CHAPTER 14: The Pectoral Region and Axilla

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Applied Anatomy

1.0 Fracture of the clavicle

The clavicle is most commonly fractured bone in the body.

It is more commonly fractured than dislocated because:

  1. Runs a sigmoid course

  2. Held in place by strong ligaments

  3. Presents areas of relative weakness

The fractures usually occur as a result of a fall on the shoulder or outstretched hand.

The commonest site of fractures is between the distal and middle thirds.

The lateral fragment is depressed the weight of the arm and the deltoid, and is also pulled medially and forward by pectoralis major.

The medial end is tilted upwards by the sternomastoid muscle.

The brachial plexus and axillary vessels are in danger of injury.

The close relationship of the supraclavicular nerves to the clavicle may result in their involvement in callus formation after fracture of the bone.

This may be the cause of persistent pain over the side of the neck.

The clavicle's subcutaneous position impairs its blood supply, thus delaying union following fracture.

2.0 Compression of the subclavian vessels and brachial plexus

The interval between the clavicle and the first rib in some patients may become narrowed, causing compression of neurovascular structures there.

  • Most of the symptoms are caused by pressure on the lower trunk of the plexus producing pain down the medial side of the forearm and hand, and wasting of the small muscles of the hand.

  • Pressure on the vessels may compromise the circulation of the upper limb.

3.0 Dislocation of the acromioclavicular joint

Falls on the shoulder may dislocate the acromioclavicular joint, forcing the acromion under the clavicle and tearing the coracoclavicular ligament.

4.0 Breast Cancer  

Cancer of the breast can spread via lymphatics, or venous channels. During haematogenous spread, the communication with the vertebral venous plexus provides a route for spread to the central nervous system.

Because of the axillary tail , and early involvement of the axillary lymph nodes in breast cancer, always examine the axilla whenever you do breast examination


5.0 Accessory mammary tissue  

Accessory breasts or nipples may occur above or below the normal breast in either sex.

  • Commonly, these accessory or supernumerary “breasts” consist only of a nipple and an areola, but sometimes, true glandular tissue is present also.

  • Supernumerary breasts are usually found along a line extending from the axilla through the normal breast to the groin, this being regarded as the milk line , or line along which mammals with multiple breasts usually develop them. Occasionally, supernumerary breasts are found beyond the usual extent of the milk line, for instance, on the neck or on the vulva or femoral triangle.


This is radiographic examinaion of the breast. Extensively used for screening breasts for benign annd malignant tumors and cysts. It can detect very small lesions unnoticed by clinical examination. Because the process is usually repeated often, only very small doses are used.

Suspensory ligaments and skin dimpling

The breast tissue is divided into 15- 20 compartments that radiate from the nipple by fibrous septa that extend from the skin to the underlying fascia.
If the fibrous tissue gets involved in malignant disease, or inflammation or abcess,they may contract and pull on the skin, causing its dimpling to give an orange peel appearance(peau de orange)

Radical mastectomy  

Operation done on patients with localized cancer of the breast with early spread to lymph nodes
It comprises of removal of the breast together with lymph vessels and nodes that drain the area. The excised mass consists of the following;

  1. A large area of the skin overlying the tumor and including the nipple
  2. All the breast tissue
  3. Pectoralis major and associated fascia
  4. Pectoralis minor and associated fascia
  5. All the fat, fascia and lymph nodes in the axilla
  6. Fascia

The following must be spared

  1. Axillary vessels
  2. Brachial plexus
  3. Nerves to serratus anterior and latismus dorsi
  4. Postoperative edema of the upper limb is due to removal of lymph vessels/nodes draining the upper limb

Modified radical mastectomy  

Done to patients with clinically localized cancer
The primary tumor is removed together with axillary lymph nodes, fat and fascia
The pectoral muscles are left intact

This is acute infection of the breast common during lactation. Bacteria gain entrance into breast tissue through a crack in the nipple. Initially, the fibrous septa contain the infection in one lobe
Abcess drainage

Radially arranged ducts usually drain these.

Simple mastectomy  

This is removal of the beast, done usually in localized cancer of the breast.
Usually combined with radiotherapy and/or hormonal therapy of axillary lymph nodes


Abnormal development of the clavicle may result in the absence of most of each clavicle. The shoulders will be very narrow and the individual may be able to bring the shoulders together in the midline.

The clavicle results from fusion of two ossification centers. Sometimes fusion fails, resulting in a defect that separates the outer third and the inner two thirds. Following upper limb trauma, this defect may be confused for a fracture

Injuries of brachial plexus

Can be caused by

    • Violent separation of the head and shoulder as may occur in a fall from a motorcycle or during delivery

    • Violent stretching of the arm above the head as in breech delivery, fall from a tree, skidding, e.t.c.

    • Wounds in the neck or axilla

    • Surgery in the lower neck or axilla

    • Chronic irritation by heavy loads carried on the side of the neck

    • Compression by a tumor, abnormal rib, or contracting muscle.

    • Fractured clavicle, and in the case of nerves, any other bone.

      The injuries may be classified into two:

      • Upper type, which involves the roots C5, 6, and results in unopposed medial rotation and in adduction of the upper limb. This position is sometimes referred to as “porter's, waiters' or policeman's hand”. The paralysis “Erb's or Erb- duchenne paralysis) affects mainly the shoulder and arm.

      • Lower type, which involve C8,T1 and result in claw hand. This is also called Lampe's or Klumpke-Dejerine paralysis.


Summary of nerve injuries in the upper limb


Common site and causes



  1. Fracture humeral shaft
  2. Axilla by poorly fitting crutches (Crutch palsy)
  3. Saturday night palsy – draping arm over chair while drunk
  4. Supracondylar humeral fracture
  1. Wrist drop
  2. Sensory loss over 1st dorsal interosseous


  1. Shoulder dislocation
  2. Fracture surgical neck humerus
  3. Misplaced injections into deltoid
  1. Weakened shoulder abduction
  2. Anaesthesia over lower part of deltoid


  1. Behind medial humeral epicondyle by fracture or compression or traction in cubitus valgus
  2. Supracondylar humeral fracture
  3. Wrist
  1. Claw hand
  2. ‘Guttering’ between metacarpals due to wasting of interossei
  3. Sensory loss on ulna side of hand


  1. Wrist- by cuts or compression in carpal tunnel
  2. At elbow by compression in cubital fossa
  3. Struther’s ligament
  4. Supracondylar humeral fracture/ brachial artery aneurysms
  1. Wasting of flexor muscles
  2. Wasting of thenar muscles
  3. Hand with index finger straight ’Pointing finger position’
  4. Sensory impairement over radial 3/5th of palmar surface of hands