Skeletal System: Organization and Major Bones

Concept: Parts of the Skeleton

Skeletal Organization

The human skeleton is a complex structure that provides support, protection, and movement for the body. It consists of 206 bones and is organized into two main parts:

• Axial Skeleton: Includes the skull, vertebral (spinal) column, and thoracic cage. It supports the body structure and protects internal organs.

• Appendicular Skeleton: Includes the limbs and the pectoral & pelvic girdles. It provides body movement.

Example: Correctly distinguishing between the axial and appendicular skeleton:

Axial	Appendicular
Skull, tail bone, ribs	Shoulder blade, wrist bones, knee cap
Frontal bone, lumbar, hyoid bone	Spine, tibia, ulna, femur
Carpus, sacrum, humerus	Phalanges, hip bone
Ribs, spine, head	Shoulder blade, finger bones, femur

Major Bones of the Axial Skeleton

Skull

• Cranium: Protects the brain.

• Upper Jaw: Maxilla

• Lower Jaw: Mandible

Thoracic Cage

• Ribs: Protects thoracic organs.

• Breastbone: Sternum

Spinal Column

• Vertebrae: Individual bones forming the spine.

• Sacrum: Base of the spine.

• Coccyx: Tailbone.

Example: Anatomical names for bones:

Common Name	Anatomical Name
Tail bone	Coccyx
Breastbone	Sternum
Upper jawbone	Maxilla
Lower jawbone	Mandible

Major Bones of the Appendicular Skeleton

Pectoral Girdle

• Clavicle: Collarbone, links to axial skeleton.

• Scapula: Shoulder blade.

Upper Limbs

• Arm: Humerus

• Forearm: Radius & Ulna

• Hand: Carpals (wrist), Metacarpals, Phalanges (fingers)

Pelvic Girdle

• Hip bone: Os coxae

Lower Limbs

• Thigh: Femur

• Leg: Tibia (shin), Fibula

• Foot: Tarsals (ankle), Metatarsals, Phalanges (toes)

Example: Anatomical names for bones:

Common Name	Anatomical Name
Collarbone	Clavicle
Forearm bone	Radius
Thigh bone	Femur
Finger bones	Phalanges

Example: Correct combinations of bone names, types, and organization:

Bone	Type	Organization
Ribs	Flat bone	Axial skeleton
Patella	Sesamoid bone	Appendicular skeleton
Fibula	Long bone	Appendicular skeleton
Vertebra	Irregular bone	Axial skeleton

Summary Table: Axial vs. Appendicular Skeleton

Axial Skeleton	Appendicular Skeleton
Skull, vertebral column, thoracic cage (ribs, sternum)	Pectoral girdle, pelvic girdle, upper and lower limbs
Protects vital organs	Enables movement
80 bones	126 bones

Additional info: The axial skeleton forms the central axis of the body, while the appendicular skeleton consists of the limbs and girdles attached to the axial skeleton. Understanding the classification and anatomical names of bones is essential for medical terminology and clinical practice.