B3M2 Lecture 2 - Postures PDF
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This document discusses human postures, including upright posture and its advantages and disadvantages. It explains the concept of center of gravity and its importance in maintaining balance. It also describes the development of postural curves throughout life.
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I NTRODUCTION he supporting surface in this case is the floor. T...
I NTRODUCTION he supporting surface in this case is the floor. T These points of contact may be body parts such Through evolution, human beings assumed an as feet, hands or things like crutches or chairs a upright, erect bipedal posture. person is sitting in. The wider the base of support the more stable the person or the object is and POSTURE vice versa. Istherelativedispositionofthebodyatanyone moment and acompositeofthepositionsofthe different joints of the body at that time. The position of each joint has an effect on the position of the other joints. The position of that particular joint will affect posture.Ifyoumoveonejoint,thentheadjacent joints will move to either stabilized or help achieve the desired position. CENTER OF GRAVITY DISADVANTAGES OF ERECT POSTURE ofanobjectisthepointatwhichweightisevenly Increased strain on the spine and lower limbs dispersed and all sides are in balance. Reduces stability A human center of gravity can change as he Comparative difficulties in respiration takes on different positions but in many other Increases the work of the heart and transport of objects it is actually fixed. the blood to the brain When the center of gravityisinsidethebaseof support, then the person maintains balance but whenthecenterofgravityshiftsoutsidethebase of support, the personhasahighertendencyto fall because the one side is now heavier comparedtotheotheranditdisruptsthebalance and also the base of support is now narrower. DEVELOPMENT OF POSTURAL CURVES lthough there are certain disadvantages of A having an erect posture, there are a lot of advantages both physically and mentally. Posture enables the hands to move freely. The eyes to be farther from the ground so that the individual can see farther ahead. Posturecanbestaticasinstationarypositionas in standing, sitting, lying or planking. Posture is dynamic as the move moves in one position to another as in dancing. Posturedealswithalignmentofthevariousbody segments. t birth, the entire vertebral column is flexed. A ○ In the human body, each jointinvolved When viewed from the sagittal plane, it is withweight-bearingcanbeconsidereda anteriorly concave. postural segment. This concave curve is called the primary curve and usually the thoracic and the sacral curves BASE OF SUPPORT are considered primary curves because it Refers to the area beneath an objectorperson assumes the same curve. that includes every point of contact that the object or person makes with the supporting surface. B3M2 Lecture 2: Postures 1of 12 the arches ofthefeetdevelopnormally nd become more evident. a VERTEBRAL ALIGNMENT Not completely straight but has a series of counterbalancing anterior-posterior curves Must be maintained during rest and activity Act as shock absorbers andreducetheamount of injury The thoracic and sacral curves are concave anteriorly and convex posteriorly; seen and viewed on a sagittal plane The lumbar and cervical curves are convex anteriorly and concave posteriorly ○ A curve has twosides:aconcaveand convexside CORRECT POSTURE s a child grows,secondarycurvesappearand A Isthepositioninwhichminimumstressisapplied are convexed forward and are also known as to each joint extended. Upright posture is the normal standing posture ○ 3 months – Lifts heads; the cervical for humans If the upright posture is correct, spine becomes convexed forward minimalmuscleactivityisneededtomaintainthe producing the cervical lordosis. In the position. lumbar spine, the secondary curve develops slightly later around 6-8 months.Thesearetheanteriorlyconvex curves of the cervical and the lumbar region. They areconsideredsecondary curves sincetheyaredevelopedduring growth. ○ 6-8 months- begins to sit up and walk ○ In the child, the center of gravity is at the level of the 12th thoracic vertebra. As the child grows older, the center of gravity drops eventually reaching the level of the 2nd sacral vertebra in adults. The child stands with a wide IDEAL POSTURE basetomaintainbalanceandtheknees Inthestandingposition,inviewingfromalateral are flexed. position,aplumblineorimaginarylineshouldbe ○ In the newborn,moderategenuvarum alignedsoitpassesstraightinfrontofthelateral can be appreciated. malleolus. ○ At the age of 6 months, there is now For ideal posture,thebodysegmentsshouldbe minimal genu varum. There is a alignedsothattheplumblinepassesthroughthe physiologicgenuvalgumuntiltheageof landmarks in the order listed. 3 years old and thereisaprotectivein toeing as well. ○ At7months,thelegsarenowstraight. BODY SEGMENT LANDMARK The knees are slightly bowed such as thegenuvarumuntilabout18monthsof Head Through the earlobe age. ○ At the age of 4-6 years old, the legs Shoulder Through the tip of the should naturally straighten with the toe acromion process pointing out. In addition, as the foot develops and the muscles strengthen, B3M2 Lecture 2: Postures 2of 12 Thoracic spine Anterior to the vertebral bodies Lumbar spine Through the vertebral bodies Pelvis Level Hip Through the greater trochanter (slightly posterior to the hip joint axis) Knee Slightly posterior to the patella (slightly anterior to the knee joint axis) with hen the pelvis is in the neutral position, the W the knees in extension lumbar curve has the desired amount of curvature. Ankle Slightly anterior to the When thepelvistiltsanteriorly,lumbarcurvature lateral malleolus, with the increases. When the pelvis tilts posteriorly, ankle joint in a neutral lumbar curvature decreases. position between GOOD POSTURE MEANS GOOD ALIGNMENT. dorsiflexion and plantar ○ Itisimportantbecauseitdecreasesthe flexion amount of stress placed in the bones, ligaments, muscles and tendons.Good alignment also improves function and decreases the amounts of muscle energy needed to keep the body straight. Towatchaballetdancermove,istowatchgood posture in motion. Maintaining good posture alignment and keeping one’s center of gravity well within one’s base of support places less stress on body parts and allows for better balance. FAULTY POSTURE Any static position that increases the stress to the joints This is the reason why you will experience musculoskeletal pain on your back, neck or shoulders or any parts of your body because you’re putting so muchstrainonthem.Injoints, PELVIS MECHANISM - IDEAL POSITION muscles, or fascia, where too much strain will Think of the pelvis in the upright position as a definitely cause pain. bowl of water. If the bowl is leveled, it willhold If a person has strong, flexible muscles, faulty the water. If the bowl is tipped forward or postures may not affect the joints because backward, water will spit out. he/she has the abilitytochangepositionreadily Similarly, the position of the pelvis has a great so that the stresses do not become excessive. influence in the vertebral column especially the But if the joints are stiff (hypomobile) or too lumbar region. mobile (hypermobile), or the musclesareweak, The pelvis should maintain a neutral position. shortened,orlengthened,theposturecannotbe A position isneutralwhen: easily altered to the correct alignment. And the ○ The anterior superior iliacspine(ASIS) results can be some form of pathology. and the posterior superior iliac spine (PSIS) are level with each other in a transverse plane and ○ The ASIS is in the sameverticalplane as the symphysis pubis B3M2 Lecture 2: Postures 3of 12 icrotrauma: irritated achilles tendon M Microtrauma: dislocation of the knee These chronic stresses can result in the same problems that are seen when a sudden severe stress is applied to the body. The abnormal stresses can cause excessive wearingofthearticularsurfacesofthejointsand produce sulfites and traction spurs which represents the body’s attempt to alter its structure to accommodate these repeated stresses. The softtissuessuchasmusclesandligaments maybecomeweakened,stretchedortraumatized by the increased stress. Thus, postural deviations do not always cause symptoms but overtime, they do so. Examples ofposturaldeviationsarewhenone Thesensoryelementsdetectchangesinposture or more of these vertebral curves either nd send signals to the higher center. a increasesordecreasessignificantlyfromwhatis Thehighercentertheninterpretsanddecideson consideredagoodpostureandresultsinapoor what to do and once movement has been posture. decided, it will then send signals to the motor A flat back is a decreased thoracic curve, elementsinordertoproduceadesiredpostureor whereas a sway back is an increased lumbar movement. curve. Both postural deviations cause upper or The adjustments done when the muscles move lower back pain. activates the sensory elements again forming a In most cases, if there is an increased lumbar feedback loop. curve, there is also an increased thoracic curve. Remember: Every move you make with your body,eventheslightestmovementwillfollowthis schematic. In the higher centers, youhavethecerebellum which regulates coordination via the dentate nucleus oftheposteriorlobeandequilibriumvia the vestigial nucleus of the flocculonodular lobe. The basal ganglia initiates and provides gross motor control as well as muscle