Question

Number of cervical vertebrae in mammals is (a) 7 (b) 6 (c) 5 (d) 11 .

Short answer

The number of cervical vertebrae in mammals is 7.

Step-by-step solution

- Understand the Concept

Recall that the number of cervical vertebrae in the vast majority of mammals is a constant. This is due to a peculiar homology across the mammal class, despite the variation in neck length and size between different mammal species.

- Identify the Correct Option

For almost all mammals, the number of cervical vertebrae is seven. This is true for both small mammals like mice and large mammals like giraffes regardless of the length of their necks.

- Confirm the Answer

Double-check the options given to find the one that indicates the number seven.

Key concepts

Number of Cervical Vertebrae

When examining the mammalian skeletal system, one remarkable constant is the number of cervical vertebrae. This number is critically important for understanding not just the anatomy of one species but the comparative anatomy of the entire mammalian class. The cervical vertebrae are the bones that make up the part of the spine within the neck region. Despite the diversity in size and shape among mammalian species, from the tiny mouse to the towering giraffe, the number typically remains at seven.

This uniformity in the number of cervical vertebrae is an intriguing example of nature's consistency. It's curious to note that a long-necked giraffe and a human share the same number of cervical vertebrae despite their vastly different physiology. Such anatomical constants raise interesting questions about developmental biology and evolutionary constraints within the mammalian lineage.

Mammalian Anatomy

Exploring mammalian anatomy gives us insight into the complexities and adaptations that have occurred over millions of years of evolution. The vertebral column, or spine, is a central component of this anatomy, providing structural support and flexibility. In mammals, the spine is divided into several regions: the cervical, thoracic, lumbar, sacral, and caudal vertebrae.

Each region of the spine serves a specific purpose and reflects the adaptations of the organism. For example, the lumbar vertebrae are robust as they support the weight of the body and permit movements such as bending and twisting. In understanding these anatomical structures, students can appreciate the functional significance behind the number and configuration of vertebrae across different mammalian species.

Vertebral Column Homology

The concept of homology is central to the study of evolutionary biology and anatomy. Homologous structures are those that are derived from a common ancestor and may serve similar or different functions in contemporary species. The vertebral column is a prime example of such homology among mammals. Despite a vast array of ecological niches and physical forms, mammals showcase a remarkable homology in the structure of their vertebral columns — especially noticeable in the cervical vertebrae.

The persistence of this 'seven vertebral formula' across such diverse species indicates a developmental constraint that has been preserved throughout mammalian evolution. This constraint may be tied to the complexity of nerve, muscle, and vascular structures within the neck and their developmental origin from the somites in embryonic stages. Understanding these homologies provides crucial insights into how evolutionary processes shape the bodies of various creatures within the mammalian lineage.