Presentation on theme: "Chapter 4 Injury Mechanism and Classification of Injury"— Presentation transcript:
1 Chapter 4 Injury Mechanism and Classification of Injury
2 Anatomic Foundations Anatomic position Joint movement Sagittal planeFrontal planeTransverse planeDirectional termsMovement TermsAnatomic positionCorrect terminology used when describing areas of the body provides precision during communication:--Axial segment = head & trunk--Appendicular segment = extremities (arms & legs)Anatomic position:--Body erect, facing forward, arms at the side with palms facing forward and feet pointed straight aheadPlanes:--Frontal (divides front to back)--Sagittal (divides side to side)--Transverse (divides top from bottomDirectional terms:--Examples: the elbow is superior to the wrist; the chest is on the anterior thorax; and the big toe is on the medial side of the footMovement:--Flexion/extension--Abduction/adduction--Internal/external rotation
3 Mechanism of Injury Mechanism of Injury (MOI): How an injury occurs Components used to analyze MOI:Application of forceTissue typeSeverity of forceThe injury and severity of injury is dependent upon the angle of the force, the amount of surface area involved, the duration of the force, and the tissue type involved.
4 Force Force: a push or pull acting on a body (e.g., gravity, friction) Force acting on a body causes:AccelerationDeformationFactors that determine injury:Magnitude of forceMaterial properties of tissues involved--Acceleration (change in velocity)--Deformation (change in shape)Generally, the stiffer the material to which a force is applied, the greater the likelihood that the deformation will be too small to be easily seen.The more elastic the material to which a force is applied, the greater the likelihood that the material can spring back to regain its original shape after deformation.
5 Force (cont’d) Small load = elastic response Large load = plastic responseYield point = load exceeds the ultimate failure point of the tissue resulting in mechanical failureAnisotropic = material is stronger in resisting force from certain directions than othersSmall load: the material will return to its original size and shapeLarge load: some deformation will remain when the load is removedYield point: fracturing of bone or tearing of soft tissuesAnisotropic: making the material more susceptible to injury from a given direction--Example: lateral ankle sprains are much more common than medial ankle sprains because ligamentous support of the ankle is much stronger on the medial side
6 Mechanical Forces - Injury CompressionForce that crushes tissuesTensionForce that pulls and stretches tissuesShearingForce that moves across the parallel design of the fibersMechanisms of injuryAxial loading: Acting along the long axis of a structureExample:-- When the opponent in fencing is touched with the foil, the foil is loaded axially.-- When the human body is in an upright standing position, body weight creates axial loads on the legs.Compression: Squeezing or crushing effect--Forces often result in bruises, or contusions.Tensile force: Opposite of compression; tension--Muscle contraction pulling on its bony attachment.When the foot and ankle are inverted, the tensile forces applied to the lateral ligaments may result in an ankle sprain.Shear force: Parallel to the surface; sliding--Tends to cause one part of the object to slide or displace with respect to another part of the object.
7 Stress Stress = Force x Surface area affected Same force over a large area vs. a small area can have very different resultsStressThe smaller the surface area where the force is applied, the worse the injury. Think in terms of being hit in the eye with either a finger tip or a flat palm. The finger would be worse.
8 Injury Types Acute Injury Single force Characterized by a definitive moment of onsetForce = macrotraumaChronic InjuryRepeated forcesCharacterized by becoming more problematic over time (Gradual onset over time)Forces = microtraumaAcute injury examples: ruptured ligament; fractured boneChronic injury examples: bursitis; stress fracture
9 Check for Understanding! Movements in the sagittal plane include flexion, extension, abduction, and adduction.TrueFalseAnswer: B
10 Check for Understanding! Which of the following is a correctly matched pair of terms? (Select all that apply)Adduction – movement away from the midline of the bodyFlexion – decreasing an angleExtension – increasing an anglePlantar flexion – movement of the forefoot toward the shinAnswer: B, C, & D
11 Check for Understanding! When tissues sustain a force, what are the primary factors that determine the occurrence of an injury? (Select all that apply)The magnitude of the forceThe direction of the forceThe material properties of the involved tissuesThe length of time the force is appliedAnswer: A & C
12 Check for Understanding! What are the three primary mechanical forces that produce injury?Answer: compression, tension, and shear
13 Anatomical Properties of Soft Tissue CollagenPrimary component of skin, tendon, ligamentsProtein substance strong in resisting tensile forcesWavy configuration that allows for an elastic type deformation or stretch but, otherwise, is inelasticCollagen fibers provide both strength and flexibility to tissues.Elasticity - enables the tissues to return to normal length following stretching or contraction.
