The Skeletal System

Recent questions

• What is the human skeleton made of?

  The human skeleton is primarily composed of bones, cartilage, joints, and ligaments. In adults, there are approximately 206 bones that make up the skeleton, which collectively account for about 20% of a person's body mass. The bones provide structure and support to the body, while cartilage serves as a flexible connective tissue that cushions joints. Joints are the points where two or more bones meet, allowing for movement, and ligaments are strong bands of tissue that connect bones to other bones, providing stability to the skeletal system.

• How many bones are in the skull?

  The human skull consists of 22 bones, which are categorized into cranial and facial bones. There are 8 cranial bones that protect the brain, including the frontal, parietal (two), occipital, temporal (two), sphenoid, and ethmoid bones. Additionally, the skull contains 14 facial bones, which include the mandible, maxillary, zygomatic (two), nasal, lacrimal, palatine, vomer, and inferior nasal conchae. These bones are interconnected by sutures, which are fibrous joints that allow for minimal movement, and foramina, which are openings that permit the passage of nerves and blood vessels.

• What is the function of the vertebral column?

  The vertebral column, also known as the spine, serves several critical functions in the human body. It consists of 26 irregular bones, which are divided into five sections: cervical, thoracic, lumbar, sacral, and coccygeal. The primary function of the vertebral column is to protect the spinal cord, which runs through the vertebral foramen of each vertebra. Additionally, it provides structural support for the body, allowing for an upright posture and facilitating movement. The vertebral column also acts as a shock absorber, thanks to intervertebral discs that sit between the vertebrae, cushioning the spine during activities such as walking and running.

• What are true ribs?

  True ribs are the first seven pairs of ribs in the human thoracic cage that are directly attached to the sternum, or breastbone, via costal cartilage. This direct connection allows for a more stable and secure attachment, which is essential for protecting vital organs in the thoracic cavity, such as the heart and lungs. The true ribs provide structural support and play a crucial role in the respiratory process, as they expand and contract during breathing. In contrast, the next three pairs of ribs are classified as false ribs because they are indirectly attached to the sternum, and the last two pairs are known as floating ribs, as they do not attach to the sternum at all.

• What bones are in the pelvic girdle?

  The pelvic girdle is a crucial structure that connects the lower limbs to the axial skeleton and consists of three main components: the sacrum and two hip bones, which are further divided into the ilium, ischium, and pubis. The sacrum is formed by the fusion of five vertebrae and provides stability to the pelvis. The hip bones are large, flat bones that support the weight of the upper body when sitting and standing. The pelvic girdle also plays a vital role in locomotion and provides attachment points for various muscles involved in movement. Additionally, it protects the pelvic organs, including the bladder and reproductive organs, making it an essential part of the skeletal system.