Skeletal System

Function of the system: provides structural support and is responsible for respiration and calcium transport.

Types of Bones found in the Chicken

Pneumatic Bones: hollow bones important for respiration

Medullary Bones: important source of calcium that provides hens with 47% of the body calcium needed to make the egg shell.

lateral view

dorsal view

Skull

The skull is a pneumatic bone that holds the brain and has a small shape to make the body lighter for flight.

On the dorsal aspect of the skull one can find the occipital bone which forms of the caudal wall of the brain and surrounds the foramen magnum of the skull.

The lower portion of the skull is made up of the maxilla and mandible which make up the upper and lower portions of the beak. In between the beak on the mandible of mouth the incisive is found. The incisive acts as the mouth opening nasopalatine cavity.

Vertebrae

The vertebrae column can be identified using the vertebral formula

C13, T7, L+S14 & C5 = 39

The vertebrae are composed of the atlas (light purple), axis (pink), cervical (green), thoracic (brown/red), lumbar (teal), and caudal (purple) sections which happen to be pneumatic bones.

The atlas is a ring-shaped bone with a dorsal arch and ventral body. While the axis is larger due to its enlongated body and articulates with the third cervical vertebrae caudally.

The cervical vertebrae is an S-shaped structure that provides the main mobility for the chicken and contains 14 vertebrae.

While the thoracic contains many unique structures. The first and sixth vertebrae are seperate bones. The second to fifth vertebrae are fused to form the notarium. Then the last of the thoracic vertebrae is an independent struture called the synsacrum. Bringing the total to 7 thoracic vertebrae. They preform the function of carrying the ribs and have large ventral processes for muscle attachment. (except the last of the thoracic vertebrae)

The lumbar and sacral vertebrae are treated as one structure that helps provide support for the upper body.

The caudal completes the vertebrae formula containing 5 vertebrae with 3 of those being individual bones.

Wings

The radius and ulna are medullary bones that correlate to eachother and makeup the forelimb. While the humerus is a large long pneumatic bone that makes up the upper arm. These limbs are modfiied for the purpose of flight and specialised feeding.

The sternum or breast bone is a complex pneumatic bone that takes on the shape of a curved plate and connects ribs.

The clavicle is a type of pneumatic bone. It presents as a thin bone connected to the coracoid bone and when attached to the other half of the wing creates the furcula. This limb is used as a spring to provide a firm base for the wing.

The scapula is a narrow curved medullary bone that articulates with the head of the humerus.

Caudal Half of the Chicken

The femur holds the meat of the thigh. It is the primary bone of the legs and all other leg bones are attached to the distal portion of the femur. The femur is the medullary bone.

While the tibia holds the meat of the drumstick. It is also a medullary bone. It connects the knee to the tarsal joints.

Abdominal Cavity of the Chicken

The ribcage, scapula, and pelvic bones (ilium and ischium) are all medullary bones with separate functions.

The ribcage protects the heart and the lungs and is made up of small bones called ribs.

The pelvic bones (Ilium and Ischium) are pneumatic bones that are purposely separated to make it easier to lay eggs. They also act as a balancing agent and support the intestines and internal sex organs.

The Metatarsals and Phalanges

The metatarsals make up the five long medullary bones of the forefoot or pes. They are used as a base when moving around.

The phalanges or digits are medullary bones that function as a grasping mechanism. They are used to hold onto an object or surface.

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