Learn about the comparison of fore limb in various vertebrates.
Comparison: Vertebrates # Bufo:
1. The bones of the fore limb consist of a humerus, a redioulna, carpal and metacarpal bones and phalanges.
2. Humerus – It has a short and slightly bent shaft. It bears a deltoid ridge on the fron side and a knob-like swelling at each end. The knob like structure at the proximal end is known as the head which fits into the glenoid cavity of the pectoral girdle. The knob at the distal ends is known as trochlea and articulates with the redioulna.
3. Radioulna – It is a short bone formed by the fusion of two bones, the radius and the ulna. At the proximal end it bears a projection, the olecranon process and a cup-like depression for the trochlea of the humerus. The distal end is broad.
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4. Carpal bones – These are six small bones of the wrist, arranged in two rows.
5. Metacarpal bones – These are four elongated bones of the palm corresponding to the four digits of the hand.
6. Phalanges – These are the bones of the fingers. The number of phalanges from the first to fourth digits are 2, 2, 3 and 3 respectively.
Comparison: Vertebrates # Calotes:
1. The bones of the fore limb consist of a humerus, a radius and an ulnacarpal and metacarpal bones and phalanges.
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2. Humerus – It has a long and narrow shaft, and the two ends are formed of an epiphysis of calcified cartilage. The proximal end is rounded and the distal end is pulley like with two articular surfaces for the radius and the ulna.
3. Radius and ulna – It consists of two narrow, elongated, separate bones, the radius and the ulna. The proximal end of the radius is rounded and the distal end bears a radial styloid process and a concave facet for the carpus. The proximal end of the ulna bears a process, the olecranon process, and the distal end a convex articular surface for the carpus.
4. Carpal bones – These are nine small bones of the wrist, arranged in two rows of 3 and 5 and the last one is with an accessory bone.
5. Metacarpal bones – These are five elongated bones of the palm corresponding to the five digits of the hand.
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6. Phalanges – These are the bones of the fingers. The number of phalanges from the first to fifth digits are 2,3,4,5 and 3 respectively.
Comparison: Vertebrates # Columba:
1. The bones of the fore limb consist of a humerus, a radicus and an ulna, carpal, carpometa carpus and phalanges.
2. Humerus – It has a long, slightly flat and bent shaft. The proximal end is greatly expanded and froms the head. Very near the head are a prominent ridge and a pneumatic foramen. The distal end is provided with articular surfaces for the radicus and the ulna.
3. Radius and ulna – It consists of two elongated, separate bones, the radius and the ulna. The radius is a slender bone, nearly straight with a concave facet for the humerus but the distal end is convex. The ulna is stouter and gently curved with an almost flat proximal end and a convex distal end.
4. Carpal bones – The bones of the wrist are united with the metacarpals except two. These are radiale and ulnare attached to the radius and ulna respectively.
5. Carpometacarpus – It consists of two bones formed by the fusion of carpal and metacarpal bones. The two fuse with one another at the ends. One is strong and nearly straight and the other is slender and curved. The carpometacarpus is formed by the fusion of distal carpals and three metacarpals.
6. Phalanges – These are the bones of the fingers. The number of phalanges in first to third digits are 1,2 and 1 respectively.
Comparison: Vertebrates # Cavia:
1. The bones of the fore limb consist of a humerus, a ridus and an ulna, carpal and metacarpal bones and phalanges.
2. Humerus – It has a short, rounded and slightly bent shaft. The proximal end bears of tuberosity and a head to fit into the glenoid cavity. The head is separated from the tuberosity by a bicipital groove. The distal end bears a pulley-like structure and a depression just anterior to it.
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3. Radius and ulna – It consists of two narrow, elongated, separate bones. The radius and the ulna. The radius is slender and smaller than the ulna and bears a concave facet at the proximal end. The distal end is almost flat. The ulna is long and bear an olecranon process and a sigmoid notch for the humerus.
4. Carpal bones – These are seven bones of the wrist, arranged in two rows.
5. Metacarpal bones – These are four elongated bones of the palm corresponding to the four digits of the hand.
6. Phalanges – These are the bones of the fingers. Each finger bears 3 digits and the distal one in each case ends in a horny claw.
Comparison: Vertebrates # Equus:
1. The bones of the fore limb consist of a humerus, a radius and an ulna, carpal and metacarpal bones and phalanges.
2. Humerus – It is like that of a cavia.
3. Radius and ulna – It is like that of a cavia.
4. Carpal bones – These are seven bones of the wrist arranged in two rows. The proximal row contains pisisform, cuneiform, lunar and scaphoid; and the distal row contains trapezoid, magnum and unciform.
5. Metacarpal bones – These are the bones of the palm. The first and fifth are completely degenerated. The 2nd and 4th are represented by narrow splint bones. The third one is a large, elongated, round bone, known as cannon bone.
6. Phalanges – These are the bones of the fingers. The 2nd and 4th fingers are represented by small bones, the sesamoids. The third finger is elongated and consists of three phalanges, the last one bearing a hoof.
