EXERCISE 5. STRUCTURE OF THE RIB CAGE

manubrium, body, xiphoid process

What does the sternum consist of?

first rib

It is the shortest, broadest, and most sharply curved.

costal notches

7 small depressions located on each side of the sternum. They serve as area of attachment for the costal cartilages of the first 7 ribs.

sternum

(breastbone). This is a flat, narrow bone located in the center of the anterior thoracic wall that measures about 15 cm (6 in). in length and consists of three parts.

xiphoid process

(sword shaped). This is the inferior, smallest part of the sternum. This is a small pointed cartilaginous or bony process at the inferior end of the sternum. •no ribs are attached to it •provides attachment for some abdominal musles

Clavicular, sternocostal, sternal symphysis, xiphisternal

What are the articulations of the sternum?

Suprasternal (jugular) notch, clavicular notch, costal notches, sternal angle

What are the landmarks of the sternum?

Their anterior ends do not attach to the sternum at all. They attach only posteriorly to the thoracic vertebrae. •The floating ribs (ribs 11-12) have no anterior attachment with the sternum.

Why are some false ribs called "floating"?

Clavicular

•These are two slender bones, each articulating with the sternum and a scapula and forming the anterior part of a shoulder; collarbone.

sternal end of rib

This is the region of the rib that attaches to the costal cartilage.

The ribs that have costal cartilages and attach directly to the sternum are called true ribs. The remaining five pairs of ribs are termed false ribs because their costal cartilages either attach indirectly to the sternum or do not attach to the sternum at all. •The true ribs (ribs 1-7) attach to the sternum by costal cartilages. The flexible (hyaline) cartilage makes the breathing process easier. •The false ribs (ribs 8-10) attach to the costal cartilage of rib 7, not directly to the sternum.

What is the difference between a false rib and a true rib?

angle of rib

This is the area of shaft with the greatest curvature.

xiphisternal

This is the lowermost of the three segments of the sternum.

They are composed of hyaline cartilage. It is adaptive because it is elastic and prevents injuries.

Of what specific kind of tissue are the costal cartilage and xiphoid sternum composed? How is the use of this kind of tissue adaptive?

body

This is the middle and largest part of the sternum. It forms a series of smaller fused segments called sternebrae.

tubercle

This is the small elevation on the posterior surface of the rib at the junction of the head and neck. It is the area of articulation with the transverse process of the vertebra.

manubrium

This is the superior part of the sternum.

Suprasternal (jugular) notch

This is a depression on the superior surface of the manubrium.

costal groove of rib

This is an elongated depression along the inferior surface of the rib. The channel provides a pathway for the intercostal blood vessels and nerves run.

sternal angle

This is formed by the junction of the manubrium and the body.

clavicular notch

This is lateral to the suprasternal notch. It articulates with the medial ends of the clavicles to form the sternoclavicular joints.

neck of rib

This is the area between the head and tubercle.

Head, neck, tubercle, body, costal groove, pit for costal cartilage, angle, articular facets (for body of thoracic vertebrae and transverse processes)

What are the parts of the rib?

sternocostal

•Between sternum and first seven pairs of ribs •Structural: cartilaginous (synchondrosis) between sternum and first pair of ribs, and synovial (plane) between sternum and second through seventh pairs of ribs •Functional: immovable between sternum and first pair of ribs, and freely movable between sternum and second through seventh pairs of ribs •None between sternum and first pair of ribs; slight gliding between sternum and second through seventh pairs of ribs