B23 - Mammary gland, blood supply and innervation

Question 1

Give the usual number of mammae in:

1. Ca
2. Fe
3. Sus
4. Cow
5. Eq

(also give the number in different locations)

Answer 1

• Ca: 10 (8-12 complexes, 5-20 units per complex that have separate ostium papillae on tip of teat)
• Fe: 8
• Sus: 14 (14 complexes)
• Cow: 4 (4 complex, single unit in each)
• Eq: 2 (2 complex, 2 units per complex)

Question 2

What does the mammary comlex consist of?

Answer 2

• Corpus mammae
  
  • ​Consisting of skin, glandular tissue, and connective tissue
  • Attached at its base to the ventral surface of the trunk and, and continued apically by papilla mammae
• Papilla (teat)
  
  • Projection of the ventral surface of each mamma through which milk is withdrawn
  • Car, sus: nipple
  • Ru, eq: teat

Question 3

What is the mammary gland covered by?

Answer 3

External fascia

Question 4

Suspension of the mammary gland

Answer 4

• Suspensory apparatus:
  
  • ​Superficialanddeeplayer ofexternal fascia of the trunk
  • Lateral laminae (dense connective tissue) & medial laminae (elastic)
    
    • Lamella suspensoriae extends between the mammillary complexes
  • Sulcus intermammarius: separates complex row (adjacent mammae)

There are seven different tissues that provide support for the udder (ru):

1. Skin
   
   • ​Covering the gland
   • Most superficial
2. Superficial fascia
   
   • ​Attaches skin to underlying the tissue
3. Coarse areolar
   
   • ​Forms loose bond between the dorsal surface of the front quarters and the abdominal wall
4. Subpelvic tendon
   
   • ​Not actually part of the suspensory apparatus, but gives rise to the superficial and deep lateral suspensory ligaments
   • Attached tot he pelvic bone at several points
5. Lateral suspensory ligament
   
   • ​Composed of fibrous (and elastic) tissue
   • Arising from subpelvic tendon
   • Attaches to areolar tissue
6. Deep lateral suspensory ligament (lamellae)
   
   • ​Arises from subpelvic tendon
   • Extends bown over the udder and almost enveloping it
7. Median suspensory ligament
   
   • ​Most important part of the suspensory system in cows
   • Composes of 2 adjacent heavy yellow elastic sheets that arise from the abdominal wall → medial flat surface of the two udder halves
   • Able to stretch somewhat as the gland fills with milk to allow for the increased weight of the gland

Question 5

Draw the mammary gland

Answer 5

Question 6

Blood supply

Arteries

Answer 6

​Abdominal & inguinal complex:

• Tr. pudendoepigastricus → a. pudenda externa → a. epigastrica caudalis superficialis → a. mammaria caudalis

Thoracic complex:

• A. subclavia → a. thoracica interna → a. epigastrica cranialis → a. mammaria cranialis
• Ca: additional blood supply from a. thoracica lateralis
• Sus: additional blood supply from a. thoracica lateralis
• Eq:
  
  • Main artery is a. pudenda externa → a. mammillaris cranialis + caudalis (anastamoses with a. epigastrica cranialis
  • A. pudenda interna gives branches to udder caudally

Question 7

Blood supply

Veins

Answer 7

• V. pudenda interna + v. subcutaneous abdominalis → v. epigastrica cranialis → v. thoracica interna → v. cava caudalis
• V. subcutaneous abdominalis:
  • “Milk vein”
  • Large in good milkers

Question 8

Innervation

Answer 8

• Types:
  
  • Sensory
  • Sympathetic
  • Parasympathetic
• Additional neurohormonal reflex arch
  
  • Suckling stimulates hormones that trigger milk production
• Thoracic complexes:
  
  • Nn. intercostales
• Abdominal and inguinal complexes:
  
  • N. iliohypogastricus
  • N. ilioinguinalis
  • N. genitofemoralis
• Inguinal:
  
  • N. pudenda

Question 9

Draw the blood supply, innervation and lymphatic system

Answer 9