Appendicular skeleton

APPENDICULAR SKELETON ENDOSKELETON OF VERTEBRATES

The Appendicular Skeleton The appendicular skeleton includes: Pectoral girdle Pelvic girdle Upper extremities Lower extremities The appendicular skeleton functions primarily to facilitate movement

Tetrapod Limb Typical 4 limbs Primarily a modification of the Rhipidistian fin wings paddles Lost 2 Lost 4 Modified elements

Recall: V p = V g + V e + V gxe V = variation p = phenotypic g = genotypic e = environmental Morphology (anatomy) Behavior & Performance Resource use (ecology) Fitness

Three main components With respect to the pectoral and pelvic girdles: Serially homologous – Propodium (= stylopodium) – upper arm, upper leg Epipodium (= zeugopodium) – forearm, shin Autopodium – manus or pes (digits, and wrist and palm, or ankle and sole

Mesopodium Metapodium Phalanges

Pectoral (Shoulder) Girdle The pectoral or shoulder girdle attaches the bones of the upper limbs to the axial skeleton Consists of scapula & clavicle Clavicle articulates with sternum ( sternoclavicular joint ) Clavicle articulates with scapula ( acromioclavicular joint ) Scapula held in place by muscle only Upper limb attached to pectoral girdle at shoulder ( glenohumeral joint )

Clavicle (Collarbone) S-shaped bone with two curves Extends from sternum to scapula above 1st rib Sternal & acromial extremities One of the most commonly fractured bones in the human body Fracture site is junction of curves Ligaments attached to clavicle stabilize its position. Shoulder separation is sprain of the acromioclavicular ligament

Anterior Surface of Scapula Articulates with the clavicle and the humerus Subscapular fossa filled with muscle Coracoid process for muscle attachment

Posterior Surface of Scapula Triangular flat bone found in upper back region Scapular spine ends as acromion process Glenoid cavity forms shoulder joint with head of humerus Supraspinous & infraspinous fossa for muscular attachments

Upper Extremity Upper extremity consists of 30 bones Humerus within the arm Ulna & radius within the forearm Carpal bones within the wrist Metacarpal bones within the palm Phalanges in the fingers Joints Shoulder ( glenohumeral ), elbow , wrist , metacarpophalangeal , interphalangeal Shoulder dislocation is separation of the humerus from the glenoid cavity of the scapula

Shoulder Dislocation Head of humerus slips out of glenoid cavity Closed reduction is term for slipping humerus back into place without surgery Severe or frequent dislocations may require surgical ligament repair

Humerus: Proximal End Largest and longest bone of upper extremity, part of shoulder joint, articulates with scapula Head Greater & lesser tubercles for muscle attachments Intertubercular sulcus or bicipital groove Shaft or body

Humerus: Distal End Forms elbow joint with ulna and radius Capitulum articulates with head of radius Trochlea articulation with ulna Olecranon fossa posterior depression for olecranon process of ulna Medial & lateral epicondyles attachment of forearm muscles

Ulna & Radius: Proximal End Ulna (on little finger side) Trochlear notch articulates with humerus & radial notch with radius Olecranon process forms point of elbow Radius (on thumb side) Head articulates with capitulum of humerus & radial notch of ulna Tuberosity for muscle attachment

Ulna & Radius: Proximal End Radius (on thumb side) Head articulates with capitulum of humerus & radial notch of ulna Tuberosity for muscle attachment Ulnar notch articulates with ulna

Elbow Joint Articulation of humerus with ulna and radius Ulna articulates with trochlea of humerus Radius articulates with capitulum of humerus Interosseous membrane between ulna & radius provides site for muscle attachment

Ulna and Radius: Distal End Ulna Styloid process provides attachment for ulnar collateral ligament Head separated from wrist joint by fibrocartilage disc Radius Forms wrist joint with scaphoid , lunate & triquetrum Forms distal radioulnar joint with head of ulna

8 Carpal Bones (Wrist) Proximal row - lateral to medial Scaphoid : boat shaped Lunate : moon shaped Triquetrum : 3 corners Pisiform : pea shaped Distal row - lateral to medial Trapezium : four sided Trapezoid : four sided Capitate : large head Hamate : hooked process S cared L overs T ry P ositions T hat T hey C an’t H andle

Metacarpals and Phalanges Metacarpals 5 total: #1 proximal to thumb base , shaft , head knuckles ( metacarpophalangeal joints) Phalanges (Digits) 14 total: each is called phalanx proximal , middle , distal on each finger, except thumb base , shaft , head

