HIND LIMB BONES OF FROG
Hind limb constitute the femur, tibio-fibula, astragalus-calcaneum and bones of foot.
- Femur :- (i) It is thigh bone having expanded ends, covered with calcified cartilages. (ii) Proximal end or head articulates with acetabulum while distal end with tibio-fibula.
- Tibio-fibula :- (i) These are shank bones and are elongated. (ii) Tibia is inner and fibula is outer, both fused together to form a compound bone. (iii) Proximally tibia contains a tibial crest. (iv) At proximal end tibio-fibula articulates with femur, and at distal end with astragalus-calcaneum. Structures seen are proximal articular facet, groove, tibia, fibula, nutrient foramen, distal groove and distal articular facet.
- Astragalus-calcareum. (i) These are proximal ankle bones united at both ends and covered by proximal and distal epiphyses of calcified cartilages at proximal and distal ends respectively. (ii) Outer thicker straight bone is calcaneum of iibulare, while inner thinner and slightly curved bone is astragalus or tibiale.
- Bones of foot. (i) Foot contains 5 long, slender bones, known as metatarsals, having five true toes.
(ii) First, second, third, fourth and fifth digits contain 2, 2, 3, 4 and 3 phalanges respectively.
(iii) Sixth toe is very small having 2 or 3 bones and is called as pre-hallux or calcar.
HIND LIMB BONES OF VARANUS
Hind limb consists of femur, tibia, fibula and bones of hind foot.
- Femur :- (i) It is thigh bone having two epiphyses. (ii) Proximal end contains head, which fits into acetabulum, while distal end is pulley-shaped, having two tuberosities or condyles for articulation with tibia and fibula,. (iii) Femur has lesser trochanter and greater trochanter on pre-axial and post-axial sides, respectively.
- Tibia and fibula and bones of hind foot :-
(i) These are shank bones, (ii) Tibia is stout, curved and on pre-axial side, while fibula is slender and on post-axial side.
- Bones of hind-foot :- (i) It is made up of 5 tarsal bones. (ii) First, second, third, fourth and fifth toes contain 2, 3, 4, 5 and 3 phalanges, respectively. (iii) Each toe bears a terminal horny claw.
HIND LIMB BONES OF FOWL
Hind limb comprises of femur, tibio-tarsus and fibula, tarsals, tarso- metatarsus and phalanges. Hind is modified for bipedal locomotion.
- Femur (Anterior view). (i) It is cylindrical, short and curved thigh bone. (ii) Head fits into acetabulum and outwardly it contains greater trochanter. (iii) Distal end is pulley-shaped for patella bone and bounded by two condyles to articulate with tibia namely outer condyles and inner condyle with inter condylar fossa.
- Femur (Posterior view). Contains nutrient foramen, head, inter condylar fossa, outer condyle and inner condyle.
- Tibio-tarsus and fibula (Anterior view). (i) Tibio-tarsus and fibula form shank bones. (ii) Tibio-tarsus is a straight and long bone formed by fusion of tibia with proximal row of tarsals (astragalus and calcaneum). (iii) Proximally, it articulates with femur and distally with tarso-metatarsus.
(iv) Fibula is reduced to a small slender bone. Other structures are tibial crest distal lateral tubercle, distal groove.
- Tarso-metatarsus female (Posterior view). (i) It is a compound bone formed by fusion of distal row of tarsals with second, third and fourth metatarsals. Other structures seen at proximal end are articular facets for tibiotarsus, nodule of I metatarsal, II metatarsal, III metatarsal and IV metatarsal.
- Tarso-metatarsus. Male (Anterior view). In males tarsometatarsus contains a spur.
- Phalanges :- (i) Four toes. (ii) First or hallux is directed backwards and remaining three forwards.
(iii) First, second, third and fourth toes have 2, 3, 4 and 5 phalanges respectively; each one is clawed.
Hind limb is formed by femur, tibio-fibula and bones of hindfoot.
- Right femur (Back view) :- (i) It is thigh bone. (ii) Proximal head articulates with acetabulum. (iii) Lesser, greater and third trochanters present for muscle attachment. (iv) Distally it has pulley-shaped structure, having two lateral condyles which enclose an intercondylar groove.
- Right femur (Front view) :- It shows head, greater trochanter, lesser trochanter, shaft, patellar groove and condyles.
- Bones of hind foot :- (i) It contains tarsal bones in two rows. (ii) Tibiale and intermedium of the proximal row are fused to form astragalus on pre-axial side, while fibulare or calcaneum is the largest tarsal bone produced into a spur on post-axial side. (iii) Distal row contains three bonesmesocuneiform, ectocuneiform and cuboid. (iv) Only four toes each having three phalanges, the terminal one bearing a claw.