels or “soft spots” (4) allow skull to “mold” during birth process and permit rapid growth of during birth process and permit rapid growth of brain (Table 8-5)brain (Table 8-5)



• Fetal skull (cont.)Fetal skull (cont.) Permits differential growth or appearance of skull Permits differential growth or appearance of skull

components over timecomponents over time

• Face—smaller proportion of total cranium at birth (1/8) than in Face—smaller proportion of total cranium at birth (1/8) than in adult (1/2)adult (1/2)

• Head at birth is ¼ total body height; at maturity is about 1/8 Head at birth is ¼ total body height; at maturity is about 1/8 body heightbody height

• Sutures appear with skeletal maturity (Table 8-5)Sutures appear with skeletal maturity (Table 8-5)

• Paranasal sinuses—change in size and placement with skeletal Paranasal sinuses—change in size and placement with skeletal maturity (Figure 8-9)maturity (Figure 8-9)

• Appearance of deciduous and, later, permanent teethAppearance of deciduous and, later, permanent teeth



• Hyoid bone (Figure 8-12)Hyoid bone (Figure 8-12)

U-shaped bone located just above the larynx and U-shaped bone located just above the larynx and below the mandiblebelow the mandible

Suspended from the styloid processes of the Suspended from the styloid processes of the temporal bonetemporal bone

Only bone in the body that articulates with no Only bone in the body that articulates with no other bonesother bones



• Vertebral column (Figure 8-13)Vertebral column (Figure 8-13) Forms the flexible longitudinal axis of the skeletonForms the flexible longitudinal axis of the skeleton

Consists of 24 vertebrae plus the sacrum and coccyxConsists of 24 vertebrae plus the sacrum and coccyx

Segments of the vertebral column:Segments of the vertebral column:

• Cervical vertebrae, 7Cervical vertebrae, 7

• Thoracic vertebrae, 12Thoracic vertebrae, 12

• Lumbar vertebrae, 5Lumbar vertebrae, 5

• Sacrum—in adult, results from fusion of five separate vertebraeSacrum—in adult, results from fusion of five separate vertebrae

• Coccyx—in adult, results from fusion of four or five separate Coccyx—in adult, results from fusion of four or five separate vertebraevertebrae



• Vertebral column (cont.)Vertebral column (cont.)

Characteristics of the vertebrae (Figure 8-14; Table 8-6)Characteristics of the vertebrae (Figure 8-14; Table 8-6)

• All vertebrae, except the first, have a flat, rounded body All vertebrae, except the first, have a flat, rounded body anteriorly and centrally, a spinous process posteriorly, and two anteriorly and centrally, a spinous process posteriorly, and two transverse processes laterallytransverse processes laterally

• All but the sacrum and coccyx have vertebral foramenAll but the sacrum and coccyx have vertebral foramen

• Second cervical vertebra has upward projection, the dens, to Second cervical vertebra has upward projection, the dens, to allow rotation of the headallow rotation of the head

• Seventh cervical vertebra has long, blunt spinous processSeventh cervical vertebra has long, blunt spinous process

• Each thoracic vertebra has articular facets for the ribsEach thoracic vertebra has articular facets for the ribs



• Vertebral column (cont.)Vertebral column (cont.)

Vertebral column as a whole articulates with the Vertebral column as a whole articulates with the head, ribs, and iliac boneshead, ribs, and iliac bones

Individual vertebrae articulate with each other in Individual vertebrae articulate with each other in joints between their bodies and between their joints between their bodies and between their articular processesarticular processes



• Sternum (Figure 8-15)Sternum (Figure 8-15)

Dagger-shaped bone in the middle of the anterior Dagger-shaped bone in the middle of the anterior chest wall made up of three parts:chest wall made up of three parts:

• Manubrium—the upper, handle partManubrium—the upper, handle part

• Body—the middle, blade partBody—the middle, blade part

• Xiphoid process—the blunt cartilaginous lower tip, which Xiphoid process—the blunt cartilaginous lower tip, which ossifies during adult lifeossifies during adult life



• Sternum (cont.)Sternum (cont.)

Manubrium articulates with the clavicle and first ribManubrium articulates with the clavicle and first rib

Next nine ribs join the body of the sternum, Next nine ribs join the body of the sternum, either directly or indirectly, by means of the either directly or indirectly, by means of the costal cartilagecostal cartilage



• Ribs (Figures 8-15 and 8-16)Ribs (Figures 8-15 and 8-16)

Twelve pairs of ribs, with the vertebral column and Twelve pairs of ribs, with the vertebral column and sternum, form the thoraxsternum, form the thorax

Each rib articulates with the body and transverse Each rib articulates with the body and transverse process of its corresponding thoracic vertebraprocess of its corresponding thoracic vertebra

Ribs 2 through 9 articulate with the body of the Ribs 2 through 9 articulate with the body of the vertebra abovevertebra above



• Ribs (cont.)Ribs (cont.)

