Human Skeletal System Anatomy and Bone Functions

Anatomy of the Human Skeletal System

Anterior View

• Collarbone (Clavicle)
• Sternum
• Rib Cage (Costal-Parrilla)
• Pelvis
• Patella

Posterior View

• Scapula
• Dorsal Column (Spinal Column)

Bones Visible from Both Views

• Skull
• Cervical Spine
• Shoulder
• Humerus
• Lumbar Spine
• Elbow
• Radius (Radio)
• Ulna (Cube)
• Hip
• Wrist (Doll)
• Hand
• Femur
• Knee
• Fibula
• Tibia
• Ankle
• Foot (Pie)

Composition and Function of Bones

Bones are the rigid part of the musculoskeletal system. The skeletal system consists of approximately 206 bones in the human body. Basically, bones are composed of water and minerals formed from calcium and phosphorus, and a substance called ossein (osteína).

Major Divisions of the Skeleton

1. Skeleton of the Head

The head bones are divided into two parts:

• Cranium (Post/Skull): The bony case of the brain.
• Facial Bones (Back/Face): These host most of the sense organs and support chewing.

The skull is made up of eight very strong flat bones.

Bones of the Skull

• Parietal bone (H. parietal)
• Temporal bone (H. temporary)
• Frontal bone (H. front)
• Ethmoid bone (H. ethmoid)
• Sphenoid bone (H. sphenoid)
• Occipital bone (H. occipital)

2. Skeleton of the Trunk

The Spinal Column

The spine, the axis or support of our body, consists of 33 or 34 vertebrae, which are bony elements superimposed on a regular basis. The vertebrae, which together define the spinal canal that houses the spinal cord, have a central hole and a few small bumps called apophyses, where muscles are attached.

Distribution of the Vertebrae

• 7 Cervical: These are less thick and more mobile. The first cervical vertebra, the atlas, is incomplete, and the second, the axis, allows for the lateral rotation of the neck.
• 12 Thoracic (Dorsal): These correspond to the back area and are thicker and less mobile than those in the neck.
• 5 Lumbar: These correspond to the waist area.
• 5 Sacral: These are fused together to form the sacrum, a very strong bone that forms the base of the spine.
• 4 or 5 Coccygeal: These are also strongly linked together to form the coccyx.

The Sternum

The sternum is a long, flat bone, about 15 to 20 cm in length, located on the front of the chest. It articulates with both the shoulder and collarbones, as well as the first seven pairs of true ribs.

The Ribs

The ribs are made of 24 long and narrow bones, attached at the back to the spine.

• True Ribs: The first seven pairs are called true ribs because they articulate with the sternum through their respective cartilage.
• False Ribs: The last five pairs are false ribs; they do not articulate with the sternum directly, but their cartilages are joined together.
• Floating Ribs: Of these, the eleventh and twelfth pairs are called floating ribs because they are free from any anterior extension.