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Quadrangular space
The quadrangular space provides a passageway for nerves and vessels passing between the axilla and the
more posterior scapular and deltoid regions. When viewed from anteriorly, its boundaries are formed by:
 inferior margin of the subscapularis muscle;
 surgical neck of the humerus;
 superior margin of the teres major muscle; and
 lateral margin of the long head of the triceps brachii muscle.
Passing through the quadrangular space are the axillary nerve and the posterior circumflex humeral artery
and vein.
Triangular interval [Lateral triangular space]
This triangular interval is formed by:
 lateral margin of the long head of the triceps brachii muscle;
 shaft of the humerus; and
 inferior margin of the teres major muscle.
The radial nerve passes out of the axilla traveling through this interval to reach the posterior compartment of
the arm. The profunda brachii artery (deep artery of arm) and associated veins also passthrough the triangular
interval.
Axillary artery
 first part is proximal to pectoralis minor; medial part of pectoralis minor & lateral part of first rib
 second part is posterior to pectoralis minor;
 third part is distal to pectoralis minor;from lateral part of pectoralis minor to inferior border of teres minor.
 Generally, six branches arise from the axillary artery:
 1 branch, the superior thoracic artery, originates from the first part;
 2 branches, the thoraco-acromial artery and the lateral thoracic artery, originate from the second part;
 3 branches, the subscapular artery, the anterior circumflex humeral artery, and the posterior circumflex
humeral artery, originate from the third part.
Axillary vein
Plexus Brachialis
Branches of the lateral cord
1) The lateral pectoral nerve
2) The musculocutaneous nerve
3) The lateral root of median nerve
Branches of the medial cord
1) The medial pectoral nerve
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2) The medial cutaneous nerve of arm (medial brachial cutaneous nerve)
3) The medial cutaneous nerve of forearm (medial antebrachial cutaneous nerve)
4) The ulnar nerve.
5) The median nerve
The musculocutaneous nerve, the lateral root of the median nerve, the median nerve, the medial
root of the median nerve, and the ulnar nerve form an M over the third part of the axillary artery. This
feature, together with penetration of the coracobrachialis muscle by the musculocutaneous nerve, can be used to
identify components of the brachial plexus in the axilla.
Branches of the posterior cord
1) Superior subscapular nerve
2) Thoracodorsal nerve
3) Inferior subscapular nerve
4) Axillary nerve
5) Radial nerve
SHOULDER
SUPERFICIAL POSTERIOR AXIOAPPENDICULAR (EXTRINSIC SHOULDER) MUSCLES
The superficial axioappendicular muscles are the trapezius and latissimus dorsi.
DEEP POSTERIOR AXIOAPPENDICULAR (EXTRINSIC SHOULDER) MUSCLES
The deep posterior thoracoappendicular muscles are the levator scapulae and rhomboids.
SCAPULOHUMERAL (INSTRINSIC SHOULDER) MUSCLES
The six scapulohumeral muscles (deltoid, teres major, supraspinatus, infraspinatus, subscapularis, and
teres minor).
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ARM
The anterior compartment of the arm contains three muscles-coracobrachialis, brachialis, and biceps
brachii muscles-which are innervated predominantly by the musculocutaneous nerve.
The only muscle of the posterior compartment of the arm is the triceps brachii muscle. The triceps brachii
muscle has three heads:
 long head originates from the infraglenoid tubercle of the scapula;
 medial & lateral heads originate from the extensive area on the posterior surface of the shaft of the humerus
inferior to the radial groove.
Brachial artery
Terminates just distal to the elbow joint, opposite to the neck of the radius where it divides into the
radial and ulnar arteries.
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Branches of the brachial artery in the arm include those to adjacent muscles and two ulnar collateral
vessels (superior and inferior ulnar collateral arteries), which contribute to a network of arteries around the
elbow joint. Additional branches are the profunda brachii artery and nutrient arteries to the humerus,
which pass through a foramen in the anteromedial surface of the humeral shaft.
Veins
Two sets of veins of the arm, superficial and deep, anastomose freely with each other. The superficial
veins are in the subcutaneous tissue, and the deep veins accompany the arteries. Both sets of veins have valves,
but they are more numerous in the deep veins than in the superficial veins.The two main superficial veins of the
arm, the cephalic and basilic veins.
Nerves
Four main nerves pass through the arm: median, ulnar, musculocutaneous, and radial.
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ANTERIOR ASPECT OF THE FOREARM
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CUBITAL FOSSA
Muscles in the anterior (flexor) compartment of the forearm occur in three layers:
 Superficial layer (pronator teres, flexor carpi radialis, palmaris longus, and flexor carpi ulnaris)
 Intermediate layer (flexor digitorum superficialis)
 Deep layer (flexor digitorum profundus, flexor pollicis longus, and pronator quadratus)
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Arteries
The main arteries of the forearm are the ulnar and radial arteries, which usually arise opposite the neck of the
radius in the inferior part of the cubital fossa as terminal branches of the brachial artery.
