Axial Skeleton is the “ blue ” Appendicular Skeleton is the “ purple ”
Ossicles of the Ear The ossicles are the bones of the middle ear and are often simply called “the ear bones.” The ossicles function to turn sound into mechanical vibrations which the human nervous system can interpret. Skull Subdivision Three
Each ear has three ossicles:
The Malleus (2) – a.k.a. as the “hammer”
The Incus (2) – a.k.a. as the “anvil”
The Stapes (2) – a.k.a. as the “stirrup”
Malleus Incus Stapes
Skull Subdivision Four Hyoid Bone This bone is located beneath the mandible and serves to support the tongue and to provide an attachment surface for many of the muscles that control the tongue and function in swallowing.
The number of wormian bones varies from person to person. They are extra bones that develop in the sutures of the cranium. Skull Subdivision Five Wormian bones
Summary of the Skull
2. Face (14)
Inferior nasal conchae (2)
3. Hyoid (1)
4. Ossicles (6)
5. Wormian (?)
The Vertebral Column
Also called the spinal column , “spine,” or “backbone,” the vertebral column consists of 26 bones in an adult, but has 33 in an infant. It is a complex structure made from alternating bone and cartilage, subdivided into five regions or “curvatures,” and responsible for many important functions.
Part Two Lateral View Posterior View
Subdivisions of the Vertebral Column
1. Cervical Curvature – the “neck”
Seven (7) cervical vertebrae
Thoracic Curvature – “the middle-back”
Twelve (12) thoracic vertebrae
3. Lumbar Curvature – “the “lower back”
F ive (5) lumbar vertebrae
4. Sacral Curvature – “small of the back”
The Sacrum – five fused vertebrae
5. Coccygeal Curvature – the “tailbone”
The Coccyx – four fused, immature vertebrae
Functions of the Vertebral Column:
Forms a tube which houses and protects the spinal cord
Provides protective channels for the lower spinal nerves
Intervertebral discs provide “ shock absorber ” action cushioning the forces created by movement
Provides posterior attachment sites for the ribs
Provides important attachment sites for many muscles of the back
C 1 – C 7 T 1 – T 12 L 1 – L 5 Cervical Vertebrae Thoracic Vertebrae Lumbar Vertebrae Sacrum Coccyx
Summary of the Vertebral Column
Bones of the Vertebral Column
Cervical Vertebrae (7)
Thoracic Vertebrae (12)
Lumbar Vertebrae (5)
Sometimes misnamed the “ribcage,” the thoracic cage is composed of 37 bones, fibrous cartilage discs and specialized hyaline cartilage.
To support and protect the soft, vital organs of the thoracic cavity
Provide support for the bones of the pectoral girdle and upper extremities
Plays an important role in breathing
Functions of the Thoracic Cage: The bones of the thoracic cage are as follows:
Sometimes called the “breastbone,” the sternum is a “dagger-shaped” bone that forms a solid plate of armor down the middle of the chest, thus protecting the heart . It articulates with the clavicles, and is also a very important site for blood cell production throughout life. The sternum is divided into three parts:
The body or gladiolus
The xiphoid process – made of hyaline cartilage.
The Costal Cartilage
Composed of hyaline cartilage, the costal cartilage attaches, either directly or indirectly, the first ten pairs of ribs to the sternum. This cartilage also gives the thoracic cage its characteristic flexibility, which is important to the mechanism of breathing.
3. The Ribs – Both males and females have twelve (12) pairs of ribs. All of these articulate posteriorly with the thoracic vertebrae. The ribs are further subdivided on the basis of how they do or do not connect with the sternum via the costal cartilage as follows:
a. True ribs – These are the first seven (7) pairs of ribs. These can be distinguished on the basis that they are attached directly to the sternum via the costal cartilage.
b. False ribs – These are the last five (5) pairs of ribs.
1. The 8 th , 9 th , and 10 th pairs are indirectly attached to the sternum via the costal cartilage.
2. The 11 th and 12 th pairs are not attached to the sternum at all. These two pairs are often referred to as floating ribs .
The Thoracic Vertebrae
Though these are actually a part of the vertebral column , they also serve as the posterior anchor for the ribs and function as a solid posterior wall for the entire thoracic cage structure.