For medical undergraduates, nursing and physiotherapy students

1. FOREARM

2. OBJECTIVES
1. Muscles of forearm
2. Vessels of forearm
3. Nerves of forearm
4. Clinical Correlation of structures in forearm

3. INTRODUCTION
• Antebrachial fascia – Deep fascia of forearm
• Attached to
1. Olecranon process
2. Posterior subcutaneous border of Ulna
• Flexor retinaculum
• Extensor retinaculum

6. COMPARTMENTS
• Anterior compartment
• Posterior compartment

7. ANTERIOR
COMPARTMENT

8. BOUNDARIES
 Floor :
• Anterior surface of Radius
• Anterior and Medial surface of Ulna.
• Inter-osseous membrane between them.
 Medially : Olecranon process and Posterior
border of Ulna.
 Laterally : Anterior border of Radius.

11. CONTENTS
 Eight muscles:
• Five : Superficial
• Three : Deep
 Two arteries : Radial and Ulnar
 Three nerves : Median, Ulnar and Radial.

12. SUPERFICIAL MUSCLES
 Five in number.
1. Pronator Teres
2. Flexor Carpi Radialis
3. Palmaris Longus
4. Flexor Digitorum Superficialis
5. Flexor Carpi Ulnaris

13. PRONATOR
TERES

14.  Origin :
• Humeral head :
1. Lower part of Medial Supracondylar ridge of
Humerus
2. Anterior and Lower part of Medial Epicondyle
of Humerus
• Ulnar head :
• Medial border of the Coronoid process of Ulna
 Insertion :
 As a Flat tendon on Middle of Lateral surface of
the shaft of Radius.

16.  Nerve supply : Median nerve
 Action :
1. Pronation of Forearm
2. Weak Flexor of Elbow joint.

17. FLEXOR CARPI
RADIALIS

18.  Origin :
1. From Medial Epicondyle of Humerus as
Common Flexor origin.
2. From Ante-brachial Fascia and adjacent Fascial
Septa.
 Insertion :
• Palmer surface of Bases of the second and third
Metacarpal bones.

20.  Nerve supply : Median nerve
 Action :
1. Flexor of Wrist joint.
2. Abduction of Wrist joint along with Extensor
carpi Radialis Longus and Brevis.

21. PALMARIS
LONGUS

22.  Origin :
• Medial Epicondyle of Humerus from Common
Flexor origin
 Insertion :
• Forms a long slender tendon passes over the
Flexor retinaculum and becomes continuous
with Central Part of Palmar Aponeurosis.
 Nerve supply : Median nerve
 Action : Weak Flexor of Wrist joint.

24. FLEXOR CARPI
ULNARIS

26.  Origin :
• Humeral head : Medial Epicondyle from
Common Flexor Origin
• Ulnar head :
• Medial margin of Olecranon process
• Upper 2/3rd of Posterior border of Ulna.
 Insertion : Pisiform bone and to Hook of Hamate
and Base of 5th metacarpal bone through Piso-
hamate and Piso-metacarpal ligaments
respectively.

27.  Nerve supply : Ulnar nerve
 Action :
• Flexor of Wrist joint
• Adduction of Wrist joint along with Extensor
Carpi Ulnaris.

28. FLEXOR
DIGITORUM
SUPERFICIALIS

29.  Origin :
• Humero-ulnar head :
• Medial Epicondyle from Common Flexor
origin
• From Anterior Band of Ulnar Collateral
Ligament
• From Medial margin of Coronoid process of
Ulna
• Radial head : From Whole Length of Anterior
Oblique Line of Radius.

32. ULNAR COLLATERAL
LIGAMENT

33. • Insertion :
• Above the wrist, the Fleshy Fibres form Four
Tendons for the Medial Four Fingers.
• The tendons are arranged in Superficial and
Deep strata, pass beneath Flexor retinaculum.
• Later they diverge on reaching palm.
• They Split at the Base of Proximal Phalanx.
• Finally insert on the Sides of Middle Phalanx.

34. • Nerve supply : Median nerve.
• Action :
• Flexion at Proximal inter-phalangeal joints
• Flexion at Meta-Carpo-phalangeal and Wrist
joints.