Pelvic Girdle and Hip Bones Pelvic girdle = two hip bones united at pubic symphysis articulate posteriorly with sacrum at sacroiliac joints Each hip bone ( os coxa ) = ilium , pubis , and ischium fuse after birth at acetabulum Bony pelvis = 2 hip bones, sacrum and coccyx

Ilium Iliac crest and iliac spines for muscle attachment Iliac fossa for muscle attachment Gluteal lines indicating muscle attachment Sacroiliac joint at auricular surface & iliac tuberosity Greater sciatic notch for sciatic nerve

Ischium and Pubis Ischium Ischial spine & tuberosity Lesser sciatic notch Ramus Pubis Body Superior & inferior ramus Pubic symphysis is pad of fibrocartilage between 2 pubic bones

Female Pelvis Male Pelvis Many differences between the two In particular, pubic arch in males is usually less than 90˚, whereas in females it is usually greater than 90˚

Lower Extremity Each lower limb = 30 bones femur and patella within the thigh tibia & fibula within the leg tarsal bones in the foot metatarsals within the forefoot phalanges in the toes Joints hip, knee, ankle proximal & distal tibiofibular metatarsophalangeal

Femur The femur or thighbone is the largest, heaviest, and strongest bone of the body It articulates with the hip bone and the tibia Head articulates with acetabulum Medial & lateral condyles articulate with tibia Neck is common fracture site Muscle attachments at greater & lesser trochanters , linea aspera , & gluteal tuberosity Patellar surface is visible anteriorly between condyles

Femur Fovea capitis in the center of the head Medial epicondyles above the condyles Intercondylar fossa between the condyles

Patella Triangular sesamoid bone Apex & base Articular facets for the femur Increases leverage of quadriceps femoris tendon

Tibia and Fibula Tibia (Shinbone) Medial & larger bone of leg Weight-bearing bone Head Lateral & medial condyles Intercondylar eminence Tibial tuberosity for patellar ligament Proximal tibiofibular joint Fibular notch Medial malleolus at ankle

Tibia and Fibula Fibula Parallel and lateral to the tibia Smaller than the tibia Not weight bearing Not part of the knee joint Muscle attachments only Head on proximal end, lateral maleolus at ankle Fits into fibular notch at distal end of tibia

Tarsals, Metatarsals, and Phalanges Seven tarsal bones constitute the ankle (tarsus) and share the weight associated with walking Five metatarsal bones are contained in the foot Fractures of the metatarsals are common among dancers, especially ballet dancers, and also among martial artists The arrangement of phalanges in the toes is the same as that described for the fingers and thumb above: fourteen bones in each foot

Tarsus (Ankle) Proximal region of foot (contains 7 tarsal bones) Talus = ankle bone (articulates with tibia & fibula ) Calcaneus = heel bone Cuboid , navicular & 3 cuneiforms Metatarsal fractures occur when you drop something heavy on your foot

Metatarsus and Phalanges Metatarsals Midregion of the foot 5 metatarsals (#1 is most medial) Each with base , shaft and head Phalanges Distal portion of the foot Similar in number and arrangement to the hand Big toe is hallux

Arches of the Foot Function distribute body weight over foot yield & spring back when weight is lifted Longitudinal arches along each side of foot Transverse arch across midfoot region navicular, cuneiforms & bases of metatarsals

HOMOLOGY OF APPENDICULAR BONES FORELIMB Humerus Radius Ulna Carpals Metacarpals Phallanges HINDLIMB Femur Tibia Fibula Tarsals Metatarsals Phallanges

HOMOLOGY OF GIRDLES PECTORAL GIRDLE Scapula * coracoid process 2. Clavicle PELVIC GIRDLE Ilia 2. Ischia 3. Pubis

I. GIRDLES PECTORAL GIRDLE - COMPOSITION: 1. Replacement Bones a. coracoid b. Scapula c. Suprascapula 2. Dermal Bones – 4 bones of more a. clavicle b. large cleithrium c. small supracleitrium d. post temporal e. post cleithria (ganoid fishes)

VARIATION OF PECTORAL GIRDLE CHONDRICHTHYES - ventral coracoid - scapula - suprascapula 2. OSTEICHTHYES - suprascapula is absent - coracoid +scapula=coracoscapula

3. TETRAPODS AMPHIBIANS - girdle retained in dermal bones -components: a. 2 coracoid c. 2 suprascapula b. 2 scapula d. 1 epicoracoid B. REPTILES - coracoids are fused to form one bone PROCORACOID

c. AVES - components: a. furcula -2 clavicles -1 interclavicle b.2 scapula c. 2 precoracoid D. MAMMALS - components: a. 2 clavicles b. 2 scapula (shoulder blade) - coracoid process - acromial process - glenoid fossa

