Frog Skeleton Labeled – Skull, Urostyle and Leg Bones

All 21 bones on the diagram

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Front half 13

Premaxilla A small bone at the very front of the upper jaw. There are two. They carry teeth.
Maxilla The long bone of the upper jaw, one on each side. It carries a row of small teeth; the lower jaw has none.
Frontoparietal One of two long, flat bones that roof the braincase. They lie side by side along the middle of the skull.
Atlas The first vertebra, which meets the skull. Unlike the others, it has no side processes.
Vertebrae A frog has only nine vertebrae. The second to the eighth each carry a pair of side processes, and there are no ribs.
Sacral vertebra The ninth vertebra, with strong side processes. They slant backward and hold the front ends of the two ilia.
Suprascapula A flat plate at the top of the shoulder girdle. It is wider at its free edge and partly cartilage.
Scapula The shoulder blade, running down from the suprascapula. It ends at the joint that holds the head of the humerus.
Humerus The bone of the upper arm. Its rounded head fits the shoulder girdle.
Radio-ulna The frog's forearm is one bone: the radius and ulna joined together.
Carpals The small bones of the wrist, in two rows.
Metacarpals The bones of the palm. A frog has four fingers, and only a hidden stump in place of a thumb.
Phalanges The bones of the fingers and toes. Four fingers on each hand and five toes on each foot.

Rear half 8

Urostyle A long rod of bone that runs back from the ninth vertebra. It reaches the point where the two ilia meet. It is almost as long as the nine vertebrae together.
Ilium One of two long hip bones. Each runs back from the ninth vertebra, and the two meet at the hip joints, in the shape of a V.
Ischium The rear part of the hip girdle. Two plates joined flat against each other behind the hip joints.
Femur The thigh bone, from the hip to the knee. It is long and slightly S-shaped.
Tibio-fibula The frog's shank is one bone: the tibia and fibula joined together. A groove at each end shows where they met.
Astragalus The inner of the two long ankle bones. They lie side by side and add one more long section to the leg.
Calcaneum The outer of the two long ankle bones, beside the astragalus.
Metatarsals The five long bones of the foot. They lie between the ankle bones and the toes.

How this list was compiled: Every bone name and detail line was checked on 2026-09-30, for facts only and with nothing copied: (1) S. J. Holmes, The Biology of the Frog, chapter XIII, The Skeleton, read in the Internet Archive scan at https://archive.org/details/biologyoffrog01holm; (2) A. Ecker, The Anatomy of the Frog, translated by G. Haslam, 1889, The Bones and Joints, https://archive.org/details/anatomyoffrog00ecke; (3) Wikipedia, Frog. A name that only one source gives is left out. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain shapes. Own original schematic drawing; nothing traced or copied. Licence: own work

How it works

This is a frog skeleton labeled bone by bone, seen from above inside the outline of the sitting frog. It is drawn as a front half and a rear half so the names stay readable.

Read the full guide

Front half, then rear half

The page opens on the front half with the names written in: skull, spine, shoulder and arm. Switch to the rear half for the urostyle, the hips and the folded hind leg. Both sides of the frog are drawn, and a name lights up the bone on both. Press Quiz me to name each bone yourself.

What is particular to a frog

The spine is short: nine vertebrae, no ribs, and a long rod behind them, the urostyle. The forearm is one bone, the radio-ulna, and so is the shank, the tibio-fibula. Two long ankle bones add another section to the leg.

Only the upper jaw of a frog carries teeth, on the maxilla and the premaxilla.
Count the long sections of the hind leg: femur, tibio-fibula, then the two ankle bones side by side.

Questions and answers

How many vertebrae does a frog have?

Nine. Behind the ninth is a long rod of bone, the urostyle, which is almost as long as the nine vertebrae together.

Do frogs have ribs?

No. A frog's vertebrae carry side processes but no ribs, so it cannot fill its lungs by widening its chest.

What is the urostyle?

A long, thin rod of bone in the rear half of a frog. It runs back from the ninth vertebra, between the two long ilia, to the point where they meet at the hips.

What is the radio-ulna?

The single bone of a frog's forearm, made of the radius and the ulna joined together. The shank is built the same way: the tibia and the fibula form one bone, the tibio-fibula.