Appendicular skeleton


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Our Lesson in Zoology 200 Appendicular Skeletons by: Mr. Claver Digamon

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  • SH – Kuo and shankland 2003, Development 131. Definition – “existence of comparable pattern elements in different segmental units of the same individual.”
  • Appendicular skeleton

    2. 2. The Appendicular Skeleton <ul><li>The appendicular skeleton includes: </li></ul><ul><ul><li>Pectoral girdle </li></ul></ul><ul><ul><li>Pelvic girdle </li></ul></ul><ul><ul><li>Upper extremities </li></ul></ul><ul><ul><li>Lower extremities </li></ul></ul><ul><li>The appendicular skeleton functions primarily to facilitate movement </li></ul>
    3. 3. Fig. 9.4
    4. 4. Tetrapod Limb <ul><li>Typical 4 limbs </li></ul><ul><li>Primarily a modification of the Rhipidistian fin </li></ul>wings paddles Lost 2 Lost 4 Modified elements
    5. 5. <ul><li>Recall: V p = V g + V e + V gxe </li></ul><ul><li>V = variation </li></ul><ul><li>p = phenotypic </li></ul><ul><li>g = genotypic </li></ul><ul><li>e = environmental </li></ul>Morphology (anatomy) Behavior & Performance Resource use (ecology) Fitness
    6. 6. Three main components <ul><li>With respect to the pectoral and pelvic girdles: </li></ul><ul><ul><li>Serially homologous – </li></ul></ul><ul><ul><li>Propodium (= stylopodium) – upper arm, upper leg </li></ul></ul><ul><ul><li>Epipodium (= zeugopodium) – forearm, shin </li></ul></ul><ul><ul><li>Autopodium – manus or pes (digits, and wrist and palm, or ankle and sole </li></ul></ul>
    7. 7. <ul><li>Mesopodium </li></ul><ul><li>Metapodium </li></ul><ul><li>Phalanges </li></ul>
    8. 9. Fig. 9.12
    9. 12. Focus 9.2
    10. 13. Pectoral (Shoulder) Girdle <ul><li>The pectoral or shoulder girdle attaches the bones of the upper limbs to the axial skeleton </li></ul><ul><li>Consists of scapula & clavicle </li></ul><ul><li>Clavicle articulates with sternum ( sternoclavicular joint ) </li></ul><ul><li>Clavicle articulates with scapula ( acromioclavicular joint ) </li></ul><ul><li>Scapula held in place by muscle only </li></ul><ul><li>Upper limb attached to pectoral girdle at shoulder ( glenohumeral joint ) </li></ul>
    11. 14. Clavicle (Collarbone) <ul><li>S-shaped bone with two curves </li></ul><ul><li>Extends from sternum to scapula above 1st rib </li></ul><ul><li>Sternal & acromial extremities </li></ul><ul><li>One of the most commonly fractured bones in the human body </li></ul><ul><li>Fracture site is junction of curves </li></ul><ul><li>Ligaments attached to clavicle stabilize its position. </li></ul><ul><li>Shoulder separation is sprain of the acromioclavicular ligament </li></ul>
    12. 15. Anterior Surface of Scapula <ul><li>Articulates with the clavicle and the humerus </li></ul><ul><li>Subscapular fossa filled with muscle </li></ul><ul><li>Coracoid process for muscle attachment </li></ul>
