1. INTRODUCTION TO ANATOMY (3)
أ.د.عبد الجبار الحبيطي
30/12/2016

2. Compartment of The Arm
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).

7. 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.

24. 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.

26. The Sensory Nerve supply of the Arm
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 Humerus.
4-Posterior cutaneous nerve of Arm from Radial nerve as it descends through the Axilla.

28. The Sensory Nerve Supply to The Forearm
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.

29. Note: The anterior compartment contains the followings:
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.

40. 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.

43. The Posterior Compartment of The Arm
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.

48. 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.

65. The Intermuscular Spaces
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.

69. 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 ).

70. The Cubital Fossa
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 & fascia.

87. 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 laterally.
3-Medial cutaneous nerve of F.A medially.
4-Bicepital Aponeurosis .
5-Some superficial lymphatic vessels & lymph nodes.

88. 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.

89. THE BRACHIAL ARTERY
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).

99. 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 epicondyle.

100. 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.

101. THE RADIAL NERVE
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.

102. THE MEDIAN NERVE
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.

124. WITH MY BEST REGARDS