Examkin

Question

Difficulty: HardSupport Structures and Locomotion

An anatomical examination of a mammalian vertebral column reveals a vertebra possessing a ring-like structure with broad transverse processes, transverse foramina, a missing centrum, and an absent neural spine. Which primary movement does this specialized structure facilitate in the axial skeleton?

  1. Nodding movement of the head in a vertical planeAnswer
  2. B
    Rotational movement of the head from side to side
  3. C
    Attachment and movement of the thoracic rib cage during respiration
  4. D
    Support of abdominal weight through large lumbar neural spines

Answer

Nodding movement of the head in a vertical plane
The structural features described—namely a ring-like bone lacking a centrum and neural spine, but possessing wide transverse processes with transverse foramina—define the atlas vertebra (C1C_1). The atlas articulates directly with the occipital condyles of the skull, forming a joint that permits up-and-down nodding movements of the head.

Step-by-Step Solution

1
Analyze the structural features provided in the question stem
Identified key features: ring-like shape, absent centrum, absent neural spine, broad transverse processes, and presence of transverse foramina.
These morphological features uniquely identify the first cervical vertebra, known as the atlas vertebra.
2
Relate the anatomical structure of the atlas vertebra to its primary physiological function
The anterior articular facets of the atlas ring fit with the double occipital condyles at the base of the skull.
This condyloid articulation creates a hinge joint mechanism allowing vertical up-and-down movement (nodding 'yes').

Key Concept

Structural adaptations of mammalian cervical vertebrae (Atlas vs. Axis)
Estimated Time:1m 30s
Rate this question

Topics

Support Structures and Locomotion

More questions from this topic