Human Anatomy Vol 1

BONES OF UPPER LIMB

Side Deierminolion

1 The lateral or glenoid (Greek shallow form) angle is
large and bears the glenoid cavity.
2 The dorsal surface is convex and is divided by the
triangular spine into the supraspinous and
infraspinous fossae. The costal surface is occupied
by the concave subscapular fossa to fit on the convex
chest wall (Figs 2.6 and 2.7).
3 The thickest lateral border runs from the glenoid
cavity above to the inferior angle below.

Feotules

$urfsces

1 The costal surface or subscapular fossa is concave and
is directed medially and forwards. It is marked by
three longitudinal ridges. Another thick ridge adjoins
the lateral border. This part of the bone is almost
rod-like: It acts as a lever for the action of the serratus
anterior in overhead abduction of the arm.
2 The dorsal surface gives attachment to the spine of
the scapula which divides the surface into a smaller
supraspinous fossa and a larger infraspinous fossa. The
two fossae are connected by the spinoglenoid notch,
Jituated lateral to the root of the spine.

Borders

L The superior border is thin and shorter. Near the root
of the coracoid process it presents the suprascapular
notch.
2 The lateralborder is thick. At the upper end it presents
the infr aglenoid tub er cle.
3 The medialborder is thin. It extends from the superior
angle to the inferior angle.

Angrles

1 The superior angle is covered by the trapezius.
2 The inferior angle is covered by the latissimus dorsi.It
moves forwards round the chest when the arm is
abducted.
3 The lateral or glenoid angle is broad and bears the
glenoid cavity or fossa, which is directed forwards,
laterally and slightly upwards (Fig.2.7).

cB$se$

L The spine or spinous process is a triangular plate of
bone with three borders and two surfaces. It divides
the dorsal surface of the scapula into the
supraspinous and infraspinous fossae. Its posterior
border is called the crest of the spine. The crest has
upper and lower lips.
2 The acromion has two borders, medial and lateral;
two surfaces, superior and inJerior; and a facet for
the clavicle (Fig. 2.7).

Lateral border

lnferior angle

Subscapular

fossa

Medial border

Fig.2.7: General features of right scapula: Costal surface

3 The coracoid (Greek like a crow's benk) process is

directed forwards and slightly laterally. It is bent and

finger like. It is atavistic type of epiphysis.

Atlochments

l The multipennate subscapularis arises from

the medial two-thirds of the subscapular fossa

(Figs 2.8 and 6.4).

2 The supraspinatus arises from the medial two-thirds

of the supraspinous fossa including the upper

surface of the spine (Fig. 2.9).

3 The infraspinatus arises from the medial two-thirds

of the infraspinous fossa, including the lower

surface of the spine (Fig. 2.9).

4 The deltoid arises from the lower border of the crest

of the spine and from the lateral border of the

acromion (Fig. 2.10). The acromial fibres are

multipennate.

5 The trapezius is inserted into the uPPer border of

the crest of the spine and into the medial border of

the acromion (Fig. 2.10).

6 The serratus anterior is inserted along the medial

border of the costal surface: One digitation from the

superior angle to the root of spine, two digitations

to the medial border, and five digitations to the

inferior angle (Fig. 2.8).

7 The long head of the biceps brachii arises from the

supraglenoid tubercle; and the short head from the

lateral part of the tip of the coracoid process

(Fis.2.e).

8 The coracobrachialis arises from the medial part of

the tip of the coracoid process.

9 The pectornlis minor is inserted into the medial

border and superior surface of the coracoid process

(Fig. 2.8).

Acromion

Coracoid process

Supraglenoid

tubercle

Glenoid cavity

Superior border

Superior angle

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CL

CL

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