Paranasal Sinuses

Five bones of the skull, the frontal, ethmoid, sphenoid, and two maxillae, contain paranasal sinuses which are paired cavities lined with mucous membranes and connected to the nasal cavity. These cavities lighten the bones of the skull and serve to provide resonance when we speak or sing.

Exercise 93

Locate the paranasal sinuses in the bones of the disarticulated skull You will not be able to see the frontal sinuses. Label the sinuses on Figure 9.7.

Sinus Labeling
Figure 9.7 Sinuses

Ethmoidal air cells (sinuses) Frontal sinus Maxillary sinus Sphenoidal sinus (X2)

Base of Skull sella turcica: anterior clinoid process hypophyseal fossa posteriorclinoid process jugular foramen hypoglossal canal

Base of Skull sella turcica: anterior clinoid process hypophyseal fossa posteriorclinoid process jugular foramen hypoglossal canal

Sella Turcica Skull Label

foramen lacerum foramen magnum

Floor of cranium crista galli cribiform plate optic foramen foramen ovale petrous portion of temporal internal auditory meatus foramen lacerum foramen magnum

Floor of cranium

THE FETAL SKULL

The human skull is not completely composed of bone at birth, but still contains a significant amount of fibrous membrane. This dense connective tissue forms "soft spots" called fontanels in the skull of the baby. The largest of these spots is the anterior fontanel. Note that the frontal bone begins in the fetus as two bones, but ossification (replacement of cartilage by osseous tissue) causes the two halves to fuse to form the frontal bone. The posterior fontanel is the smaller fontanel located at the lambdoidal suture. The sagittal suture connects the posterior and anterior fontanels. There are two smaller fontanels on each side of the skulls, making a total of six fontanels.

Exercise 9 A

Carefully examine the fontanels on the laboratory fetal skull DO NOT PUSH ON THE FONTANELS! THEY ARE NO LONGER SOFT! Label the fontanels on Figure 9.8.

Labeling Facial Bones

Figure 9.8 Fetal Skull

Figure 9.8 Fetal Skull

Anterior fontanel (X2) Coronal suture Lambdoidal suture Posterior fontanel Sagittal suture

List the bones of the cranium in alphabetical order.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment