11.10
胸郭：肋骨
肋骨は、胸郭の壁を形成する湾曲した平らな骨で、胸郭筋肉と一緒に存在します。胸郭には12対の肋骨があります。全ての肋骨の後端はT1-T12の胸椎と連結されます。それに対して、多くの肋骨の前端は肋軟骨を介して胸骨に連結されます。
典型的な肋骨の部位
典型的な肋骨は頭部、首部、本体から成ります。肋骨の後端…
胸郭は、胸骨、12対の肋骨、およびそれらの肋軟骨で構成されています。
最初の7対、真または椎骨胸骨は、前軟骨伸展または肋軟骨を介して胸骨に直接付着します。
残りの5つのペア、偽肋骨または椎骨軟骨は、その上の肋軟骨に結合するか、肋軟骨が胸壁に埋め込まれて自由に浮遊しています。
典型的な肋骨には、頭、首、体があります。短い首から生じる結節は、同じ番号の椎骨の横肋骨面と結合します。
各肋骨では、頭の関節面が2つの胸椎の肋骨面を結合しています。これは、同じ番号とその上の番号です。
体には、血管や神経が通過するための内部肋骨溝があります。その外面は骨盤帯と体幹の筋肉に付着します。
肋骨の間の肋間筋は呼吸中に収縮して弛緩し、胸郭の幅と深さが変化します。これにより、息を吸うときに胸腔の容積を増やし、息を吐くときに胸腔の容積を減らすことができます。
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Q1: What are the main components of a typical rib?
A typical rib has three main parts: the head, neck, and body. The head articulates with costal facets of thoracic vertebrae, while a small bump called the tubercle on the neck joins the transverse process of the same-numbered vertebra. The body, or shaft, contains a costal groove along its inferior margin for blood vessels and nerves to pass through.
Q2: How do true ribs differ from false ribs?
True ribs, ribs 1-7, attach directly to the sternum through their costal cartilages. False ribs, ribs 8-12, attach indirectly to the sternum. Ribs 8-10 connect to the cartilage of the 7th rib, while ribs 11-12, called floating ribs, do not attach to the sternum at all and terminate within the abdominal wall musculature.
Q3: Where do ribs articulate with the vertebral column?
All 12 pairs of ribs articulate posteriorly with thoracic vertebrae T1-T12. The articular facet in each rib's head joins the costal facets of two vertebrae: the same-numbered vertebra and the one above it. The tubercle on the rib's neck articulates with the transverse process of the same-numbered vertebra.
Q4: What is the costal groove and what structures pass through it?
The costal groove is a shallow groove located along the inferior margin of each rib. Blood vessels and nerves pass through this groove, allowing them to travel safely along the rib without obstruction. This anatomical feature protects vital neurovascular structures during respiration and movement.
Q5: How do intercostal muscles affect the thoracic cage during breathing?
Intercostal muscles between the ribs contract and relax during respiration, changing the width and depth of the thoracic cage. When these muscles contract during inhalation, they increase the volume of the thoracic cavity. During exhalation, they relax, decreasing the cavity's volume and facilitating air expulsion.
Q6: What is the angle of the rib and why is it anatomically significant?
The angle of the rib is the point on the rib where it has its highest degree of curvature, located just posterior to the tubercle. The angles of all ribs form the posterior extent of the thoracic cage, providing structural support and defining the cage's posterior boundary.
Q7: How many ribs comprise the thoracic cage and what are they called?
The thoracic cage comprises 12 pairs of ribs along with the sternum and costal cartilages. These ribs are classified as true ribs (1-7), false ribs (8-10), and floating ribs (11-12). Together with thoracic muscles, they form the thoracic cavity wall and are part of the overview of the axial skeleton.