Flexor Forearm pdf - د. نوفل الحديثي

The forearm

Flexor compartment

OBJECTIVES

…



To list muscles of the anterior compartment of

the forearm



To describe the course of main arteries in the

region



To follow the main nerves in the region with

their branches



To relate to some clinical states

The forearm is divided into anterior (flexor) & posterior (extensor)

compartments by:

1- Medial intermuscular septum

2- Lateral intermuscular septum (very short)

3- Interosseoue membrane

Interosseoue membrane:

- A

strong

fibrous

membrane

attaching

the

interosseous borders of the forearm bones to each

other

- Its fibers are directed downward & medially

transmitting force from radius to ulna (then to

humerus & scapula)

- Gives attachment to some muscles in the forearm

- It is considered as a fibrous joint (middle RU joint)

Cutaneous innervation:

Lymphatics of the forearm:

Deep lymphatics:

Accompany arteries

Drain to the axillary nodes

Superficial lymphatics:

-Accompany superficial veins

-Those with cephalic vein drain to

the

deltopectoral (infraclavicular)

nodes

-Those with basilic vein drain to the

supratrochlear

nodes

Superficial Layer:

Pronator teres

Flexor carpi radialis

Palmaris longus

Flexor carpi ulnaris

Intermediate layer

Flexor digitorum superficialis

Deep layer:

Flexor pollicis longus

Flexor digitorum profundus

Pronator quadratus

The common flexor tendon:

• The front of the medial condyle of humerus

• Gives attachment to the superficial layer of anterior forearm

muscles

Muscle

Common

origin

Additional

origin

Insertion

Innervation

Action

Pronator

teres

Common

flexor

tendon

Coronoid

process

Lateral surface &

mid-shaft of radius

Median

nerve

[C6,C7]

• Elbow flexor

• Pronator of RUJ

Flexor

carpi

radialis

Base of

metacarpals II and

III

• Wrist flexor

• Abductor

Palmaris

longus

Palmar

aponeurosis

Anchors skin of the

hand

Flexor

carpi

ulnaris

Posterior

border of

ulna

Base of metacarpal

Ulnar nerve

[C7,C8, T1]

• Elbow flexor

• Wrist flexor

• Adductor

Muscles of the superficial layer:

Flexor digitorum superficialis:

Origin:

- Common flexor tendon

- Oblique line of radius

Insertion:

Bifid tendon in the middle

phalanges of medial 4 fingers

Innervation:

Median nerve (C8 & T1)

Action:

Flexion of the wrist, MPJ & PIPJ

of the medial 4 fingers

Muscle

Origin

Insertion

Innervation

Function

Flexor

digitorum

profundus

•

Anterior surface of ulna

•

Interosseous membrane

Distal phalanges

of the medial four

fingers

C8 & T1

•

Lateral ½: median n.

•

Medial ½: ulnar n.

Flexor of the

wrist, MPJm PIPJ

& DIPJ

Flexor

pollicis

longus

•

Anterior surface of radius

•

Inter-osseous membrane

Distal phalanx of

thumb

Anterior interosseous n.

[C7,C8]

Flexor of IPJ of

the thumb

Pronator

quadratus

Anterior surface of ulna

(distal part)

Anterior surface

of radius (distal

part)

•

Pronator

•

Opposes the

bones to each

other

Muscles of the deep layer:

Pronation

Is the movement by which the radius rotates at the RU joints around

the ulna

Pronator teres & quadratus assist each other in doing this movement

Pronation

Supination

Vessels of the forearm:

Radial artery:

-Originates from the brachial artery at

the neck of the radius

- Lies deep to the brachioradialis muscle

in the proximal forearm

-In the distal forearm, it lies between

brachioradialis & FCR

-The radial pulse can be felt by gently

palpating the radial artery against the

underlying muscle and bone.

-The radial artery leaves the forearm,

passes around the lateral side of the

wrist

Radial pulse

-Branches:

Radial recurrent artery; enters the

anastomosis around the elbow joint

Muscular

Palmar carpal branch

Superficial palmar branch enters the

hand

Ulnar artery:

-The ulnar artery is larger than the

radial artery

-Passes deep to the pronator teres

muscle

- In the distal forearm it remains

under flexor carpi ulnaris tendon,

and is therefore not easily palpable

-The ulnar artery leaves the forearm,

& enters the hand by passing lateral

to the pisiform bone

Branches:

Anterior & posterior ulnar recurrent

branches to the elbow anastomosis

Muscular arteries

Common interosseous artery which

divides into anterior and posterior

interosseous arteries

The anterior interosseous artery

passes on the interosseous membrane

and supplies muscles of the deep

compartment of the forearm with the

bones of the forearm

Nerves:

Median nerve:

-Leaves the cubital fossa by passing between

the two heads of the pronator teres

-Passes deep to flexor digitorum superficialis

-Just proximal to the wrist, it becomes between

the tendons of the FCR & FDS muscles

-Enters the hand by passing deep to the flexor

retinaculum

Branches:

The anterior interosseous nerve;

which innervates the muscles in the

deep layer & terminates as articular

branches to joints of the distal

forearm and wrist

Palmar branch; originates from the

median nerve just proximal to the

flexor

retinaculum

passes

superficially

into

the

hand

and

innervates the skin over the base and

central palm (spared in CTS)

Branches to the forearm muscles

except FCU & medial

½ of FDP

Ulnar nerve:

-In the forearm it lies under the flexor

carpi ulnaris

- The ulnar artery is lateral to the ulnar

nerve in the distal two-thirds of the

forearm, and both the ulnar artery and

nerve enter the hand by passing

superficial to the flexor retinaculum and

immediately lateral to the pisiform bone

Branches:

 Muscular to FCU & medial

½ of FDP

 Cutaneous branches to the medial

aspect of the hand & fingers