The skeletal system is body’s framework, made up of 206 bones, cartilage, ligaments, and joints. It helps us stand tall, protects important organs, lets us move around, makes blood cells, and stores important minerals like calcium and phosphorus.
The body is supported, protected, and able to move thanks to the skeletal system.
- 206 bones work with joints, cartilage, and ligaments to maintain structure.
- Cartilage cushions joints and supports flexible areas (e.g., nose, ears).
- Ligaments connect bones, stabilize joints, and support organs.Two main divisions:
- Axial skeleton: Skull, spine, and rib cage.
- Appendicular skeleton: Limbs and girdles.
Skull
The skull consists of 22 bones that protect the brain and form the structure of the face. It includes the cranium, which houses the brain, and the facial bones that provide the shape of our face. The cranium is made up of eight bones fused together, while the facial structure includes the mandible, maxilla, nasal bones, and others.
Vertebral Column
There are 33 vertebrae that make up the spine, or vertebral column. The cervical, thoracic, lumbar, sacral, and coccygeal regions are the five divisions of these vertebrae. In addition to providing the head and protecting the spinal cord, the spine also acts as a point of attachment for muscles and ribs. Additionally, it absorbs shocks during activities like walking and jumping and permits flexible movement.
Rib Cage
The rib cage consists of 12 pairs of ribs that protect the heart and lungs. The ribs are connected to the thoracic vertebrae at the back and most are attached to the sternum at the front. This bony structure also supports the shoulder girdle and upper limbs.
Appendicular Skeleton
The skeleton component that levels that occur and interaction with the environment is the appendicular skeleton. It contains your hips, shoulders, arms, and legs. Which included 126 bones, it forms your entire skeletal system in conjunction with the axial skeleton, which includes your spine, ribs, and skull.
Shoulder Girdle
The scapulae (shoulder blades) and clavicles (collarbones) make up the shoulder girdle. It allows a large number of shoulder movements and joins the upper limbs to the axial skeleton. The muscles that move the arms have attachment points on the shoulder girdle.
Upper Limbs
The shoulder in the upper arm, the radius and ulna in the forearm, and the carpals, metacarpals, and phalanges in the hand make up the human skeletal system’s upper limbs. These bones allow for dexterity and complex movements, which are necessary for fine motor skills and daily tasks.
Pelvic Girdle
Three fused bones—the ischium, pubis, and ilium—make up each of the two hip bones that make up the pelvic girdle. Along with supporting the weight of the upper body, it joins the lower limbs to the axial skeleton. The reproductive and bladder organs, as well as other lower abdominal organs, are shielded by the pelvic girdle.
Lower Limbs
In Human Skeletal System the lower limbs include the femur in the thigh, the patella (kneecap), the tibia and fibula in the lower leg, and the tarsals, metatarsals, and phalanges in the foot. These bones support the body’s weight and enable locomotion. The femur is the longest and strongest bone in the body, essential for supporting the body’s weight during walking and running.
Joints
Where two or more bones converge to form a joint, flexibility and movement are made possible. Their structure and function determine their classification. The most mobile joints are synovial joints, like the knee and shoulder, which are lubricated by a cavity filled with synovial fluid. Similar to the joints between vertebrae, cartilaginous joints are completely cartilage-connected and have restricted range of motion. Dense connective tissue holds the skull’s fibrous joints together and prevents them from moving.
Cartilage
All throughout body, cartilage is a rubbery, flexible tissue. It absorbs shock and lessens friction by covering the ends of bones at joints. The nose and trachea contain hyaline cartilage, while the knee menisci and intervertebral discs contain fibrocartilage. The ear and epiglottis contain elastic cartilage.
Ligaments
At joints, ligaments—strong, elastic bands of connective tissue—bind one bone to another. They stop dangerous or excessive movements by offering support and stability. Maintaining the integrity and functionality of joints, particularly weight-bearing joints like the knees and ankles, depends heavily on ligaments.
