Chapter 7: The Skeleton

The axial skeleton, examined in this chapter, comprises the skull, vertebral column, and thoracic cage—three major structural components that form the central framework of the human body. The skull consists of 22 bones divided into two functional groups: eight cranial bones that protect the brain and cerebrospinal fluid, including the frontal, parietal, occipital, temporal, sphenoid, and ethmoid bones, and fourteen facial bones that support the sensory organs and provide structural foundation for the face, among them the mandible, maxillae, zygomatics, and nasals. These skull bones connect through sutures, which are immobile joints characterized by specific names such as the coronal, sagittal, squamous, and lambdoid sutures, and contain numerous foramina through which nerves and blood vessels pass. The vertebral column extends inferiorly from the skull and comprises twenty-six bones organized into distinct regions: seven cervical vertebrae in the neck, twelve thoracic vertebrae in the mid-back, five lumbar vertebrae in the lower back, the sacrum, and the coccyx. Structural specializations of vertebral regions reflect their functional demands, with particular attention given to the atlas and axis cervical vertebrae that enable head rotation and support. Between adjacent vertebrae lie intervertebral discs composed of fibrocartilage and nucleus pulposus that absorb shock and allow flexibility. The chapter addresses vertebral column disorders including scoliosis, an abnormal lateral curvature, kyphosis, excessive thoracic curvature, and lordosis, excessive lumbar curvature. The thoracic cage protects the lungs, heart, and upper abdominal organs while facilitating respiratory mechanics through the sternum, which consists of the manubrium, body, and xiphoid process, and twelve pairs of ribs classified functionally as true ribs, false ribs, and floating ribs. Throughout, surface anatomy landmarks and palpable bony prominences are emphasized to connect gross structure with clinical examination and anatomical orientation.