14 Anatomical Properties of Soft Tissue (cont’d) Collagen fibersElastinProtein substance in connective tissueAdds elasticity
15 Skin Epidermis Multiple layers Dermis Loose, multidirectional arrangement of collagen fibersEpidermis contains:Melanin, hair, nails, sebaceous glands, sweat glandsDermis contains:Blood vessels, nerve endings, hair follicles, sebaceous glands, sweat glands--Composed of dense, irregular connective tissue--Arrangement enables resistance to multidirectional loads, including compression, tension, and shear
16 Skin Injury Classification Abrasions:--Skin scrapes against rough surface; capillary oozing--Caused by shear--Force is usually in one direction--Bleeding is usually not severe--Extremely painful because of the number of nerve endings exposed--Primary concern is microorganisms infectionIncision:--Smooth edges caused by sharp object or compression over bone; can bleed profusely--Produced by the application of a tensile force to the skin as it is stretched along a sharp edge--When caused by compression, there is an associated contusionLaceration:--Irregular tear of skin with jagged edges; profuse bleedingAvulsion:--Complete separation of the skin; major bleeding & scarring--Severe lacerationPuncture:--Penetration of skin; little bleeding; infection is a problem--Results when a sharp, cylindrical object penetrates the skin and underlying tissues with tensile loading
17 Skin WoundsBlistersAccumulation of fluid between epidermis and dermisCaused by repeated application of shear in one or more directionsSkin bruisesAccumulation of blood within skinResults from compression sustained during a blowBlisters-- Example: a shoe rubbing back and forth against the foot
18 Muscles Produce skeletal movement and maintain postural alignment Muscle tissueProduce skeletal movement and maintain postural alignmentViscoelasticExtensibilityElasticityAnatomic Considerations:--Endomysium--Perimysium--Epimysium--AponeurosisViscoelastic:--Extensibility: ability to be stretched--Elasticity: ability to return to normal lengthTime dependent extensibility significance: a static stretch maintained for 30 seconds is more effective in increasing muscle length than a series of short, ballistic stretches.
19 Muscle (cont’d) Irritability: ability to respond to a stimulus Electrochemical – nerve impulseMechanical – external blowContractility: ability to develop tensionIsometricConcentricEccentricElectrochemical: such as an action potential from the attaching nerveMechanical: such as with an external blow to the muscleIf the stimulus is of sufficient magnitude, muscle responds by developing tension.The ability to develop tension is a property unique to muscle.A muscle may or may not contract (shorten) when tension is developed.Isometric contraction: involves no joint movement and no change in muscle lengthEccentric contraction: involves lengthening of the muscle developing tensionConcentric contraction: Involves shortening of the muscle developing tensionWhen a stimulated muscle develops tension, the amount of tension present is the same throughout the muscle and tendon and at the site of the tendon attachment to bone.
20 TendonsMuscle to boneDense connective tissue with unidirectional bundles of collagen & some elastinCollagen – parallel arrangementHelps in resisting high, unidirectional tension loads from the attached muscle2X as strong as muscle it servesYield point 5-8% in lengthThe muscle and tendon are referred to as the musculotendinous unit.
