The Ribs and Sternum Form the
Framework for the Thorax
The sternum is made of three parts that fuse by age 25:
The
manubrium
(
ma-NOO-bre-um
) articulates with
the collarbone, or clavicle, and the first rib.
The body articulates with part of the second rib and
ribs 3 through 10.
The
xiphoid process
(
Zl-foyd
) is made of cartilage
that ossifies by age 40. No ribs attach to this pointed
structure, which rescuers use to locate the proper hand
position for cardiopulmonary resuscitation (CPR).
The sternum attaches directly to the first through seventh
pairs of ribs by a form of hyaline cartilage called
costal car-
tilage.
The remaining pairs of ribs either attach indirectly
to the sternum (pairs 8-12) or do not attach at all (pairs
11-12). Ribs are named based on how they attach to the
sternum; rib pairs 1
through 7 are called
true ribs
, rib pairs
8 through 12 are called
false ribs
, and rib pairs 11 and 12
are referred to as
floating ribs
. The bones of the thorax
THE PLANNER^
Shoulder
_ Phalanges
i
CARPALS:
A
Scaphoid
\ \
Trapezium
\ \
Trapezoid
Sesamoid
bones
Thorax
Metacarpal
Thumb
PHALANGES
LATERAL
Radius
Ulna
CARPALS:
Lunate
Pisiform
Triquetrum
Capitate
Hamate
Base
Body
Head
Base
Body
Head
. Little finger
f
Index finger
Ï f
Middle finger
MEDIAL
Ring finger
e. Anterior view of right wrist and hand
d. Anterior view of upper limb
131
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