Practical work

1. Practical work SKELETAL SYSTEM

3. Terms used in osteology Skeleton of a frog: web-footed amphibian which lives near lakes and ponds. Moves by swimming and jumping.Maxillary: bony part of the jaw.Orbital cavity: skull cavity that contains the eye.Quadratojugal: cheek bone.Prootic: bones forming the auditory region.Phalange: each of the small bones forming the fingers.Occipital lateral: occipital lateral bone.Carpus: each of the bones forming the wrist.Metacarpus: each of the bones forming the part of the hand between the fingers and the wrist.Urostyle: adaptation of one or several vertebrae, stretching the hindquarters.Ilium: projecting hip bone.Ischium: one of three bones forming the ilium.Calcaneum: projecting heel bone.Talus: bone jointed with the leg bones.Phalanges: each of the bones forming the toes.Metatarsus: each of the bones forming the part of the foot between the toes and the heel.Tarsus: each of the bones forming the heel.Femur: thigh bone.Tibiofibula: leg bone.Sacral vertebra: vertebra of the sacrum.Vertebra: each of the bones forming the spinal column.Humerus: arm bone.Radio-ulna: forearm bone.Scapular: shoulder bone.Pterygoid: one of the bones of the palate, forming the root of the mouth.Skull: bony case of the brain.

4. Frog skeleton similar to human • As anyone who has dissected one in biology class knows, a frog's internal organs look a lot like what you'd find inside a much larger animal. Just like mammals -- including people -- a frog's body has a heart and lungs as well as a stomach, pancreas, liver, gallbladder and intestines. • Even though frogs don't look much like people on the outside, their skeletons are similar to people's skeletons, especially when it comes to their limbs. Just like in a person's arms, in a frog's front legs are bones called the humerus, the radius and the ulna. However, a frog's radius and ulna are fused into one bone. The same is true for a frog's legs -- the femur supports its upper leg, and the bones of the lower leg, the tibia and fibula, are fused. A frog has two scapulae, or shoulder blades, and clavicles, or collarbones, that are shaped a lot like the same bones in a person's body. • A collection of small bones makes up a frog's digits, or its fingers and toes. Most of the time, a frog has five toes on its back legs and four toes on its front legs. The length and shape of the toes has a big impact on how the frog moves. Tree frogs have long, flexible toes that allow them to grasp stems and branches as they climb around. Aquatic frogs also have long toes -- the spaces between them are webbed so they can use their feet like flippers. Some frogs burrow into the soil in the summer or winter. Often, their feet are shorter and wider, like shovels or spades. • Sticky Feet • Some frogs use a wet or sticky substance on their feet to help them climb trees and cling to surfaces. In some species, this is a very thin layer of watery fluid that increases the friction between the frog's feet and the surface. In others, it's an adhesive. These frogs have textured feet -- the surface acts like series of microscopic canals that keep the adhesive flexible and prevent it from cracking as the frog moves. • But a frog's skeleton isn't so similar to a human's once you get past the extremities. Frogs have skulls but don't have necks, so they can't turn, lift or lower their heads like people can. A frog also doesn't have ribs. The rib-like structures you can see in the picture above are part of its spine. A frog's pelvis can slide up and down its spine, which may help it jump. The vertebrae at the bottom end of the spine are fused into one bone called the urostyle. • Read on to find out how frogs hear without ears and why their eyes are perched on top of their heads.

5. SKULL OF FROG • The skull of frog is somewhat triangular and ventrally flattened. In tadpole stage, the skull is made up of only cartilage and hence is called chondrocranium, but in the adult frog most of these cartilagenous components are transformed into bones. Some other bones arising from the dermal tissue are added in the skull of frog. These bones are known as membrane bones or investing bones. • The skull is divided into three regions: (1) Cranium (2) sensory capsules (3) pharyngeal skeleton

9. Frogs have a skeletal structure similar to humans, it is just less complex. One of the main places this can be observed is the vertebrae. While a human skeleton is made up of twenty-four vertebrae, a frog only has nine complete ones. There is a tenth that is incomplete. Also like a human, the vertebrae serves many purposes. The Atlas • The atlas is the first vertebrae of a frog, laying right underneath the base of the skull. The joint that is formed here is responsible for fifty percent of the head movement. This vertebrae is what allows a frog to move its head in an up and down motion. The atlas is also the only cervical vertebrae in a frog. A cervical vertebrae is what creates the neck, so the frog can only move its head in the one small motion the atlas allows.

10. The Abdominal Vertebrae • A frog has only four to seven abdominal vertebrae, depending on their size. These connect the limbs to the front of the body, while also supporting the organs within the abdominal cavity. These vertebrae also have zygapophyses coming from them, which look a lot like small, straight ribs. Because of this, a frog can only bend a very small amount side to side. • Postsacral Vertebrae • The urostyle, or postsacral vertebrae, is the last one in a frog. This is much longer than the others and modified from other amphibians. Most amphibians have more vertebrae in the postsacral section, but in a frog they are fused into one.

11. Pectoral girdle

12. Fore limb bones • Pelvic girdle • Hind limb bones