General Features And Attachments Of

Typical Ribs Learning Objectives

At the end of the class, student should be able to :

Classify the ribs. Mention the different parts of typical rib. Discuss the features of Typical ribs. Enumerate the Atypical ribs and compare with Typical ribs

Classification of Ribs

• Twelve pairs of ribs, each terminating anteriorly in a costal cartilage

Classification of Ribs• True Ribs: Costal cartilages of the upper seven ribs articulate directly with the sternum, known as TRUE

RIBS.

• False Ribs: Costal cartilages lower five do not articulate directly to the sternum called as FALSE RIBS. • Floating ribs: Ribs 11th and 12th have no anterior connection with other ribs or with the sternum

Nomenclature

• Costal Margin: Costal cartilages of 8th to 10th ribs articulate anteriorly with costal cartilages of

the ribs above, (like 8th articulates with 8th and so on) forming a continuous margin, Costal Margin.

Typical Ribs• The Ribs 3rd to 9th or 10th have similar features and called as TYPICAL RIBS

Typical RibConsists of:Three parts A curved shaft with anterior and posterior ends.

Anterior end is continuous with its costal cartilage.

Posterior end articulates with the vertebral column and is characterized by a head, neck, and tubercle.

Head of Rib• Head is somewhat expanded. • On its posterior end there are two articular surfaces separated by crest.

• Smaller superior surface articulates with inferior costal facet on body of vertebra above• While larger inferior facet articulates with superior costal facet of its own vertebra.

Neck of Rib • Short flat region of bone. • Separates the head from the tubercle.

Tubercle of rib• Projects posteriorly from the junction of the neck with the shaft.• Consists of two regions

– An articular part and – A non-articular part.

Tubercle of rib1. Articular part: It is medial.

Has an oval facet for articulation with a corresponding facet on the transverse process of the associated vertebra

2. non-articular part: Raised non-articular part is roughened by ligament attachments.

Shaft of Rib Shaft is generally thin and flat.• Has two borders.• Two surfaces. Borders: • Upper Border • Lower Border Surfaces: • Outer Surface • Inner Surface

Shaft of Rib• Superior margin is smooth and rounded,

• Inferior margin is sharp.

• Inferior margin of internal surface of shaft extends beyond the limit of bone, called as costal groove.

Shaft of Rib• Beyond the tubercle the shaft of rib bends on itself, known as costal angle.

• Along its long axis the shaft of ribs gently twisted, this can be visible when rib placed on the table. This is helpful in respiration.

Attachments on

Typical RibsProvide attachment to intercostal muscles, Muscles between ribs

External Intercostal Muscles

Internal Intercostals Muscle

Innermost Intercostal Muscles

Innermost Intercostal Muscle

Transversus Thoracis

Subcostales

General Features and attachment of Atypical Ribs

Atypical Ribs Ribs having dissimilar features are the Atypical ribs.

These are 1st, 2nd, 10th, 11th and 12th.

1 st Rib The 1st rib is: The broadest (i.e., Its body is widest and nearly horizontal), Shortest, and Most sharply curved of the seven true ribs. Has a single facet on its head for articulation with the t1 vertebra only.

In comparison of typical rib the first rib has outer and inner borders and superior and inferior surfaces On its superior has two transversely directed grooves crossing for the subclavian vessels; Grooves are separated by a scalene tubercle and ridge, to which the anterior scalene muscle is attached.

2 nd Rib More typical Body is thinner, less curved, and substantially longer than the 1st rib. Head has two facets for articulation with the bodies of the T1 and T2 vertebrae Main atypical feature is a rough area on its upper surface, The tuberosity for serratus anterior, from which part of that muscle originates.

10 th Rib

Head of rib tenth has a single facet for articulation with its own vertebra.

11 th & 12 th Ribs 11 and 12 Ribs articulate only with the bodies of their own vertebrae and have no

tubercles or necks. Both ribs are short, have little curve, and are pointed anteriorly

Anterior ends are free and covered with costal cartilages

References GRAYS ANATOMY FOR STUDENTS 2004, -by Richard Drake, Wayne Vogl,

Adam W.M. Mitchell

GRANT'S.ATLAS.OF.ANATOMY.12th. Anne M. R. Ager and Arther F. Delly

MOORE, KEITH L. - CLINICALLY ORIENTED ANATOMY, by Keith L.

Moore and Keith L. Moore

General Features and attachment of Atypical Ribs

Learning Objective At the end of the lecture, the student should be able to:

Mention the different parts of atypical rib. Discuss the features of atypical ribs.

Atypical Ribs Ribs having dissimilar features are the Atypical ribs.

These are 1st, 2nd, 10th, 11th and 12th.

1 st Rib The 1st rib is: The broadest (i.e., Its body is widest and nearly horizontal),

Shortest, and

Most sharply curved of the seven true ribs. Has a single facet on its head for articulation with the t1 vertebra only.

1 st Rib On its superior has two transversely directed grooves crossing for the subclavian vessels; Grooves are separated by a scalene tubercle and ridge, to which the anterior scalene muscle is attached.

2 nd Rib More typical; Body is thinner, less curved, and substantially longer than the 1st rib. Head has two facets for articulation with the bodies of the t1 and t2 vertebrae; Main atypical feature is a rough area on its upper surface, The tuberosity for serratus anterior, from which part of that muscle originates.

10 th Rib Head of rib tenth has a single facet for articulation with its own vertebra.

11 th & 12 th Ribs 11 and 12 Ribs articulate only with the bodies of their own vertebrae and have no

tubercles or necks. Both ribs are short, have little curve, and are pointed anteriorly

References GRAYS ANATOMY FOR STUDENTS 2004, -by Richard Drake,

Wayne Vogl, Adam W.M. Mitchell GRANT'S.ATLAS.OF.ANATOMY . 12th. Anne M. R. Ager and Arther

F. Delly MOORE, KEITH L. - CLINICALLY ORIENTED ANATOMY, by

Keith L. Moore and Keith L. Moore

THANKS