Anatomy (Internal Organs+Glands) · MU Sofia

95. Breast.

Covers the breast as a modified sweat gland in the superficial fascia of the pectoral region, outlining its development at puberty, hemispherical shape, extent between the second and sixth ribs, and axillary tail. It then describes blood supply, venous drainage and intercostal innervation, before setting out the structure of the nipple, areola, lobes, lactiferous ducts, and the fibrous and fatty supporting framework. The note also includes a brief section on the perineum, its boundaries and urogenital and anal triangles.

Inside: 10 sections · 7 labelled pictures · 10 flashcards · 5 min

Topic 39 of 44 in the MU Sofia syllabus for Anatomy (Internal Organs+Glands) (Medicine, Years 1 and 2). The free AceMed note covers it in 10 sections, about 695 words (5 min of reading), with 10 flashcards.

In this note

  1. PERINEUM
  2. Boundaries:
  3. Divisions :
  4. The Anal triangle:
  5. The urogenital triangle:
  6. Muscles :
  7. BREAST
  8. Blood supply :
  9. Innervation:
  10. Structure of the breast

PERINEUM

  • The perineum is situated in the pelvis between the thighs .

Boundaries:

  • Anterior : pubic symphysis
  • Posterior : the tip of the coccyx
  • Laterally : pubic arches.
  • Roof : pelvic floor
  • Base : skin & fascia

Divisions :

  • Anterior Urogenital Triangle:
  • Located anteriorly.
  • Contains structures related to the urogenital system.
  • Posterior Anal Triangle:
  • Located posteriorly.
  • Contains structures associated with the anus.

The Anal triangle:

Contains :

  1. 1. Anal canal
  2. 2. right & left ischio-rectal fossae.
  • the perineal muscles are missing here.

The urogenital triangle:

  • Contains the perineal muscles
  • Divided by the horizontal perineal membrane into deep & superficial perineal pouches
  • ↳ sac-like structures
  • ↳ form the pelvic floor
  • ↳ seperate the pelvic cavity, above, from the perineum.

Muscles :

  • Acts as sphincters and contribute to erection & ejaculation.
  • They are innervated by the pudendal nerve .

→ Urigenital floor in male :

  • 1 Perineal membrane (membrana perinei) – a fibrous sheet covering the inferior aspect of the deep transverse perineal muscle
  • 2 Deep transverse perineal muscle (musculus transversus perinei profundus) – the deep muscular part of the urogenital floor
  • 3 Superficial transverse perineal muscle (musculus transversus perinei superficialis) – forms the posterior border of the urogenital floor

Muscles located superficial to the perineal membrane

  • 4 Ischiocavernosus (musculus ischiocavernosus) – compresses the crus of the penis, contributing to erection
  • 5 Bulbospongiosus (musculus bulbospongiosus) – evacuates the urethra during micturition and ejaculation

Muscles located deep to the perineal membrane

  • 6 External urethral sphincter (musculus sphincter urethrae externus)

→ Urogenital floor in female:

  • 1 Perineal membrane – a fibrous sheet containing disperse muscle fibers
  • 2 Superficial transverse perineal muscle (musculus transversus perinei superficialis) – adjacent to the posterior edge of urogenital floor, weak or often absent

Muscles located superficial to the perineal membrane

  • 3 Ischiocavernosus – compresses the crus of the clitoris
  • 4 Bulbospongiosus – compresses the vestibule, evacuating the vestibular glands

Muscles located deep to the perineal membrane

  • 5 External urethral sphincter
  • 6 Compressor urethrae (musculus compressor urethrae) – compresses and extends the urethra
  • 7 Sphincter urethrovaginalis (musculus sphincter urethrovaginalis) – compresses and extends the urethra

* Superficial fascia of the urogenital triangle:

The superficial fascia of the urogenital triangle is continuous with similar fascia on the anterior abdominal wall.

As with the superficial fascia of the abdominal wall, the perineal fascia has a membranous layer on its deep surface. This membranous layer (Colles' fascia), is attached:

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