Flexor compartment of forearm

1. The Flexor Compartment Of
Forearm

2. Neurovascular Pattern of Forearm
 3 nerves supply of the forearm and each nerve passes between 2 heads of
muscle
 Nerve supply of the flexor compartment
The median nerve passes between the 2 heads of pronator teres.
The ulnar nerve passes between the 2 heads of flexor carpi ulnaris.
 Nerve supply of the extensor compartment
The posterior interosseous nerve (a branch from the radial nerve)
passes between the 2 layers of the supinator.
 The arterial supply of the forearm comes from the common interosseous
branch of the ulnar artery .This divides into the anterior and posterior
interosseous arteries.
 The anterior (from the median nerve) and posterior (from the radial nerve)
interosseous nerves remain in their own compartment and supply muscles,
They do not reach skin.

3. Superficial group
 Common origin from
medial epicondyle of
the humerus.
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris

4. Pronator Teres
 Origin by two heads
Superficial head: Medial
epicondyle.
Deep Head : Coronoid process of
ulna
 Insertion: middle of lateral side
of shaft of radius.
 Innervated by median nerve.
 Action: Pronates and flexes
forearm.
Note :
 Median nerve lies between its
two heads and the ulnar
artery passes deep to the
deep head
 It forms medial border of
cubital fossa.

5. Flexor Carpi Radialis
 Origin: medial
epicondyle of humerus.
 Insertion: Bases of
second and third
metacarpals.
 Innervated by median
nerve.
 Action:
Flexor and radial
abductor of wrist.
Flexes the elbow.

6. Palmaris longus
 Origin: Medial Epicondyle of
humerus.
 Inserted into the flexor retinaculum
and the palmar aponeurosis
 Innervated by median nerve.
 Action: Weak flexor of wrist.
 Degenerating muscle absent in 13%
of arms.(cf. the plantaris in leg)
 The palmar aponeurosis represents
the distal part of the tendon of
Palmaris longus.

7. Flexor Carpi Ulnaris
 Origin:
Humeral head –Medial Epicondyle
Ulnar head (medial border of
olecranon and posterior border)
 Inserted into the pisiform and by
the pisohamate and
pisometacarpal ligaments to the
base of fifth metacarpal.
 Nerve Supply: Ulnar nerve
(C7,C8,T1)
 Action: Flexor and adductor of
wrist .
 Note: The pisiform is a
sesamoid bone in the tendon
of this muscle.
 Ulnar nerve passes between
two heads of this muscle.

8. Flexor Digitorum
Superficialis
 Origin:
medial epicondyle of humerus,
sublime tubercle on medial border of
coronoid process
oblique line of radius
 The tendons run in two layers going into
the carpal tunnel: tendons to digits 3
and 4 lie superior, tendons to digits 2 and
5 lie inferior
 After the flexor retinaculum, the tendons
lie side-by side.
 Inserts into the middle phalanges and
flexes the proximal interphalangeal joints
 Innervated by median nerve
 Action:
Flexor of proximal interphalangeal
joints,metacarpophalangeal and wrist
joints.
Flexor of elbow and wrist
Note: the median nerve runs deep to this
muscle.

9. Flexor Digitorum Profundus
Origin:
From the upper ¾ of the anterior surface of
the shaft of the ulna and adjoining
part of the interosseus membrane.
Insertion:The muscle divides into 4 tendons
which pierce the tendons of the flexor
digitorum superficialis and are inserted
into the bases of the distal phalanges of
the medial 4 fingers.
Nerve Supply:
Its lateral half: from the anterior interosseus
nerve (branch of the median nerve)
It medial half: from the ulnar nerve.
Action:
1. Flexion of the distal interphalangeal
joints of the medial 4 fingers.
2. Helps in flexion of the proximal
interphalangeal joints and
metacarpophalangeal joints of the
medial 4 fingers.
3. Helps of flexion of the hand at the
wrist joint.

10. Flexor Digitorum Profundus
Note:
• It has a dual nerve supply so a
composite or hybrid muscle
(medial half ulnar nerve and lateral
half by anterior interosseous
nerve.)
• The tendons give origin to the
lumbricals in the palm.
• The tendons of flexor digitorum
profundus with the tendons of
flexor digitorum superficialis are
enclosed in a common synovial
sheath i.e. the ulnar bursa
passing deep to the flexor
retinaculum.
• Vincula longa and brevia are
synovial folds connecting the long
flexor tendons to phalanges and
transmitting vessels.

11. Pronator Quadratus
• Arises from anterior
surface of distal ulna.
• Inserted into anterior
surface of distal radius.
• Innervated by anterior
interosseous nerve
• Action: Pronates the
forearm and helps to hold
lower ends of radius and
ulna together, especially
when hand is weight
bearing.

12. Flexor Pollicis Longus
 Origin
From the anterior surface of the
middle of the shaft of the
radius and adjoining part of
the interosseus membrane.
 Insertion:
Into the palmar surface of the base
of the distal phalanx of the
thumb.
 Nerve Supply:
From the anterior interosseus nerve
(branch of the median nerve).
 Action:
Flexion of the thumb.

