The anatomy of the anterior compartment of the forearm

2. The anatomy of anterior compartment of
forearm
By:
Dr. Mehrdad Asgari
Ph.D of Anatomical Sciences, Department of Anatomy, School of Medicine, Guilan University of Medical
Sciences, Rasht, Iran
In The Name Of Allah

3. The front of the forearm
• Skin
• Superficial fascia
• Deep fascia

4. -Basilic vein
-Cephalic vein
-Accessory Cephalic vein
-Median antebrachial vein
Superficial fascia

6. Superficial fascia

7. he front of the forearm
• Deep fascia
• The forearm is enclosed in a sheath of deep fascia, which is attached to the
posterior border of the ulna .
• This fascial sheath, together with the interosseous membrane & fibrous
intermuscular septa,
• divides the forearm into several compartments, each having its own muscles,
nerves, and blood supply.

11. Anterior (flexor) compartment muscles
• Superficial group (origin at
medial epicondyle)
• Pronator teres (pronates forearm)
• Flexor carpi radialis (flexes and abducts
wrist)
• Palmaris longus (absent in some
individuals; tenses palmar aponeurosis)
• Flexor carpi ulnaris (flexes and adducts
wrist)
• Flexor digitorum superficialis (flexes
PIP joints via four tendons)

13. Superficial Flexors
• They arise - more or less-
from the common flexor
origin (front of medial
epicondyle).
• All are supplied by median
nerve except one, flexor
carpi ulnaris, FCU (ulnar
n.).
• All cross the wrist joint
except one, pronator teres,
(PT).

14. Pronator teres
• Origin:
- 1. humeral head: from medial epicondyle of the
humerus
- 2. ulnar head: from the medial margin of the
coronoid process
• Insertion:
Middle part of the lateral surface of the shaft of the
radius
• Nerve:
median
• Action:
- Pronation of the forearm at the radio-ulnar joints
- help to Flexion of the forearm at the elbow joint.
• Relations:
median nerve passes between the two heads and ulnar
artery is deep to both heads

15. Flexor carpi radialis
• Origin:
medial epicondyle of the humerus
• Insertion:
into palmar surface of the bases of the 2nd & 3rd
metacarpal bones
• Nerve:
median
• Action:
flexion & abduction of the hand at the wrist joint
• Relations:
in the lower part of forearm, radial artery lies between the
tendons of the brachioradialis and flexor carpi radialis

18. Palmaris longus
• Origin:
medial epicondyle of the humerus
• Insertion:
Into the palmar aponeurosis and flexor
retinaculum
• Nerve:
median
• Action:
- flexion of the hand at the wrist joint
- makes the palmar aponeurosis tense.
• Relations:
- 1. lies over the median nerve
- 2. passing superficial to flexor retinaculum

19. Flexor carpi ulnaris
• Origin:
- 1. humeral head:
medial epicondyle of the humerus
- 2. ulnar head:
- medial margin of olecranon process
- posterior border of ulna
• Insertion:
- pisiform bone
- pisohamate lig.
- pisometacarpal lig.
• Nerve:
ulnar
• Action:
flexion & adduction of the hand at the wrist joint
• Relations:
ulnar nerve passes between the two heads

20. Flexor digitorum superficialis
• Origin:
1. Humeroulnar head ;
- medial epicondyle
- medial border of coronoid process of the ulna
2. Radial head :
- anterior border of radius( ant. Oblique line)
3. Fibrous arch
- ulna to radius
• Insertion:
Its tendon divides into 4 tendons which are inserted into the middle
phalanges of the medial 4 fingers
• Nerve:
median
• Action:
- Flexion of the PIP, MP of the medial 4 fingers
- Helps of flexion of the hand at the wrist joint
• Relations:
median nerve and ulnar artery pass deep to this arch

22. Deep group
• Flexor digitorum profundus
(flexes at DIP joint)
• Flexor pollicis longus
(flexes thumb)
• Pronator quadratus
(pronates forearm)
Anterior (flexor) compartment muscles

23. Flexor digitorum profundus
• Origin:
- 1. upper ¾ of the ant. & med. Surface of ulna
- 2. upper ¾ of the post. Border of ulna
- 3. med. Surface of olecranon & coronoid process
- 4. adjoining part of ant. Surface 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:
- Its lateral half: from the anterior interosseus nerve (median nerve).
- Its medial half: from the ulnar nerve
• Action:
- Flexion of DIP of the medial 4 fingers
- Helps in flexion of the PIP, MP of the medial 4 fingers
- Helps of flexion of the hand at the wrist joint
- is the chief gripping

24. • Relations:
ant. Interosseus nerve and vessels descend
on the anterior surface of the interosseus
membran
between
 Flexor digitorum profundus
and Flexor pollicis longus

26. Flexor pollicis longus
• Origin:
- 1. upper ¾ of the ant. Surface of radius
- 2. adjoining part of ant. Surface of the interosseus
membrane
• Insertion:
The base of the distal phalanx of the thumb
• Nerve:
median (anterior Interosseus branch)
• Action:
flexion of the thumb
• Relations:
Simillar to previously

27. Pronator quadratus
• Origin:
on the lower ¼ of ant. Surface of ulna
• Insertion:
into the lower ¼ of ant. Surface of radius
• Nerve:
Median nerve (anterior Interosseus branch)
• Action:
pronator of forearm at the radio-ulnar joints.

