Anatomy of the Human ribs

Anatomy of the Human ribs

Anatomy of the Human ribs

Ribs (costae) are one of the integral parts of the chest wall; they make up the lateral part of its anterior and posterior wall and entirely build the lateral parts of the chest wall. There are 12 pairs or ribs that are marked with Roman numerals I-XII.Ribs are divided into two basic groups: “proper” ribs (costae verae, I-VII) and “fake” ribs(costae spuriae, VIII-XII). Proper ribs are directly connected to the sternum over their cartilage, while fake ribs connect indirectly, over the cartilage of the 7th rib, or are not connected to the sternum at all (in the case of the 11th and 12th rib), which are then called floating ribs (costae fluctuantes).The rib cartilage of the 8th, 9th and 10th rib rounds upwards and connects to the cartilage of the next upper rib and after this also with the cartilage of the 7th rib, thus creating the rib arch, arcus costarum.

Ribs have several parts: head, caput costae;neck,collum costae;body, corpus costae;and the front part of the rib. The head of the rib includes the articular surface, facies articularis capitis costae. The head of every rib (except in the case of the 1st, 11th and 12th) includes an upper and lower part that are divided by the ridge, crista capitis costae. The upper part is joined with the same numeral chest vertebra, and the lower one with the first lower vertebra. The ridge itself is connected to the inter-vertebral plate. The head of the 1st, 11th and 12th rib connects only with the same numeral vertebra.

The neck of first 3-4 ribs is rounded while others have the already mentioned ridge, crista colli costae. The neck ends with a nodule, tuberculum costae.On the bottom side of the nodule is the joint surface for connection with the transverse end of the same numeral vertebra, facies articularistuberculi costae. The exceptions are the 11th and 12th ribs that don’t have this surface, which enables them much higher mobility. With the upper ribs, closer to the nodule (and in the case of lower ribs, a little further from the nodule) they are curved and have a rough surface that connects them with muscles, angulus costae.

A rib has a flat body. The upper edge is round and the lower sharp. On the interior wall of the rib body is a channel, sulcus costae, with blood vessels and nerves. This furrow isn’t present in the 11th and 12th rib. The front edge ends with an ellipsoidal shape on which the rib cartilage connects.

The rib length increases from 1st to 7-8th and after this it decreases till the 12th. Ribs also are different in curve: curve by radius, curve by edge (horizontal plane) and according to longitudinalaxis. A radius curve is higher at the beginning of the rib and smaller in the end. This curve increases according to the rib’s number, i.e. from 1st to 12th. Due to the edge curve, the head of the rib is in a higher position than its front end. This is particularly evident in ribs that are in the middle. Due to the curve on the longitudinal axis, the interior plate on the back of the rib is pointed upwards, while on the front end it is pointed downwards.

The first rib is short, wide and flat without any curve on its edge and axis. This is why its radius curve is very expressive. On the upper plate of the rib there is an additional nodule, tuberculum musculiscalenianterioris. In the front and in the back of the nodule there are two channels. The front one is called sulcus venae subclaviae and the back one is called sulcus arteriae subclaviae. Both of them carry an equally named blood vessel.

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