35. DEEP MUSCLES
 Three in number.
1. Pronator Quadratus
2. Flexor Digitorum Profundus
3. Flexor Policis Longus

36. PRONATOR
QUADRATUS

39.  Origin : From a Bony ridge on the Antero-medial
surface of the Lower 1/4th of the Ulna.
 Insertion :
• Superficial Fibres : Lower 1/4th of Anterior
surface and Anterior border of Radius.
• Deep Fibres : Triangular area above the Ulnar
notch.

40.  Nerve supply : Anterior Interosseus Nerve
 Action :
 Superficial fibres : Principal Pronator the
forearm
 Deep fibres : Binds Lower ends of Radius and
Ulna.

41. FLEXOR
DIGITORUM
PROFUNDUS

43.  Origin :
• Upper 3/4th of the Anterior and Medial surface
of the Shaft of Ulna.
• Upper 3/4th of Posterior border of Ulna.
• Medial surface of Olecranon and Coronoid
processes of Ulna.
• Adjoining part of Anterior surface of Inter-
osseous membrane.

44.  Insertion :
• Forms Four Tendons for Medial four digits
passing Deep to Flexor Retinaculum and insert on
Base of Distal Phalanx after piercing the tendon
of FDS opposite the Base of Proximal Phalanx.
 Nerve supply :
• Medial half : Ulnar Nerve
• Lateral half : Anterior Inter-osseous Nerve.
 Action :
• Flexion of Distal Inter-phalangeal joints after
• Flexion at Meta-carpo-phalangeal and Wrist
joints.

45. FLEXOR POLLICIS
LONGUS

47.  Origin :
• Upper 3/4th of Anterior surface of the shaft of
Radius
• Adjoining part of Anterior surface of inter-
osseous membrane
• Insertion :
• Palmar surface of Base of Distal phalanx of
Thumb after passing Deep to Flexor
Retinaculum.

48.  Nerve supply: Anterior Inter-osseous nerve
 Action :
• Flexes Distal Inter-phalangeal joint of Thumb.

49. POSTERIOR
COMPARTMENT

50. BOUNDARIES
 Floor –
• Posterior surfaces of radius and ulna
• Intervening Inter-osseous membrane
 Medially –
• Subcutaneous border of Ulna

51. CONTENTS
 Twelve muscles:
• Seven : Superficial
• Five : Deep
 Main artery :
 Anterior Interosseous artery (Medial)
 Posterior Interosseous artery (Radial)
 Main nerve : Posterior Interosseous br. of Radial
nerve.

52. COMMON EXTENSOR ORIGIN
• Front of the Lower part of Lateral epicondyle
of Humerus

53. Muscles – Superficial set
• Lateral group :
1. Brachioradialis
2. Extensor Carpii Radialis Longus
3. Extensor Carpii Radialis Brevis
• Posterior group :
1. Extensor Digitorum
2. Extensor Digiti Minimi
3. Extensor Carpii Ulnaris
4. Anconeus

54. BRACHIORADIALIS
 Origin :
• Upper 2/3rd of Lateral supra-condylar ridge
• Lateral inter-muscular septa
 Insertion :
• Base of Styloid process of radius
 Nerve supply: Radial nerve above the
elbow

55. BRACHIORADIALIS
 Action :
• Flexor of elbow
• Acts best in mid-prone position
• It is not a pronator or supinator of
forearm.

57. EXTENSOR CARPII RADIALIS
LONGUS
 Origin :
• Lower 1/3rd of Lateral supra-condylar ridge
• Lateral inter-muscular septa
 Insertion :
• Dorsal surface of Base of second
metacarpal bone

60. EXTENSOR CARPII RADIALIS BREVIS
 Origin :
• Common Extensor origin
• Radial Collateral ligament of elbow
 Insertion :
• Dorsal surface of Base of second & third
metacarpal bone

65. EXTENSOR CARPII RADIALIS
LONGUS & BREVIS
 Nerve supply :
• ECRL – Radial nerve above elbow
• ECRB - Posterior Inter-osseous nerve
(Deep branch of radial nerve.
• Action :
• Along with ECU - Extension of wrist joint
• Along with ECR - Abductors of wrist joint

66. EXTENSOR DIGITORUM
 Origin : Common Extensor origin
 Insertion : In middle of forearm, Belly divides
into four tendons for Medial four fingers.
 Each tendon covers the dorsal surface of
metacarpal bone and proximal phalanx and
forms a triangular Dorsal Digital Expansion.

