SKELETAL SYSTEM OVERVIEW

A.D.A.M. Interactive Anatomy Online Student Lab Activity Guide, 4e Scott D.Schaeffer (Lab Guide Answer Key) (Download link at the end of this file) 1 / 3

9 Skeletal System 1

SKELETAL SYSTEM OVERVIEW

The skeletal system is made up of 206 bones, cartilages, and ligamentous tissues that serve to provide sup- port to the body and protect internal soft organs as well as provide attachments for skeletal muscles that are used to move the body. Additionally, the skeleton serves as a storage site for lipids and minerals such as calcium and phosphorus and as the site for hematopoiesis (blood cell production).The skeleton is divided into two primary divisions: the axial skeleton (including the skull, vertebral column, and rib cage) and the appendicular skeleton (including the shoulder and pelvic girdles as well as the upper and lower extremities). Upon examination of the skeleton, it will be noticed that the bones are not smooth, but rather, they have various bumps, ridges, and openings that serve as sites of muscle ­attachment, articulations with other bones, and as passageways for blood vessels and nerves. Common names for bony projections that serve as attachment sites for tendons and ligaments include tubercles, tuberosities, trochanters, crests, lines, spines, and rami (ramus). Common names for projections that help form articulations include heads, processes, facets, and condyles. Common names for openings or spaces in bones include fissures, grooves, foramina (foramen), fossas, meatuses, and sinuses. ­Familiarity with these terms will come in handy when identifying common features of the human skeleton in the ­laboratory setting.

SKULL OVERVIEW

The skull is composed of 8 cranial bones that make up the cranium that encases and protects the brain and 14 facial bones that serve as the basis for attachment for the muscles of facial expression. The cranial bones include the paired parietal and temporal bones as well as the single frontal, occipital, sphenoid, and ethmoid bones. The facial bones include the paired maxilla, zygomatic, palatine, nasal, lacrimal, and inferior nasal conchae in addition to the singular mandible and vomer bones.

LEARNING OBJECTIVES

Upon completion of this chapter, the student should be able to:

■■Locate and identify the bones (and their features) of the axial skeleton ■■Locate and identify the bones (and their features) of the appendicular skeleton ■■Identify important internal and external features of the skull, including: surface features, sutures, foram-ina, sinuses, bones of the orbit, and fontanelles (in the fetal skull) ■■Identify the primary and secondary curvatures of the spine and describe the vertebrae that contribute to the distinct regions of the spinal column ■■Identify the regions of the sternum and distinguish between the different classifications of ribs ■■Locate the bones of the pectoral girdle and upper extremity and identify their major surface markings ■■Locate the bones of the pelvic girdle and lower extremity and identify their major surface markings ■■Describe some differences between the female and male bony pelvis ■■Be familiar with some of the more common pathological conditions of the skeletal system 2 / 3

10 CHAPTER 1  Skeletal System For a unique interactive experience, click on the 3D Anatomy icon and then select 3D Skull.Skull From there you are able to manipulate a three-dimensional skull by rotating it, moving it, zooming in and out, and even experience cutaway views.Lab Activity 1.1 Anterior View of the Skull From this view of the skull, the zygomatic, temporal, nasal, lacrimal, inferior nasal conchae, and parietal bones are evident. The frontal bone with the supraorbital margin and supraorbital foramen (notch in some individuals) makes up the superior border of the orbit. In all, seven bones of the skull contrib- ute to the orbit. To view a close-up of the orbit in its entirety, click on Walls of Orbit (Ant) . The perpendicular plate and middle nasal conchae of the ethmoid bone can be seen within the nasal cavity. The vomer (along with the perpendicular plate of the ethmoid bone) comprises the nasal septum. To view the nasal septum in its entirety, click on  A49 or  A49 as well as  L209 or  L210. The maxilla (upper jaw) with the infraorbital foramen and the ramus and body of the mandible (lower jaw) with the mental foramina are easily seen from the anterior.Identify and label the bones of the skull and their common markings visible from the anterior view in the following figure.

 A48

or

 A47

Frontal bone Parietal bone Temporal bone Lacrimal bone Zygomatic bone Infraorbital foramen Middle nasal conchae Mental foramen Supraorbital foramen Supraorbital margin Nasal bone Perpendicular plate Inferior nasal conchae Vomer Ramus (mandible) Body (mandible)

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