tone. Thepremotorareaisresponsibleforplanningof motor activity while the primary motor area regulates the force of muscle contraction. SENSORY (AFFERENT) Somatosensory-thesearesensationsperceived through joint receptors. ○ Free nerve endings: respondstopain and awareness ○ Golgi tendon: detects the rate of motion ○ Ruffini endings: detects the direction and velocity of the joint motion ○ Pacinian corpuscles: monitors rapid joint movement B3M2 Lecture 2: Postures 4of 12 These are all mechanisms of posture aintenance m Visual - refers to the visual receptors ○ Retina - with its photoreceptors: rods MECHANICS OF POSTURE MAINTENANCE and cones INTERNAL FORCES (CONTRACTILE) Vestibular - located in the inner ear ○ Otoliths-insidetheutricleandsaccule and are also part of the basic sensory elements of postural control uscle contraction is primarily responsible for M ○ Utricle - lies mainly in the horizontal keeping the body in the upright positioninboth plane anddeterminestheorientationof static and dynamic posture. the head when the head is upright; it The muscles most involved are called detects linear acceleration and head antigravity muscles because gravity is position constantly pushing usdownbutluckily,wehave ○ Saccule - locatedmainlyinthevertical the antigravity muscles throughout our bodies. plane,signalsheadorientationwhenthe Thejobofthesemusclesistosupportourbones person is lying down and joints in order to maintain their alignment ○ Semicircular canals - detect angular against the constant forces. acceleration Thesearethehipandkneeextensors,thetrunk and neck extensors and othermusclesinvolved toalesserintactbutalsoplaysanimportantrole intheuprightposition,thetrunkandneckflexors in the lateral benders, hip adductors, andankle pronators andsupinators.Ifallofthesemuscles relax, the body would actually collapse. Antigravity muscles support and maintain alignmentinthebodyagainstgravity.It’seasyfor the antigravity muscles to stay contracted and maintain posture even though gravity is there. MOTOR (EFFERENT) Muscles: erector spinae, abdominals, neck and leg muscles B3M2 Lecture 2: Postures 5of 12 POSTURAL SWAY Posturalswayisanterior-posteriormotionofthe upright body caused by motion occurring primarily at the ankles. The ankle plantar flexors and dorsiflexors are important in controlling postural sway. Aswaythatresultsfromaconstantdisplacement and correction ofthecenterofgravitywithinthe base of support. Demonstration: stand upright with feet slightly ore: common term for these group of muscles C apartandcloseyoureyes.Leanyourentirebody Core muscles or deep antigravity muscles start slightlyforwardbybendingattheanklesandyou downinthefeetandgoallthewayupandbehind will reach apointwhereyouwillneedtocorrect our eyes. These muscles need to be strong the forward lean or you will lose your balance. throughout the body to maintain proper joint Notice thatyourankleplantarflexorscontractto alignment. bring youbacktoanuprightposition.Next,lean backwards and notice what happens. You will ANTIGRAVITY MUSCLES againreachapointwhereyoueithercorrectthe They are stronger than their antagonists. lean or lose balance. Notice that your ankle ○ For example: dorsiflexorsmusclescontracttobringyoubackto Wrist flexors arestrongerthan upright position. wrist extensors Triceps is stronger than biceps Trunk extensors are stronger than flexors Plantar flexors are stronger than dorsiflexors INTERNAL FORCES (NON-CONTRACTILE) Neck muscles: Longissimus, capitis, splenius These are thesofttissuetension,boneintegrity, apitis, longissimus cervicis, semispinalis c ligaments, and joint capsules. Cervical muscles: sternocleidomastoid and Ligaments: provides stability in the joints by scalenes promoting passive tension and stabilizes the Upper back: Trapezius body evenwheninconstantmotionwhichhelps Lower back: multifidus and erector spinae Abdominal muscles: Transversus and rectus in maintaining a good posture abdominis muscles ○ Examples: Hip joint ligaments Deep hip muscle: Iliopsoas (strongest ligament in the body) Hamstrings, quadriceps group Joint capsules: (knee joints) gives lubrication, Calf muscles: gastrocnemius and soleus making the movement more fluid and easy to Tibialis anterior move during dynamic posture. Thesemusclesbytheirtoneresiststheconstant Bone integrity: an intact bone to have good pull of gravity in the maintenance of normal posture. The basic foundation of posture is the posture. bone. B3M2 Lecture 2: Postures 6of 12 EXTERNAL FORCES (GRAVITY) nown as the driving force. The ground in turn k exerted an equivalent force on the body known as the ground reaction force. Gravity:istheattractionoftheearthforthemass f an object o Constantpullofgravityreinforcesthebonesand muscles,andourbodiesareconstantlyadapting FACTORS AFFECTING POOR