Rib Cage Anatomy: Complete Guide with Parts, Names & Diagram

Overview of Rib Cage Anatomy

The rib cage is an essential body element that protects the heart and lungs. It creates the chest area known as the thorax, which comprises ribs, the sternum, and a portion of the spine. The rib cage anatomy has 24 ribs, 12 on each side, as well as 12 vertebrae, which are bones that form the spine in the chest area. The ribs wrap across the chest, becoming broader as you progress from the top ribs to the lowest ones. While the rib cage is robust, it may expand somewhat, aiding breathing. The tiny joints between the ribs and the spine allow the ribs to move easily when breathing and doing other tasks.

Rib Cage Anatomy Diagram

Rib Cage Anatomy, Parts, Names & Diagram

Anatomy of Rib Cage

Ribs
Sternum (Breastbone)
Costal Cartilages
Thoracic Vertebrae
Intercostal Muscles

Costal Margin
Costovertebral Joints
- Costocorporeal Joints (Joints of the Head of Ribs):
- Costotransverse Joints:
Pleura

Rib Cage Anatomy

Detailed Rib Cage Anatomy

Ribs

The rib cage is a flat bone collection that protects vital organs such as the heart and lungs. Most humans have 24 ribs grouped into 12 pairs.

Occasionally, someone may have an additional rib, known as a cervical rib, on one or both sides of the neck. Each rib is attached to the spine in the back and numbered according to the thoracic vertebrae it joins, beginning with the first rib (T1).

Most ribs in the front link to the sternum (breastbone) via flexible cartilage. Costovertebral joints are where the ribs connect the vertebrae.

True Ribs (1-7):
False Ribs (8-10):
Floating Ribs (11-12):

Sternum (Breastbone)

The sternum, or breastbone, is a flat, central bone in your chest that helps form the rib cage. It has three main parts:

Manubrium

It is a top section shaped like a broad, flat rectangle. It has a notch at the top (suprasternal notch) and two side notches for the collarbones to create the sternoclavicular joints.

Body (Gladiolus)

The longest part of the sternum. It has ridges where the cartilages of ribs 3 through 7 attach. This section connects with the manubrium at a prominent ridge called the sternal angle. Also, it connects with the second pair of ribs.

Xiphoid Process

The smallest and lowest section is shaped like a triangle. Its size and shape can differ from person to person.

The sternal angle is the visible bump where the manubrium and body meet. The main job of the sternum is to protect important organs like the heart and lungs.

Costal Cartilages

Costal cartilage is made of hyaline cartilage and helps extend the ribs forward, adding flexibility to the chest wall. It is found only at the front ends of the ribs.

The first seven pairs of costal cartilage attach to the sternum.
The next three connect to the rib cartilage above.
And the last two end in the abdominal wall.

Costal cartilages vary in length, width, and direction. They get longer from the first to the seventh rib, then shorten toward the twelfth. They also get narrower from the first to the last rib.

Most are wider, where they attach to the ribs and taper as they approach the sternum. Except for the first two, they are evenly wide, and the sixth, seventh, and eighth are wider where they meet.

Their direction also varies: the first cartilage slopes slightly downward, the second is horizontal, and the third tilts up a bit. While the others angle, following the rib’s curve briefly before moving up to the sternum or the cartilage of the rib above.

Thoracic Vertebrae

In vertebrates, the thoracic vertebrae form the middle part of the spine. It is between the neck (cervical vertebrae) and the lower back (lumbar vertebrae).

Humans have twelve of these vertebrae, labeled T1 to T12. It starts from the top near the skull and moves down toward the lower back. These vertebrae get bigger as you go down the spine.

They are special because they have surfaces called facets that connect to the ribs. Most of them, except the last two, also have extra facets on their side branches called transverse processes. It helps attach the ribs.

Intercostal Muscles

The intercostal muscles are essential for breathing. It is positioned between your ribs in two layers. These muscles are crucial in altering your chest cavity’s size to allow you to breathe effectively. Each side of your ribcage houses 11 pairs of these muscles, organized into two layers.

External Intercostal Muscles

It is located on the outer side of your ribcage. These muscles extend from the rear of the ribs toward the front, stopping just before the rib ends. When you inhale, these muscles contract, lifting your ribs and expanding your chest.

Internal Intercostal Muscles

It is found on the inner side of your ribcage. These muscles begin at the front and curve around to the back. They work in tandem with the external intercostals but are oriented to support different movements.

Both sets of intercostal muscles contract during inhalation, causing your ribcage to move upward and outward. This action enlarges the chest cavity to allow air to flow into your lungs.

Costal Margin

The costal margin is also known as the costal arch. It forms the lower boundary of the chest, shaped by the cartilages of the seventh through tenth ribs.

These cartilages connect to the sternum, including its body and xiphoid process. This structure provides an attachment point for the diaphragm, the primary muscle involved in breathing. The costal angle is where the left and right costal margins converge at the sternum.

It creates a protective zone for vital organs in the upper abdomen, such as the liver. This region protects these organs while facilitating respiratory movements.

Costovertebral Joints

The costovertebral joints are two types of joints that connect the ribs to the spine at the back, helping form the chest cage. These are synovial plane joints, which allow limited movement.

Costocorporeal Joints (Joints of the Head of Ribs): These joints link the heads of the ribs to one or two adjacent vertebrae.
Costotransverse Joints: These connect the ribs’ necks and tubercles (small rounded projections) to the corresponding thoracic vertebrae’s transverse processes (side projections).

These joints enable small movements, often called ‘pump-handle’ or ‘bucket-handle.’ This limited motion allows the ribs to lift slightly upward and outward during breathing. It increases the chest’s width and helps the lungs expand as you inhale.

Rib Cage Anatomy: Complete Guide with Parts, Names, Functions & Diagram