    13. 16. Posterior Surface of Scapula <ul><li>Triangular flat bone found in upper back region </li></ul><ul><li>Scapular spine ends as acromion process </li></ul><ul><li>Glenoid cavity forms shoulder joint with head of humerus </li></ul><ul><li>Supraspinous & infraspinous fossa for muscular attachments </li></ul>
    14. 17. Upper Extremity <ul><li>Upper extremity consists of 30 bones </li></ul><ul><ul><li>Humerus within the arm </li></ul></ul><ul><ul><li>Ulna & radius within the forearm </li></ul></ul><ul><ul><li>Carpal bones within the wrist </li></ul></ul><ul><ul><li>Metacarpal bones within the palm </li></ul></ul><ul><ul><li>Phalanges in the fingers </li></ul></ul><ul><li>Joints </li></ul><ul><ul><li>Shoulder ( glenohumeral ), elbow , wrist , metacarpophalangeal , interphalangeal </li></ul></ul><ul><ul><li>Shoulder dislocation is separation of the humerus from the glenoid cavity of the scapula </li></ul></ul>
    15. 18. Shoulder Dislocation <ul><li>Head of humerus slips out of glenoid cavity </li></ul><ul><li>Closed reduction is term for slipping humerus back into place without surgery </li></ul><ul><li>Severe or frequent dislocations may require surgical ligament repair </li></ul>
    16. 19. Humerus: Proximal End <ul><li>Largest and longest bone of upper extremity, part of shoulder joint, articulates with scapula </li></ul><ul><li>Head </li></ul><ul><li>Greater & lesser tubercles </li></ul><ul><li>for muscle attachments </li></ul><ul><li>Intertubercular </li></ul><ul><li>sulcus or bicipital </li></ul><ul><li>groove </li></ul><ul><li>Shaft or body </li></ul>
    17. 20. Humerus: Distal End <ul><li>Forms elbow joint with ulna and radius </li></ul><ul><li>Capitulum </li></ul><ul><ul><li>articulates with head of radius </li></ul></ul><ul><li>Trochlea </li></ul><ul><ul><li>articulation with ulna </li></ul></ul><ul><li>Olecranon fossa </li></ul><ul><ul><li>posterior depression for olecranon process of ulna </li></ul></ul><ul><li>Medial & lateral epicondyles </li></ul><ul><ul><li>attachment of forearm muscles </li></ul></ul>
    18. 21. Ulna & Radius: Proximal End <ul><li>Ulna (on little finger side) </li></ul><ul><ul><li>Trochlear notch articulates with humerus & radial notch with radius </li></ul></ul><ul><ul><li>Olecranon process forms point of elbow </li></ul></ul><ul><li>Radius (on thumb side) </li></ul><ul><ul><li>Head articulates with capitulum of humerus & radial notch of ulna </li></ul></ul><ul><ul><li>Tuberosity for muscle attachment </li></ul></ul>
    19. 22. Ulna & Radius: Proximal End <ul><li>Radius (on thumb side) </li></ul><ul><ul><li>Head articulates with capitulum of humerus & radial notch of ulna </li></ul></ul><ul><ul><li>Tuberosity for muscle attachment </li></ul></ul><ul><ul><li>Ulnar notch articulates with ulna </li></ul></ul>
    20. 23. Elbow Joint <ul><li>Articulation of humerus with ulna and radius </li></ul><ul><li>Ulna articulates with trochlea of humerus </li></ul><ul><li>Radius articulates with capitulum of humerus </li></ul><ul><li>Interosseous membrane between ulna & radius provides site for muscle attachment </li></ul>