21 Collagen arrangements in tendon and ligament tissue Tendons (cont’d)Collagen arrangements in tendon and ligament tissue
22 Contusions MOI: compression Can be both deep and superficial Must be cautious and aware of more severe injuries associated with repeated blowsS&S:Onset - acuteEcchymosis: if superficialHematomaRestrictions in ROMPain – localizedSwellingAssociated nerve compressionEcchymosis: bleeding resulting in discoloration of skin (bruise)Hematoma: formation of a hard mass composed of blood, dead tissue and lymph flow into surrounding tissueMuscle contusions rating--associated joint range of motion is impaired--first-degree: little or no range of movement restriction--second-degree: noticeable reduction in range of motion--third-degree: severe restriction of motion; fascia surrounding the muscle may be ruptured, causing swollen muscle tissues to protrude
24 Strains Damage to muscle or tendon Key factor: magnitude of force and structure's cross-sectional areaMOI:Abnormally high tensile forceMost common site for tears: near the musculotendinous junction--Stretch producing tear or rip & hemorrhage to muscle or adjacent tissueTendon rupturesLarge tendon ruptures will require surgery--Increased cross-sectional area of the muscle translates to reduced stress.--A tendon begins to develop tears when it is stretched to approximately 5 to 8% beyond normal length.--Be aware that once a muscle or tendon ruptures (third degree), there is little to no pain with stretching of that muscle.
25 Classification of Strains <table 4.4, classifications of strains>
26 Muscle Cramps and Spasms Involuntary muscle contractionCramp:Biochemical imbalance (dehydration) associated with muscle fatiguePainfulTypesClonic – alternating contraction/relaxationTonic – constantAlthough typically not associated with injury, muscle cramps and spasms are painful, involuntary muscle contractions common to the sport setting.
27 Muscle Cramps and Spasms (cont’d) Reflex action caused by:Biochemical imbalance orMechanical blow to nerve or muscle
28 Myositis and Fasciitis MOI: repeated movements irritate the tissuesMyositis:Inflammation of muscle tissue (e.g., shin splints)Fasciitis:Inflammation of the fascia (e.g., plantar fasciitis)--Fascia surrounds the tissues of the body (like the white, shiny tissue you see when you pull the skin from a chicken).
29 Tendinitis and Tenosynovitis Tendinitis: inflammation of a tendonRelated to aging and degenerative changesS&S: pain and swelling with tendon movementTenosynovitis: inflammation of the tendon sheathAcute: rapid onset, crepitus, local swellingChronic: same as acute, thickened tendon, nodule formation in sheath
30 Myositis OssificansMineral deposits in muscle associated with prolonged chronic inflammationEctopic calcificationCommon site: quadricepsCalcific tendinitis: mineral deposits in the tendonCondition can also result from a single traumatic blow.
31 Overuse Injuries Results from repetitive use Factors: Intrinsic Extrinsic--Intrinsic: from within (e.g., malalignment of limbs, muscular imbalances, other anatomic factors)--Extrinsic: external (e.g., training errors, faulty technique, incorrect surfaces and equipment, poor environmental conditions)
32 Overuse Injuries (cont’d) ClassificationStage 1: pain after activity onlyStage 2: pain during activity, does not restrict performanceStage 3: pain during activity, restricts performanceStage 4: chronic unremitting pain, even at restFour stages of classification are based on pain and dysfunction.
