Skeletal System

1
Skeletal System

• Chapters 6-8

2
The Skeletal System

• 206 bones in the adult skeleton
• Divisions
• Axial Skeleton (Chapter 7)
• Skull
• Vertebral Column
• Rib Cage
• Appendicular Skeleton (Chapter 8)
• Pectoral Girdle
• Upper Extremities
• Pelvic Girdle
• Lower Extremities

3
Functions of the Skeletal System

• Support
• Protection
• Body Movement
• Hemopoiesis (Blood Formation)
• Red marrow
• 2.5 million/sec!
• Fat Storage
• Electrolyte balance
• Acid/base balance
• Detoxification

4
Long Bone Structure

• Compact bone
• Outer, dense white osseous tissue
• Spongy bone
• Loosely organized osseous tissue enclosed by
  compact bone
• Diaphysis
• Cylinder of compact bone surrounding a marrow
  cavity.
• Epiphysis
• Ends of a bone
• Spongy bone surrounded by layer of compact bone.
• Epiphyseal plate (line)
• Region of bone growth (plate). Line left after
  growth ends (line).
• Articular cartilage
• Hyaline cartilage caps epiphysis and facilitates
  movement between two bones.
• Marrow (medullary) cavity
• Red bone marrowhemopoietic (entire marrow in
  youth, marrow of skull vertebrae, ribs, sternum
  in adulthood)
• Yellow bone marrowfat storage (adulthood)
• Periosteum
• Dense regular connective tissue covering the
  outside of a bone. Highly vascular. Point of
  tendon attachment.
• Endosteum

5
Bone Histology

• Bone Cells
• Osteoblasts
• Bone forming cells
• Bone growth
• Osteocytes
• Maintain healthy bone
• Osteoclasts
• Break down bone tissue
• Bone remodeling

6
Bone Histology

• Osteon
• Central canal and its lamellae
• Lamellae
• Layers of matrix arranged around a central canal
• Central canal
• Blood and nerve supply for living osseous tissue
• Lacunae
• Contain osteocytes
• Canaliculi
• Connections between lacunae containing
  cytoplasmic extensions of osteocytes

7
Bone Development

• Cartilage Model
• Growth results in hypertrophy, calcification, and
  restriction of nutrients to interior.
• Cartilage cells die and the model begins to
  hollow.
• Perichondrium cells differentiate into
  osteoblasts (forming the periosteum) and lay down
  the bone collar.
• Blood vessels invade the diaphysis as the primary
  ossification center forms.

8
Bone Development (cont.)

• Bone collar and the medullary cavity expand.
• Blood vessels penetrate the epiphyses and the
  process repeats itself in the secondary
  ossification centers where spongy bone is laid
  down.
• Cartilage is entirely replaced by bone, except at
  epiphyseal plates.
• Bone growth continues at epiphyseal plate until
  late teens when epiphyseal line forms.
• Remodeling occurs throughout life.

9
The Bones and Their Parts

• Learn the names of the bones and their parts as
  described on the study guide.
• Work from the bones while in class. Work on
  memorization outside of class.
• Suggestion Begin with the appendicular skeleton
  (Chapter 8) and then come back to the axial
  skeleton (Chapter 7).

10
Surface FeaturesBecome familiar with these terms.
11
Skeletal System Review

• Layers of matrix arranged around the central
  canal of compact bone are called _____________.
• The middle portion of a long bone such as the
  femur is called the __________.
• In endochondral bone growth, the osseous tissue
  that is first observed is called the ___________.
• A secondary marrow cavity would be found in the
  __________ of a long bone.
• Bone cells, called __________, are found within
  the ___________ of an osteon.
• A smooth, flat, slightly concave or convex
  articular surface is a
• Condyle.
• Facet.
• Crest.
• Process.
• A round hole through a bone is a(n)
• Alveolus.
• Sinus.
• Meatus.
• Foramen.

12
Answers to Review Questions

• Concentric lamellae
• Diaphysis
• Bone collar
• Epiphysis
• Osteocytes, lacunae
• 2 (facet)
• 4 (foramen)