POSTURE to the force that is put on them including the NATOMICAL FACTORS AFFECTING CORRECT A force of gravity. POSTURE Gravitycandirectlyaffectourposture.It’saforce Bony contours (e.g. hemivertebra) that impacts every activity a person does Laxity of ligamentous structures throughout their daily life. Fascial and musculotendinous tightness (e.g., Gravitydoesnotonlykeepusgroundedbutitcan tensor fasciae latae, pectorals, hip flexors) also change the way our bodies function with Muscle tonus (e.g., gluteus maximus, both the presence or the absence of it. abdominals, erector spinae) Pelvic angle (normal is 30°) EXTERNAL FORCES (LAW OF INERTIA) Joint position and mobility Neurogenic outflow and inflow Inertia resists change inmotion.Objectsstayin ○ These features may enhance or cause rest or motionunlessanoutsideforcecausesa additional problems when combined change. with pathological or congenital states Inertia of rest such as for example Klippel-Feil ○ Anobjectstayswhereitisplaced,andit syndrome,whichisaconditionaffecting will stay there until you or something the development of the bones in the elsemovesit.(i.eDustparticlesstayat spine. rest until you shake a carpet) Inertia of motion KLIPPEL-FEIL SYNDROME ○ An object will continue at the same speeduntilaforceactsonit.(i.e.Body going forward when a car stops) Inertia of direction ○ An object will stay movinginthesame direction unless a force acts onit.(i.e. one’s body movementtothesidewhen a car makes a sharp turn) Inertia of motion and inertia of direction are external forces that will change orshiftposture and most probably in an attempt to maintain balance XTERNAL FORCES (GROUND REACTION FORCE) E eople with KFS are born withabnormalfusion P This force follows Newton's law of reaction. of at least two spinal bones or vertebrae inthe Itistheforceexertedbythegroundonabodyin neck. contact with it. Common features may include ashortneck,a Example: Athletes inasprintingcompetition.An lower hairline at the back of the head, and athlete usually positions themselves like this restricted movements of the upper spine. because it’s the optimal posture or position to Actually also known astorticollis. gaininitialspeedbecauseofthegroundreaction force In this image,assoonasheperformsthelunge using his right foot, therightfootexertsaforce from the athlete’s body to the ground and is B3M2 Lecture 2: Postures 7of 12 SCHEUERMANN DISEASE Torticollis or the KFS ○ Thoracolumbar area Scoliosis Kyphosis Lordosis UPPER EXTREMITY cheuermann kyphosis, also known as S Scheuermann disease, juvenile discogenic disease, juvenile kyphosis, vertebral epiphysitis, so it is actually common condition whichresultsinakyphosisofthethoracicorthe thoracolumbar spine. The diagnosisisusuallymadeonfilmandother factors or other pathologic conditions are pper extremity in full supinationandextension U scoliosis and your disc diseases the elbow joint deviates between 5 and 15 degrees in the coronal plane known as the carrying angle or physiologic valgus of the elbow Cubitus varus, the carrying angle decreases and the hands are close to the midline Cubitus valgus, carrying angle actually increasesandthehandsarefurtherawaytothe midline ○ L ofLateralisalsoinvaLgusbutnotin varus ○ L lateral going away CLINICAL ABNORMALITIES ny variations of theanglethatismorethan15 A degrees, more than 15 degrees it's cubitus valgus and if it's less – cubitus varus Abnormalities in posture are divided into two: ○ Appendicular ○ Axial abnormalities Appendicular ○ Upper and lower extremities ○ Most common ones are your Cupidus varus and your Cubitus valgus ○ Lower extremities Genu valgum Genu Varum Axial abnormalities ○ Cervical B3M2 Lecture 2: Postures 8of 12 LOWER EXTREMITY femoralepiphysisisindicatedandifleft untreatedcancauseosteoarthritisofthe knee in adulthood. Q-ANGLE OF THE KNEE hecarryingangleisasmalldegreeofcubitus T valgus form between the axis of a radially he measurement of a lateral line ofpullofthe T deviated forearm and the axisofthearmorthe quadriceps relative tothepatellaandisreferred humerus. to as the Q angle Ithelpsthearmstoswingwithouthittingthehips This is formed by two lines. while walking. ○ The first one is a line connecting from Normallyitisactually5to15degreesawayfrom the anterior superior iliac spine to the the body or about 165 to 175 towards the body middle of the patella ○ And the other one, from the anterior superior iliac spine of the pelvis and thentothemidlineofthepatellaandthe otherlineisconnectingfromthemidline ofthepatellatothetibialtuberosityorto the tibial tubercle Themeasurementorthedifferencebetweenthat angle is known as theQ angle Normal Q angle is less than 15 degrees (10 to 15) owerextremitiesyouverycommongenuvarum L Knock-knees >20 degrees in angle and genu valgum Bow-legged
