The Axial Skeleton
121
Materials ? Intact skull and Beauchene skull ? X-ray images of individuals with scoliosis,
lordosis, and kyphosis (if available) ? Articulated skeleton, articulated vertebral
column, removable intervertebral discs ? Isolated cervical, thoracic, and lumbar
vertebrae, sacrum, and coccyx ? Isolated fetal skull
For related exercise study tools, go to the
Study Area of MasteringA&P. There you will find: ? Practice Anatomy
Lab
? PhysioEx
? A&PFlix
? Practice quizzes,
Histology Atlas,
eText, Videos,
and more!
Pre-Lab Quiz 1. The axial skeleton can be divided into the skull, the vertebral column,
and the: a. thoracic cage c. hip bones
b. femur d. humerus 2. Eight bones make up the , which encloses and protects the
brain. a. cranium b. face c. skull 3. How many bones of the skull are considered facial bones? 4. Circle the correct underlined term. The lower jawbone, or maxilla /
mandible, articulates with the temporal bones in the only freely movable joints in the skull.
5. Circle the correct underlined term. The body / spinous process of a typical vertebra forms the rounded, central portion that faces anteriorly in the human vertebral column.
6. The seven bones of the neck are called vertebrae. a. cervical b. lumbar c. spinal d. thoracic 7. The vertebrae articulate with the corresponding ribs.
a. cervical b. lumbar c. spinal d. thoracic 8. The , commonly referred to as the breastbone, is a flat
bone formed by the fusion of three bones: the manubrium, the body, and the xiphoid process.
a. coccyx b. sacrum c. sternum 9. Circle True or False. The first seven pairs of ribs are called floating ribs
because they have only indirect cartilage attachments to the sternum.
10. A fontanelle: a. is found only in the fetal skull b. is a fibrous membrane c. allows for compression of the skull during birth d. all of the above
Objectives ? Name the three parts of the axial skeleton.
? Identify the bones of the axial skeleton, either by examining isolated bones or by pointing them out on an articulated skeleton or skull, and name the important bone markings on each.
? Name and describe the different types of vertebrae.
? Discuss the importance of intervertebral discs and spinal curvatures.
? Identify three abnormal spinal curvatures.
? List the components of the thoracic cage.
? Identify the bones of the fetal skull by examining an articulated skull or image.
? Define fontanelle, and discuss the function and fate of fontanelles.
? Discuss important differences between the fetal and adult skulls.
122 Exercise 9
9
The axial skeleton (the green portion of Figure 8.1 on p. 108) can be divided into three parts: the skull, the ver-tebral column, and the thoracic cage. This division of the skeleton forms the longitudinal axis of the body and protects the brain, spinal cord, heart, and lungs. The Skull
The skull is composed of two sets of bones. Those of the cra- nium (8 bones) enclose and protect the fragile brain tissue. The facial bones (14 bones) support the eyes and position them anteriorly. They also provide attachment sites for facial muscles. All but one of the bones of the skull are joined by interlocking fibrous joints called sutures. The mandible is attached to the rest of the skull by a freely movable joint.
Activity 1 Identifying the Bones of the Skull The bones of the skull (Figures 9.19.10, pp. 123131) are described in Tables 9.1 and 9.2 on p. 128. As you
read through this material, identify each bone on an in- tact and/or Beauchene skull (see Figure 9.10).
Note: Important bone markings are listed in the tables for the bones on which they appear, and each bone name is colored to correspond to the bone color in the figures.
The Cranium The cranium may be divided into two major areas for study the cranial vault, or calvaria, forming the superior, lateral, and posterior walls of the skull; and the cranial base, forming
