1. THE AXILLA (Arm pit )
أ.د.عبد الجبار الحبيطي

2. THE AXILLA (Arm pit )
Is a pyramidal space between the upper part of the arm & the lateral thoracic wall.It has 4 walls (anterior,posterior,medial & lateral ), apex & base.The apex is pointed upward in the direction of the root of the neck (to receive the brachial plexus) & communicates with the superior aperture ( Inlet of thorax) of thorax to receive the axillary artery ( continuity of subclavian artery).The apex is known as Cervico-axillary canal & has bony boundaries which are :

3. 1-The clavicle anteriorly.
2-Outer border of the first rib medially
3-Upper part of the scapula posteriorly
It allows the passage of the Neuro-vascular bundle( brachial plexus & Axillary artery) to the upper limb .

4. The base : Is formed by skin & superficial fascia of the axilla,it is concave when the limb is beside the trunk & becomes flat & straight on raising and abducting the limb due to suspensory ligament of the axilla.
The anterior wall is formed by the clavicle, 3 muscles ( pectoralis major & minor Ms in addition to the subclavius M ) and the Clavi-pectoral fascia

5. outer lip of the intertubercular groove Medial & lateral pectoral Ns
Muscle
Origin
Insertion
Nerve supply
Pectoralis Major
1-Side of sternum (sternal) 2-Medial 2 /3 of anterior Border of clavicle (Clavicular head)
outer lip of the intertubercular groove
Medial & lateral pectoral Ns
Pectoralis minor
from 3rd – 5th ribs Near their costal cartilages
Coracoid process of scapula
medial pectora
Subclavius
from costal cartilage of the first rib
subclavius groove on inferior surface of clavicle
N. to subclavius

6. The clavipectoral fascia: Is part of the deep fascia attached to the clavicle,it encloses the subclavius M,then descends down ward deep to pectoralis major & enclosing pectoralis minor M & ends as suspensory ligament of the axilla.It is pierced by the following structures:
1-Lateral pectoral nerve.
2-Cephalic vein .
3-Pectoral branch of thoracoacromial artery.
4-Some lymphatic vessels.

7. The lateral border of pectoralis major M forms the anterior fold of the axilla.
The posterior wall of the axilla is formed by 3 muscles, these are subscapularis, teres major & latissimus dorsi Ms.The posterior fold by latissimus dorsi & teres major Ms
Subscapularis takes origin from the subscapular fossa& inserts into the lesser tuberosity of the humerus.It is innervated by upper & lower subscapular nerves ( from post.cord ).
Teres major takes origin from posterior surface of lateral border of scapula near the inferior angle & is inserted in to the medial lip of intertubercular groove.It is innervated by the lower subscapular nerve .

8. Latissimus dorsi takes origin from the following sites:
A-Spines of T 7 __T 12 vertebrae.
B-Thoracolumbar fascia.
C-Iliac crest of the Hip bone.
D-Inferior angle of scapula

9. The muscle is inserted into the floor of intertubercular ( Bicepital0 groove & is innervated by the middle subscapular ( Thoracodorsal ) nerve.
The medial wall is formed by the upper ribs,their intercostal spaces& the upper part of serratus anterior muscle covering them,which arises from the outer surfaces of upper ribs& is inserted into the anterior aspect of the medial(vertebral ) border of the scapula.It is innervated by the long thoracic nerve( C 5—C 7).
The lateral wall is formed by the intertubercular ( Bicepital ) groove containing the corachobrachialis M & short head of Biceps..

10. The Contents of the Axilla
1-The axillary vessels: The axillary artery,starts as the continuity of the subclavian artery at the outer border of the first rib& ends at the lower border of teres major M( the lower limit of the axilla),where it continue as the Brachial artery.It is crossed by the pectoralis minor M ,which divides it into 3 parts.The first part between outer border of first rib & the upper border of pectoralis minor M( it gives a single branch known as highest thoracic or superior thoracic A ).The second part lies behind pectoralis minor M& is related to the 3 cords of the brachial plexus* laterally to lateral cord, medialy to medial cord & posteriorly to the posterior cord) ,while anteriorly it is related to pectoralis minor M.It gives 2 branches, the thoracoacromial & lateral thoracic .The thoracoacromial gives 4 branches ,2 of them to bones ( acromial & clavicular) & other 2 to muscles (Deltoid & pectoral branches).While the lateral thoracic branch descends to the side of the chest wall to accompany the long thoracic nerve within the substance of serratus anterior muscle..

11. The third part of the axillary artery extends from lower border of pectoralis minor to lower border of teres major muscle,where it continues as the Brachial artery,it is related to the derivatives of the 3 cords of the brachial plexus & it gives 3 branches these are subscapularis ( bifurcates into thoracodorsal & circumflex scapular branches ) ,anterior & posterior circumflex humeral arteries around the surgical neck of the humerus.

12. 2-The Brachial plexus:It is formed by the ventral rami of lower 4 cervical nerves & the ventral ramus of the first thoracic nerve.The first stage is roots arrangement to form trunks ( C 5& 6th form the upper trunk , C 7 alone forms the middle trunk,while C 8 & T 1 form the lower ( inferior ) trunk.

13. The second stage is the splitting of each trunk to form anterior & posterior divisions.
The third stage is the formation of the 3 cords by the Re-union of these divisions.The posterior divisions of the 3 trunks unite to form the posterior cord,the anterior division of the upper & middle trunks unite to fornm the lateral cord,while the anterior division of inferior trunk forms the medial cord of the brachial plexus.

14. The last stage is the derivatives of each cord as follows:
The posterior cord gives off:
1-Upper subscapular.
2-Middle subscapular ( Thoracodorsal ).
3-Lower subscapular .
4-Axillary nerve.
5- Radial nerve.