33 Anatomical Considerations of Joints Articulation of two bonesClassified by structure and functionStructureCartilaginousFibrousSynovial--Fibrous: bone ends are united by collagenic fibers; tend to be immobile or slightly mobile--Cartilaginous: united by cartilage--Synovial: bones covered with articular cartilage, enclosed by an articular capsule, containing synovial fluid; freely moving
34 Anatomical Considerations of Joints (cont’d) Function: based on the amount of movement allowedSynarthosesAmphiarthrosesDiarthroses--Synarthroses: immovable--Amphiarthroses: slightly movable--Diarthroses: freely movable
35 Diarthrodial Joints Components Articular cartilage Joint (synovial) cavityArticular capsuleSynovial fluidReinforcing ligamentsIntrinsic or ExtrinsicArticular cartilage:--Glassy-smooth hyaline cartilage covers the ends of the bony surfaces.--These cushions absorb compression placed on the joint and thereby protect the bone ends from being crushed; no nerves or blood vessels; it is nourished by the synovial fluid covering its free surface.--Nutrients in the synovial fluid come from the capillaries in the synovial membrane.Joint (synovial) cavity:--Unique to synovial joints, the joint cavity is filled with synovial fluid.Articular capsule:--Joint cavity is enclosed by a double-layered capsule.--External layer is a tough, flexible fibrous capsule that is continuous with the periosteum of the articulating bones; the capsule functions to help hold the bones of the joint in place.--Inner layer is a synovial membrane composed of loose connective tissue, which covers all internal joint surfaces that are not hyaline cartilage; the synovial membrane produces synovial fluid that lubricates the joint.Synovial fluid:--Small amount of synovial fluid occupies all free spaces within the joint capsule.--Derived largely by filtration from blood flowing through the capillaries in the synovial membrane.--Has a viscous, egg-white consistency due to its content of hyaluronic acid secreted by cells in the synovial membrane, but it thins and becomes less viscous as it warms during joint activity.--Also found within the articular cartilages, providing a slippery weight-bearing film that reduces friction between the cartilages. In a weeping action, the fluid is forced from the cartilages when a joint is compressed. As pressure on the joint is relieved, the synovial fluid seeps back into the articular cartilages like water into a sponge.--Also contains phagocytic cells that clear the joint cavity of microbes or cellular debris.Reinforcing ligaments:--More commonly, the ligaments are intrinsic, or capsular; that is, they are thickened parts of the fibrous capsule.--In some cases, ligaments may remain distinct and are found outside the capsule (extracapsular) or deep to it (intracapsular).--Since intracapsular ligaments are covered with synovial membrane, they do not actually lie within the joint cavity (extrasynovial).
37 Articular CartilageEnds of bones covered by hyaline cartilage…solid type of connective tissueMore resistant to deformation than fibrous connective tissue and more resilient than boneNo blood supply; nourished by synovial fluidThese cushions absorb compression placed on the joint and thereby protect the bone ends from being crushed. The cartilage has no nerves or blood vessels; it is nourished by the synovial fluid covering its free surface. The nutrients in the synovial fluid come from the capillaries in the synovial membrane.
39 Articular Capsule Cuff of fibrous tissue Primarily bundles of collagen Primary function: hold bones togetherInner layer: synovial membraneProduces synovial fluid that lubricates the joint.The joint cavity is enclosed by a double-layered capsule. The external layer is a tough, flexible fibrous capsule that is continuous with the periosteum of the articulating bones.The inner layer is a synovial membrane composed of loose connective tissue, which covers all internal joint surfaces that are not hyaline cartilage. The synovial membrane produces synovial fluid that lubricates the joint.
40 Synovial Fluid Functions Lubricate joint Reduce friction Nourish joint A small amount of synovial fluid occupies all free spaces within the joint capsule. This fluid is derived largely by filtration from blood flowing through the capillaries in the synovial membrane. Synovial fluid has a viscous, egg-white consistency due to its content of hyaluronic acid secreted by cells in the synovial membrane, but it thins and becomes less viscous as it warms during joint activity.Synovial fluid is also found within the articular cartilages, providing a slippery weight-bearing film that reduces friction between the cartilages. In a weeping action, the fluid is forced from the cartilages when a joint is compressed. As pressure on the joint is relieved, the synovial fluid seeps back into the articular cartilages like water into a sponge. Synovial fluid also contains phagocytic cells that clear the joint cavity of microbes or cellular debris.
41 Ligaments Bone to bone Intrinsic Extrinsic Maintain anatomical integrity and structural alignmentCollagen and elastin intermixed (contain elastin – more elastic than tendons)ViscoelasticThe ligaments are intrinsic, or capsular; that is, they are thickened parts of the fibrous capsule. In some cases, ligaments may remain distinct and are found outside the capsule (extrinsic or extracapsular) or deep to it (intracapsular).