From its vertebral attachment, each rib curves outward, then From its vertebral attachment, each rib curves outward, then forward and downwardforward and downward

Rib attachment to the sternum:Rib attachment to the sternum:

• Ribs 1 through 8 join a costal cartilage that attaches it to the Ribs 1 through 8 join a costal cartilage that attaches it to the sternumsternum

• Costal cartilage of ribs 8 through 10 joins the cartilage of the rib Costal cartilage of ribs 8 through 10 joins the cartilage of the rib above to be indirectly attached to the sternumabove to be indirectly attached to the sternum

• Ribs 11 and 12 are floating ribs, because they do not attach Ribs 11 and 12 are floating ribs, because they do not attach even indirectly to the sternumeven indirectly to the sternum


Appendicular SkeletonAppendicular Skeleton

• Upper extremity (Table 8-7)Upper extremity (Table 8-7)

Consists of the bones of the shoulder girdle, upper Consists of the bones of the shoulder girdle, upper arm, lower arm, wrist, and handarm, lower arm, wrist, and hand

Shoulder girdle (Figure 8-17)Shoulder girdle (Figure 8-17)

• Made up of scapula and clavicleMade up of scapula and clavicle

• Clavicle forms only bony joint with trunk, the Clavicle forms only bony joint with trunk, the sternoclavicular jointsternoclavicular joint

• At its distal end, clavicle articulates with the acromion At its distal end, clavicle articulates with the acromion process of the scapulaprocess of the scapula



• Upper extremity (cont.)Upper extremity (cont.)

Humerus (Figures 8-18 and 8-19)Humerus (Figures 8-18 and 8-19)

• The long bone of the upper armThe long bone of the upper arm

• Articulates proximally with the glenoid fossa of the Articulates proximally with the glenoid fossa of the scapula and distally with the radius and ulnascapula and distally with the radius and ulna




UlnaUlna

• Long bone found on little finger side of forearmLong bone found on little finger side of forearm

• Articulates proximally with humerus and radius and Articulates proximally with humerus and radius and distally with a fibrocartilaginous diskdistally with a fibrocartilaginous disk




RadiusRadius

• Long bone found on thumb side of forearmLong bone found on thumb side of forearm

• Articulates proximally with capitulum of humerus and Articulates proximally with capitulum of humerus and radial notch of ulna; articulates distally with scaphoid radial notch of ulna; articulates distally with scaphoid and lunate carpals and with head of ulnaand lunate carpals and with head of ulna



• Upper extremity (cont.)Upper extremity (cont.) Carpal bones (Figure 8-20)Carpal bones (Figure 8-20)

• Eight small bones that form wristEight small bones that form wrist

• Carpals are bound closely and firmly by ligaments and Carpals are bound closely and firmly by ligaments and form two rows of four carpals eachform two rows of four carpals each

Proximal row is made up of pisiform, triquetrum, lunate, Proximal row is made up of pisiform, triquetrum, lunate, and scaphoidand scaphoid

Distal row is made up of hamate, capitate, trapezoid, Distal row is made up of hamate, capitate, trapezoid, and trapeziumand trapezium

• The joints between radius and carpals allow wrist and The joints between radius and carpals allow wrist and hand movementshand movements




Metacarpal bonesMetacarpal bones

• Form framework of handForm framework of hand

• Thumb metacarpal forms the most freely movable joint Thumb metacarpal forms the most freely movable joint with the carpalswith the carpals

• Heads of metacarpals (knuckles) articulate with Heads of metacarpals (knuckles) articulate with phalangesphalanges



• Lower extremityLower extremity

Consists of the bones of hip, thigh, lower leg, Consists of the bones of hip, thigh, lower leg, ankle, and foot (Table 8-8)ankle, and foot (Table 8-8)



• Lower extremity (cont.)Lower extremity (cont.)

