Human Anatomy Vol 1

UPPEB LIMB

Medial surface

of olecranon

Medial surface of

coronoid process

Medial surface

Posterior border

gives origin to flexor

digitorum profundus,

flexor carpi ulnaris,

extensor carpi ulnaris

Head of the ulna

lyloid Frocess

Fig.2.32: Posterior aspect of ulna

2 The brachialis is inserted into the anterior surface of

the coronoid process including the tuberosity of the

ulna (Fig.2.25).

3 The supinator arises from the supinator crest and from

the triangular area in front of the crest (Fig. 2.25).

4 The ulrrar head of the flexor digitorum superficialis

arises from a tubercle at the upper end of the medial

margin of the coronoid process (Fig.2.25).

5 The ulnar head of the pronator teres arises from the

medial margin of the coronoid process (Fig.2.25).

6 Theflexor digitorumprofundus (Latndeep) arises from:

a. The upper three-fourths of the anterior and

medial surfaces of the shaft.

b. The medial surfaces of the coronoid and

olecranon processes.

c. The posterior border of the shaft through

an aponeurosis which also gives origin to the

flexor carpi ulnaris and the extensor carpi ulnaris

(Fig.2.26).

7 The pronator quadratus takes origin from the oblique

ridge on the lower part of the anterior surface

(Fig.2.25).

8 The flexor carpi ulnaris (ulnar head) arises from the

medial side of the olecranon process and from the

posterior border (Fig. 2.32).

9 The extensor carpi ulnaris arises from the posterior

border (Fig.2.32).

10 The anconeus is inserted into the lateral aspect of

the olecranon process and the upper one-fourth of

the posterior surface (Fi9.2.26) of the shaft.

LL The lateral part of the posterior surface gives origin

from above downwards to the abductor pollicis

longus, the extensor pollicis longus and the extensor

indicis (Fig.2.26).

12 The interosseous membrane is attached to the

interosseous border (Fig. 2.32).

13 The oblique cord is attached to the ulnar tuberosity

(Fis.2.25).

14 The capsular ligament of the elborn joint is attached to

the margins of the trochlear notch, i.e. to the

coronoid and olecranon processes (Fig. 2.25).

1 5 The annular ligament of the superior radioulnar j oint

is attached to the two margins of radial notch of

uhra (Fig. 2.31b).

15 The ulnar collaternl ligament of the wrist is attached

to the styloid process (Fig.2.31a).

\7 TI:re articular disc of the inferior radioulnar joint is

attached by its apex to a small rough area just lateral

to the styloid process (Fig. 2.31a).

The shaft and most of the upper end ossify from a

primary centre which appears.during the 8th week

of development.

The superior part of the olecranon process ossifies

from a secondary centre which appears during the

10th year. It forms a scale-like epiphysis which joins

the rest of the bone by 1-6th year.

The lower end ossifies from a secondary centre

which appears during the Sth year, and joins with

the shaftby l8th year. This is the growing end of the

bone (Table 2.1).

Superior surface

Olecranon process

Posterior surface

Radial notch

Supinator crest

Oblique line

of posterior surface

Vertical line on

posterior surface

lnterosseous

membrane

on the lateral

border

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The ulna is the stabilising bone of the forearm,

with its trochlear notch gripping the lower end of

the humerus. On this foundation, the radius can

pronate and supinate for efficient working of the

upper limb.

The shaft of the ulna may fracture either alone or

along with that of the radius. Cross-union between

the radius and uLna must be prevented to preserve

pronation and supination of the hand.

Dislocntion of the elbow is produced by a fall on the

outstretched hand with the elbow slightly flexed.

The olecranon shifts posteriorly and the elbow is

fixed in slight flexion.

Normally in an extended elbow, the tip of the

olecranon lies in a horizontal line with the two