Anatomy of musculoskeletal system

simple & easy way to understand the musculoskeletal system by Dr.Shamili Balaji.

1. THE MUSCULOSKELETAL SYSTEM

2. THE SKELETAL SYSTEM The Human Skeletal System consists of a set of 206 bones that support and protect the body. They also work with the muscles to provide movement. The skeleton is divided into 2 parts: the Axial and the Appendicular Skeleto n.

3. THE AXIAL SYSTEM The Axial System is made up with the Skull bones, the Vertebrae, the Ribs and the Sternum.

4. THE SKULL BONES

5. THE VERTEBRAE The spine is divided into several sections. The cervical vertebrae make up the neck. The thoracic vertebrae comprise the chest section and have ribs attached. The lumbar vertebrae are the remaining vertebrae below the last thoracic bone and the top of the sacrum. The sacral vertebrae are caged within the bones of the pelvis, and the coccyx represents the terminal vertebrae or vestigial tail.

6. THE APPENDICULAR SYSTEM The appendicular system is formed by the bones of pectoral girdle, pelvic girdle and upper and lower limbs .

7. THE UPPER/LOWER LIMBS BONES

8. THE HUMAN SKELETON

9. STRUCTURE OF THE BONES There are two types of bone tissue: 1) Compact and 2)Spongy . .

10. Compact Bone The hard outer layer of bones is composed of Compact bone tissue , so-called due to its minimal gaps and spaces. This tissue gives bones their smooth, white, and solid appearance, and accounts for 80% of the total bone mass of an adult skeleton.

11. Spongy Bone Spongy bone fills the interior of the bone which is composed of a network of rod- and plate-like elements that make the overall organ lighter and allowing room for blood vessels and marrow. Spongy bone accounts for the remaining 20% of total bone mass, but has nearly ten times the surface area of compact bone.

12. CLASSIFICATION OF BONES The bones of the body come in a variety of sizes and shapes. The four principal types of bones are long, short, flat and irregular

13. LONG BONES Bones that are longer than they are wide are called Long bones . They consist of a long shaft with two bulky ends or extremities. They are primarily compact bone. Eg:- Long bones include bones of the thigh, leg, arm, and forearm .

14. SHORT BONES Short bones consist primarily of spongy bone , which is covered by a thin layer of compact bone. Eg:- Short bones include the bones of the wrist and ankle .

15. FLAT BONES Flat bones are thin, flattened, and usually curved. Eg:- Flat bones include most of the bones of the cranium and sternum .

16. IRREGULAR BONES Bones that are not in any of the above three categories are classified as Irregular bones . They are primarily spongy bone that is covered with a thin layer of compact bone . Eg:- The vertebrae and some of the bones in the skull are irregular bones.

17. BONE DEVELOPMENT & GROWTH Osteoblasts, osteocytes and osteoclasts are the three cell types involved in the development, growth and remodeling of bones. Osteoblasts are bone-forming cells, Osteocytes are mature bone cells and Osteoclasts break down and reabsorb bone.

18. THE JOINTS A Joint is the point where two or more bones meet. There are three main types: Fibrous  (immoveable)- Eg:-Skull Joint.  Cartilagenous  (partially moveable)- Eg:- Intervertebral disc of spinal column. Synovial  (freely moveable) joint.

19. FIBROUS JOINT This type of joint is held together by only a ligament.

20. CARTILAGENOUS JOINT

21. SYNOVIAL JOINT There are six types of synovial joints: 1) Pivot joint, 2) Ball-and-socket joint, 3) Hinge joint, 4) Condyloid joint, 5) Saddle joint, 6) Gliding joint.

22. SYNOVIAL JOINT Pivot joint  Enables rotation around a lengthwise axis: the cylindrical terminal part of a bone is encased in a hollow cylinder. Examples include the tibia and the fibula. Ball-and-socket joint  Allows movement along three axes, such as in the shoulder: flexion and extension, rotation, and adduction (arm drawing near the trunk) and abduction (arm drawing away from the trunk). Eg:- Shoulder and Hip Joint. Hinge joint  Enables flexion and extension along a single axis. Eg:- Elbow,Knee,Ankle joint.

23. Condyloid joint  An example is the wrist, which the hand can move on two axes: flexion and extension; it can also be tilted sideways. Eg:- Wrist joint. Saddle joint  Resembles the condyloid joint but allows a wider range of motion; this type of joint is rare. Eg:- Thumb. Gliding joint  Surfaces of these joints are relatively flat and not very mobile; they allow only a narrow gliding range. Eg:- Vertebrae, certain bones of the wrist and ankle).

24. THE TENDONS A Tendon is a tough but flexible structure made of fibrous tissue that joins a bone to a muscle. When a muscle contracts it pulls on a bone to cause movement. The tendon transmits the force from the muscle to the bone. The tendonitis is the inflammation of a tendon.

25. THE LIGAMENTS Ligaments are bands of connective tissues that link two or more bones to make joints stable and prevent from excessive movements .

26. THE MUSCULAR SYSTEM Our Skeletal has more than 650 muscles, most of them disposed in pairs to provide movement.

27. THE MUSCULAR TISSUE Muscular cells are called Muscle fibers. Every fibers contain thousand of Myofibrils . Inside each myofibril there are many Myofilaments that are made of two proteins: the Actin and the Myosin. The myofibrils are divided in subunits called Sarcomeres .

28. MYOFILAMENT

29. MUSCLE CONTRACTION

30. TYPES OF MUSCLES There are three types of muscles: Skeletal Muscle Cardiac Muscle Smooth Muscle

31. SKELETAL MUSCLE The Skeletal muscles are also known as Striated or Voluntary. They are attached to bones by tendons providing movement. Their contraction is quick and variable from powerful to precise. It is controlled by the CNS.

32. CARDIAC MUSCLE Cardiac Muscle is only found in the Heart. It is made of striated fibers and its contraction is directed by the ANS. It contracts involuntarily and rhythmically. It’s also very resistant to fatigue due to the large number of mitochondria they have.

33. SMOOTH MUSCLE Smooth muscle are also known as involuntary as its contraction is lead by the CNS and the glands. It covers the hollow walls of many organs such as the oesophagus, the broncchi, the uterus or the stomach. It contracts slowly.

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