Download ANATOMY OF THE FOREARM

2015-2016
ANATOMY OF THE
FOREARM
The forearm is the
structure and distal
region of the upper limb,
between the elbow and
the wrist.
The forearm is covered by
skin, the anterior
surface usually being
less hairy than the
posterior surface.
The forearm contains two
long bones, the radius
and the ulna, forming
the radio-ulnar joint.
The interosseous
membrane connects
these bones.
THE SKIN-SENSORY NERVE SUPPLY
FROM the anterior and posterior
branches of the lateral cut.n.of
the forearm,A continuation of the
musculocutaneous n.
FR0M the anterior and posterior
branches of the medial
cut.branches of the forearm.
ANARROW strip of the skin down the
middle of the posterior surface is
supplied by the posterior cut.n. of
the fore arm.
THE SKIN –SUPERFICIAL VEINS
The superficial veins lies in the
superficial fascia .
THE CEPHALIC VEIN arises from the
lateral side of the dorsal venous
arch on the back of the hand and
winds around the lateral border of
the forearm .
It ascend into the cubital fossa and
up the front of the arm on the
lateral side of the biceps .
It terminate in the axillary vein.
As it ascend up ,it receives a
variable numbers of tributaries
from the lateral and posterior
surfaces of the limb.
THE SKIN –SUPERFICIAL VEINS
THE MEDIAN
CUBITAL VEIN
a branch of the
cephalic vein in the
cubital fossa, run
ward and medially
and joins the basilic
vein.
THE SKIN –SUPERFICIAL VEINS
The basilic vein arise from the
medial side of the dorsal
venous arch on the back of the
hand and winds around the
medial border of the forearm.
It ascend into the cubital fossa
and up the front of the arm on
the medial side of the biceps .
It terminate by joining the venae
comitantes of the brachial
artery to form the axillary
vein.
As it ascend up ,it receives a
variable numbers of tributaries
from the lateral and posterior
surfaces of the limb.
THE SUPERFICIAL LYMPHATIC VESSELS
From the thumb and lateral fingers and
lateral areas of the hand and forearm
follow the cephalic vein to the infraclavicular group of nodes.
Those from the medial fingers and
medial areas of the hand and forearm
follow the basilic vein to the cubital
fossa .
Here ,some drain into the
supratrochlear L.N.
other to the lateral group of the
axillary nodes .The efferant vessels
from the supratrochlear node also
drain into the lateral group of the
axillary nodes
FASCIAL COMPARTMENT OF THE FOREARM
The forearm is enclosed in a
sheath of deep fascia which
is attached to the
periosteum of the posterior
subcutaneous border of the
ulna.
This fascial sheath together
with the interosseous
membrane and fibrous
intermuscular septa divides
up the forearm into a
number of compartments
each having its own
muscles,nerves and blood
supply.
IN CROSS-SECTION THE FOREARM CAN BE
DIVIDED INTO TWO FASCIAL COMPARTMENTS.
The posterior
compartment contains
the extensors of the
hands, which are
supplied by the radial
nerve.
The anterior
compartment contains
the flexors, and is
mainly supplied by the
median nerve.
The ulnar nerve also runs
the length of the
forearm
The interosseous membrane of the forearm
(rarely middle or intermediate radioulnar
joint)
is a fibrous sheet that connects the radius
and the ulna. It is the main part of the
radio-ulnar syndesmosis, a fibrous joint
between the two bones.
The interosseus membrane divides the
forearm into anterior and posterior
compartments, serves as a site of
attachment for muscles of the forearm,
and transfers forces from the radius, to
the ulna, to the humerus.
As the forearm moves from Pronation to
Supination the Interosseous membrane
fibres change from a relaxed state, then
become tense in the neutral position and
then once again become relaxed as the
forearm enters Supination.
Radius
 head
 neck
 radial tuberosity
 styloid process
Ulna
 coronoid process
 olecranon process
 ulnar tuberosity
 slyloid process
Interosseous Membrane
CONTENTS OF THE ANTERIOR
FASCIAL COMPARTMENT
Muscles in the Anterior
Compartment of the
Forearm are split into
three categories:
Superficial
Intermediate
Deep
A
SUPERFICIAL COMPARTMENT
The superficial muscles
in the anterior
compartment are the
flexor carpi ulnaris,
palmaris longus,
flexor carpi radialis
and pronator teres.
They all originate from
a common tendon,
which arises from the
medial epicondyle of
the humerus
FLEXOR CARPI ULNARIS
Attachments: Originates from the
medial epicondyle with the other
superficial flexors. It also has a
long origin from the ulna which
springs from the medial aspect
of the olecranon process of the
ulna and the posterior border of
the ulna .
It passes into the wrist, and
attaches to the pisiform carpal
bone.
Actions: Flexion and adduction at
the wrist.
Innervation: Ulnar nerve.
PALMARIS LONGUS
This muscle is absent is
about 15% of the
population.
Attachments: Originates
from the medial
epicondyle, attaches to
the flexor retinaculum
of the wrist.
Actions: Flexion at the
wrist.
Innervation: Median
nerve.
FLEXOR CARPI RADIALIS
Attachments:
Originates from the
medial epicondyle.
Insertion: attaches to
the base of
metacarpals II and
III.
Actions: Flexion and
abduction at the
wrist.
Innervation: Median
nerve.
PRONATOR TERES
The lateral border of the
pronator teres forms the
medial border of the cubital
fossa, an anatomical triangle
located over the elbow.
Attachments: It has two
origins, one from the medial
epicondyle, and the other
from medial border of the
coronoid process of the ulna.
It attaches laterally to the
mid-shaft of the radius.
Actions: Pronation of the
forearm.
Innervation: Median nerve.
THE SUPERFICIAL MUSCLES OF THE ANTERIOR FOREARM.
INTERMEDIATE COMPARTMENT
It can sometimes be classed as a
superficial muscle, but in most
cadavers it lies between the deep
and superficial muscle layers.
The muscle is a good anatomical
landmark in the forearm – the median
nerve and ulnar artery pass between
its two heads, and then travel
posteriorly.
Attachments: It has two heads – one
originates from the medial
epicondyle of the humerus, the other
from the radius from oblique lineon
the anterior surface of the radial
shaft.
Insertion:The muscle splits into four
tendons at the wrist, which travel
through the carpal tunnel behind
the flexor retinaculum, and attache
to the middle phalanges of the four
fingers.
On reaching the proximal phalandes
each tendon split into two slips
,these two then unite and the
tendon finally divideds again into
two slips which are inserted into
the sides of the middle phalanx
.the corresponding tendon of the
flexor digitorum profundus pass
through the division of each
superficialis tendon and is inserted
into the base of the distal phalanx.
Actions: Flexes the
metacarpophalangeal joints and
proximal interphalangeal joints at
the 4 fingers, and flexes at the
wrist.
Innervation: Median nerve.