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The Skull Laboratory Exercise 13

Background A human skull consists of twenty-two bones that, except for the lower jaw, are firmly interlocked along sutures. Eight of these immovable bones make up the braincase, or cranium, and thirteen more immovable bones and the mandible form the facial skeleton. Materials Needed Textbook Articulated human skull Disarticulated human skull Fetal skull Purpose of the Exercise Examine the structure of the human skull and identify the bones and major features of the skull. Procedure 1. Label figures 13.1, 13.2, 13.3, and 13.4. 2. Examine the cranial bones and the facial bones of the articulated and

disarticulated skulls. Locate as many features as possible. 3. Using your own skull, palpate as many bones and features as possible. 4. Complete Parts A and B.

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Figure 13.1 Label the anterior view of bones and features of the skull. Figure 13.2 Label the lateral view of bones and features of the skull.

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Figure 13.3 Label the inferior view of bones and features of the skull. Figure 13.4 Label the bones and features of the infant skull.

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Part A Match the bones in column B with the features in column A. Place the letter of your choice in the space provided. (Some answers are used more than once.) Column A Column B ___ 1. Forms sagittal, coronal, squamosal, and a. ethmoid bone

lamdoidal sutures b. frontal bone ___ 2. Cribriform plate c. occipital bone ___ 3. Crista galli d. parietal bone ___ 4. External auditory meatus e. sphenoid bone ___ 5. Foramen magnum f. temporal bone ___ 6. Mandibular fossa ___ 7. Mastoid process ___ 8. Middle nasal concha ___ 9. Occipital condyle ___10. Sella turcica ___11. Styloid process ___12. Supraorbital foramen Part B Complete the following statements. 1. The _______________ suture joins the frontal bone to the parietal bones. 2. The parietal bones are firmly interlocked along the midline by the

_______________ suture. 3. The _______________ suture joins the parietal bones to the occipital bone. 4. The temporal bones are joined to the parietal bones along the

_______________ sutures.

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5. Name the three cranial bones that contain sinuses. ________________________________________________________________

6. Name a facial bone that contains a sinus. _______________________________ Critical Thinking Application Examine the inside of the cranium. What area appears to be the weakest area? Explain your answer. Examine the fetal skull. Note that the skull is incompletely developed and that the cranial bones are separated by fibrous membranes. These membranous areas are called fontanels, or “soft spots.” The fontanels close as the cranial bones grow together. The posterior fontanel usually closes within a few months after birth, whereas the anterior fontanel may not close until the middle or end of the second year. What other features characterize the fetal skull?