5
CHAPTER SUMMARY
The skeletal system is one of the body systems that students enjoy studying most. Naming the bones
is, at first, a challenge, then rapidly becomes a source of confidence as students develop their
identification skills. Learning about the dynamic nature of bones also dispels many preconceived ideas
that students may have about bones resembling dead twigs or other inanimate objects.
This chapter begins with an overview of the many healing properties of bones, including their
role in the support, protection, and movement of the body, as well as in the storage of nutrients and in
blood cell formation. Next, bones are classified as long, short, flat, or irregular, each made up of either
spongy or compact bone, or a combination of both to meet unique body needs. The macroscopic
(gross) anatomy of a long bone provides a conceptual image of bone structure, and the microscopic
anatomy helps students to begin to understand the complexity of bone and the reasons for its dynamic
nature. The principles of bone ossification, growth, and remodeling are explored, along with the role
of calcium and vitamin D in keeping bones strong and healthy. The various types of bone fractures
and their resultant medical corrections are also presented to round out the students’ understanding of
some common bone disorders.
In the final sections of Chapter 5, the 206 named bones that make up the axial and
appendicular skeletons are presented, and their major projections and depressions are identified. The
differences observed in the fetal skeleton, along with other developments throughout the life span are
introduced, are examined and explained. A discussion of articulations found in the body follows the
bone identification section, and the types of joints and their related inflammatory disorders.
SUGGESTED LECTURE OUTLINE
I.
BONES: AN OVERVIEW (pp. 130–139)
A.
Functions of the Bones (pp. 130–131)
1.
Supportive internal framework
2.
Protection of soft body organs
3.
Movement using bones as levers
4.
Storage of calcium and phosphorus
5.
Hematopoiesis—blood cell formation in marrow cavities of certain bones
B.
Classification of Bones (pp. 131–132)
1.
Compact Bone Tissue—dense, smooth, and homogeneous
2.
Spongy Bone Tissue—needle-like bone pieces within open space
3.
Classification According To Shape
a.
Long Bones
b.
Short Bones
c.
Fat Bones
d.
Irregular Bones
C.
Structure of a Long Bone (pp. 132–133)
1.
Gross Anatomy
a.
Diaphysis
b.
Periosteum
c.
Sharpey’s Fibers
d.
Epiphyses
e.
Articular Cartilage
f.
Epiphyseal Line
D.
E.
II.
g.
Epiphyseal Plate
h.
Yellow Marrow—medullary cavity
i.
Red Marrow
j.
Bone Markings
2.
Microscopic Anatomy
a.
Osteocytes—mature bone cells
b.
Lacunae—tiny cavities within matrix
c.
Lamellae—concentric circles
d.
Central (Haversian) System—lengthwise central canal carrying
blood vessels and nerves
e.
Canaliculi—tiny radiating canals
f.
Perforating (Volkmann’s) Canals—run into compact bone at right
angles to shaft
Bone Formation, Growth, and Remodeling (pp. 134–138)
1.
Ossification—process of bone formation
2.
Osteoblasts—bone-forming cells
3.
Appositional Growth—increase in bone diameter
4.
Osteoclasts—giant bone-destroying cells activated by parathyroid hormone
(PTH)
5.
Bone Remodeling
Bone Fractures (pp. 138–139)
1.
Reduction—realignment of broken bone ends
2.
Types of Fractures
3.
Repair of Fractures
a.
Hematoma Formation
b.
Splinting of Break by Fibrocartilage Callus
c.
Bony Callus Formation
d.
Bone Remodeling In Response To Mechanical Stress
AXIAL SKELETON (pp. 139–153)
A.
Skull (pp. 139–145)
1.
Cranium—eight large and flat bones
a.
Frontal Bone
b.
Parietal Bones—paired
c.
Temporal Bones—paired
i.
External Auditory Meatus
ii.
Styloid Process
iii.
Zygomatic Process
iv.
Mastoid Process
v.
Jugular Foramen
vi.
Carotid Canal
d.
Occipital Bone
e.
Sphenoid Bone— sella turcica holds pituitary gland
f.
Ethmoid Bone—cribriform please allow nerve passage
2.
Facial Bones—twelve are paired and two are single
a.
