226
UNIT TWO
muscles. On the lateral surface of the scapula between the
processes is a depression called the
glenoid cavity
(glenoid
fossa of the scapula). It articulates with the head of the arm
bone (humerus).
The scapula has three borders. The
superior border
is on
the superior edge. The
axillary,
or
lateral border,
is directed
toward the upper limb. The
vertebral,
or
medial border,
is
closest to the vertebral column, about 5 cm away.
PRACTICE
29
Which bones form the pectoral girdle?
30
What is the function of the pectoral girdle?
7.10
UPPER LIMB
The bones of the upper limb form the framework of the arm,
forearm, and hand. They also provide attachments for mus-
cles and interact with muscles to move limb parts. These
bones include a humerus, a radius, an ulna, carpals, meta-
carpals, and phalanges
(f
g. 7.42)
.
Humerus
The
humerus
is a long bone that extends from the scapula
to the elbow. At its upper end is a smooth, rounded
head
that F ts into the glenoid cavity of the scapula
(f g. 7.43)
.
Just below the head are two processes—a
greater tubercle
on the lateral side and a
lesser tubercle
on the anterior side.
These tubercles provide attachments for muscles that move
the upper limb at the shoulder. Between them is a narrow
furrow, the
intertubercular groove,
through which a ten-
don passes from a muscle in the arm (biceps brachii) to the
shoulder.
The narrow depression along the lower margin of the
head that separates it from the tubercles is called the
ana-
tomical neck.
Just below the head and the tubercles of the
humerus is a tapering region called the
surgical neck,
so
named because fractures commonly occur there. Near
the middle of the bony shaft on the lateral side is a rough
V-shaped area called the
deltoid tuberosity.
It provides an
attachment for the muscle (deltoid) that raises the upper
limb horizontally to the side.
At the lower end of the humerus are two smooth
condyles
—a knoblike
capitulum
(kah-pit
u-lum) on the lat-
eral side and a pulley-shaped
trochlea
(trok
le-ah) on the
medial side. The capitulum articulates with the radius at
the elbow, whereas the trochlea joins the ulna.
Above the condyles on either side are
epicondyles,
which provide attachments for muscles and ligaments of the
elbow. Between the epicondyles anteriorly is a depression,
the
coronoid
fossa,
that receives a process of the ulna (cor-
onoid process) when the elbow bends. Another depression
on the posterior surface, the
olecranon
(o
lek
ra-non)
fossa,
receives an olecranon process when the elbow straightens.
Anterior end
(sternal end)
Shaft
Facet
Head
Neck
Tubercle
Facet
Spinous process
Costal groove
Shaft
Anterior end
Head
Tubercle
Neck
(a)
(b)
FIGURE 7.39
A typical rib. (
a
) Posterior view. (
b
) Articulations of a
rib with a thoracic vertebra (superior view).
Scapulae
The
scapulae
(skap
u-le) are broad, somewhat triangular
bones located on either side of the upper back. They have fl
at
bodies with concave anterior surfaces
(f
g. 7.41)
. The poste-
rior surface of each scapula is divided into unequal portions
by a
spine.
Above the spine is the
supraspinous fossa,
and
below the spine is the
infraspinous fossa.
This spine leads
to an
acromion
(ah-kro
me-on)
process
that forms the tip
of the shoulder. The acromion process articulates with the
clavicle and provides attachments for muscles of the upper
limb and chest. A
coracoid
(kor
ah-koid)
process
curves ante-
riorly and inferiorly to the acromion process. The coracoid
process also provides attachments for upper limb and chest
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