42 Ligaments (cont’d)Resists large tensile loads along the long axis of the ligament and smaller loads from other directions – static stabilizersFail in fast loading situationsStrongest in their middle and weakest at their endsHealing process – slow due to a limited blood supply
43 Classification of Diarthrodial Joints PlaneHingePivotCondyloidSaddleBall-and-socketPlane--Articulating surfaces are nearly flat--Movement is nonaxial gliding or short slipping movement--Intermetatarsal, intercarpal, vertebral facet jointsHinge--One articulating bone surface is concave and the other convex--Single plane movement (uniaxial); flexion and extension only--Elbow and interphalangeal jointsPivot--Rounded or conical end of one bone rotates within a sleeve or ring composed of bone--Uniaxial rotation--Atlantoaxial joint, proximal and distal radioulnar jointsCondyloid--Oval surface of one bone fits into a concavity of another--Flexion, extension, abduction, adduction, and circumduction--Radiocarpal joint, MCP jointSaddle--Biaxial joints; each articular surface has both concave and convex areas--Carpometacarpal joint of the thumbBall-and-socket--Spherical or hemispherical head of one bone fits into the cuplike socket of another--Multiaxial joint; movement in all axes and planes, including rotation--Shoulder and hip joints
44 Injury to the LigamentCompromises the ability of the ligament to stabilize the jointMOI:High tensile forceS&S:Pain; point tenderness; swelling; loss of function; instability
45 Classification of Sprains <table 4.5, classification of sprains>
46 Dislocations and Subluxations Joint forced beyond normal limitsMOI: tensionIncreased susceptibility for chronic or recurrent dislocationsS&S:PainSwellingPoint tendernessDeformityLoss of limb functionDislocations:--Displacement of bones in joint and NO return; bones stay out of place--Supporting ligaments ruptured--Possibly musculotendinous unitSubluxations:--Partial displacement of bones in joint and return to normal--Many acute dislocations have an associated fracture or nerve injury.Due to extensive stretching of the connective tissues surrounding a joint associated with a traumatic dislocation, there is increased susceptibility for chronic or recurrent dislocations. Less force is required to sustain a recurrent dislocation. While recurrent dislocations may be less painful, the subsequent damage to joint structures can be extensive and lead to chronic joint problems.Most common sites for dislocations are the fingers and the glenohumeral joint of the shoulder.
47 Osteoarthritis Degeneration of articular cartilage S&S: Pain Limited movementNo definitive cause; rather, several contributing factorsThere is no definitive cause of osteoarthritis; it is attributed to a combination of factors, including stresses sustained during certain types of physical activity, joint trauma, and the aging process.It is one of the leading causes of disability among American adults.It should be noted that physical activity is being promoted as a potential strategy for managing arthritis.
48 Bursitis Inflammation of bursa Acute or chronic MOI: Compression S&S: Localized swellingPoint tendernessWarm to touchAcute bursitis:--Caused by sudden irritation (trauma)--InfectionChronic bursitis:--Caused by overuse and constant external compression
49 Soft Tissue Injury Check for Understanding! The discoloration or swelling outside a joint in the surrounding soft tissue is termed:BruisingEcchymosisEdemaEffusionAnswer: B
50 Soft Tissue Injury Check for Understanding! The ability of a muscle to be stretched or increased in length is termed:ContractilityElasticityPlasticityExtensibilityAnswer: B
51 Soft Tissue Injury Check for Understanding! Joint capsules are fluid-filled sacs that serve to reduce friction in the tissues surrounding the joints.TrueFalseAnswer: B
52 Soft Tissue Injury Check for Understanding! Which of the following statements is true? (Select all that apply)A tear of a ligament is referred to as a sprain.A muscle spasm is brought on by a biochemical imbalance, sometimes associated with muscle fatigue.Overuse injuries are more often attributed to intrinsic rather than extrinsic factors.The onset of bursitis can be acute or chronic.Answer: A & D
53 Soft Tissue Injury Check for Understanding! Strains and sprains that produce moderate discomfort, tenderness, swelling, ecchymosis, detectable joint instability, and/or muscle weakness are categorized as:1st degree2nd degree3rd degreeSevereAnswer: B
54 Anatomical Properties of Bone Primary constituents:Calcium carbonateCalcium phosphateCollagenWaterPrimary constituents:-- Minerals: provide stiffness and strength in resisting compression-- Collagen: provides some flexibility and strength in resisting tension-- WaterAging causes a progressive loss of collagen and increase in bone brittleness; as such, children’s bones are more pliable than adults’ bones.
