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‫أ‪.‬د‪.‬عبد الجبار الحبيطي‬
The arm is surrounded by deep fascia which
sends 2 septae attaching to medial & lateral
compartments,an anterior ( B.B.C muscles
which are flexors at the Elbow joint),these Ms
are Biceps brachi,Brachialis &
Coracobrachialis.The posterior compartment
is an Extensor compartment at the Elbow
joint mainly Triceps M & lower down a small
M (Anconeus M ).
The anterior compartment Ms are innervated
by Musculocutaneous N ( from lateral cord).
The Biceps takes origin from 2 sites,long head
from supraglenoid tubercle of the scapula,while
the short head takes origin from coracoid
process of scapula in common origin with the
Coracobrachialis muscle,then the 2 head leads to
a common belly of the muscle before going to
insert ( by a single tendon) into the radial
tubercle of the radius bone.Biceps is a powerfull
supinater of the forearm in addition to flexion at
the Elbow joint.
The Brachialis M takes origin from the anterior
surface of the lower part of the shaft of the
humerus& its insertion into the front(anterior
surface) of Coronoid process of the Ulna bone.It
is a flexor at Elbow joint along with the Biceps M.
The Coracobrachialis M takes origin from the
Coracoid process of the Scapula in common with
the short head of Biceps M& is being inserted on
the medial aspect of upper part of the shaft of
the humerus.
Note: As the tendon of Biceps passes through
the front of Elbow(Cubital fossa) in its way to its
insertion site,it sends a flat ribbon like
aponeurosis medially & superficially to cover the
terminal part of the brachial A+ the Median nerve
known as Bicepital Aponeurosis.
The three B.B.C muscles are supplied by
musculocutaneous nerve ( from lateral cord ).It
is motor to the 3 Ms & sensory to the skin on the
lateral side of the F.A,where after supplying
motor to the 3 Ms of anterior compartment of
Arm,it will continue as lateral cutaneous nerve to
the forearm.
1-Medial cutaneous nerve of Arm from the
Medial cord of the Brachial Plexus.
2-Upper lateral cutaneous of of Arm from
the Axillary nerve.
3-Lower lateral cutaneous nerve of Arm from
the Radial nervewhile runnibg in the spiral (
Radial ) groove on the back of the shaft of the
4-Posterior cutaneous nerve of Arm from
Radial nerve as it descends through the
1-Medial cutaneous of F.A from the medial
cord of the Brachial plexus.
2-Lateral cutaneous of F.A from
Musculocutaneous nerve.
3-Posterior cutaneous of F.A from the Radial
nerve as it runs in the spiral groove.
Note: The anterior compartment contains the
1-The 3 Ms i.e B.B.C .
2-The Brachial Artery.
3-Three nerves i.e the Musculocutaneous
,Median & Ulnar nerves.
The Musculocutaneous nerve motor
component is only to the 3 Ms of the anterior
compartment ,while both the Median & Ulnar
are not supplying any structure in the
Arm,these 2 nerves just passing through the
anterior compartment to reach their areas of
destination( supply) in the F.A & the Palm of
the Hand.
The Ulnar nerve runs in the anterior
compartment,then inters the medial
intermuscular septa( leave the arm ) to reach the
F.A by passing behind the medial Epicondyle of
the humerus( i.e bypassing the cubital
fossa),then it passes through the 2 heads of
origin of flexor carpi ulnaris M of the F.A.
The Median nerve is formed on the anterolateral
aspect of the beginning of the brachial A,then it
becomes on the lateral side of the upper third of
the Brachial A,then crossing obliquely in front of
the middle third of the A ( from lateral to medial )
to becomes on the medial side of the lower third
of the Brachial A& then both the terminal part of
the Brachial A + the Median nerve are sheltered
by Bicepital aponeurosis within the Cubital fossa.
It contains mainly the Triceps M + the Radial
nerve & Profunda Brachi A ,and just inferiorly
near the back of the Elbow joint, there is a
small superficially placed slightly triangular
muscle known as Anconeus.
Triceps origin : The long head from
infraglenoid tubercle of the scapula,the .The
lateral head from posterior aspect of the shaft
of the Humerus above the spiral groove,while
the Medial head takes origin from the back of
the humerus below the spiral groove &
slightly from the medial side of the Humerus.
Thus the spiral groove separates the lateral
head from the medial head of the Triceps.The
muscle fibers of the 3 heads of origin
converge inferiorly into a single tendon which
is inserted into the top of the Olecranon
process of the Ulna bone.The M is supplied
by many branches from the Radial nerve at
different levels& it is a powerfull Extensor
muscle at the Elbow joint.
