Sheet no . 11

Posterior compartment of forearm:

The muscles of this compartment are divided into 2 layers: - superficial layer.
- deep layer.

The muscles of Superficial layer of posterior compartment of forearm:
1-Brachioradialis
2-Extensor carpi radialis longus
3-Extensor carpi radialis brevis
4-Extensor digitorum
5-Extensor digiti minimi
6-Extensor carpi ulnaris
7-Anconeus

The muscles of Deep layer of posterior compartment of forearm:
1-Abductor pollicis longus
2-Extensor pollicis brevis
3-Extensor pollicis longus
4-Extensor indicis
5-Supinator


Abductor pollicis longus

Named according to action
Nerve supply: Radial nerve
Action: abduct the thumb

Extensor pollicis brevis

Nerve supply: radial nerve
Ins: Proximal phalanx of the thumb
Action: extend proximal phalanx of thumb

Extensor pollicis longus

Nerve supply: radial nerve
Ins: Distal phalanx of thumb
Action: extend distal phalanx of thumb (full extension of thumb)

*** there are 3 muscles for the thumb(F.P.L/E.P.L/E.P.B) and that’s why it can move in all directions.

Extensor Indicis

Nerve supply: radial nerve
Ins: extensor expansion of index
Action: full extension of index

Supinator

Winds (i.e. wraps) around proximal quarter of radius forming 1.5 circle.
Passing through it is the deep branch of radial nerve that will continue as posterior Interosseous nerve.
Ins: neck,shaft of radius.

*** the radial nerve divides into 2 parts: superficial branch and deep branch that then becomes posterior Interosseous nerve.

***If the muscles of the posterior compartment of forearm are paralyzed we will have "wrist drop", where the hand is pulled only by flexors and extension cannot be done.


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Hand

The skeleton of hand is formed by metacarpals(5) and phalanges(14).
Has the following layers:
Palmer skin:
thick and full with sweat glands. The places where bends (18-81) are called skin crease, which are proximal and distal.
Superficial fascia:
contains large amount of fat within pockets to protect our hands from thorns, needles…
Deep fascia:
it is thickened to form a triangular part called palmer aponeurosis to protect underlying structures

muscles
Muscles of the hand
small muscles of the hand are arranged into 5 groups
The groups are:

1.Thenar muscles:3 in #
At base of thumb
(FAO):
-Flexor pollicis brevis
-Abductor pollicis brevis
-Opponens pollicis
Nerve supply: median nerve

2.Hypothenar muscles:3 in #
To little finger
(FAO):
-Flexor digitiminimi
-Abductor digitiminimi
-Opponens digitiminimi
Nerve supply: Ulnar nerve


3.Lumbrical muscles:4 in #
Named from lat. To med.
lumbrical :worm-like
Origin: flexor digitorum profundus
Ins: Extensor expansion of med. 4 fingers.
Nerve supply:
-2,3 digit>>>median nerve
-4,5 digit>>>ulnar nerve
Action: (writing position)
- flex MCPJS
-extend IPJS

4.Palmar Interossei:3 in #

named from lat. To med.
Nerve supply: ulnar nerve
Action: adduct medial 4 fingers(towards axial line)

5. Dorsal Interossei: 4 in #

named from lat. To med.
Nerve supply: deep ulnar branch
Action: abduct medial 4 fingers(away from axial line)
***N.B: due to the lateral muscles (adduction- group 4) and medial muscles (abduction- group 5) on the axis, or middle finger, it is centralized


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Arteries of forearm:

The brachial artery, ends at opposite neck of radius and divides into 2 arteries:

Radial artery: smaller branch/lateral

Ulnar artery: larger branch/ medial


Radial artery
It is the lateral smaller branch of brachial artery
Upon reaching the wrist it divides into
superficial branch
deep branch: It is the one located within the floor of the snuff box

***The snuff box:
A space between 3 tendons:
-2 tendons lateral ( abductor pollicis longus + extensor pollicis brevis).
-1 tendon medial (extensor pollicis longus).
It contains deep branch of radial artery
Its base is formed by scaphoid bone


Ulnar artery:
It’s the medial larger branch of brachial artery
It gives a branch called common interosseous artery which divides into
anterior interosseous artery to the anterior compartment
posterior interosseous artery to the posterior compartment
The proper Ulnar artery continues until it reaches the wrist at the pisiform where it divides into superficial branch + deep branch
Superficial palmar arch:
Contributed mainly from superficial ulnar artery and minimally from superficial radial artery.
Deep palmar arch:
Contributed mainly from deep radial artery and minimally from deep ulnar artery.

***N.B: Both arches are important for supplying the palm and finger.

*** N.B: the index is moved by 4 tendons(two flexors/two extensors).

***N.B: median nerve innervates 5 muscles only in hand (all thenar muscles+first,second lumbricals)

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Special thanks to all my friends:
Mohammad 3awad, Muhanad rsheidat, Zaydoon 5raisat, 3abood , Rami ya3’i, omar abu baker. Mohammad al wazeer, mohammad abu haneya, waseem samara…. All of the rest.