General Features and Attachments of Typical AND Ribs Atypical 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
LECTURE OUT LINE
•Classification of Ribs
•Twelve pairs of ribs, each terminating anteriorly in a costal cartilage.
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, forming a continuous margin, Costal Margin.
•Typical Ribs:
•The Ribs 3rd to 9th or 10th have similar features and called as TYPICAL RIBS.
•Typical rib consists of:
• 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.
•Presents 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.
1. 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.
•Have two borders.
•Two surfaces.
•
•Borders:
• Upper Border.
• Lower Border.
•Surfaces:
•Outer Surface.
•Inner Surface.
•Superior margin is smooth and rounded,
• Inferior margin is sharp.
• Bends forward just laterally to tubercle at a site termed the angle.
•Has a gentle twist around its longitudinal axis.
•Inferior margin of internal surface is marked by a distinct costal groove.
Attachments on Typical Ribs
•Provide attachment to intercostal muscles, Muscles between ribs
•External Intercostal Muscles
•Internal Intercostals Muscle
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.
•1st 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.
•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.
•
•2nd 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.
•10th Rib
•Head of rib tenth has a single facet for articulation with its own vertebra.
•11th & 12th 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