Pelvic girdle is made up of the sacrum and the two coxal Pelvic girdle is made up of the sacrum and the two coxal bones, bound tightly by strong ligaments (Figure 8-21)bones, bound tightly by strong ligaments (Figure 8-21)

• A stable circular base that supports the trunk and attaches the A stable circular base that supports the trunk and attaches the lower extremities to itlower extremities to it

• Each coxal bone is made up of three bones that fuse together Each coxal bone is made up of three bones that fuse together (Figure 8-22):(Figure 8-22):

Ilium—largest and uppermostIlium—largest and uppermost

Ischium—strongest and lowermostIschium—strongest and lowermost

Pubis—anteriormostPubis—anteriormost



• Lower extremity (cont.)Lower extremity (cont.) Femur—longest and heaviest bone in the body Femur—longest and heaviest bone in the body

(Figure 8-23)(Figure 8-23)

Patella—largest sesamoid bone in the bodyPatella—largest sesamoid bone in the body

TibiaTibia

• The larger, stronger, and more medially and superficially The larger, stronger, and more medially and superficially located of the two leg boneslocated of the two leg bones

• Articulates proximally with the femur to form the Articulates proximally with the femur to form the knee jointknee joint

• Articulates distally with the fibula and the talusArticulates distally with the fibula and the talus




FibulaFibula

• The smaller, more laterally and deeply placed The smaller, more laterally and deeply placed of two leg bonesof two leg bones

• Articulates with tibiaArticulates with tibia




Foot (Figures 8-24 and 8-25)Foot (Figures 8-24 and 8-25)

• Structure is similar to that of the hand, with adaptations Structure is similar to that of the hand, with adaptations for supporting weightfor supporting weight

• Foot bones are held together to form spring archesFoot bones are held together to form spring arches

Medial longitudinal arch is made up of calcaneus, talus, Medial longitudinal arch is made up of calcaneus, talus, navicular, cuneiforms, and medial three metatarsalsnavicular, cuneiforms, and medial three metatarsals

Lateral longitudinal arch is made up of calcaneus, cuboid, Lateral longitudinal arch is made up of calcaneus, cuboid, and fourth and fifth metatarsalsand fourth and fifth metatarsals


Skeletal Differences Skeletal Differences in Men and Womenin Men and Women

• Male skeleton is larger and heavier than Male skeleton is larger and heavier than female skeletonfemale skeleton

• Pelvic differences (Figure 8-26; Table 8-9)Pelvic differences (Figure 8-26; Table 8-9)

Male pelvis—deep and funnel-shaped with a Male pelvis—deep and funnel-shaped with a narrow pubic archnarrow pubic arch

Female pelvis—shallow, broad, and flaring with Female pelvis—shallow, broad, and flaring with a wider pubic archa wider pubic arch


Cycle of Life: The Aging Skeleton Cycle of Life: The Aging Skeleton

• Aging changes begin at fertilization and continue Aging changes begin at fertilization and continue over a lifetimeover a lifetime

Changes can be positive or negativeChanges can be positive or negative

• Normal bone development is a skeletal aging processNormal bone development is a skeletal aging process

Intramembranous ossificationIntramembranous ossification

Endochondral ossificationEndochondral ossification

Appearance of ossification centers and closure of Appearance of ossification centers and closure of epiphyseal plates can be used to estimate potential growth epiphyseal plates can be used to estimate potential growth and heightand height


Cycle of Life: The Aging SkeletonCycle of Life: The Aging Skeleton

• Characteristics of bone during ageCharacteristics of bone during age

• Bone produced early in life is properly Bone produced early in life is properly calcified but not brittlecalcified but not brittle

• Osteoblastic activity during early periods of bone Osteoblastic activity during early periods of bone remodeling results in deposition of more bone than is remodeling results in deposition of more bone than is resorbedresorbed

Prior to puberty results in growth of bonesPrior to puberty results in growth of bones

After puberty and until early thirties, replaced bone After puberty and until early thirties, replaced bone is strongeris stronger



Negative outcomes of skeletal aging begin Negative outcomes of skeletal aging begin between 30 and 40 years of agebetween 30 and 40 years of age

• Decrease in osteoblast numbers with production of lower Decrease in osteoblast numbers with production of lower quality matrixquality matrix

• Increase in osteoclast numbers and activity with Increase in osteoclast numbers and activity with increased bone lossincreased bone loss

• Mature osteocytes coalesce and shrink, producing a Mature osteocytes coalesce and shrink, producing a honeycomb of tiny holes in the compact bonehoneycomb of tiny holes in the compact bone



Negative outcomes (cont.)Negative outcomes (cont.)

