Sheet no. 9

THE FOREARM

*Forearm is divided into 2 compartments by 2 intermuscular septi

ANTERIOR COMPARTMENT
(flexor pronator compartment)

- Most originated from medial epicondyle of humerous
- All enervated by median nerve except one and half by ulnar nerve.
- All flex the wrist except (pronator teres)
- Arranged in three layer.

&&& First layer (Superficial layer) ( consist of 4 muscles):*

1. Pronator teres: ( named according to action+shape)
- Nerve supply: median nerve
- Action: pronation of forearm

2. Palmaris longus :
- Nerve supply: median nerve
- Action: flexion of wrist.

3. Flexor Carpi Radialis : ( carpi = comes to carpals)

- Nerve supply: median nerve
- Action: flexion and abduction of wrist

4. Flexor Carpi Ulnaris :
- Nerve supply: ulnar nerve
- Action: flexion and adduction
- Insertion: pisiform bone.

&&& Second layer (intermediate layer):

1. Flexor Digitorum superficialis:

- Origin: medial epicondyle of humerous
- Insertion: it divides into 4 tendons , to the medial 4 fingers , where it insert into middle phalanx of these fingers
- Action: flex the middle phalanx in the medial 4 fingers.
- Nerve supply: median nerve.

&&& Third layer (deep layer):

1. Flexor digitorum profundus :

Note: this is the muscle which you use while typing, writing, painting , …..

- Insertion: it divides into 4 tendons to insert to the destal phalanx of medial 4 fingers.
- Action: flex the destal phalanx of the medial 4 fingers.
Note: the finger names (from medial to lateral) is
[little, ring, middle, index, thumb]
- Nerve supply: little and ring are supplied by ulnar nerve . middle and index are supplied by median nerve]

2. Flexor Pollicic longus : ( pollicies = to the thumb )

Note: the thumb is considered to be the half of the hand!!
- Insertion: Destal phalanx of the thumb
- Nerve supply: median nerve.
- Action: flex the destal end of thumbs


3. Pronator quadratus :

- It binds the destal end of Radius and Ulna.
- Nerve supply : median nerve.
- Action : Assist in pronation.

$$$ Little Note : Carpal bones consist of 2 rows proximal which is concave and distal which is convex.


** Flexor Retinaculum** :

- It is a thickened deep fascia between carpal bones forming a tunnel to traverse 9 tendons + 1 nerve:
9 tendons: 4 tendons from flexor digitorum superficialis
4 tendons from flexot digitorum profundus
1 tendon from flexor pollicis longus.

1 nerve: median nerve.

- Excessive work make this bridge to be thickened and tense , when it tense it will compress the underlying structures ( specially the median nerve ) , so you will lose feeling in that area !!!!

$$$ Good Notes:

* Median nerve is lateral to palmaris longus muscle.
* Radial artery is lateral to flexor carpi radialis
* Ulnar artery is lateral to flexor carpi ulnaris.
…………………………………………………………………..
POSTERIOR COMPARTMENT OF FOREARM
(extensor supinator compartment)

- There is 1 supinator only.
- All supplied by radial nerve (father of the extensors!)
- Most originated from lateral epicondyl of humerous (C.E.O)
- All extend the wrist and fingers.
- All supplied by Ulnar artery.
- consist of 2 layers.


&&& First layer : Superficial layer ( consist of 6 muscles)

1. Brachioradialis :
- Origin: Brachium.
- Insertion: styloid process of radius.
- Nerve supply: radial nerve.
- Action: Restore the midprone position of forearm.

2. Extensor carpi radialis longus :

- Insertion: 2 metacarpal bones.
- Origin: Humerous.
- Nerve supply: radial nerve.
- Action: extend the wrist.

3. Extensor carpi radialis brevis (brevis = short)

- Nerve supply: radial nerve.
- Action: extend the wrist.

4. Extensor digitorum (includes superficial+profundus)

- Nerve supply: radial nerve.
- Origin: lateral epicondyl of humerous.
- Insertion: by dividing into 4 tendons to medial 4 fingers this muscle insert into (middle + destal) phalanx of these fingers.
- when this muscle reaches the proximal phalanx it will flattened forminf a bird shape which has 1 central + 2 wings . (the central is short reaching the middle phalanx , and to 2 wings is long reaching destal phalanx )
- Action: extend the 4 fingers + wrist.

5. Extensor digiti minimi (to little finger)
6. Extensor carpi ulnaris..



7abb ahde hade el sheet la kol ahel 3'azzeh el 9am9'een wla kol el shohada2 …wla kol 97abe, 59o9an:

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Best wishes…
3bdelra7man 3attili…

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