55 Anatomical Properties of Bone (cont’d) Bone macrostructureStructure:DiaphysisEpiphysisMembranesPeriosteumMedullary cavityApophysis
56 Anatomical Properties of Bone (cont’d) Bone growth:LongitudinalContinues until epiphysis closesDiameterContinues to grow throughout lifeNew bone formed via the periosteum; bone is resorbed around the medullary cavityOsteoblasts: form new boneOsteoclasts: resorb bone--Most epiphyses close around age 18, but some may be present until about age 25.--In healthy adult bone, the activity of osteoblasts and osteoclasts, referred to as bone turnover, is largely balanced.--The total amount of bone remains approximately constant until women reach their forties and men reach their sixties, when a gradual decline in bone mass begins.--Sport participants past these ages may be at increased risk for bone fractures.--Regular participation in weight-bearing exercise has been shown to be effective in reducing age-related bone loss.
58 Anatomical properties of Bone (cont’d) CompositionCorticalCompact bone tissue of high density (low porosity)OutsideCan withstand greater stress but less strainCancellousBone tissue of low density (high porosity)InsideCan tolerate more strain--No matter what the athlete’s age, some bones are also more susceptible to fracture as a result of their internal composition.--The mineralization of cancellous bone varies with the individual’s age and location of the bone in the body.--Both cortical and cancellous bone are anisotropic (exhibit different strengths and stiffness in response to forces applied from different directions).
59 Bone Injury Classifications Bone injury mechanisms
60 Bone Injury Classifications (cont’d) Fracture: Disruption in the continuity of boneS&S:Rapid swellingEcchymosisDeformity or shortening of the limbPrecise point tendernessGrating or crepitusGuarding or disability
61 Bone Injury Classifications (cont’d) Type of fracture dependent upon:Force appliedThe health and maturity of the bone at the time of injuryBone susceptible to:Compression, tension, shear, bending, and torsion
62 Types of FracturesSimple fracture: broken bone does not pierce the skinCompound fracture: broken bone causes an open wound by piercing the skin. Infection is a concern.Depressed fracture: depression of bone fragments into the underlying tissuesTransverse fracture: bone broken straight across, results from a sharp, direct blow or a stress fractureComminuted: bone splinters and can shatter into more than two pieces, usually caused by severe forceOblique: bone broken at an angle, usually the result of a sharp angled blow to the bone (tackle)Epiphyseal: growth plate disruptionSpiral: caused by excessive torsional and bending load (planting and cutting against an oncoming force) creating an angled fracture around and through the boneGreenstick: Usually occurs in children, whose bones are still soft and cartilaginous. The bone bends and only partially breaks; sudden force causes only the outer side of the bent bone to break.Avulsion: a piece of the bone is pulled off, usually by a tendon or ligamentImpacted fracture - the opposite sides of the fracture are compressed together
63 Stress Fracture MOI: repeated lower magnitude forces Can become worse over timeBegins as a small disruption in the outer layers of cortical bone and ending as complete cortical fracture with possible displacementStress fractures (fatigue fractures)-- Examples: the metatarsals, the femoral neck, and the pubis - among runners who have apparently overtrained; pars interarticularis of the lumbar vertebrae - among football linemen and female gymnasts
64 Osteopenia Reduced bone mineral density Predisposes individual to fractureParticularly stress fracturesPossible causes:Amenorrhea, hormonal factors, dietary insufficienciesOsteopenia--Primarily found among adolescent female athletes, especially distance runners, who are amenorrheic; the link between cessation of menses and osteopenia is also not well understood.--Low percentage of body fat and/or high training mileage--Possible contributing factors:-- Hyperactivity of osteoclasts-- Hypoactivity of osteoblasts-- Hormonal factors-- Insufficiencies of dietary calcium or other minerals or nutrients
65 Classification of Epiphyseal Injuries ClassificationsInjury to growth plate could result in alteration in normal growthAcute injuryTypes I-VEpiphyseal injuriesType I: Complete separation of the epiphysis from the metaphysis with no fracture to the bone; rarely produces complicationsType II: Separation of the epiphysis and a small portion of the metaphysis; rarely produces complicationsType III: Fracture of the epiphysis; growth disturbance is uncommonType IV: Fracture of a part of the epiphysis and metaphysis; growth disturbance can resultType V: Compression of the epiphysis without fracture, resulting in compromised epiphyseal function; can result in angular deformity--Epiphyseal fractures occur only when the epiphysis has not closed (hence, knowing that they close by age 25). The majority of fractures are Type II (85%) and heal nicely. Less than 5% are Type V which cause angulation of the bone.
