Download ULNA BONE:

ULNA BONE
LEARNING OBJECTIVES
1. Students should able to:
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Recognize the bone.
Determine side of bone.
Identify the features of bone.
Identify the muscles attached to bone.
Identify clinical significance of bone.
DETERMINATION OF SIDE
1. Strong Upper end.
2. Has hook-like projection (trochlear notch), concavity of which faces forward.
3. Lower end has small head.
4. Thin sharp crest like interosseous border of shaft lies laterally.
5. Styloid process projects downwards from posteriomedial aspect of head.
PARTS OF BONE
1. Upper end
2. Shaft.
3. Lower end.
FEATURES OF UPPER END
1. Two processes
• Olecranon .
• Coronoid.
2. Two articular notches
• Trochear.
• Radial.
•
OLECRANON PROCESS
1. Bent forwards, forming beak like projection.
2. Occupies the olecranon fossa of humerus when elbow is extended.
3. Posses 6 surfaces.
1. Anterior surface, form upper part of trochlear notch, covered by articular
cartilage.
2. Posterior surface, subcutaneous, forms point of elbow.
3. Lateral surface, anconeous is inserted.
4. Medial surface ,origin of flexor digitorium profundus&flexor carpi
ulnaris,&attachment of ulnar collateral ligament.
5. Superior surface,attachment of capsular ligament, insertion of triceps
brachii.
6. Inferior suface.
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CORONOID PROCESS:
Possess 4 surfaces.
o Anterior surface triangular.Bears tuberosity of ulna,gives insertion to
brachialis .
o Lateral surface has radial notch of ulna articulates with side of
head,below notch hollow part ,below hollow part,supinator crest gives
orgin to supinator.
o Medial surface, origin of flexor digitorium profundus
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Two borders.
o Medial border is sharp, bears tubercle gives attachment to flexor
digitorium superficialis & ulnar collateral ligament, below tubercle origin
of Pronator teres
o Lateral border gives origin to ulnar head of flexor pollicis longus .
TROCHLEAR NOTCH
The Semilunar Notch (incisura semilunaris; greater sigmoid cavity
1. Articulates with trochlea of humerus.
2. Formed by anterior surface of olecranon process & upper surface of coronoid
process.
RADIAL NOTCH
The Radial Notch (incisura radialis; lesser sigmoid cavity).—
1. Oval depression on lateral surface of coronoid process.
2. Articulates with head of radius
3. 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.
Its lower part is rounded, smooth
Has three borders and three surfaces.
BORDERS
1. The volar border (margo volaris; anterior border) .
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This border separates the volar from the medial surface.
Prominent. begins above at the medial angle of the coronoid process
ends below in front of the styloid process
upper part, well-defined
its middle portion, smooth and rounded
give origin to the Flexor digitorum profundus
its lower fourth serves for the origin of the Pronator quadratus
2. The interosseous crest (crista interossea; external or interosseous border
 Sharp crest like lateral border of bone.
 Upper part is continuous with supinator crest.
 Interosseous membrane is attached to it, except at upper part.
3. Dorsal border (margo dorsalis; posterior border )
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Begins at posterior aspect of olecranon.
Subcutaneous throughout its extent.
Ends at back of styloid process.
gives attachment to an aponeurosis in upper 3\4
Apponeurosis affords a common origin to the:
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Flexor carpi ulnaris,
the Extensor carpi ulnaris
Flexor digitorum profundus
lower fourth is smooth and rounded
SURFACES:
1.The volar surface (facies volaris; anterior surface)
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Lies between anterior and interosseous borders.
Nutrient foramen directed upwards.
nutrient artery is a branch of anterior interrosseous artery.
its upper three-fourths gives origin to the Flexor digitorum profundus
Lower 1\4 has Pronator quardatus origin
2. Medial surface
 Covex.
 Lies between anterior &posterior borders.
 Flexor digitorum profundus from upper 3\4
MUSCLES ATTACHMENT ON THE ANTERIOR SURFACE OF ULNA
BRACHIALIS
SUPINATOR
FLEXOR DIGITORUM SUPERFICIALIS
FLEXOR DIGITORUM PROFUNDUS
3. Posterior surface
 Lies between posterior & interosseous borders.
 Has oblique line at its upper part.
 Below the oblique line,surface is divided into a larger medial &narrower lateral
part by a vertical ridge.
 Lateral is adjoining the interosseous border while the medial area is adjoining the
posterior border.
 Lateral area gives origin to
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Abductor pollicis longus from upper 1\4.
Extensor pollicis longus from 2\4.
Extensor indicis from 3\4.
Anconeous is inserted above oblique line.
5.
MUSCLES ATTACHMENT ON THE POSTERIOR SURFACE OF ULNA
LOWER END
 PARTS.
1. Head.
2. Styloid process.
HEAD
 Has smooth ,convex articular surface on lateral part for articulation with ulnar notch
of radius.
 Inferior surface is separated from carpal bones by articular disc of inferior
radioulnar joint, attached by its apex to the area between articular surface & styloid
process.
 Anterior & posterior margins of head give attachment to capsular ligamentsof wrist
joint
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STYLOID PROCESS
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Short , rounded process projects from posterio-medial aspect of lower end of ulna.
Its tip lies 1.25 cm above the level of styloid process of radius .
gives attachment to ulnar collateral ligament of wrist joint.
Between the styloid process & head on dorsal surface is a groove which lodges
tendon of extensor carpi ulnaris.
5. Posterior surface gives attachment to extensor retinaculum.
6.