Skeletal System (Part 3) - Vertebrae, ribs and sternum

Summary

This module discusses the vertebral formula, structure, and classification of the vertebrae, ribs, and sternum in animals, with a focus on dogs. It explains the arrangement of vertebrae (cervical, thoracic, lumbar, sacral, caudal), the features of each type, and their role in supporting the body. The rib structure and their articulation with the thoracic vertebrae and sternum are also covered. Notable sections include descriptions of the atlas, axis, anticlinal vertebra, and the differences between sternal and floating ribs. A quiz is offered at the end of the module.

Takeaways

• 📚 The vertebral formula of a dog is C7, T13, L7, S3, and Ca 20-24, meaning 7 cervical, 13 thoracic, 7 lumbar, 3 sacral, and 20-24 caudal vertebrae.
• 🦴 Vertebrae are irregular bones that form the vertebral column, extending from the skull to the tail.
• 🦓 The vertebrae are grouped by location: cervical (neck), thoracic (chest), lumbar (loin), sacral (pelvic), and caudal (tail).
• 🐕‍🦺 A typical vertebra has a body, an arc, and several processes; the sixth cervical vertebra is used as an example.
• 🏗️ The first cervical vertebra, the atlas, supports the head, and the second cervical vertebra, the axis, forms a pivot joint with the atlas.
• 🔧 The thoracic vertebrae are characterized by tall spinous processes and articulate with the ribs, with T11 serving as the anticlinal vertebra in dogs.
• 🐾 There are 13 pairs of ribs in dogs, corresponding to the number of thoracic vertebrae, with 9 true ribs, 3 false ribs, and 1 floating rib.
• 🧩 The sternum is composed of 8 fused bones called sternebrae and is divided into the manubrium, body, and xiphoid process.
• 🔩 The ribs are divided into different types based on their attachment to the sternum: true ribs, false ribs, and floating ribs.
• 🔍 Key processes on vertebrae include spinous, transverse, and articular processes, with additional features like transverse foramina in cervical vertebrae.

Q & A

What is the vertebral formula of a dog?

The vertebral formula of a dog is C7, T13, L7, S3, Ca20-24. This means there are 7 cervical, 13 thoracic, 7 lumbar, 3 sacral, and 20-24 caudal vertebrae.

Where are the cervical vertebrae located, and how many are there in a dog?

The cervical vertebrae are located in the neck region, and there are 7 cervical vertebrae in a dog.

What are the key characteristics of thoracic vertebrae?

Thoracic vertebrae are characterized by tall spinous processes, short bodies, and transverse processes. They also articulate with the ribs.

What is the function of the atlas (C1) in the vertebral column?

The atlas, or C1, supports the head and connects it with the rest of the body. It is morphologically unique, lacking a spinous process and having wing-like transverse processes.

How do the ribs articulate with the vertebral column in dogs?

Ribs articulate with the thoracic vertebrae. The head of the rib connects with the costal fovea on the body of the vertebra, while the tubercle of the rib connects with the transverse fovea on the transverse process of the vertebra.

How are sternal and asternal ribs different in dogs?

Sternal ribs, also called true ribs, directly articulate with the sternum via costal cartilages, while asternal ribs, or false ribs, do not directly attach to the sternum and are instead fused into the costal arch.

What is the role of the sacrum in the vertebral column?

The sacrum is formed by the fusion of sacral vertebrae and articulates with the hip bones to form the sacroiliac joint, providing support to the pelvis.

What are the typical components of a vertebra?

A typical vertebra consists of a body, an arc (composed of the lamina and pedicle), and various processes, including spinous, transverse, and articular processes.

What is the anticlinal vertebra, and where is it located in a dog?

The anticlinal vertebra in a dog is T11, characterized by a vertically oriented spinous process, in contrast to the adjacent thoracic vertebrae that have spinous processes angled cranially or caudally.

What is the purpose of the hemal arches in the caudal vertebrae of dogs?

Hemal arches are bony structures found on the ventral surface of the 4th to 6th caudal vertebrae in dogs. They protect the median caudal artery.