    21. 24. Ulna and Radius: Distal End <ul><li>Ulna </li></ul><ul><ul><li>Styloid process provides attachment for ulnar collateral ligament </li></ul></ul><ul><ul><li>Head separated from wrist joint by fibrocartilage disc </li></ul></ul><ul><li>Radius </li></ul><ul><ul><li>Forms wrist joint with scaphoid , lunate & triquetrum </li></ul></ul><ul><ul><li>Forms distal radioulnar joint with head of ulna </li></ul></ul>
    22. 25. 8 Carpal Bones (Wrist) <ul><li>Proximal row - lateral to medial </li></ul><ul><ul><li>Scaphoid : boat shaped </li></ul></ul><ul><ul><li>Lunate : moon shaped </li></ul></ul><ul><ul><li>Triquetrum : 3 corners </li></ul></ul><ul><ul><li>Pisiform : pea shaped </li></ul></ul><ul><li>Distal row - lateral to medial </li></ul><ul><ul><li>Trapezium : four sided </li></ul></ul><ul><ul><li>Trapezoid : four sided </li></ul></ul><ul><ul><li>Capitate : large head </li></ul></ul><ul><ul><li>Hamate : hooked process </li></ul></ul>S cared L overs T ry P ositions T hat T hey C an’t H andle
    23. 26. Metacarpals and Phalanges <ul><li>Metacarpals </li></ul><ul><ul><li>5 total: #1 proximal to thumb </li></ul></ul><ul><ul><li>base , shaft , head </li></ul></ul><ul><ul><li>knuckles ( metacarpophalangeal joints) </li></ul></ul><ul><li>Phalanges (Digits) </li></ul><ul><ul><li>14 total: each is called phalanx </li></ul></ul><ul><ul><li>proximal , middle , distal on each finger, except thumb </li></ul></ul><ul><ul><li>base , shaft , head </li></ul></ul>
    24. 27. Pelvic Girdle and Hip Bones <ul><li>Pelvic girdle = two hip bones united at pubic symphysis </li></ul><ul><ul><li>articulate posteriorly with sacrum at sacroiliac joints </li></ul></ul><ul><li>Each hip bone ( os coxa ) = ilium , pubis , and ischium </li></ul><ul><ul><li>fuse after birth at acetabulum </li></ul></ul><ul><li>Bony pelvis = 2 hip bones, sacrum and coccyx </li></ul>
    25. 28. Ilium <ul><li>Iliac crest and iliac spines for muscle attachment </li></ul><ul><li>Iliac fossa for muscle attachment </li></ul><ul><li>Gluteal lines indicating muscle attachment </li></ul><ul><li>Sacroiliac joint at auricular surface & iliac tuberosity </li></ul><ul><li>Greater sciatic notch for sciatic nerve </li></ul>
    26. 29. Ischium and Pubis <ul><li>Ischium </li></ul><ul><ul><li>Ischial spine & tuberosity </li></ul></ul><ul><ul><li>Lesser sciatic notch </li></ul></ul><ul><ul><li>Ramus </li></ul></ul><ul><li>Pubis </li></ul><ul><ul><li>Body </li></ul></ul><ul><ul><li>Superior & inferior ramus </li></ul></ul><ul><ul><li>Pubic symphysis is pad of fibrocartilage between 2 pubic bones </li></ul></ul>
    27. 30. Female Pelvis Male Pelvis <ul><li>Many differences between the two </li></ul><ul><li>In particular, pubic arch in males is usually less than 90˚, whereas in females it is usually greater than 90˚ </li></ul>
    28. 31. Lower Extremity <ul><li>Each lower limb = 30 bones </li></ul><ul><ul><li>femur and patella within the thigh </li></ul></ul><ul><ul><li>tibia & fibula within the leg </li></ul></ul><ul><ul><li>tarsal bones in the foot </li></ul></ul><ul><ul><li>metatarsals within the forefoot </li></ul></ul><ul><ul><li>phalanges in the toes </li></ul></ul><ul><li>Joints </li></ul><ul><ul><li>hip, knee, ankle </li></ul></ul><ul><ul><li>proximal & distal tibiofibular </li></ul></ul><ul><ul><li>metatarsophalangeal </li></ul></ul>