15. The letral cord gives the following derivatives:
1-Lateral pectoral nerve.
2-Musculocutaneous nerve.
3-Lateral root to median nerve.
The medial cord gives:
1-Medial pectoral nerve.
2-Medial cutaneous of Arm.
3- Medial cutaneous of forearm.
4-Ulnar nerve.
5- Medial root to median nerve.

16. In addition to these derivatives ,the upper trunk gives 2 branches suprascapular & nerve to subclavius muscle,while the roots gives dorsal scapular & long thoracic nerve) C5-7)

17. 3-The axillary lymph nodes which are arranges in the following groups:
A-Anterior ( pectoral ) group,under anterior border of pectoralis major M.
B-Posterior ( subscapular ) group along the course of subscapular vessels.
C-Central group within the loose areolar tissueof the base of the axilla.
D-Lateral group along the course of the axillary V near bicipital groove.
E-Medial group along the course of lateral thoracic vein.
F-Apical group in the apex of the axilla,it receives lymphatics from the above groups & takes them ( direct them ) to the deep cervical nodes in the root of the neck.

18. THE BREAST:
Is rudimentary in male & well developed in the female specially in lactating woman.It is a modified sweat gland located under the superficial fascia covering the pectoral region& lying on the deep fascia covering pectoralis major & part of the serratus anterior Ms.It extends from the sde of the sternum medially to the anterior axillary fold laterally( part of it extends into the axilla as axillary tail of the breast),while supero-inferiorly it extends from the level of 2nd rib to the 6th rib.The gland consists of lobes extending from the periphery of the gland to the area near the nipple.Each lobe has its own duct( lactiferous duct) which opens externally in to the nipple( has about openings).The nipple is a small conical projecting part surrounded by a lighter area ( Areola).The breast is supplied by:

19. 1-Pectoral branch of thoracoacromial artery.
2-Mammary branches from the lateral thoracic artery.
3-Perforating branches from the internal thoracic artery(i.e internal mammary A ).
4-Branches from intercostal arteries for the spaces 3rd-5th.

20. Rotater Cuff Muscles: are 4 in number surrounding the capsule of the shoulder joint to support &share in stabilizing the shoulder joint.One of these Ms inserts into the lesser tuberosity ( Subscapularis ),the other 3 are inserted into the greater tuberosity ( Supraspinatous,infraspinatous & teres minor muscles)

21. Muscle
Origin
Insertion
Nerve supply
Supraspinatous
from supraspinous fossa Of the scapula
into the superior facet of the greater tuberosity
Suprascapular N
Infraspinatous
from infraspinous fossa
middle facet of greater tuberosity
Teres minor
from posterior aspect of lateral Border of scapula just above the origin of teres major
inferior facet of = = =
Axillary N

22. The muscles responsible for Abduction movement of the arm at shoulder joint are:
1-From 0 – 18 degree by Supraspinatous muscle.
2-18—90 degree by Deltoid muscle(innervated by the Axillary nerve ).
3-Beyond 90 degree & above the head is by Trapezius & Serratus anterior muscles.

23. The muscles attaching the limb to the back are by Trapezius,Rhomboid minor,Rhomboid major, Levaetor scapula & Latissimus dorsi.
The latissimus dorsi id active during swimming , climbing, rowing ,pulling & scratching the opposite scapular region.

24. The Trapezius takes origin from the following sites:
a-From medial third of the superior nuchal line.
b-From ligamentum nuchae.
c-From the spine of C 7 vertebra
d-From spines of T1 –T 12 vertebrae( T = Thoracic ).

25. The M is inserted into the front of lateral third of the clavicle,acromion process & upper lip of the spine of the scapula.It is innervated by the spinal root of accessory nerve( 11th cranial nerve)which is motor ,while proprioception sensations from C4 & C5 nerves.
Levaetor scapula takes origin from transverse processes of upper 4 cervical vertebrae.
It is inserted in the area around the superior angle of scapula.
It is innervated by dorsal scapular nerve from the ventral ramus of C 5.

26. Rhomboideus minor takes origin from the spines of C 7 & T 1 vertebrae.
It is inserted into dorsal aspect of vertebral border of scapula at the base of the spine.
Is innervated by dorsal scapular nerve.
Rhomboideus major arises from the spines of T 2 – T 5 vertebrae.It is inserted into dorsal aspect of vertebral border below the base of the spine till inferior angle of scapula & being innervated by dorsal scapular nerve.

27. The last 3 Ms are known collectively as Elevators of the scapula( one of them is levaetor scapula)& all the 3 has a common nerve supply( dorsal scapular nerve) and all the 3 has a common action i.e all of them work in elevating the scapula.

28. The Deltoid M takes origin from the same areas of the insertion of the trapezius M .Thus it arises from the inferior aspect of the crest of spines of scapula,acromion process& lateral third of the clavicle.The M fibers from the 3 sites of origin converted into a single tendon of insertion & being inserted into the Deltoid tuberosity( on the lateral aspect of the middle part of the humerus).The deltoid is supplied by the Axillary nerve& its main action is flexion of arm at shoulder joint( anterior fibers),extension of the arm ( posterior fibers)& abduction of the arm at shoulder ( middle fibers) & in fact it is considered as powerfull & main abductor M of the arm( from degree).

29. Thus if the Axillary nerve is injured or compressed by local haematoma due to fracture at the surgical neck of the humerus,abduction becomes impossible because of loss of innervation of the deltoid M.8-90 degree).Thus if the Axillary nerve is injured or compressed by local haematoma due to fracture at the surgical neck of the humerus,abduction becomes impossible because of loss of innervation of the deltoid M.