66 Classification of Epiphyseal Injuries (cont’d) OsteochondrosisDisruption of blood supply to epiphysisIdiopathicCausing necrosis and possible deformityExample: Legg-Calvé-Perthes diseaseOsteochondrosis--Occurs most commonly between ages 3 and 10; more prevalent among boys than girls--Example: Legg-Calvé-Perthes disease - osteochondrosis of the femoral head
67 Classification of Epiphyseal Injuries (cont’d) ApophysitisOsteochondrosis of apophysisIdiopathic or traumatic avulsion fractureExample:Sever’s diseaseOsgood-Schlatter diseaseApophyses-- Sites of tendon attachments to bone; bone shape is influenced by the tensile loads at these sites.Apophysitis-- Common sites for apophysitis: calcaneus (Sever’s disease); tibial tubercle at the site of the patellar tendon attachment (Osgood-Schlatter disease)
68 Bone Tissue Injury Check for Understanding! In a comminuted fracture, the bone fragments into several pieces.TrueFalseAnswer: A
69 Bone Tissue Injury Check for Understanding! Osteopenia is a condition:That is exclusive to an older adult populationThat predisposes an individual to stress fracturesThat only involves femalesThat inhibits longitudinal bone growthAnswer: B
70 Bone Tissue Injury Check for Understanding! Epiphyseal injuries can include damage to the: (select all that apply)Epiphyseal plateLigamentsArticular cartilageThe apophysisAnswer: A, C, & D
71 Anatomical Properties of Nerves Nervous SystemCNS:BrainSpinal cordPNS:12 pairs of cranial nerves31 pairs of spinal nerves, along with their branchesCentral nervous system:-- The brain-- The spinal cordPeripheral nervous system:-- 12 pairs of cranial nerves-- 31 pairs of spinal nervesNerve fibers are heavily vascularized and encased in a multilayered, segmental protective sheath called the myelin sheath.Myelin-- protects and electrically insulates fibers from one another-- increases the speed of transmission of nerve impulsesMyelinated fibers (axons bearing a myelin sheath) conduct nerve impulses rapidly, whereas unmyelinated fibers tend to conduct impulses quite slowly.
73 Nerve Injury Classifications MOI: Tensile or compression forceNeurapraxia (grade 1)Localized conduction block: temporary loss of sensation and/or motorResolves within days to a few weeksTensile:--When a nerve is loaded in tension, the nerve fibers tend to rupture prior to the rupturing of the surrounding connective tissue sheath.--Most common in high speed accidents.--Because the nerve roots on the spinal cord are not protected by connective tissue, they are particularly susceptible to tensile injury, especially in response to stretching of the brachial plexus or cervical nerve roots.--Axonal regrowth occurs at a rate of 1 to 2 mm per day; full or normal function is usually restored.
74 Nerve Injury Classifications (cont’d) Axonotmesis (grade 2)Significant motor and mild sensory deficitsLasts at least 2 weeksNeurotmesis (grade 3)Motor and sensory deficitLasts up to 1 year
75 Nerve Injury Classifications (cont’d) Compression:More complex; dependent upon:Force magnitude and durationDirect or indirectNerve injuries result in a variety of afferent symptomsHyperesthesiaHypoesthesiaParesthesiaCompression:--Because nerve function is highly dependent on oxygen provided by the associated blood vessels, damage to the blood supply caused by a compressive injury results in damage to the nerve.Hypoesthesia - a reduction in sensationHyperesthesia - heightened sensationParesthesia - a sense of numbness, prickling, or tinglingPinching of a nerve can result in a sharp wave of pain that is transmitted through a body segment.Irritation or inflammation of a nerve can result in chronic pain along the nerve’s course, known as neuralgia.