    29. 32. Femur <ul><li>The femur or thighbone is the largest, heaviest, and strongest bone of the body </li></ul><ul><li>It articulates with the hip bone and the tibia </li></ul><ul><ul><li>Head articulates with acetabulum </li></ul></ul><ul><ul><li>Medial & lateral condyles articulate with tibia </li></ul></ul><ul><li>Neck is common fracture site </li></ul><ul><li>Muscle attachments at greater & lesser trochanters , linea aspera , & gluteal tuberosity </li></ul><ul><li>Patellar surface is visible anteriorly between condyles </li></ul>
    30. 33. Femur <ul><li>Fovea capitis in the center of the head </li></ul><ul><li>Medial epicondyles above the condyles </li></ul><ul><li>Intercondylar fossa between the condyles </li></ul>
    31. 34. Patella <ul><li>Triangular sesamoid bone </li></ul><ul><li>Apex & base </li></ul><ul><li>Articular facets for the femur </li></ul><ul><li>Increases leverage of quadriceps femoris tendon </li></ul>
    32. 35. Tibia and Fibula <ul><li>Tibia (Shinbone) </li></ul><ul><li>Medial & larger bone of leg </li></ul><ul><li>Weight-bearing bone </li></ul><ul><li>Head </li></ul><ul><li>Lateral & medial condyles </li></ul><ul><li>Intercondylar eminence </li></ul><ul><li>Tibial tuberosity for patellar ligament </li></ul><ul><li>Proximal tibiofibular joint </li></ul><ul><li>Fibular notch </li></ul><ul><li>Medial malleolus at ankle </li></ul>
    33. 36. Tibia and Fibula <ul><li>Fibula </li></ul><ul><li>Parallel and lateral to the tibia </li></ul><ul><li>Smaller than the tibia </li></ul><ul><li>Not weight bearing </li></ul><ul><li>Not part of the knee joint </li></ul><ul><li>Muscle attachments only </li></ul><ul><li>Head on proximal end, lateral maleolus at ankle </li></ul><ul><li>Fits into fibular notch at distal end of tibia </li></ul>
    34. 37. Tarsals, Metatarsals, and Phalanges <ul><li>Seven tarsal bones constitute the ankle (tarsus) and share the weight associated with walking </li></ul><ul><li>Five metatarsal bones are contained in the foot </li></ul><ul><li>Fractures of the metatarsals are common among dancers, especially ballet dancers, and also among martial artists </li></ul><ul><li>The arrangement of phalanges in the toes is the same as that described for the fingers and thumb above: fourteen bones in each foot </li></ul>
    35. 38. Tarsus (Ankle) <ul><li>Proximal region of foot (contains 7 tarsal bones) </li></ul><ul><li>Talus = ankle bone (articulates with tibia & fibula ) </li></ul><ul><li>Calcaneus = heel bone </li></ul><ul><li>Cuboid , navicular & 3 cuneiforms </li></ul><ul><li>Metatarsal fractures occur when you drop something heavy on your foot </li></ul>
    36. 39. Metatarsus and Phalanges <ul><li>Metatarsals </li></ul><ul><ul><li>Midregion of the foot </li></ul></ul><ul><ul><li>5 metatarsals (#1 is most medial) </li></ul></ul><ul><ul><li>Each with base , shaft and head </li></ul></ul><ul><li>Phalanges </li></ul><ul><ul><li>Distal portion of the foot </li></ul></ul><ul><ul><li>Similar in number and arrangement to the hand </li></ul></ul><ul><ul><li>Big toe is hallux </li></ul></ul>