68. DORSAL DIGITAL EXPANSION
 Three Oblique Inter-tendinous bands
(Vincula)
 Base of Dorsal Digital Expansion – forms a
hood over head of metacarpal
 Each Basal angle – Deep Transverse ligament
 A fibro-areolar ribbon – connects the hood
with the base of proximal phalanx

69. DORSAL DIGITAL EXPANSION
• Apex of expansion –
• Margins of expansion - thickened
• Wing tendons – proximal and distal
• Nerve supply : Posterior Inter-osseous
(deep branch) of Radial nerve.
• Action : Prime extensors of MC-P and I-P
joints.

72. EXTENSOR CARPII ULNARIS
 Origin :
 Common extensor origin
 From subcutaneous posterior border of
Ulna by an aponeurosis in common with
origin of Flexor carpi ulnaris.
 Insertion :
 Tubercle on the medial side of the base of
fifth metacarpal bone.

74. EXTENSOR CARPII ULNARIS ….
 Nerve supply : Posterior Inter-osseous
nerve
 Action :
1. Extension of wrist joint
2. Adduction of wrist joint

75. EXTENSOR DIGITI MINIMI
 Origin : Common extensor origin
 The tendon accompanies the medial side
of common extensor tendon for little
finger
 Insertion : Joins dorsal digital expansion of
little finger from medial side

77. EXTENSOR DIGITI MINIMI
 Nerve supply : Posterior inter-osseous
nerve
 Action :
• Extension of little finger
• Assists the action of Extensor digitorum

78. ANCONEUS – TRIANGULAR MUSCLE
 Origin : Posterior surface of Lateral
epicondyle
 Insertion : Broad base
• Upper fibres - Lateral surface of olecranon
process
 Lower fibres - Upper 1/4th of posterior
surface of shaft of Ulna

80. ANCONEUS
 Nerve supply – a branch of Radial nerve
given within spiral groove (through the
nerve to medial head of triceps).
 Action :
• Extensor of elbow joint
• Upper horizontal fibres – Help abduction
of ulna during pronation of forearm

81. Muscles – Deep set
1. Supinator
2. Abductor Pollicis Longus
3. Extensor Pollicis Longus
4. Extensor Pollicis Brevis
5. Extensor Indicis

82. SUPINATOR
• Origin :
• Superficial fibres –
1. Lateral epicondyle
2. Annular ligament
3. Radial collateral ligament
• Deep fibres –
1. Supinator crest of ulna
2. Depressed triangular area of bone in front of crest

83. SUPINATOR
• Insertion :
• Superficial fibres – (pass down and forwards) - Upper
1/3rd of Anterior part of Lateral surface of Radius
above the Anterior oblique line.
• Deep fibres – (pass horizontally) - Posterior, Anterior
and Lateral surface of Proximal 1/3rd of Radius.

84. SUPINATOR
• Nerve supply :
• Posterior Inter-osseous nerve before it passes
between the two strata of muscle.
• Action :
1. Supinator in extended elbow
2. Fixes the forearm in supination

88. ABDUCTOR POLLICIS LONGUS
• Origin :
• Posterior surface of Radius (Middle 1/3rd )
• Posterior surface of ulna
• Intervening Inter-osseous membrane
• Insertion :
• Radial side of the base of the first Metacarpal bone.

90. ABDUCTOR POLLICIS LONGUS
• Nerve supply : Posterior Inter-osseous nerve
• Action :
1. Abductor of thumb
2. Extensor of thumb

91. EXTENSOR POLLICIS LONGUS
• Origin :
• Posterior surface of shaft of Ulna below Abductor
Pollicis Longus
• Adjacent Inter-osseous membrane
• Insertion :
• Lodges in a groove Medial to the Dorsal tubercle of
radius, changes direction and inserts into
• Dorsal surface of the base of distal phalanx of the
thumb.