Maxillae—upper jawbone
b.
Palatine Bones—failure to fuse medially results in cleft palate
c.
Zygomatic Bones—cheekbones
d.
Lacrimal Bones—passageway for tears
e.
Nasal Bones—bridge of nose
f.
Vomer Bone—most of nasal septum
g.
Inferior Conchae
h.
Mandible—lower jawbone
3.
4.
B.
C.
III.
The Hyoid Bone—no articulation with other bones
Fetal Skull—large in comparison to body
a.
Fontanels—enable compression and growth of fetal skull
Vertebral Column (Spine) (pp. 145–152)
1.
Cervical Vertebrae—C1 to C7
a.
C1 (Atlas) has no body
b.
C2 (Axis) has dens (odontoid process) as pivot point
2.
Thoracic Vertebrae—T1 to T12
3.
Lumbar Vertebrae—L1 to L5
4.
Abnormal Spinal Curvatures
a.
Scoliosis
b.
Kyphosis
c.
Lordosis
5.
Sacrum—five fused vertebrae
6.
Coccyx—three to five fused vertebrae
Bony Thorax (pp. 152–153)
1.
Sternum—breastbone
a.
Manubrium
b.
Body
c.
Xiphoid Process
2.
Ribs—twelve pairs all attaching posteriorly with spinal column
a.
True Ribs—superior seven rib pairs
b.
False Ribs—inferior five rib pairs
c.
Floating Ribs—inferior two rib pairs
APPENDICULAR SKELETON (pp. 153–163)
A.
Bones of the Shoulder Girdle (pp. 153–155)
1.
Clavicle (Collarbones)
2.
Scapulae (Shoulder Blades)
B.
Bones of the Upper Limbs (pp. 155–156)
1.
Arm
a.
Humerus
2.
Forearm
a.
Radius—lateral bone which follows thumb
b.
Ulna—medial bone
3.
Hand
a.
Carpals—two irregular rows of four bones each
b.
Metacarpals—palm bones numbered one to five beginning with
thumb
c.
Phalanges—three in each digit except thumb
C.
Bones of the Pelvic Girdle (pp. 157–159)
1.
Coxal (Hip) Bones
a.
Ilium
b.
Ischium
c.
Pubis
2.
Sacroiliac (SI) Joint
D.
Bones of the Lower Limbs (pp. 159–163)
1.
Thigh
a.
Femur
2.
Leg
a.
Tibia—weight-bearing shinbone
b.
Fibula
3.
Foot
a.
b.
c.
d.
IV.
V.
Tarsal Bones
Metatarsals
Phalanges
Arches
JOINTS (pp. 163–168)
A.
Functional Categories of Joints (p. 163)
1.
Synarthroses—immovable
2.
Amphiarthroses—slightly movable
3.
Diarthroses—freely movable
B.
Structural Categories of Joints (pp. 163–165)
1.
Fibrous Joints
a.
Sutures—no movement
b.
Syndesmoses—allow minimal “give”
2.
Cartilaginous Joints
a.
Hyaline cartilage connection at bone ends
3.
Synovial Joints
a.
Articular Cartilage—covers bone ends
b.
Fibrous Articular Capsule—synovial membrane lining
c.
Joint Cavity—lubricating synovial fluid
d.
Reinforcing Ligaments
4.
Types of Synovial Joints Based on Shape (pp. 165–167)
a.
Plane Joint
b.
Hinge Joint
c.
Pivot Joint
d.
Condyloid Joint
e.
Saddle Joint
f.
Ball-and-Socket Joint
C.
Inflammatory Disorders of Joints (pp. 167–168)
1.
Osteoarthritis (OA)—degenerative “wear and tear”
2.
Rheumatoid Arthritis (RA)—autoimmune-related and most crippling
3.
Gouty Arthritis—painful uric acid crystals in joints
DEVELOPMENTAL ASPECTS OF THE SKELETON (pp. 168–170)
A.
Primary Curvatures—present at birth
1.
Thoracic
2.
Sacral
B.
Secondary Curvatures—develop when baby lifts head and walks
C.
Osteoporosis—chronic bone-thinning disease from hormone deficiency or inactivity
in elderly
D.
Pathologic Fractures—spontaneous breaks