• Skeleton as a whole loses strength, and fracture risk Skeleton as a whole loses strength, and fracture risk increasesincreases

• Decrease in number of trabeculae in spongy bone in Decrease in number of trabeculae in spongy bone in vertebral bodies and other bones results in vertebral bodies and other bones results in “spontaneous” as well as compression fractures“spontaneous” as well as compression fractures

• Overall height decreases beginning at about age 35Overall height decreases beginning at about age 35

• Osteoporosis is a common and very serious bone Osteoporosis is a common and very serious bone disease in old agedisease in old age


The Big PictureThe Big Picture

• Skeletal system is a good example of increasing Skeletal system is a good example of increasing structural hierarchy in the bodystructural hierarchy in the body

Skeletal tissues are grouped into discrete organs—bonesSkeletal tissues are grouped into discrete organs—bones

Skeletal system consists of bones, blood vessels, nerves, Skeletal system consists of bones, blood vessels, nerves, and other tissues grouped to form a complex operational unitand other tissues grouped to form a complex operational unit

Integration of skeletal system with other body organ systems Integration of skeletal system with other body organ systems permits homeostasis to occurpermits homeostasis to occur

Skeletal system is more than an assemblage of individual Skeletal system is more than an assemblage of individual bones—it represents a complex and interdependent bones—it represents a complex and interdependent functional unit of the bodyfunctional unit of the body


Mechanisms of Disease—Mechanisms of Disease—Bone FracturesBone Fractures

• Fracture defined as partial or complete break in Fracture defined as partial or complete break in continuity of a bonecontinuity of a bone

Mechanical stress and traumatic injury are most common Mechanical stress and traumatic injury are most common causescauses

Pathological or spontaneous fractures occur in absence of Pathological or spontaneous fractures occur in absence of traumatrauma

Stress fractures may not be apparent in clinical examination Stress fractures may not be apparent in clinical examination or standard x-ray images but can be seen in bone scansor standard x-ray images but can be seen in bone scans

• Bone damage is microscopicBone damage is microscopic

• Caused by repetitive trauma (e.g., marathon runners)Caused by repetitive trauma (e.g., marathon runners)



• Fracture defined (cont.) Fracture defined (cont.)

Displaced, open or compound fractures—do not produce a break in Displaced, open or compound fractures—do not produce a break in the skin and pose less danger of infectionthe skin and pose less danger of infection

Nondisplaced, closed or simple fractures—do not produce a break Nondisplaced, closed or simple fractures—do not produce a break in the skin and pose less danger of infectionin the skin and pose less danger of infection

Fracture types:Fracture types:

• Impacted—one end of fracture driven into diaphysis of other fragmentImpacted—one end of fracture driven into diaphysis of other fragment

• Complete—break extends across entire section of boneComplete—break extends across entire section of bone

• Incomplete—some fracture components still partially joinedIncomplete—some fracture components still partially joined

• Dentate—fracture components jagged and fit together like teeth on a Dentate—fracture components jagged and fit together like teeth on a geargear

• Comminuted—crushed, small, crumbled bone fragments near fractureComminuted—crushed, small, crumbled bone fragments near fracture



Fracture types (cont.)Fracture types (cont.)

• Avulsion—bone fragments pulled away from underlying bone Avulsion—bone fragments pulled away from underlying bone surface or bone totally torn from body partsurface or bone totally torn from body part

• Linear—fracture line parallel to the bone’s long axisLinear—fracture line parallel to the bone’s long axis

• Transverse—fracture line at right angle to long axis of boneTransverse—fracture line at right angle to long axis of bone

• Oblique—fracture line slanted or diagonal to longitudinal axisOblique—fracture line slanted or diagonal to longitudinal axis

• Spiral—fracture line spirals around long axisSpiral—fracture line spirals around long axis

• Hairline—common in skull—fracture components small and Hairline—common in skull—fracture components small and aligned; if fracture is pushed downward, called a depressed aligned; if fracture is pushed downward, called a depressed fracturefracture



Fracture types (cont.)Fracture types (cont.)

• Greenstick—bone bent but broken only on one side Greenstick—bone bent but broken only on one side (common in children)(common in children)

• Pott’s—fracture of lower tibiaPott’s—fracture of lower tibia

• Colles’—fracture of distal radiusColles’—fracture of distal radius

• LeFort—fracture of face and/or base of skullLeFort—fracture of face and/or base of skull

• Hangman’s—fracture of posterior elements in upper Hangman’s—fracture of posterior elements in upper cervical spine, especially the axiscervical spine, especially the axis

• Blowout—fracture of the eye orbitBlowout—fracture of the eye orbit



Osgood-Schlatter disease Osgood-Schlatter disease

Avulsion fracture of tibial tuberosity fragments the Avulsion fracture of tibial tuberosity fragments the surfacesurface