II. PELVIC GIRDLES VARIATION OF PELVIC GIRDLES FISHES - fusion of ishium and pubis forming ISHIIO-PUBIC PLATE - (median pubic symphysis) 2. AMPHIBIANS - 2 Ilia - 1 sichium (ischiac sysmphysis) - 1 pubis (pubic symphysis)

3. REPTILES - 2 Ilia - sacral rib – fused with the carapace - 2 ishia - 2 pubis 4. AVES - 2 Ilia (concave and convex area) - 2 pubis - 2 ischia - 2 foramens a. obturator foramen b. ilio-ischiac foramen – fused to synsacrum

5. MAMMALS - 2 Ilia - 2 ischia - 2 pubis (os coxae, innominate bone, pelvic bone)

III. LIMBS VARIATION OF FORELIMBS AMPHIBIANS - 2 humerus - 2 radio-ulna (fused) - 2 rows of carpals a. proximal row * radiale, ulnare,centrale b. distal row * 3 ordinary fused carpals - phalanges : 2: 3: 3:2

2. REPTILES - different size and shape, diameter - addition – increase in number - fusion - reduction in size 3. AVES - modified for flight - 2 Humerus - 2 radius - 2 ulna - 2 carpometacarpus - phalanges: 1:3:2

4. MAMMALS 2 humerus 2 radius 2 ulna 8 carpals a. proximal row * scaphoid * triquetral * lunate * pisiform b. distal row *trapezium *capitate * trapezoid * hamate * Phalanges : 2:3:3:3:3

II. HINDLIMB FEMUR – THIGH TIBIA AND FIBULA – SHANK TARSALS - ANKLE METATARSALS – SOLE PHALANGES – DIGITS /TOES

VARIATION OF HINDLIMB AMPHIBIANS - 2 Femur - 2 tibio-fibula - 2 proximal tarsals * astragalus *calcaneum - 2 ordinary tarsals – fused - 5 metatarsals - phalanges : 1 :3:4:4:3

2. REPTILES - in sphenodons and lizards- tarsal bones are fused forming ASTRAGALOCALCANEUM 3.AVES - TIBIOTARSUS - TARSOMETATARSUS - METATARSALS - 4 DIGITS WITH CLAWS, KNEE CAP

3. MAMMALS - 2 FEMUR - 2 TIBIA - 2 FIBULA - 7 TARSALS A. PROXIMAL - calcaneum,talus,navicular B. DISTAL - 3 cunieforms, 1 cuboid - 5 metatarsals - phalanges: 2:3:3:3:3

ADAPTATION OF MANUS WRIST PALM DIGITS FUNCTIONS: For grasping For swift-footedness Digitigrade * unguligrade Plantigrade

For flight – wings For swimming – flippers for life in the ocean FINS - stabilizers - steering device for undulation

TYPES OF FINS PAIRED FINS 1.A BONY FISH A. PECTORAL FINS –coracoscapula B. PELVIC FINS - ischio-pubic plate 1.B. CARTILAGINOUS FIS A. PECTORAL FINS – coracoid,scapula, suprascapula B. PELVIC FINS - ischio-pubic plate

2. UNPAIRED FINS A. ANAL FINS B.CAUDAL FINS C. MEDIAN DORSAL FINS A. ANTERIOR DORSAL FIN B. POSTERIOR DORSAL FIN

DIVERSITIES IN SKELETAL STRUCTURES OF PAIRED FINS SPINY FINS LOBED FINS FINFOLD FINS FIN SPINE VARIATION OF MEDIAN FINS HETEROCERCAL -unidentical HOMOCERCAL - identical DIPHYCERCAL - symmetrical HYPOCERCAL - directed downward

THEORIES OF THE ORIGIN OF FINS FIN FOLD HYPOTHESIS – paired fins are derived from a pair of continuous fleshy folds of the lateral body wall analogous to the metapleural folds of amphioxus 2. GILL ARCH HYPOTHESIS (Gegenbaur) - pectoral and pelvic fins are modified gill arches and the skeleton within the fin is an expansion of gill rays 3. FIN SPINE HYPOTHESIS (Gregory and Raven) -in early acanthodians, pectoral and pelvic appendages were the largest of the series of lateral hollow spiny appendages -lateral extension of the trunk

LOCOMOTION OF LIMBLESS VERTEBRATES SERPENTINE OR LATERAL UNDULATION – movement forming irregular loops CONCERTIVE OR RECTILINEAR - move from place to place by gliding using the cervical ribs 3. SIDESWINDING - occupy territory or sandy dessert - rattlesnakes

Appendicular skeleton

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