What Are Ribs 11 And 12 Called?

The rib cage is the bony structure that surrounds the thoracic cavity and encloses the heart and lungs. It is formed by 12 pairs of ribs attached to the thoracic vertebrae, as well as the sternum in the front of the chest. The rib cage provides important protection for the vital organs within, while also enabling respiratory motions like inhalation and exhalation. Together with the sternum, the ribs form a semi-rigid chest wall that is both protective and flexible.

The ribs are elongated, curved bones that articulate posteriorly with the thoracic vertebrae. The ribs form the majority of the thoracic skeleton, lending shape and structure to the chest wall. They serve to protect the thoracic viscera – namely the heart and lungs. The ribs also provide attachments for the intercostal muscles between them. Contractions of these muscles change thoracic volume during breathing.

Anatomy of Ribs

The ribs are a set of 12 bones that form the rib cage around the chest cavity. Each rib is attached posteriorly to the thoracic vertebrae of the vertebral column. The first seven ribs, known as the true ribs, connect directly to the sternum via cartilage anteriorly. Ribs 8-10 are called the false ribs since they connect indirectly to the sternum via the cartilage of the rib above. Ribs 11 and 12 are called floating ribs as they do not connect to the sternum at all.

The ribs serve to protect the vital organs within the thorax, including the heart and lungs. They also play a role in breathing by elevating and depressing to facilitate inhalation and exhalation.

The anatomy of the ribs allows them to form the flexible rib cage that expands and contracts during respiration. The ribs are long, thin, curved bones with a head, neck, tubercle, angle and body. The posterior head articulates with the vertebrae while the anterior end connects with cartilage to form the costal margin. The ribs slope downward as they wrap around the thorax.

Numbering of Ribs

Humans typically have 24 ribs in total, with 12 ribs on each side of the body. Each rib is numbered to identify its location and type. The ribs are numbered in ascending order from 1-12, starting at the top of the thoracic cage.

There are 12 thoracic vertebrae in the spine that have articulations with the ribs. Ribs 1-7 connect directly to the sternum through cartilage, which is why they are called “true ribs.” Ribs 8-12 are called “false ribs” because instead of attaching to the sternum directly, they connect to the cartilage of the rib above them. The last two ribs, 11 and 12, are also sometimes called “floating ribs” because they do not attach to the sternum at all. Their cartilage ends freely between the abdomen and chest.

So in summary, humans typically have 12 pairs of ribs, numbering from 1-12 on each side of the body. Ribs 11 and 12 are called the floating ribs since they do not directly attach to the sternum.

Sources:

https://www.medicalnewstoday.com/articles/how-many-ribs-do-humans-have

https://www.healthline.com/health/bone-health/how-many-ribs-do-men-have

True Ribs

True ribs are ribs 1-7 in a human’s rib cage. These ribs attach directly to the sternum via their own costal cartilage (Definition of True rib).

Ribs 1-7 are unique in that they have their own distinct costal cartilage connecting them to the sternum. This cartilage attachment allows for articulation and movement of the true ribs during breathing. The direct cartilage connection also provides protection and support for vital internal organs located in the thoracic region underneath the true ribs, including the heart and lungs (True rib | anatomy).

In summary, true ribs are the first seven rib pairs in humans that connect via their own costal cartilage directly to the sternum (TRUE RIB Definition & Usage). This anatomical arrangement allows the true ribs to protect vital organs and assist with respiration.

False Ribs

Ribs 8-12 are known as the false ribs because their costal cartilages do not articulate directly with the sternum or breastbone (Source). Unlike the true ribs (ribs 1-7), which connect directly to the sternum, the false ribs connect indirectly by joining the costal cartilage above them. For example, ribs 8-10 have their cartilages attached to the cartilage of the seventh rib, while ribs 11-12 are free of any anterior bony attachment (Source).

The false ribs consist of three types:

• Ribs 8-10 are known as vertebrosternal ribs since they connect indirectly to the sternum via the costal cartilage of rib 7.
• Ribs 11-12 are known as vertebral ribs or floating ribs since they do not connect to the sternum at all.