93. EXTENSOR POLLICIS LONGUS
• Nerve supply : Posterior Inter-osseous nerve
• Action : Extends Distal Phalanx of the thumb

94. EXTENSOR POLLICIS BREVIS
• Origin :
• Posterior surface of Radius below the Abductor Pollicis
Longus
• Adjacent Inter-osseous membrane
• Insertion :
• Lies medial to and closely follows the course of
Abductor Pollicis Longus.
• Lodge in a groove on lateral side and inserts
• Dorsal surface of the base of proximal phalanx of
thumb.

95. EXTENSOR POLLICIS BREVIS
• Nerve supply : Posterior Inter-osseous nerve
• Action : Extends the Proximal Phalanx of Thumb

97. EXTENSOR INDICIS
• Origin :
• Posterior surface of Ulna distal to Extensor
Pollicis Longus
• Adjacent Inter-osseous membrane
 Insertion :
• It joins with Index tendon of Extensor Digitorum
on its ulnar side
• Enters in formation of Dorsal Digital Expansion of
Index finger, on the Head of 2nd Metacarpal.

98. EXTENSOR INDICIS
 Nerve supply : Posterior Inter-osseous nerve
 Action : Extends Index finger

100. ANATOMICAL SNUFF BOX
 It is a triangular depression on radial side
of the wrist and becomes visible when the
thumb is fully extended.
 Contents :
• Radial artery lies across its floor

101. BOUNDARIES - ANATOMICAL SNUFF BOX
• Laterally : Tendons of Abductor Pollicis Longus
and Extensor Pollicis Brevis
• Medially : Extensor Pollicis Longus
• Roof : Skin, Fascia, Cephalic vein and Superficial
branch of Radial nerve
• Floor : Styloid process of radius, scaphoid,
trapezium and the base of first metacarpal.

104. EXTENSOR RETINACULUM
• It is an oblique fibrous band derived from deep
fascia and stretches across the dorsal surface of
the wrist to retain the extensor tendons in
position.

105. ATTACHMENTS
• Laterally : Anterior border of Radius above its
Styloid process
• Medially : Pisiform and Triquetral bone.
• It is not attached to Ulna.

106. COMPARTMENTS
• Septa arising from Deep surface of Extensor
retinaculum to the radius and meta carpals.
• Six Osseo-fascial compartments for nine tendons are
formed.
• From Lateral to Medial :

107. EXTENSOR RETINACULUM

109. CLINICAL CORRELATION
• Hammer thumb – rupture of tendon due to
avascular necrosis due to occlusion of vessels in
Colles’s fracture.
• Unopposed action of Flexor pollicis longus.

110. SPACE OF PARONA
Fascial lined potential
space deep to the long flexor
tendons of Forearm where
the proximal parts of
synovial sheaths of the flexor
tendons of the hand extend.

111. BOUNDARIES
 In front : FDP and FPL (along with synivial
sheaths)
 Behind : PQ and Inter-osseous membrane
 Above : Oblique origin of FDS
 On each side : Outer and inner borders of
forearm.

112. RADIALARTERY

113. RELATIONS
 Anteriorly :
1. Brachio-radialis in upper part
2. Skin, Superficial and Deep fascia in lower half.
 Posteriorly :
• Anterior surface of radius and muscles attached to
it.
 Medially :
1. Pronator Teres in upper part
2. FCR in lower part
 Laterally : Brachio-radialis in whole extent.

114. BRANCHES
1. Radial Recurrent artery
2. Muscular branches
3. Palmar carpal branch
4. Dorsal carpal branch
5. Superficial palmar branch

115. ULNAR ARTERY

116. RELATIONS
 Anteriorly :
• Upper part – covered by muscles arising form
Common Flexor origin & Median nerve
• Lower part – covered only by Skin and Fascia.
 Posteriorly :
• Brachialis and Flexor Digitorum Profundus
 Medially : Flexor Carpi Ulnaris and Ulnar
nerve
 Laterally : Flexor Digitorum Superficialis

117. BRANCHES
1. Anterior and Posterior Ulnar Recurrent artery
2. Common Inter-osseous artery
3. Muscular branches
4. Palmar and Dorsal Carpal branches

118. NERVES

119. CLINICAL CORRELATION
1. Accumulation of pus in the space of Parona

120. THANK YOU