There are 2 main Triangular spaces, a superior
horizontal one between teres minor ( above ),
teres major ( below )& the Surgical neck of the
Humerus laterally.This space is divided by the
long head of Triceps into a smaller triangular
space medially ( between teres minor,teres major
& long head of Triceps)which transmits the
Circumflex scapular branch of the Subscapular
artery & a lateral Quadriangular space bounded
by teres minor above,teres major below,long
head of Triceps mediall and the Surgical neck of
the Humerus laterally.This Quadriangular space
transmits the Axillart nerve & posterior
circumflex humeral A.The Axillary nerve as it
passes through this space ,it divides into anterior
& posterior divisions.
The anterior division supplies the major part of
the Deltoid M,while the posterior division
supplies teres minor,the remaining part of the
Deltoid and then continues as upper lateral
cutaneous nerve of the Arm ( i.e supplies the skin
on the upper lateral part of Deltoid.
The inferior vertical Triangular space between
teres major ( above ),long head of Triceps (
medially ) & the side of the Humerus.It transmits
the Radial nerve & Profunda Brachi A (a branch
from the Brachial A ).
Is a triangular depressed space in front of the
Elbow joint.It is bounded by the Pronater
teres medially,brachioradialis laterally,its
base is formed by an imaginary line joining
the 2 epicondyles of the humerus&its apex is
formed as brachiradialis M crosses over the
pronater teres .The floor is formed by the
insertion of Brachialis M & the supinater M
below it,while its roof is formed by the skin &
The contents includes 2 groups as follows:
A-The superficial contents are :
1-Median cubital vein joining the Cephalic &
Basilic veins.
2-Lateral cutaneous nerve of the F.A
3-Medial cutaneous nerve of F.A medially.
4-Bicepital Aponeurosis .
5-Some superficial lymphatic vessels & lymph
B-Deep group of structures includes :
 1-The termination of the Brachial A & its
bifurcation into Radial and Ulnar As.
 2-The Median nerve just medial to the
terminal part of the Brachial A.
 3-Tendon of Biceps Brachi in its way to reach
its insertion site.
 4-Radial nerve laterally emerging in the
groove between Brachialis & Brachioradialis.
Is the direct continuity of the Axillary artery at
the lower border of Teres major M ,it runs in
the anterior compartment of the Arm & ends
opposite the Neck of the Radius bone ( in the
cubital fossa ) by dividing into Ulnar & Radial
As.It gives the following branches:
1-Profunda brachi ( Deep brachial )which
goes to the Radial( spiral ) groove on the back
of the shaft of the humerus accompanies by
the Radial nerve ( after the Axilla).
The A divides into 3 smaller branches while
running in the spiral groove these
are,ascending branch to reach surgical neck
of humerus & share in the anastomosis there
with both anterior & posterior circumflex
humeral A from 3rd part of Axillary A,the
second one is middle collateral descends on
the back of the Arm to reach the back of
Elbow joint & the 3rd branch is the Radial
collateral ( considered the continuity of the
profunda brachi A.This branch accompanies
the Radial nerve into the front of lateral
2-Superior ulnar collateral A which
accompanies the Ulnar nerve into the medial
intermuscular septum.
3-Nutrient branch to the Humerus bone .
4-Muscular branches to supply B.B.C muscles
of anterior compartment of Arm.
5-Inferior ulnar collateral which arises just
above the cubital fossa& goes to the medial
intermuscular septum to join the Ulnar N.
Is the direct continuity of the posterior cord after
giving off its branches.In the Axilla it gives branches
to long head & medial head of Triceps M & posterior
cutaneous nerve of Arm. In the spiral groove it gives
4 branches 2 muscular ( many branches to medial &
lateral heads of triceps + Nerve to Anconeus M) &
other 2 branches as sensory these are lower lateral
cutaneous of Arm & posterior cutaneous of F.A.Then
the Radial N leaves the spiral groove & enters the
lateral intermuscular septum with the Radial collateral
A,then it leaves the septum to appear in the Cubital
fossa between Brachialis & Brachioradialis Ms ( gives
branches to both ),then it divides within the Cubital
fossa into Superficial (sensory) & deep branch (
motor).The deep branch will pierce supinator &
becomes posterior interosseous N.
Is formed by a contribution from both lateral & medial
cords of the Brachial plexus,then descends within the
anterior compartment of the Armin direct relation with the
Brachial A.It reaches the Cubital fossa just medial to the
terminal part of the Brachial A& becomes sheltered with
the A by the Bicepital aponeurosis&then the N leaves the
Cubital fossa by passing between the 2 heads of the
Pronater teres M.It supplies 4 Ms of the superficial group
of the flexor Ms of the F.A ( Pronater teres, Flexor carpi
radialis, Palmaris longus & Flexor digitorum superficialis)
directly& it supplies two & a half Ms of the deep Flexor
group indirectly( i.e via the anterior interosseous branch of
the Median N ) to the lateral half of Flexor digitorum
profundus ,Flexor pollicis longus & Pronater quadratus
Ms.Finally it leaves the F.A by passing deep to Flexor
Retinaculum to reach the Palm of the Hand.