Relations and Extent of the Breast
Definition and Location
The breast (mammary gland) is a modified sweat gland lying in the superficial fascia of the pectoral region. A small extension from its superolateral part — the axillary tail of Spence — pierces the deep fascia through an aperture called the foramen of Langer and extends into the axilla.
The axillary tail is a high-frequency site of breast tumours.
Shape
Hemispherical bulge (flattened cone in Cunningham’s).
Extent
| Direction | Extent |
|---|---|
| Vertical | 2nd rib to 6th rib |
| Horizontal | Lateral border of sternum to the midaxillary line |
The breast lies largely on the pectoralis major muscle. Inferolaterally, it extends onto the costal origins of the serratus anterior and the external oblique muscle.
Four Quadrants of the Breast
The breast is divided into four quadrants by two imaginary lines through the nipple:
| Quadrant | Abbreviation | Clinical Note |
|---|---|---|
| Upper lateral (superolateral) | UL | Most common site of carcinoma (~60%) |
| Upper medial (superomedial) | UM | — |
| Lower lateral (inferolateral) | LL | — |
| Lower medial (inferomedial) | LM | May communicate with subperitoneal plexus |
Deep Relations
The deep surface of the breast is related to the following structures, from superficial to deep:
- Pectoral fascia — the deep fascia covering pectoralis major
- Three muscles (deep to pectoral fascia):
- Pectoralis major (main)
- Serratus anterior (inferolateral)
- External oblique (inferolateral)
Retromammary Space
- The breast is separated from the pectoral fascia by loose areolar tissue — the retromammary space
- This space allows the normal breast to move freely over the pectoralis major in all directions
- Surgical importance: The plane of the retromammary space is used in simple mastectomy
Clinical significance: When carcinoma infiltrates through the retromammary space into pectoral fascia and pectoralis major, the breast becomes fixed and immobile — a sign of advanced carcinoma.
Axillary Tail of Spence
- A superolateral extension of breast tissue
- Passes through foramen of Langer in the deep fascia
- Enters the axilla, lying up to the level of the 3rd rib (Cunningham’s)
- Clinically significant — high percentage of breast tumours occur here
- Must be included in examination and removed during mastectomy
Surface Markings
- Nipple: 4th intercostal space, 10 cm from midline
- Breast base: 2nd–6th rib, sternum to midaxillary line
- Axillary tail: superolateral, through foramen of Langer into axilla
Viva Pearls
- Breast lies in superficial fascia of pectoral region
- Extent: 2nd–6th rib vertically; lateral sternum to midaxillary line horizontally
- Axillary tail of Spence — pierces deep fascia through foramen of Langer — high tumour incidence
- Retromammary space = loose areolar tissue between breast and pectoral fascia → allows free movement
- Most common site of carcinoma = upper lateral quadrant (60%)
- Breast fixed to chest wall = cancer infiltrating retromammary space and pectoral fascia
- Three muscles deep to breast: pectoralis major, serratus anterior, external oblique