Bones of the thorax – The course is designed for the basic understanding of anatomical structures and physiological functions of human body, musculoskeletal system, digestive system, respiratory system; cardiovascular system; urinary system, endocrine system, reproductive system, nervous system, hematologic system, sensory organs, integumentary system, and immune system.
The aim of the course is to acquire knowledge and skills regarding anatomy and physiology.
Bones of the thorax
The term thoraxrefers to the entire chest. The skeletal portion of the thorax, the thoracic cage, is a bony cage formed by the sternum, costal cartilages, ribs, and the bodies of the thoracic vertebrae The thoracic cage encloses and protects the organs in the thoracic cavity and upper abdominal cavity. It also provides support for the bones of the shoulder girdle and upper limbs.
Sternum
The sternum, or breastbone, is a flat, narrow bone located inthe center of the anterior thoracic wall and consists of threeparts that usually fuse by age 25. The upperpart is the manubrium, the middle and largest part is the boxfy, and the lowest, smallest part is the xiphoid process (sword-shaped).
Ribs
Twelve pairs of ribs make up the sides of the thoracic cavity. The ribs increase in length from the first through seventh ribs, then decrease in length to the twelfth rib. Each rib articulates posteriorly with its corresponding thoracic vertebra.
The first through seventh pairs of ribs have a direct anterior attachment to the sternum by a strip of hyaline cartilage called costal cartilage. These ribs are called true ribs.
The remaining five pairs of ribs are termed false ribsbecause their costal cartilages either attach indirectly to the sternum or do not attach to the sternum at all. The cartilages of the eighth, ninth, and tenth pairs of ribs attach to each other and then to the cartilages of the seventh pair of ribs.
The eleventh and twelfth false ribs are also known as floating ribs because the costal cartilage at their anterior ends does not attach to the sternum at all. Floating ribs attach only posteriorly to the thoracic vertebrae. Spaces between ribs, called intercostal spaces, are occupied by intercostal muscles, blood vessels, and nerves.
True ribs (pairs 1-7) = 07 pairs
False ribs (pairs 8-12) =05pairs {Floating ribs (pairs 11-12) = 02}
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Total = 12 pairs (24 pcs)
Clavicle
Each clavicle or collarbone is a long, slender S-shaped bone that is positioned horizontally above the first rib. The medial end of the clavicle articulates with the sternum, and the lateral end articulates with the acromion of the scapula. Because of its position, the clavicle transmits mechanical force from the upper limb to the trunk.
Scapula
Each scapula, or shoulder blade, is a large, flat, triangular bone situated in the posterior part of the
thorax.
(Ref- J. Tortora, The essentials of anatomy and physiology, 8th edition, P-144,145)
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