Upper 7 pairs attached anteriorly to sternum via costal cartilages
False ribs
8th, 9th and 10th pairs attached anteriorly to each other and to 7th rib via costal cartilages and small synovial joints
Floating ribs
11th and 12th pairs have no anterior attachment
Typical rib
Long twisted flat bone
Round smooth superior border
Sharp thin inferior border
Inferior border forms costal groove which hosts the intercostal vessels and nerve
Anterior end of rib attached to costal cartilage
Parts: head, neck, tubercle, shaft and angle
Head: two facets, one with corresponding vertebral body, other with vertebrae immediately above
Neck: constricted portion between head and tubercle
Tubercle: prominence on outer surface of rib, at junction of neck with shaft. Has facet for articulation with transverse process of corresponding vertebra
Shaft: thin, flattened, twisted. Inferior border has costal groove
Angle: shaft bends sharply forward
Atypical rib
First rib: small, flattened. Scalenus anterior attaches to upper surface and inner border. Anterior to scalenus anterior, subclavian vein crosses rib, posterior to muscle attachment. Subclavian artery and lower trunk brachial plexus cross rib and lie in contact with bone
Cervical rib: rib from anterior tubercle of transverse process of 7th cervical vertebra. .5% humans. Anterior end can be free or attached to first rib by fibrous band or articulate with first rib.
