A13 - Bursae and tendon sheaths of the equine fore- and hindlimb

Question 1

Give the accessory structures of muscles and define them

Answer 1

• Recessus: dilation of the joint capsule (not in this topic)
• ​Retinaculum: Thickened part of the fascia, which participates in fastening of the tendons without synovial layer (not in this topic)
• Bursa: Closed cavity that contains synovia
• Vagina synovialis: tendon sheath

Question 2

Bursa

Give the structure of the bursa

Answer 2

• Closed cavity that contains synovia
• Major role: padding
• soma bursa may communicate with the cavity of a nearby joint
• Layers:
  
  • Stratum synoviale
  • Stratum fibrosum
• Types:
  
  • ​Bursa synovialis submuscularis
  • ​Bursa synovialis subfacialis
  • ​Bursa synovialis subtendinea
  • ​Bursa synovialis subcutanea

Question 3

Vagina synovialis

Answer 3

• Vagian synovialis = tendon sheath
• Some tendon sheaths may communicate with the cavity of nearby joint
• Role:
  
  • Padding
  • Providing sliding surface
  • Nutrition
• Vagina synoviales communis (contains more tendons)
• General structure (numbers on picture):
  
  1. Stratum fibrosum
  2. Stratum synoviale parietalis (lamina externa)
  3. Cavitas synovialis
  4. Stratum synoviale visceralis (lamina interna)
  5. Mesotendineum (blood and nerve supply of the tendon runs through this)

Question 4

Forelimb (eq)

Answer 4

• Bursa subligamentosa supraspinalis
  
  • Lig. nuchae/lig. supraspinale → proc. spinosus of the first thoracic vertebra (Th 2-5)
  • Role: formation of the withers and carrying the saddle load
• ​Bursa subcutanea prescapularis
  
  • ​Skin → spina scapulae
• ​Bursa intertubercularis
  
  • In the sulcus intertubercularis, under the originating tendon of the m. biceps brachii (origin: tub. supraglenoidale)
  • Communicates with the shoulder joint (!)
  • In canine there is a tendon sheath instead (vagina synovialis intertubercularis), which does not communicate with the shoulder joint
• ​Bursa subcutanea olecrani
  
  • ​Skin → olecranon
• ​Bursa intratendinea olecreani
  
  • ​M. triceps brachii, caput mediale & caput longum → olecranon
• ​Bursa subtendinea m. tricipitalis brachii
  
  • ​Inserting tendon of m. triceps brachii → olecranon

On the extensor side of the carpal joint:

• All muscles are running through in their own tendon sheath, in the corresponding groove of the distal cranial part on the radius
  
  • e.g.: sulcus tendinis m. extensor carpi radialis

On the flexor side of the carpal joint:

• ​Canalis carpi
  
  • ​Bony base: proximal row of carpus
  • Retinaculum flexorium closes it to be a channel where the digital flexors run through
• Vagina synovialis communis mm. flexorum (proximal common tendon sheath)
  
  • ​In the canalis carpi
  • Fastened by retinaculum flexorium
  • Contains the tendon for both digital flexors:​
    
    • M. flexor digitorum superficialis
    • M. flexor digitorum profundus
  • Includes the:
    
    • A. dig. palmaris communis II (palmari, final portion of a. mediana)
    • N. palmaris medialis (n. digitalis palmaris communis II, ex n. medianus)
• ​Vagina tendineum digitorum manus (distal common tendon sheath)
  
  • Behind the fetlock joint, on the surface of the scutum proximale
  • Fastened by lig. anulare digiti
  • Contains the tendons for both digital flexors:
    
    • ​M. flexor digitorum superficialis
    • M. flexor digitorum profundus
  • Contains manica flexoria
    
    • ​The superficial digital flexor’s tendon surrounds the deep digital flexor’s tendon
• ​​Bursa subtendinea m. extensorius digitorum communis
  
  • ​M. extensor digitorum communis → fetlock joint
• ​Bursae subtendinea mm. interosseum manus
  
  • ​Under the tractus appostus (ex. m. interosseus medius) on both sides, at the vental lateral/medial margins of the fetlock joint before they merge with the m. extensor digitorum communis
• ​Bursa podotrochlearis manus
  
  • ​M. flexor digitorum profundus → distal sesamoid bone

Question 5

Hindlimb (eq)

Answer 5

• Bursa subcutanea trochanterica
  
  • ​Skin → trochanter major
• ​Bursa subcutanea iliaca (coxalis)
  
  • ​Skin → tuber coxae
  • Run next to:
    
    • A. circumflexa ilium profunda
    • N. cutanea femoris lateralis
• ​Bursa subfascialis prepatellaris
  
  • ​Fascia → patella
• ​​Bursa subtendiae prepatellaris
  
  • ​M. quadriceps femoris→ patella
• ​Bursa infrapatellaris proximalis
  
  • ​Lig. patellae intermedium → patella
• ​Bursa infrapatellaris distalis
  
  • ​Lig. patellae intermedium → tibia
• ​Bursa subcutanea calcanea
  
  • Skin → tendo plantaris at tuber calcanei
• ​Bursa calcanea m. flexoris digitorum superficialis (​Bursa subtendinea calcanea)
  
  • ​​Tendo m. gastrocnemii → tendo m. flexor digitorum superficialis
  • Extends one hand’s with proximal over the tarsus
  • Extends until the middle of the tarsus distally, located between the tendo plantaris and the lig. plantare longum
  • Eq: communicate with bursa tendinis calcanei
• ​Bursa tendinis calcanei
  
  • ​Tendo accessorius → tendo m. gastrocnemii
  • Eq: communicates with bursa calcanea m. flexoris digitorum superficialis

On the flexor side of the tarsus:

• All tarsus flexors and digital extensors run in their own tendon sheath
  
  • In canine, the m. ext. digitorum lateralis and the m. fibularis brevis run in a common tendon sheath
• Bursa subtendinea m. tibialis cranialis
  
  • ​medial insertion tendo of m. tibialis cranialis → inserting part om medial collateral ligament of tarsus

On the extensor side of the tarsus:

• M. flexor diitorum superficialis
  
  • ​Galea calcaneia fastens it onto the tuber calcanei
• M. flexor digitorum profundus
  
  • ​Each part runs on the tarsus in their own tendon sheath
  • M. flexor digitorum profuncus is fastened by the retinaculum flexorium
  • M. flexor digitorum medialis and m. tibialis caudalis runs on the sulcus mallelus medialis
  • M. flexor digitorum lateralis runs on the sustentaculum tali
• Because of these, there is no need for proximal common tendon sheath
• Vagina tendineum digitorum pedis
  
  • ​Distal common tendon sheath
  • Behind the fetlock joint, on the surface of the scutum proximale
  • Fastened by the lig. anulare digiti
  • Contains:
    
    • The tendon for both digital flexors:
      
      • M. flexor digitorum superficialis
      • M. flexor digitorum profundus
    • ​​Manica flexoria
      
      • ​​T​**​he superficial digital flexor’s tendon surrounds the deep digital flexor’s tendon)
• Bursa subtendinea m. extensoris digitori longi
  
  • ​M. extensoris digitori longi → fetlock joint
• Bursae subtendineae mm. interosseum pedis
  
  • ​Under the tractus appositus (Ex. m. interosseus medius) on both sides, at the ventral lateral/medial margins of the fetlock joint before they merge with the a m. extensor dig. longus
• Bursae podotrochlearis pedis
  
  • ​M. flexor digitorum profundus → distal sesamoid bone