Bone Tissue
Bone tissue, or osseous tissue, is a hard, dense tissue that forms the skeleton. It has a honeycomb-like structure, which makes it strong yet lightweight. Bone tissue is composed of a matrix of collagen fibers and mineral deposits, primarily calcium phosphate. This structure gives bones their strength and rigidity.
Bone Marrow
The soft tissue component of the human skeletal system that is located inside bones is called bone marrow. There are two varieties: yellow marrow, which stores fat, and red marrow, which makes blood cells. Yellow marrow is located in the central cavities of long bones, whereas red marrow is found in flat bones such as the sternum and pelvis.
Bone Growth and Repair
The dynamic structures that make up bones are always changing. Cells called osteoblasts create new bone tissue, whereas osteoclasts degrade existing bone tissue. Bones can develop, recover from fractures, and stay strong thanks to this process. Physical activity, diet, and hormones all affect bone growth and repair.
References
- Gray’s Anatomy: The Anatomical Basis of Clinical Practice
- Fundamentals of Anatomy & Physiolhttps://usq.pressbooks.pub/anatomy/ogy
- Tortora, G. J., & Derrickson, B. (2014). Principles of Anatomy and Physiology (14th ed.). Wiley.
- Marieb, E. N., & Hoehn, K. (2018). Human Anatomy & Physiology (11th ed.). Pearson.
- Saladin, K. S. (2019). Anatomy & Physiology: The Unity of Form and Function (9th ed.). McGraw-Hill Education.
- Drake, R. L., Vogl, W., & Mitchell, A. W. M. (2019). Gray’s Anatomy for Students (4th ed.). Elsevier.
- Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2017). Clinically Oriented Anatomy (8th ed.). Wolters Kluwer.
- Hall, J. E. (2015). Guyton and Hall Textbook of Medical Physiology (13th ed.). Elsevier.
- Ross, M. H., Pawlina, W. (2015). Histology: A Text and Atlas (7th ed.). Lippincott Williams & Wilkins.
- Lieberman, D. E. (2011). The Evolution of the Human Head. Harvard University Press.
- Khan, A., & Dufour, C. (2019). Basic Musculoskeletal Imaging (2nd ed.). McGraw-Hill Education.
- Pfaller, M. A., & Sornson, R. (2020). Pathophysiology of Blood Disorders. Springer.
- “Bone Structure and Function.” (2019). National Institutes of Health. https://www.ncbi.nlm.nih.gov/books/NBK279394/
- Zhang, Y., & Wang, J. (2018). “The Molecular Basis of Bone Development.” Journal of Biological Chemistry, 293(25), 9958-9969. https://doi.org/10.1074/jbc.TM118.003292
- Seeman, E., & Delmas, P. D. (2006). “Bone Quality — The Material and Structural Basis of Bone Strength and Fragility.” New England Journal of Medicine, 354(21), 2250-2261. https://doi.org/10.1056/NEJMra053077
- Martin, R. B. (1993). “Aging and Strength of Bone as a Structural Material.” Calcified Tissue International, 53(1), S34-S39. https://doi.org/10.1007/BF01673489
- Frost, H. M. (2003). “Bone’s Mechanostat: A 2003 Update.” The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology, 275A(2), 1081-1101. https://doi.org/10.1002/ar.a.10119
- Burr, D. B. (2002). “Bone, Exercise, and the Mechanostat.” Journal of Musculoskeletal & Neuronal Interactions, 2(3), 201-203. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5192369/
- Glimcher, M. J. (1998). “The Nature of the Mineral Component of Bone and the Mechanism of Calcification.” Instructional Course Lectures, 47, 421-428. https://journals.lww.com/jbjsjournal/Abstract/1998/09000/THE_NATURE_OF_THE_MINERAL_COMPONENT_OF_BONE_AND_THE.5.aspx
- Rho, J. Y., Kuhn-Spearing, L., & Zioupos, P. (1998). “Mechanical Properties and the Hierarchical Structure of Bone.” Medical Engineering & Physics, 20(2), 92-102. https://doi.org/10.1016/S1350-4533(98)00007-1