appendicular skeleton

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  • The Appendicular SkeletonBy- Dr. Armaan Singh

  • THE SKELETAL SYSTEMThe Appendicular Skeleton2 pairs of limbs and 2 girdlesPectoral (shoulder) girdle attaches upper limbsPelvic (hip) girdle secures lower limbs3-Segmented limbsUpper = armArmForearmHandLower = legThighLegFoot

  • Pectoral Girdle(Shoulder Girdle)Clavicle anterior: collar boneSternal end attaches to the manubrium mediallyAcromial end articulates with the scapula laterallyScapula posterior: shoulder blade

  • Scapulae: triangular, paired, but dont connect in back (adds thoracic flexibility)

  • ScapulaGlenoid cavity articulates with the humerusAcromium articulates with clavicleCoracoid process projects anteriorly

  • Upper extremityArm or Brachium = upper armBetween shoulder and elbow (humerus)Forearm or AntebrachiumRadius & ulnaHand includes: Wrist (carpus)Palm (metacarpus)Fingers (phalanges)

  • ArmHumerus is the only boneHead of humerus fits into glenoid cavity of scapulaDistal & medially, trochlea articulates with the ulnaDistal & laterally capitulum articulates with the radiusMedial & lateral epicondyles

  • Right humerus, anterior view

  • Right humerus, posterior view

  • Forearm2 bones: articulate with each other proximally and distallyInterosseous membrane between themUlnaOlecranon hinges with the humerus forming elbowStyloid process distally RadiusContributes to wrist jointStyloid process anchors a ligament to wrist (thumb side)

    Radius is thinner proximally, like a spool of thread, and wide distally; ulna is slightly longer and looks like a monkey wrench (supposedly!)

  • Right forearm bones, anterior view

  • Right forearm bones, posterior view

  • In the anatomical position, the radius is lateral (thumb side); with pronation the palm faces posteriorly and the bones cross

    Left forearmProne: body lying face downSuppine: body lying face up

    (you can remember prone if you think about how you would fall forward onto your face if you passed out) Anatomical positionpronepronation moves the forearm into the prone position and supination moves it back to the anatomical position

  • proximal ulnaProximal and distal joints of the forearm

  • HandProximal is wrist 8 carpal bonesPalm of hand - 5 metacarpalsFingers (or digits) consist of miniature long bones called phalanges: thumb (pollex) has 2; fingers have 3: proximal, middle, distalRight hand, 2 views:

  • Pelvic Girdle (Hip Girdle)Strongly attached to axial skeleton (sacrum)Deep socketsMore stable than pectoral (shoulder) girdleLess freedom of movementMade up of the paired hip bonesBony pelvis is basin-like structure: hip bones plus the axial sacrum and coccyx

  • Hip bone (os coxae): 3 separate bones in childhood which fuseIlium

    Ischium

    Pubis

  • IliumIliac crestAnterior superior iliac spineGreater sciatic notchForms part of acetabulum (hip socket) which receives ball-shaped head of femur

    iliumilium

  • IschiumBodyRamusIschial spineIschial tuberosityPart of socket

    ischiumischium

  • PubisJoins medially in pubic symphysisForms obturator foramen (large hole) with ischiumPart of socketpubispubis

  • Hip bones with labels

  • LigamentsFalse (greater) andtrue (lesser) pelvis

  • Pelvis and childbearingMale/female differencesLarge & heavy vs light & delicateHeart shaped pelvic inlet vs ovalNarrow deep true pelvis vs wide & shallowNarrow outlet vs wideLess than 90 degree pubic arch vs more than 90 degreeBirth canal changes shape as baby descends: head turns Higher: pelvic inlet (brim) - side to side largestLower: pelvic outlet - largest in AP direction

  • Lower limbThigh: femur

    Leg (lower leg)TibiaFibula

    Foot

  • ThighFemur is largest, longest and strongest bone in the bodyHead fits in socket (acetabulum) of pelvisNeck is weakestGreater trochanterDistal: lateral & medial condyles and epicondylesPatella: sesmoid bone

  • Right femur, anterior view

  • Right femur, posterior view

  • LegTibia: shin boneMedial and lateral condylesTibial tuberosityDistal medial malleolus (medial ankle)FibulaDistal lateral malleolus (lateral ankle)Interosseous membrane

  • Right lower leg, anterior view

  • FootTarsus: 7 tarsal bonesTalus: articulates with tibia and fibula anteriorly and calcaneus posteriorlyCalcaneus: heel boneSmaller cuboid, navicular, and 3 cunieforms (medial, intermediate and lateral)5 metatarsals14 phalangesGreat toe is hallux

  • Right foot, superior (dorsal) view and inferior (plantar) view

  • Right foot, lateral and medial views

  • Arches