13. Radial artery
Smaller lateral branch of brachial artery in cubital
fossa.
Runs through the anatomical snuffbox on the
surface of scaphoid and trapezium
enters palm by passing between two heads of first
dorsal interosseous muscle
divides into princeps pollicis and deep palmar
branch.
Radial recurrent artery
Superficial palmar branch
Anastomoses with superficial branch of ulnar artery
to complete the superficial palmar arterial arch.
Princeps pollicis artery
Divides into two proper digital arteries for each side
of thumb.
Radialis indicis artery
Deep palmar Arch
Is formed by main termination of radial artery and is
usually completed by deep palmar branch of ulnar
artery.

14. Ulnar artery
 Larger medial branch of brachial artery in the
cubital fossa.
 It passes between the arch formed by the radial
and ulnar attachment of the flexor digitorum
superficialis and descends through the anterior
compartment
 Enters the hand superficial to flexor retinaculum.
Anterior ulnar recurrent artery
Posterior ulnar recurrent artery
common interosseous artery further divides into
The anterior interosseous artery has:
 a median branch (following the nerve), nutrient
arteries to the radius and ulna, muscular
branches, an anterior communicating and terminal
branches.
 It pierces the interosseous membrane at the upper
border of pronator quadratus to enter the extensor
compartment.
The posterior interosseous artery has:
 Interosseous recurrent and terminal branches
 Muscular branches
 Anastomoses with dorsal carpal branch of anterior
interosseous artery.
 Superficial palmar arterial arch
Is the main termination of the ulnar artery, usually
completed by the superficial palmar branch of
radial artery.

15. The Median Nerve
 In the cubital fossa, it runs on
the medial side of the brachial
artery.
 It descends between the 2 head
of pronator teres and runs
between flexor digitorum
superficialis and profundus.
 It lower part, emerges from the
lateral side of the flexor
digitorum superficialis and
becomes superficial (or covered
by palmaris longus tendon).
 It enters the hand deep to the
flexor retinaculum.

16. Median Nerve-Branches
1. Muscular branches: to
pronator teres, flexor carpi
radialis, palmaris longus and
flexor digitorum superficialis.
2. Articular branches: to the
elbow joint.
3. Anterior interosseus nerve.
4. Palmar cutaneous branches:
passes superficial to the flexor
retinaculum and supplies skin
of the lateral 2/3 of the palm.
5. Enters the palm of hand
through the carpal tunnel ,
gives off a muscular branch
(recurrent branch )to the
thenar muscles and
terminates by dividing into
three common palmar digital
nerves.

17. Median Nerve
Ape Hand deformity
Injury to median nerve is cause
due to supracondylar fracture of
humerus or by compression in the
carpal tunnel.
It results in loss of pronation,
opposion of thumb, flexion of
lateral two interphalangeal joints.
The thumb is adducted and
laterally rotated.
It produces characteristic
flattening of thenar eminence
referred to as Ape thumb.
The median nerve enables the
hand to grip as it supplies most of
thenar muscles. So it is called
Labourer’s nerve.

18. Anterior interosseus nerve
Origin: from the median nerve as it emerges
between the 2 heads of the pronator
teres.
It descends on the interosseus membrane
(with the anterior interosseus artery)
between the flexor pollicis longus and
flexor digitorum profundus.
Terminates the nerve ends on the anterior
surface of the carpal bones.
Branches
1. Muscular branches to flexor
pollicis longus, pronator
quadratus and the lateral half of
flexor digitorum profundus.
2. Articular branches to wrist,
inferior radio-ulnar and
intercarpal joints.

19. Ulnar nerve
• Passes behind medial
epicondyle.
• Enters anterior compartment
of forearm by passing
between two heads of flexor
carpi ulnaris.
• Runs on medial side of ulnar
artery .
• In between Flexor carpi ulnaris
and Flexor digitorum
superficialis
• Enters hand superficial to
flexor retinaculum

20. Ulnar Nerve 1. Muscular branches: to flexor
carpi ulnaris and medial half
of flexor digitorum
profundus muscles.
2. Articular branches: to the
elbow joint.
3. Palmar cutaneous branches:
passes superficial to the
flexor retinaculum and
supplies skin of the medial
1/3 of the palm.
4. Dorsal cutaneous branches:
it supplies the skin of the
medial 1/3 of the dorsal
surface of the hand and the
dorsal surface of the medial
1.5 fingers (except nail
beds).

21. Ulnar Nerve Injury
• Injury to ulnar nerve at elbow caused by a
fracture dislocation of elbow results in a
Claw Hand in which ring and little fingers
are hyperextended at metacarpophalangeal
joints and flexed at interphalangeal joints.
• It results in loss of abduction and adduction
of fingers and flexion of
metacarpophalangeal joints (due to
paralysis of palmar and dorsal interossei
and medial two lumbricals)
• It produces a wasted hypothenar eminence
and loss of adduction of thumb.
• Injury to ulnar nerve at wrist due to
superficial cuts or injuries at wrist causes
paralysis of hypothenar muscles, all
interossei, adductor pollicis and medial two
lumbricals. The ulnar claw hand is more
marked than at the level of elbow, since
flexor digitorum profundus is spared.
• The ulnar nerve is responsible for intricate
movements of the hand as it supplies most
of the small intrinsic muscles of hand. So it
is called Musician’s nerve.