ULNA BONE
LEARNING OBJECTIVES
• Students should able to:
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Recognize the bone.
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Determine side of bone.
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Identify the features of bone.
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Identify the muscles attached to bone.
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Identify clinical significance of bone.
DETERMINATION OF SIDE
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Strong Upper end.
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Has hook-like projection (trochlear notch), concavity of which faces forward.
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Lower end has small head.
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Thin sharp crest like interosseous border of shaft lies laterally.
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Styloid process projects downwards from posteriomedial aspect of head.
PARTS OF BONE
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Upper end.
Shaft.
Lower end.
FEATURES OF UPPER END
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Two processes
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Olecranon .
Coronoid.
Two articular notches
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Trochear.
Radial.
OLECRANON PROCESS
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Bent forwards, forming a beak like projection
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Occupies the olecranon fossa of humerus when elbow is extended
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Posses 6 surfaces
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Anterior
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Posterior
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Lateral
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Medial
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Superior
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Inferior
CORONOID PROCESS
Possess:
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4 surfaces.
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Anterior.
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Lateral.
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Medial surface.
Two borders.
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Medial border
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Lateral border
TROCHLEAR NOTCH
The Semilunar Notch (incisura semilunaris; greater sigmoid cavity

Articulates with trochlea of humerus.

Formed by anterior surface of olecranon process & upper surface of
coronoid process
RADIAL NOTCH
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Oval depression on lateral surface of coronoid process.
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Articulates with head of radius
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Annular ligament is attached.
The Body or Shaft (corpus ulnæ)
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The body at its upper part is prismatic in form .
its central part is straight.
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its lower part is rounded, smooth .
has three borders and three surfaces.
Borders

The volar border (margo volaris; anterior border) .
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separates the volar from the medial surface.

Prominent.
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begins above at the medial angle of the coronoid process
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ends below in front of the styloid process
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upper part, well-defined

middle portion, smooth and rounded

give origin to the Flexor digitorum profundus

lower fourth serves for the origin of the Pronator quadratus
The interosseous crest (crista interossea; external or interosseous border
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Sharp crest like lateral border.
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Upper part continuous with supinator crest.
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Interosseous membrane is attached to it, except at upper part.
The dorsal border (margo dorsalis; posterior border )
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Begins at posterior aspect of olecranon.
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Ends at back of styloid process.
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gives attachment to an aponeurosis in upper 3\4

Apponeurosis gives a common origin to the:

Flexor carpi ulnaris,

the Extensor carpi ulnaris

Flexor digitorum profundus

lower fourth is smooth and rounded
Surfaces
The volar surface (facies volaris; anterior surface)
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between anterior and interosseous borders.

Nutrient foramen.

nutrient artery is a branch of anterior interrosseous artery.

upper 3/4th gives origin to the Flexor digitorum profundus

Lower 1\4 Pronator quardatus origin
Medial surface
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Covex.
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Lies between anterior &posterior borders.
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Flexor digitorum profundus from upper 3\4
MUSCLE ATTACHMENTS ON ANTERIOR
SURFACE OF ULNA
Posterior surface

between posterior & interosseous borders.
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oblique line.

Surface divided into a medial & a lateral part by a vertical ridge.

Lateral adjoins the interosseous border; medial area adjoins the posterior
border.
Lateral area gives origin to

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Abductor pollicis longus.
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Extensor pollicis longus.
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Extensor indicis.
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Anconeous
MUSCLES ATTACHMENT ON POSTERIOR
SURFACE OF ULNA
LOWER END

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PARTS.
Head.
Styloid process.
HEAD
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Articular part
Inferior surface.
Anterior & posterior margins (give attachment to capsular ligaments of
wrist joint)
STYLOID PROCESS
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projects from posterio-medial aspect of lower end of ulna.
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1.25 cm above level of radial styloid process
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gives attachment to ulnar collateral ligament of wrist joint.
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Groove on dorsal surface lodges tendon of extensor carpi ulnaris.
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Posterior surface gives attachment to extensor retinaculum.
THANKS