Radial artery
When the brachioradialis is pulled laterally, the entire length of the artery is visible.
Branches of the radial artery originating in the forearm include:
1) radial recurrent artery, which contributes to an anastomotic network around the elbow joint
2) small palmar carpal branch
3) superficial palmar branch enters the hand by passing through, or superficial to, the thenar muscles at the
base of the thumb, which anastomoses with the superficial palmar arch formed by the ulnar artery.
Ulnar artery
The ulnar artery is larger than the radial artery and passes down the medial side of the forearm.
Branches of the ulnar artery that arise in the forearm include:
1) ulnar recurrent artery with anterior and posterior branches, which contribute to an anastomotic network
of vessels around the elbow joint (The anterior and posterior ulnar recurrent arteries anastomose with the
inferior and superior ulnar collateral arteries, respectively, thereby participating in the periarticular arterial
anastomoses of the elbow)
2) numerous muscular arteries, which supply surrounding muscles
3) common interosseous artery, which divides into anterior and posterior interosseous arteries
4) two small carpal arteries (dorsal carpal branch and palmar carpal branch)
Ner v es
Nerves in the anterior compartment of the forearm are the median and ulnar nerves, and the superficial
branch of the radial nerve.
CUBITAL FOSSA
The contents of the cubital fossa are the:
 Terminal part of the brachial artery and the commencement of its terminal branches, the radial and ulnar
arteries. The brachial artery lies between the biceps tendon and the median nerve.
 (Deep) accompanying veins of the arteries
 Biceps brachii tendon
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 Median nerve
 Radial nerve
POSTERIOR ASPECT OF THE FOREARM
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ANATOMY OF THE HAND
Superficial layer
The seven muscles in the superficial layer are the brachioradialis, extensor carpi radialis longus, extensor
carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, and anconeus.
Deep layer
The deep layer of the posterior compartment of the forearm consists of five muscles: supinator,
abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis.
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Arteries
The blood supply to the posterior compartment of the forearm occurs predominantly through branches of
the radial, posterior interosseous, and anterior interosseous arteries.
Nerves
Radial nerve
The nerve of the posterior compartment of the forearm is the radial nerve.
HAND
Muscles
The intrinsic muscles of the hand are the palmaris brevis, interossei, adductor pollicis, thenar,
hypothenar, and lumbrical muscles.
Thenar muscles
The three thenar muscles (opponens pollicis, flexor pollicis brevis, and abductor pollicis brevis muscles) are
associated with opposition of the thumb to the fingers and with delicate movements of the thumb and are
responsible for the prominent swelling (thenar eminence) on the lateral side of the palm at the base of the
thumb.
Hypothenar muscles
The hypothenar muscles (opponens digiti minimi, abductor digiti minimi, and flexor digiti minimi brevis
contribute to the swelling (hypothenar eminence) on the medial side of the palm at the base of the little finger.
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Arteries and veins
The blood supply to the hand is by the radial and ulnar arteries, which form two interconnected vascular
arches (superficial and deep) in the palm. Vessels to the digits, muscles, and joints originate from the two arches
and the parent arteries.
Ulnar artery and superficial palmar arch
The ulnar artery and ulnar nerve enter the hand on the medial side of the wrist. Distally, the ulnar artery
swings laterally across the palm, forming the superficial palmar arch, which is superficial to the long flexor
tendons of the digits and just deep to the palmar aponeurosis. One branch of the ulnar artery in the hand is the
deep palmar branch.
Radial artery and deep palmar arch
The radial artery curves around the lateral side of the wrist, passes over the floor of the anatomical snuffbox
and into the deep plane of the palm by penetrating anteriorly through the back of the hand. It accesses the deep
plane of the palm and forms the deep palmar arch.
Superficial palmar arch
Deep palmar arch
Nerves
Ulnar nerve
The ulnar nerve ends at the distal border of the flexor retinaculum by dividing into superficial (mainly sensory)
and deep (mainly motor) branches.
Median nerve
The median nerve enters the hand by passing through the carpal tunnel and divides into a recurrent
branch and palmar digital branches.
Superficial branch of the radial nerve
The only part of the radial nerve that enters the hand is the superficial branch.
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PECTORAL REGION & MAMMARY GLANDS
MUSCLES OF THE PECTORAL REGION
Four anterior axioappendicular muscles (thoracoappendicular or pectoral muscles) move the pectoral
girdle: pectoralis major, pectoralis minor, subclavius, and serratus anterior.
SUPERFICIAL GROUP OF BACK MUSCLES
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Trapezius
Latissimus dorsi
Rhomboid major
Rhomboid minor
Levator scapulae
INTERMEDIATE GROUP OF BACK MUSCLES
The serratus posterior superior lies deep to the rhomboids, and the serratus posterior inferior lies
deep to the latissimus dorsi.