    37. 40. Arches of the Foot <ul><li>Function </li></ul><ul><ul><li>distribute body weight over foot </li></ul></ul><ul><ul><li>yield & spring back when weight is lifted </li></ul></ul><ul><li>Longitudinal arches along each side of foot </li></ul><ul><li>Transverse arch across midfoot region </li></ul><ul><ul><li>navicular, cuneiforms & bases of metatarsals </li></ul></ul>
    38. 41. HOMOLOGY OF APPENDICULAR BONES <ul><li>FORELIMB </li></ul><ul><li>Humerus </li></ul><ul><li>Radius </li></ul><ul><li>Ulna </li></ul><ul><li>Carpals </li></ul><ul><li>Metacarpals </li></ul><ul><li>Phallanges </li></ul><ul><li>HINDLIMB </li></ul><ul><li>Femur </li></ul><ul><li>Tibia </li></ul><ul><li>Fibula </li></ul><ul><li>Tarsals </li></ul><ul><li>Metatarsals </li></ul><ul><li>Phallanges </li></ul>
    39. 42. HOMOLOGY OF GIRDLES <ul><li>PECTORAL GIRDLE </li></ul><ul><li>Scapula </li></ul><ul><li>* coracoid process </li></ul><ul><li>2. Clavicle </li></ul><ul><li>PELVIC GIRDLE </li></ul><ul><li>Ilia </li></ul><ul><li>2. Ischia </li></ul><ul><li>3. Pubis </li></ul>
    40. 43. I. GIRDLES <ul><li>PECTORAL GIRDLE </li></ul><ul><li>- COMPOSITION: </li></ul><ul><li>1. Replacement Bones </li></ul><ul><li>a. coracoid </li></ul><ul><li>b. Scapula </li></ul><ul><li>c. Suprascapula </li></ul><ul><li>2. Dermal Bones – 4 bones of more </li></ul><ul><li>a. clavicle </li></ul><ul><li>b. large cleithrium </li></ul><ul><li>c. small supracleitrium </li></ul><ul><li>d. post temporal </li></ul><ul><li>e. post cleithria (ganoid fishes) </li></ul>
    41. 44. VARIATION OF PECTORAL GIRDLE <ul><li>CHONDRICHTHYES </li></ul><ul><li>- ventral coracoid </li></ul><ul><li>- scapula </li></ul><ul><li>- suprascapula </li></ul><ul><li>2. OSTEICHTHYES </li></ul><ul><li>- suprascapula is absent </li></ul><ul><li>- coracoid +scapula=coracoscapula </li></ul>
    42. 45. 3. TETRAPODS <ul><li>AMPHIBIANS </li></ul><ul><li>- girdle retained in dermal bones </li></ul><ul><li>-components: </li></ul><ul><li>a. 2 coracoid c. 2 suprascapula </li></ul><ul><li>b. 2 scapula d. 1 epicoracoid </li></ul><ul><li>B. REPTILES </li></ul><ul><li>- coracoids are fused to form one bone </li></ul><ul><li>PROCORACOID </li></ul>
    43. 46. <ul><li>c. AVES </li></ul><ul><li>- components: </li></ul><ul><li>a. furcula </li></ul><ul><li>-2 clavicles </li></ul><ul><li>-1 interclavicle </li></ul><ul><li>b.2 scapula </li></ul><ul><li>c. 2 precoracoid </li></ul><ul><li>D. MAMMALS </li></ul><ul><li> - components: </li></ul><ul><li>a. 2 clavicles </li></ul><ul><li>b. 2 scapula (shoulder blade) </li></ul><ul><li>- coracoid process </li></ul><ul><li>- acromial process </li></ul><ul><li>- glenoid fossa </li></ul>