76 Nerve Injury Classifications (cont’d) NeuralgiaChronic pain along nerve courseHealing: if completely severed, healing does not occur
77 The Neurological Basis of Pain SourcesSomatic, visceral, and psychogenicNociceptors: produce pain sensationMechanosensitive: initiate pain by acute traumaChemosensitive: causes persistent pain in chronic injuries and the early stages of healingPain: A negative sensory and emotional experience associated with actual or potential tissue damage.--Somatic pain - originates in the skin, as well as in internal structures in the musculoskeletal system--Visceral pain - originates from the internal organs and is often diffuse or referred rather than localized to the problem site--Psychogenic pain - no physical cause of the pain is apparent, although the sensation of pain is felt
78 The Neurological Basis of Pain (cont’d) Fibers transmitting painA fibersC fibersT cellsGate control theory of painTwo types of afferent nerves transmit the sensation of pain to the spinal cord:C fibers - small-diameter, slow-transmission, unmyelinated and transmit low-level pain that might be described as dull or achingA fibers - larger, faster, thinly myelinated and transmit sharp, piercing types of pain--Activity in A and C fibers from the visceral organs can also provoke autonomic responses such as changes in blood pressure, heart rate, and respiration.Pain from somatic and visceral sources is carried from afferent fibers to the substantia gelatinosa (SG) of the spinal cord’s dorsal horn to specialized T cells up the spinal cord to the brain.--each T cell carrying a single impulseGate control theory of pain (proposed by Melzack and Wall in 1965):--The SG acts as a gate keeper by allowing either a pain response or one of the other afferent sensations to be transported by each T cell.--The theory is substantiated by the observation that increased sensory input can reduce the sensation of pain.--For example, extreme cold can often numb pain; because hundreds or thousands of “gates” are in operation, however, it is more common that added sensory input reduces rather than eliminates the feeling of pain because pain impulses get through to some of the T cells.
79 The Neurological Basis of Pain (cont’d) Factors than mediate painBrain production of opioid peptides and endorphinsCognitive and affective filtersReferred painPain perceived at a location remote from the site actually causing the painRadiating painPain felt both at its source and along a nerveSome brain cells produce opioid peptides (narcotic-like, pain-killing compounds) including:--Beta-endorphin and methionine enkephalin; work by blocking neural receptor sites that transmit pain.--Endorphin release; provoked by stressors (physical exercise, mental stress, and electrical stimulation)-- “runner’s high” attributed to endorphin release--Enkephalin release block pain neurotransmitters in the dorsal horn of the spinal cord-- produced by the brainstem and pituitary glandCognitive and affective filters--CNS imposes a set of cognitive (quality of knowing or perceiving) and affective (pertaining to feelings or a mental state) filters on the perception and expression of pain.--Social and cultural factors can be powerful influences on pain tolerance level; example: in American society, it is much more acceptable for females than males to express feelings of pain.Referred pain:--Proposed explanation:--Neurons carrying pain impulses split into several branches within the spinal cord- Example: pain from the internal organs is typically projected outward to corresponding dermatomes of the skin; heart attacks can produce a sensation of pain in the superior thoracic wall and the medial aspect of the left arm.Radiating pain-- Example: pinching of the sciatic nerve at its root may cause pain that radiates along the nerve’s course down the posterior aspect of the leg.
80 Bone Tissue Injury Check for Understanding! The posterior branches are the afferent (sensory) nerves that transmit information from sensory receptors in the skin, tendons, ligaments, and muscles to the central nervous system.TrueFalseAnswer: A
81 Bone Tissue Injury Check for Understanding! ___________ is perceived at a location remote from the site of the tissues actually causing the pain.Radiating painCognitive painAcute painReferred painAnswer: D
82 Bone Tissue Injury Check for Understanding! Grade II nerve injuries that produce significant motor and mild sensory deficits that last at least two weeks are termed:NeurapraxiaAxonotmesisNeurotmesisAnswer: B