The skeletal system is a complex structure in the human body that provides support, protection and facilitates movement. It is divided into two main divisions: the axial skeleton and the appendicular skeleton. These divisions help organize and describe the bones of the human skeleton.
1. Axial Skeleton:
The axial skeleton is the central portion of the skeletal system, primarily consisting of bones along the body’s central axis. This division includes the following components:
a. Skull: The skull comprises the cranium and the facial bones. The skull encases and protects the brain, while the facial bones form the structure of the face.
b. Vertebral Column (Spine): The vertebral column is a flexible, segmented structure comprising individual vertebrae. It provides support, protects the spinal cord, and allows for various degrees of movement. There are five regions of the vertebral column: cervical (neck), thoracic (upper back), lumbar (lower back), sacral (pelvic), and coccygeal (tailbone).
c. Ribs and Sternum (Breastbone): The ribcage comprises 12 ribs attached to the thoracic vertebrae. The ribs encircle and protect vital organs like the heart and lungs. The sternum is a flat bone in the front of the ribcage that provides a central anchor point for the ribs.
2. Appendicular Skeleton:
The appendicular skeleton includes the bones of the limbs (appendages) and the bones that connect them to the axial skeleton. It is responsible for movement and locomotion. The appendicular skeleton is further divided into two categories:
a. Upper Limbs:
Shoulder Girdle: The shoulder girdle consists of the clavicle (collarbone) and scapula (shoulder blade). These bones attach the upper limbs to the axial skeleton and provide mobility at the shoulder joint.
Arm: The arm includes a single long bone, the humerus, which extends from the shoulder to the elbow.
Forearm: The forearm comprises two bones, the radius and ulna. These bones allow for pronation and supination of the hand.
Hand: The hand consists of multiple bones, including the carpals (wrist bones), metacarpals (palm bones), and phalanges (finger bones).
b. Lower Limbs:
Pelvic Girdle: The pelvic girdle includes two hip bones (os coxae) that fuse to form the pelvis. The pelvis connects the lower limbs to the axial skeleton, providing stability and support for the body’s weight.
Thigh: The thigh bone is called the femur and is the longest bone in the human body. It extends from the hip to the knee.
Leg: The leg consists of two bones, the tibia (shinbone) and the fibula. The tibia is larger and bears most of the body’s weight, while the fibula provides lateral support.
Foot: The foot is made up of multiple bones, including the tarsals (ankle bones), metatarsals (sole bones), and phalanges (toe bones).
The axial and appendicular skeletons together form the complete human skeleton, providing the structural framework for the entire body. Each bone in the skeletal system has a specific function and contributes to the body’s overall mobility, support, and protection. This division of the skeletal system helps anatomists and healthcare professionals describe and study the intricate structure of the human skeleton.