    44. 47. II. PELVIC GIRDLES <ul><li>VARIATION OF PELVIC GIRDLES </li></ul><ul><li>FISHES </li></ul><ul><ul><li>- fusion of ishium and pubis forming </li></ul></ul><ul><ul><li>ISHIIO-PUBIC PLATE </li></ul></ul><ul><ul><li>- (median pubic symphysis) </li></ul></ul><ul><ul><li>2. AMPHIBIANS </li></ul></ul><ul><ul><li>- 2 Ilia </li></ul></ul><ul><ul><li>- 1 sichium (ischiac sysmphysis) </li></ul></ul><ul><ul><li>- 1 pubis (pubic symphysis) </li></ul></ul>
    45. 48. <ul><li>3. REPTILES </li></ul><ul><li>- 2 Ilia </li></ul><ul><li>- sacral rib – fused with the carapace </li></ul><ul><li>- 2 ishia </li></ul><ul><li>- 2 pubis </li></ul><ul><li>4. AVES </li></ul><ul><li>- 2 Ilia (concave and convex area) </li></ul><ul><li>- 2 pubis </li></ul><ul><li>- 2 ischia </li></ul><ul><li>- 2 foramens </li></ul><ul><li>a. obturator foramen </li></ul><ul><li>b. ilio-ischiac foramen </li></ul><ul><li>– fused to synsacrum </li></ul>
    46. 49. <ul><li>5. MAMMALS </li></ul><ul><li>- 2 Ilia </li></ul><ul><li>- 2 ischia </li></ul><ul><li>- 2 pubis </li></ul><ul><li>(os coxae, innominate bone, pelvic bone) </li></ul>
    47. 50. III. LIMBS <ul><li>VARIATION OF FORELIMBS </li></ul><ul><li>AMPHIBIANS </li></ul><ul><li>- 2 humerus </li></ul><ul><li>- 2 radio-ulna (fused) </li></ul><ul><li> - 2 rows of carpals </li></ul><ul><li>a. proximal row </li></ul><ul><li>* radiale, ulnare,centrale </li></ul><ul><li>b. distal row </li></ul><ul><li>* 3 ordinary fused carpals </li></ul><ul><li> - phalanges : 2: 3: 3:2 </li></ul>
    48. 51. <ul><li>2. REPTILES </li></ul><ul><li> - different size and shape, diameter </li></ul><ul><li> - addition – increase in number </li></ul><ul><li> - fusion - reduction in size </li></ul><ul><li>3. AVES - modified for flight </li></ul><ul><li> - 2 Humerus </li></ul><ul><li> - 2 radius </li></ul><ul><li> - 2 ulna </li></ul><ul><li> - 2 carpometacarpus </li></ul><ul><li> - phalanges: 1:3:2 </li></ul>
    49. 52. 4. MAMMALS <ul><li>2 humerus </li></ul><ul><li>2 radius </li></ul><ul><li>2 ulna </li></ul><ul><li>8 carpals </li></ul><ul><li>a. proximal row </li></ul><ul><li>* scaphoid * triquetral </li></ul><ul><li> * lunate * pisiform </li></ul><ul><li>b. distal row </li></ul><ul><li>*trapezium *capitate </li></ul><ul><li>* trapezoid * hamate </li></ul><ul><li>* Phalanges : 2:3:3:3:3 </li></ul>
    50. 53. II. HINDLIMB <ul><li>FEMUR – THIGH </li></ul><ul><li>TIBIA AND FIBULA – SHANK </li></ul><ul><li>TARSALS - ANKLE </li></ul><ul><li>METATARSALS – SOLE </li></ul><ul><li>PHALANGES – DIGITS /TOES </li></ul>
    51. 54. VARIATION OF HINDLIMB <ul><li>AMPHIBIANS </li></ul><ul><ul><li>- 2 Femur </li></ul></ul><ul><ul><li>- 2 tibio-fibula </li></ul></ul><ul><ul><li>- 2 proximal tarsals </li></ul></ul><ul><ul><li> * astragalus *calcaneum </li></ul></ul><ul><ul><li>- 2 ordinary tarsals – fused </li></ul></ul><ul><ul><li>- 5 metatarsals </li></ul></ul><ul><ul><li>- phalanges : 1 :3:4:4:3 </li></ul></ul>
    52. 57. <ul><li>2. REPTILES </li></ul><ul><li>- in sphenodons and lizards- tarsal </li></ul><ul><li>bones are fused forming </li></ul><ul><li>ASTRAGALOCALCANEUM </li></ul><ul><li>3.AVES </li></ul><ul><li>- TIBIOTARSUS </li></ul><ul><li>- TARSOMETATARSUS </li></ul><ul><li>- METATARSALS </li></ul><ul><li>- 4 DIGITS WITH CLAWS, KNEE CAP </li></ul>