29. Supination
and
pronation
It occurs in the superior and
inferior radioulnar joints;
(pivot synovial joint)
Muscles produce
supination
Biceps brachii.
Supinator.
Muscles produce
pronation
Pronator teres.
pronator quadratus.
NB. Brachioradialis put
the forearm in
midprone-supine
position.

31. Arterial Supply to the Forearm
• Radial artery
- It begins in the cubital fossa when the
brachial artery divides into the radial and
ulna artery.
- It passes distally, travels under the
brachioradialis, resting on the deep flexor
muscles.
- The artery briefly travels on the lateral
side of the radius, before travelling over the
anterior surface of the radius.
- The artery then winds around the lateral
aspect of the wrist, before entering the palm
of the hand to form the deep palmer arch.

32. RADIAL ARTERY
•Relations:
• Anterior:
• Brachioradialis & Skin and fascia.
• Posterior:
Tendon of biceps
 Supinator
Insertion of Pronator teres
 Flex. Dig.Sup.
 Flex. Poll. Lon.
 Pronator Quadratus
Radius.
• Medially:
• Pronator teres , Flex. Carpi Radialis
• Laterally:
• Brachioradialis , Superficial br. Radial
N.

33. RADIAL ARTERY
• 1- Radial Recurrent
• 2- Muscular
• 3- Palmar Carpal
• 4-Dorsal Carpal
• 5- Superficial Palmar

38. Arterial Supply to the Forearm
• Ulnar artery
- Larger than the radial artery.
- It passes between the arch formed by
the radial and ulnar attachment of
the flexor digitorum superficialis
- and descends through the anterior
compartment. It enters the palm of
the hand in front of the flexor
retinaculum,
- and promptly divides in superficial
and deep palmer branches.

39. •Relations:
• Anterior:
• Pronator teres,
Flex.Carp.Rad.,Palmaris
Long., Flex. Dig.Sup. ,
Flex.Carp.Ulnaris, Skin &
fascia, Palmar cutaneus br.
Ulnar N.
• Posterior:
• Flex. Digitorum Profundus
• Medially:
• Ulnar N. , Flex. Carpi Ulnaris
• Laterally:
• Flex. Digitorum Superficialis

40. ULNAR ARTERY
Branches:
1- Ant. Ulnar Recurrent
2- Post. Ulnar Recurrent
3- Common Interosseous
*Ant. Interosseous
- Nutrient branches for radius & ulna
- Median a.
*Post. Interosseous
- Recurrent Interosseous
4- Muscular
5- Palmar Carpal
6- Dorsal Carpal

43. • 3- Common Interosseous
• Ant. Interosseous
 Nutrient branches for radius & ulna
 Median a.
• Post. Interosseous
 Recurrent Interosseous

46. Dorsal Carpal branch

48. https://web.duke.edu/anatomy/lab11/lab1
2_prelab.html

50. Nerves 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:
- passes between the 2 layers of the
supinator
• - The posterior interosseous nerve (a
branch from the radial nerve)

51. 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.

53. Median Nerve-Branches
• 1. Muscular branches:
all the superficial muscles of the anterior
compartment except flexor carpi ulnaris
• 2. Articular branches: to the elbow
joint.
• 3. Anterior interosseus nerve.
Branches-
- Muscular branches: all the muscles of
deep flexion in the anterior compartment
except the medial part of digitorum
profundus.
- Articular branches: to the wrist joint,
the distal radioulnar joint, and the joints
of the carpus.

54. ian Nerve-Branches
• 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

56. Ulnar Nerve
• The ulnar nerve passes behind the medial
epicondyle and enters the forearm between the
two heads of flexor carpi ulnaris.
• It descends between the flexor carpi ulnaris and
the flexor digitorum profundus.
• The ulnar nerve becomes superficial at the wrist,
before entering the palm in front of the flexor
retinaculum.

57. Ulnar Nerve-Branches
• Muscular branches:
- flexor carpi ulnaris
- medial half of the flexor digitorum
profundus.
• Articular branches: to the elbow joint.
• Palmar cutaneous branch:
- passes superficial to the flexor retinaculum
- supplies skin of the medial 1/3 of the palm.
• Dorsal cutaneous branch:
- 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).