• Caused by powerful contraction of quadriceps muscle Caused by powerful contraction of quadriceps muscle group pulling on patellar ligament attached to tibial group pulling on patellar ligament attached to tibial tuberositytuberosity

• Common in adolescent athletes in whom patellar Common in adolescent athletes in whom patellar ligament is stronger than underlying boneligament is stronger than underlying bone


Mechanisms of Disease—Mechanisms of Disease—Treatment of FracturesTreatment of Fractures

• Clinical signs of fracture include pain, loss of function, Clinical signs of fracture include pain, loss of function, false motion, soft tissue edema, deformity, and crepitusfalse motion, soft tissue edema, deformity, and crepitus

• Initial treatment is realignment and immobilization of bone Initial treatment is realignment and immobilization of bone fragmentsfragments

Closed reduction—alignment completed without surgeryClosed reduction—alignment completed without surgery

Open reduction—surgery required to align and internally Open reduction—surgery required to align and internally immobilize bone fragments with screws, wires, plates, or other immobilize bone fragments with screws, wires, plates, or other orthopedic devicesorthopedic devices

After reduction, immobilization generally accomplished by casts, After reduction, immobilization generally accomplished by casts, splints, and bandagessplints, and bandages

Traction sometimes used—especially in childrenTraction sometimes used—especially in children

Restoration of function is treatment priority following healingRestoration of function is treatment priority following healing


Mechanisms of Disease—Mastoiditis Mechanisms of Disease—Mastoiditis

• Inflammation of air spaces within mastoid portion of Inflammation of air spaces within mastoid portion of temporal bonetemporal bone Pus may enter mastoid air spaces from middle ear infection Pus may enter mastoid air spaces from middle ear infection

or otitis mediaor otitis media

Mastoid air cells do not drain into nose as do paranasal Mastoid air cells do not drain into nose as do paranasal sinusessinuses

Infectious material may erode thin, bony partition separating Infectious material may erode thin, bony partition separating air cells from cranial cavity, causing intracranial infectionair cells from cranial cavity, causing intracranial infection

Treatment is antibiotic therapy and surgical incision of Treatment is antibiotic therapy and surgical incision of eardrum to drain pus from middle eareardrum to drain pus from middle ear

Surgical removal of part of mastoid process of temporal Surgical removal of part of mastoid process of temporal bone—mastoidectomy—is rarebone—mastoidectomy—is rare


Mechanisms of Disease—Mechanisms of Disease—Abnormal Spinal Curvatures Abnormal Spinal Curvatures

• Normal curvature of spine is convex through Normal curvature of spine is convex through the cervical and lumbar regionsthe cervical and lumbar regions

Normal curves give spine strength for support of Normal curves give spine strength for support of body and balance required to stand and walkbody and balance required to stand and walk

• Abnormal curvaturesAbnormal curvatures

Lordosis—abnormally accentuated lumbar curve Lordosis—abnormally accentuated lumbar curve (“swayback”)(“swayback”)

• Frequently seen during pregnancyFrequently seen during pregnancy

• May be secondary to traumatic injuryMay be secondary to traumatic injury


Mechanisms of Disease—Mechanisms of Disease—Abnormal Spinal CurvaturesAbnormal Spinal Curvatures

• Abnormal curvatures (cont.)Abnormal curvatures (cont.)

Kyphosis—abnormally accentuated thoracic Kyphosis—abnormally accentuated thoracic curvature (“hunchback”)curvature (“hunchback”)

• Frequent consequence of vertebral compression Frequent consequence of vertebral compression fractures in osteoporosisfractures in osteoporosis

• Sign of Scheuermann’s disease, which may develop Sign of Scheuermann’s disease, which may develop in children at pubertyin children at puberty


Mechanisms of Disease—Mechanisms of Disease—Abnormal Spinal Curvatures Abnormal Spinal Curvatures

• Abnormal curvatures (cont.)Abnormal curvatures (cont.)

Scoliosis—abnormal side-to-side spinal curvatureScoliosis—abnormal side-to-side spinal curvature

• Often appears before adolescenceOften appears before adolescence

• Treatments vary with severity of curvatureTreatments vary with severity of curvature

Milwaukee braceMilwaukee brace

Transcutaneous stimulationTranscutaneous stimulation

Surgical grafting to the deformed vertebrae of bone from Surgical grafting to the deformed vertebrae of bone from elsewhere in skeleton or of metal rodselsewhere in skeleton or of metal rods

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Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 1 Chapter 8 Skeletal System