Rib 11

Rib 11 is anatomically referred to as the eleventh rib or eleventh thoracic rib. It is located in the lower portion of the thoracic cage, just above rib 12.

Unlike the first seven ribs, rib 11 does not articulate directly with the sternum via costal cartilage. Instead, it articulates posteriorly with the eleventh thoracic vertebrae and is free floating anteriorly. This means rib 11 does not form a direct bony connection with the sternum. Due to this lack of anterior attachment, rib 11 along with rib 12 are referred to as “floating ribs.”

The eleventh rib is longer and more curved than the twelfth rib. It contains one facet on the head for articulation with the vertebral body of the eleventh thoracic vertebrae. It does not contain a neck or tubercle.

Overall, rib 11 serves as one of the lower floating ribs that provides structural support to the thoracic cage while still allowing for expansion and movement during respiration. Its anatomy and articulations differ from the upper ribs that attach directly to the sternum.

Sources:

https://www.elsevier.com/resources/anatomy/skeletal-system/axial-skeleton/eleventh-rib/18750

https://teachmeanatomy.info/thorax/bones/ribcage/

Rib 12

The twelfth rib, also referred to as the twelfth thoracic rib, is one of the two floating ribs of the thoracic cage. It is the shortest and least curved rib in the body. The twelfth rib is considered an atypical rib because it does not attach directly to the sternum ^[1].

The twelfth rib is located inferior to the eleventh rib. It has a single facet on its head that articulates with the T12 thoracic vertebra. The twelfth rib has a short neck and no tubercle or costal groove. It lacks a direct cartilage connection to the sternum ^[2].

Floating Ribs

Ribs 11 and 12 are specifically referred to as the floating ribs. Floating ribs are the lowest ribs in the rib cage that do not attach to the sternum or other ribs (Medical Definition of Floating rib). Unlike the other ribs, ribs 11 and 12 do not form a stable anterior attachment. They are attached posteriorly to the vertebrae but remain “floating” anteriorly, giving them their name. The 11th rib articulates with the 11th thoracic vertebra and the 12th rib articulates with the 12th thoracic vertebra (Floating ribs: Anatomy and function).

Since the floating ribs are not firmly anchored down, they can sometimes become displaced or fractured from trauma like a blow to the torso. A displaced or fractured floating rib may cause pain or discomfort in the abdomen or lower back. However, treatment for a fractured floating rib is usually just rest and pain medication, since the fractures often heal on their own over time (Floating Rib: Symptoms, Causes, Treatment).

Injuries

The ribs are susceptible to various types of injuries, including fractures and bruising. Rib fractures occur when one or more ribs break, which usually happens from a direct blow or penetrating injury to the chest. according to Mayo Clinic. The most commonly fractured ribs are the middle ribs like ribs 7-10. Fractures can range from simple cracks in the bone to complete breaks that separate the rib into multiple pieces.

Rib fractures cause sharp pain that worsens with breathing, coughing or movement. They may lead to complications like a collapsed lung. Treatment involves pain medication, rest, and bracing. Healing takes several weeks. Proper treatment is important to prevent lung injuries.

Rib bruising, or contusions, happen when an impact damages the blood vessels and soft tissues over the bone without breaking it, according to Better Health Victoria. This causes bleeding under the skin and muscle that leads to swelling and soreness over the affected area. Bruising often occurs from sports collisions but can also happen from violent coughing. Healing takes 1-2 weeks. Rest, ice, and over-the-counter pain relievers help manage symptoms.

Conclusion

In conclusion, ribs 11 and 12 are called floating ribs. All ribs are numbered 1-12, with ribs 1-7 being true ribs that articulate directly with the sternum. Ribs 8-10 are false ribs that articulate indirectly with the sternum via costal cartilage. Ribs 11 and 12 are unique in that they do not attach to the sternum at all, giving them the name floating ribs.

Floating ribs 11 and 12 only attach posteriorly to the vertebral column. They serve important functions like the other ribs in protecting internal organs, aiding in breathing, and providing structural support. However, due to their free nature, the floating ribs are more susceptible to injury and fractures. Understanding the anatomy and purpose of the various types of ribs is key for medical professionals.