How to Draw the Skeletal System of a Frog
What makes a frog jump so high? The truth behind the frog's amazing jumping ability lies in the interaction between its skeletal and muscular systems. Its skeleton is perfectly designed to allow it to achieve great heights and long distances when acted on by its muscles. It is a marvel of biological science. Instead of dissecting one of these magnificent creatures, you can gain a thorough understanding of the frog's skeletal system by drawing a sketch of it. It's a hands-on, no-harm-done activity and you don't have to be an artist.
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Things You'll Need
- Picture of a frog skeletal system
- 1 sheet of white printing paper
- Pencil
- Ruler
- Protractor
- Black marker, fine-tip
Instructions
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Drawing the Frog's Skull and Spine
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1
Turn the paper horizontally. Place the picture of the frog skeletal system next to the paper. This will be your guide.
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2
Draw a semicircle on the right side of the paper. The semicircle should be about 3 inches in diameter. This is the frog's skull.
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3
Move the ruler so that the 10-inch mark is directly in the center of the semicircle. Draw a line exactly 10 inches long starting from the beginning of the ruler all the way to the dot in the center of the semicircle. This is the frog's spine.
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4
Draw an arrowhead shape at the beginning of the 10-inch line. It should look like the "<" symbol . The shape should be 3 inches long and 1-inch wide at the open end. This shape represents the pelvic girdle.
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5
Draw five vertical lines starting at the open end of the arrowhead shape. The first line closest to the arrowhead should be 7/8 of an inch long and the next four lines should each be slightly longer than the one before (15/16 of an inch, 1 inch, 1-1/16 inches and 1-1/8 inches). The lines should be spaced about 1/8 inch apart. These are the frog's ribs.
Drawing the Arm, Leg, Hand and Feet Bones
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6
Draw a straight line 1/2-inch long and at a 30-degree angle connecting the top of the longest rib and the top of the open end of the frog's skull. Repeat this process by drawing a second line exactly the same length and angle at the bottom of the long rib and connecting the bottom of the frog's skull. Lastly, draw a straight vertical line connecting the center of these two lines. This is the pectoral girdle.
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7
Draw a line at the top of the pectoral girdle, exactly 1-1/2 inches long and at a 150-degree angle. Draw another line exactly the same length and angle at the bottom of the pectoral girdle. These are the frog's humeri.
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8
Draw a 1/2-inch line at 20 degrees extending from the end of the frog's top humerus. Draw a second line, same length and angle, extending from the bottom humerus. These are the radio-ulnae.
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9
Draw three lines extending from each radio-ulna. The lines should be 1/4 inch, 1/2 inch and 1/4 inch in that order and should be pointing in three different directions (You have some liberty in drawing these.) These are the metacarpals.
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10
Draw a 4-inch line at 75 degrees extending from the narrow end of the pelvic girdle (about 1/2 inch away from the tip). Draw another line, exactly the same, on the opposite side. These are the femurs.
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11
Draw another 4-inch line at 75 degrees parallel to the first femur and 1/2 inch apart. Repeat this with the second femur. Connect these lines to each femur by drawing a connecting line at the top of each femur to the top of these lines. These are the tibio-fibulae.
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12
Draw a 1-inch vertical line extending from the end of each tibio-fibula. These are the tarsals.
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13
Draw five lines all extending from the end of the tarsal at 1 inch, 1-1/2 inches, 3 inches, 2-1/2 inches and 2 inches long in that order and spaced 1/8 inch apart. Repeat for the second tarsal. These are the metatarsals and phalanges.
Adding Details
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14
Trace the entire sketch with the black marker.
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15
Make all lines more detailed by holding the pencil so that the side of the lead (not the tip) touches the paper and retrace all lines.
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16
Draw small circles at the points where lines connect. These will represent the joints.
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17
Draw the inner details of the skull, spine and appendages as best you can, carefully following the picture.
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1
Tips & Warnings
Do not press hard with your pencil, as you will likely be erasing a few times.
A picture of a frog skeletal system has been provided in the Resources section of this article.
Challenge yourself. Don't just print the picture of the frog's skeletal system and trace it; try to actually draw it. It will be easier than you think.
