Skeletal system of the frog

Updated April 17, 2017

Bones provide structure for the body, protect internal organs, and support movement. In a frog, the skeleton is adapted for jumping, swimming and eating.

Spinal Column and Skull

The skull of a frog is flattened, except for a small area surrounding the brain. The backbone contains five to nine vertebrae, including a very short, stiff neck with limited mobility. The jaw is designed to grab rather than chew, and to allow tongue extension.

Front Legs

Frogs have a single upper forearm bone, the humerus. Lower forearm bones are fused together, forming the radioulna. Much like humans, frogs have phalanges, metacarpals and carpals forming the hands and wrists. The arms are adapted to begin the push-off of a jump and to absorb shock on landing.

Hind Legs

Jumping power comes from the hind legs, which have three segments—upper leg or femur, fused lower leg bones or tibiofibular, and two long tarsals forming the ankle—plus feet. The hind legs are also suited for swimming.

Internal Organs

In humans, bones such as the rib cage provide structure to the torso and protect soft inner organs. The frog has no rib cage, and all internal organs are located in a single body cavity called the coelom. The heart is slightly protected by the pericardium and the breastbone.

Urostyle and Pelvis

Vertebrae at the base of the spine are fused into a pillar called the urostyle. The pelvis comprises three fused bones. The stiffness of these skeletal structures provide strength and shock absorption for leaping.

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About the Author

Hollis Margaret has been writing and editing for print and Internet since 2000. Her work has been published on eHow and Answerbag. She has a Bachelor of Education from Mount Saint Vincent University, with a specialty in elementary education.