    53. 60. <ul><li>3. MAMMALS </li></ul><ul><li>- 2 FEMUR </li></ul><ul><li>- 2 TIBIA </li></ul><ul><li>- 2 FIBULA </li></ul><ul><li>- 7 TARSALS </li></ul><ul><li>A. PROXIMAL </li></ul><ul><li>- calcaneum,talus,navicular </li></ul><ul><li>B. DISTAL </li></ul><ul><li>- 3 cunieforms, 1 cuboid </li></ul><ul><li>- 5 metatarsals </li></ul><ul><li>- phalanges: 2:3:3:3:3 </li></ul>
    54. 63. ADAPTATION OF MANUS <ul><li>WRIST </li></ul><ul><li>PALM </li></ul><ul><li>DIGITS </li></ul><ul><li>FUNCTIONS: </li></ul><ul><ul><li>For grasping </li></ul></ul><ul><ul><li>For swift-footedness </li></ul></ul><ul><ul><ul><li>Digitigrade * unguligrade </li></ul></ul></ul><ul><ul><ul><li>Plantigrade </li></ul></ul></ul>
    55. 65. <ul><li>For flight – wings </li></ul><ul><li>For swimming – flippers for life in the ocean </li></ul><ul><li>FINS </li></ul><ul><li>- stabilizers </li></ul><ul><li> - steering device for undulation </li></ul>
    56. 66. TYPES OF FINS <ul><li>PAIRED FINS </li></ul><ul><ul><li>1.A BONY FISH </li></ul></ul><ul><ul><li> A. PECTORAL FINS –coracoscapula </li></ul></ul><ul><ul><li> B. PELVIC FINS - ischio-pubic plate </li></ul></ul><ul><ul><li>1.B. CARTILAGINOUS FIS </li></ul></ul><ul><ul><li> A. PECTORAL FINS </li></ul></ul><ul><ul><li>– coracoid,scapula, suprascapula </li></ul></ul><ul><ul><li> B. PELVIC FINS - ischio-pubic plate </li></ul></ul>
    57. 67. 2. UNPAIRED FINS <ul><li>A. ANAL FINS </li></ul><ul><li>B.CAUDAL FINS </li></ul><ul><li>C. MEDIAN DORSAL FINS </li></ul><ul><li>A. ANTERIOR DORSAL FIN </li></ul><ul><li>B. POSTERIOR DORSAL FIN </li></ul>
    58. 68. DIVERSITIES IN SKELETAL STRUCTURES OF PAIRED FINS <ul><li>SPINY FINS </li></ul><ul><li>LOBED FINS </li></ul><ul><li>FINFOLD FINS </li></ul><ul><li>FIN SPINE </li></ul><ul><li>VARIATION OF MEDIAN FINS </li></ul><ul><li>HETEROCERCAL -unidentical </li></ul><ul><li>HOMOCERCAL - identical </li></ul><ul><li>DIPHYCERCAL - symmetrical </li></ul><ul><li>HYPOCERCAL - directed downward </li></ul>
    59. 71. THEORIES OF THE ORIGIN OF FINS <ul><li>FIN FOLD HYPOTHESIS </li></ul><ul><li>– paired fins are derived from a pair of continuous fleshy folds of the lateral body wall analogous to the metapleural folds of amphioxus </li></ul><ul><li>2. GILL ARCH HYPOTHESIS (Gegenbaur) </li></ul><ul><li>- pectoral and pelvic fins are modified gill arches and the skeleton within the fin is an expansion of gill rays </li></ul><ul><li>3. FIN SPINE HYPOTHESIS (Gregory and Raven) </li></ul><ul><li>-in early acanthodians, pectoral and pelvic appendages were the largest of the series of lateral hollow spiny appendages </li></ul><ul><li>-lateral extension of the trunk </li></ul>
    60. 72. LOCOMOTION OF LIMBLESS VERTEBRATES <ul><li>SERPENTINE OR LATERAL UNDULATION – movement forming irregular loops </li></ul><ul><li>CONCERTIVE OR RECTILINEAR </li></ul><ul><li>- move from place to place by </li></ul><ul><li>gliding using the cervical ribs </li></ul><ul><li>3. SIDESWINDING </li></ul><ul><li>- occupy territory or sandy dessert </li></ul><ul><li>- rattlesnakes </li></ul>