Dr. Jacki Houghton, jhoughton@vcccd.edu ( 818)-397-2506 (TEXT ONLY)           Links:  HOME   UNIT 1   UNIT 2   UNIT 3   UNIT 4   UNIT 5   UNIT 6            Lessons: 1   2   3   4

Bones, Part 1: The Axial Skeleton  Composed of the skull, vertebral column and the thoracic cage (sternum and ribs)

Axial ppt  also available on Unit 2 page

Flash cards here http://www.easynotecards.com/notecard_set/5682?list

What to Know  (bone pictures below) 

  1.  Compare the functions of the cranial and facial bones.  Both comprise the head.

Cranial bones protect the brain, facial bones form the framework of the face, anchor the muscles, provide openings for passage of air and food and form cavities for the sense organs of sight, smell and taste.

The cranium is also called the calvarium.

Name the sutures of the skull:  Coronal, squamous, sagittal and Lambdoid

Cranial (8)

 

facial bones (14): In the middle ears (6):

 

  2.  Name and describe the bones of the skull. Identify their important features.  (see ppt)

  3.  Define the bony boundaries of the nasal cavity, paranasal sinuses, and orbit.

  4.  Name a function performed by both the spinal curvatures and the intervertebral discs.

  5.  Describe the general structure of the vertebral column, and list its components.

In the vertebral column (24):

  6.  Discuss the structure of a typical vertebra, and describe the special features of cervical, thoracic, and lumbar vertebrae.

  7.  Identify the distinctive features of the ribs and sternum.

In the thorax (25):

  8.  Differentiate true ribs from false ribs, and explain how they relate to floating ribs.

  9.  Describe how a typical rib attaches to the vertebral column.

10. Describe the causes and consequences of cleft palate.

11. List three types of abnormal curvatures of the spinal column, and explain spinal stenosis.

12. Describe how the axial skeleton changes as we grow.

      I.  Bones, Part 1: The Axial Skeleton

A. The 206 bones of the body are grouped into the axial and appendicular skeletons.

1. The axial skeleton is composed of the skull, vertebral column, and thoracic cage.

2. The appendicular skeleton is made up of the upper and lower limbs, including the
pectoral and pelvic girdles.

    II.  The Skull

A. The skull is the most complex bony structure in the body; it is formed from the cranial and facial bones. Cranial bones protect the brain. Facial bones form the framework of the face, anchor the muscles, provide openings for passage of air and food, and form cavities for the sense organs of sight, smell, and taste.

1. The anterior, middle, and posterior cranial fossae are prominent internal bony ridges that divide the cranial base into three distinct steps.

2. Approximately 85 named foramina, canals, and fissures are located within the skull bones.

  • 3. Sutures are located between the bones of the skull. We look at sites at which the
    parietal bones articulate with other cranial bones. These are the four largest sutures.

  •  Coronal suture

  •  Squamous suture

  •  Sagittal suture

  •  Lambdoid suture

4. The cranium, or calvaria, is the bony cavity protecting the brain. Several cranial bones are paired, whereas others occur singly. Eight major bones form the calvaria (frontal, parietal, occipital, temporal, sphenoid, and ethmoid bones).

5. Fourteen facial bones form the cheeks, nose, and chin (mandible, maxillae, zygomatic, nasal, lacrimal, palatine, vomer, and inferior nasal conchae).

B. Special parts of the skull are formed by parts of many skull bones.

  • Nasal cavity

  • Paranasal sinuses

  • Orbits

  • Hyoid bone

   III.  The Vertebral Column

A. The spinal column, or spine, consists of 24 individual vertebral bones, plus the two
composite bones: the sacrum and the coccyx.

B. The 70-cm vertebral column has five major regions.

  •  Seven cervical vertebrae are in the neck.

  •  Twelve thoracic vertebrae form the rib cage.

  •  Five lumbar vertebrae support the lower back.

  •  The sacrum articulates with coxal bones.

  •  The tiny coccyx is the most inferior portion.

C. The normal curvatures of the spine are the cervical and lumbar curvatures and the
thoracic and sacral curvatures.

D. The major supporting ligaments of the spine are the anterior and posterior longitudinal ligaments. Additionally, the ligamentum flavum connects the lamina of adjacent
vertebrae.

E. Intervertebral discs separate the 24 individual vertebrae and function as shock absorbers; they also contribute to the flexibility of the spine.

F. All vertebrae have several common structural features.

  •  Body (centrum)

  •  Vertebral arch

  •  Pedicles

  •  Laminae

  •  Vertebral foramen

  •  Spinous process

  •  Transverse processes

8. Superior and inferior articular processes

9. Intervertebral foramina (between adjacent vertebrae)

G. Vertebral structure shows regional variations.

1. C1C7 are the smallest and lightest vertebrae. C1C6 have bifid spinous processes, and all cervical vertebrae possess transverse foramina. The atlas (C1) lacks a vertebral body, the axis (C2) possesses a process called the dens, and C7 is termed the vertebra prominens.

2. The vertebral bodies of T1T12 articulate with the heads of ribs. Transverse processes of T1T10 articulate with tubercles of ribs, whereas T11 and T12 lack such articulations. T1T10 have direct or indirect attachments to the sternum. Superior and inferior
articular facets lie in the frontal (coronal) plane.

3. L1L5 possess massive vertebral bodies and blunt posterior-facing spinous processes.

4. The sacrum forms from the fusion of S1S5. Transverse ridges mark the regions where the sacral vertebrae fuse. The ala of the sacrum is formed from fused rib elements of S1S5. The sacrum forms the posterior wall of the pelvis.

5. The coccyx (tailbone) is formed from three to five variously fused vertebrae, which offer slight support to the pelvic organs.

  •    IV. The Thoracic Cage

  • The protective bony framework of the chest (thorax) includes the sternum and costal
    cartilages, the 12 pairs of ribs, and the thoracic vertebrae. (

  • The sternum articulates with the clavicles, rib pairs 1 and 2, and costal cartilages of rib pairs 37.

  • The 12 pairs of ribs are classed as true or false ribs. Rib pairs 17 articulate directly
    to the sternum by way of costal cartilages. Rib pairs 812 are false ribs because they attach to the sternum indirectly or not at all. Ribs 1112 are floating ribs because they have no anterior attachments.

    V.  Disorders of the Axial Skeleton

  • A. Cleft palate is the most common congenital abnormality of the skull. It results when the right and left halves of the palate fail to fuse medially during embryonic development.
     

  • B. Abnormal spinal curvatures include scoliosis (lateral curvature), kyphosis (exaggerated thoracic curvature), and lordosis (exaggerated lumbar curvature). Spinal stenosis is a
    narrowing of the vertebral canal in the lumbar region.

   VI.  The Axial Skeleton Throughout Life

  • A. Beginning with ossification of skull bones late in month 2, skull bones change
    throughout life. Changes are most dramatic during childhood.

  • B. Primary curvatures of the vertebral column are well developed at birth; secondary
    curvatures are usually evident by year 1.

  • C. Aging results in loss of bone mass.  Osteoporosis

 

 c

 

Quiz on bone markings

More bone features quiz

Extensive overview quiz

Skull Video

Axial Skeleton