A28 - General features of muscles, muscular auxiliary structures

Question 1

General features of muscles

Answer 1

• The active part of the locomtoive apparatus is represented by the muscles of the skeleton and their accessory structures
  
  • Fascia​
    
    • ​Subdivision:
      
      • Superficial facia (eg. cutaneous muscle)
      • Deep fascia (strengthened by yellow elastic fibers (eq): tunica flava)
  • Tendon sheets
    
    • ​Double-layered, elongated tubes which enclose tendons
    • Contain synoviae, and reduces friction during movemnt
    • Compartments:
      
      • Synovial fluid
      • Visceral layer
      • Parietal layer
      • Mesotendineum (connects synovial and visceral layers)
  • Bursae
    
    • Location: where muscles, tendons or ligaments pass over hard tissue
    • ​Subdivision:
      
      • Subtendinous bursae
      • Submuscular bursae
      • Sublingamentous bursae
      • Subcutaneous bursae
• Muscles:
  
  • Moves parts of the body and the body as a whole
  • Helps the walls of the body cavity
  • Supports the function of the viscera (respiratory movement, abdominal pressure, etc.)
• Muscle belly:
  
  • Compasity of contraction
  • Contractile proteins in muscle fibers
• Synercyst: same kind of action
• Each fibre is surrounded by a network of reticular fibres, form the endomysium

Question 2

Types of muscles

Answer 2

1. Skeletal muscles
   
   • Part of the locomotive apparatus
   • Connects to bone
   • Origin:
     
     • Proximal
     • Fixed point
     • The less mobile/immobile part
   • Insertion:
     
     • Distal
     • Greater mobility
   • Belly: fleshy part
   • Tendon: may have
2. Smooth muscle
   
   • Visceral
   • Mucle in organs
3. Cardiac muscle

Question 3

On which terms can muscles be divided into

Answer 3

• Orientation of fibers
• Shape
• Number of joints they traverse
• Function

Question 4

Division of skeletal muscles accodring to the orientation of fibers

Answer 4

1. Unipennate ​(two parallel tendon sheets)
2. Bipennate (two tendon sheets of different direction
3. Multipennate (several tendon sheets of different direction)

By increasing the number of division, the number of muscle fibers can be increased without enlargning the thickness of the muscle, resulting in an increase in muscular strength

Question 5

Division of skeletal muscles according to their shape

Answer 5

1. ​Spindle-shaped muscle (​M. fusiformis)
2. Sheet-like muscle (​M. Planus)
3. Two-headed muscle (​M. biceps (ø animals))
4. Three-headed muscle (​M. triceps)
5. Four-headed muscle (​M. quadriceps)
6. Two-bellied muscle (​M. digastricus)
7. Ring-shaped muscle (​M. orbicularis)
8. Spincter

Question 6

Division of skeleatal muscle according to the number of joints they traverse

Answer 6

1. ​Uniarticular
2. Biarticular
3. Polyarticular

Question 7

Division of skeletal muscles according to their function

Answer 7

1. Extensor or flexor
2. Adductor or abductor
3. Supinator or pronator
4. Sphincter or dilatator
5. Levator or depressor
6. Rotator

Question 8

Connective tissue elements

Answer 8

1. Perimysium (Covering muscle)
2. Epimysium (Separating parts)
3. Endomysium (Small connective tissue)
4. Fascia (Tissue capsule)

Nubers corresponds with the figure

Question 9

Tendon

Answer 9

• Affector organ of the muscle, acts as passive tension bands
• Lig. anulare: Must stay close to the bones

Tendinous cord (tendon)

• In spindle shaped muscle

Tendon sheet (*vagina tendinis)*

• In flat muscle
• “Wrapping”
• Double layer:
  
  1. Synovia (Lubricates)
  2. Fibrous layer (Supplied by arteries from the surface of the bone)
• Mesotendineum (connects synovial and visceral layers)
• The two layers can slide above eachother → smooth sliding over the bone

Question 10

Cutaneous muscles

Definition

Answer 10

• Cutaneous musculature has the same histological structure as the skeletal muscles, even though they are inserted into superficial fascia
• Action: to stretch and move the skin
  
  • Car: also mimic movements of the lips, nose and ears

Question 11

Cutaneous muscles

Superficial fascia

Answer 11

1. Fascia capitis superficialis
   
   1. Fascia masseterica (covers gl. parotidea and m. masseter, attaches to crista fascialis and arcus zygomaticus)
   2. Fascia temporalis superficialis (covers m. temproalis, covers cheek muscles)
   3. Fascia frontalis
2. Fascia cervicalis superficialis
   
   • Attaches
     
     • Dorsally: lig. nuchae
     • Caudally: fascia superficialis of the trunk/shoulder
     • Cranially: blends with fascia masseterica
3. Fascia trunci superficialis
   
   • Ensheaths the entire trunk
     
     • From shoulder → gluteal regions
   • Ru, eq:
     
     • Attached to proc. spinosus of thoracic and lumbar vertebrae
     • Ventrally it fuses with linea alba
   • Ca:
     
     • Continous movable sheeth of connective tissue
     • Not attached to proc. spinosus or linea alba
   • Panniculis adiposus: Between superficial and deep fascia (car)
4. Superficial fascia of the limbs (fuse distally with deep layer, forming a “stocking”

Question 12

Cutaneous muscles

1. Give the division of regions of the cutaneous system
2. List the muscles

Answer 12

• The cutaneous system is divided into:
  
  • Head
  • Neck
  • Trunk

Head:

1. M. sphincter colli superficialis (ca)
2. M. cutaneous faciei
3. M. sphincter colli profundus
4. M. frontalis (ru)

Neck:

1. M. sphincter colli superficialis
2. M. platysma (ca, sus)
3. M. sphincter colli profundus
4. M. cutaneus colli (ø ca)

Trunk:

1. M. cutaneous trunci
2. M. cutaneous omobrachialis (eq, ru)
3. M. praeputiales (ø eq)
4. M. supramammarii (female ca)

Question 13

Cutaneous muscles

Head region

Answer 13

• Grouped together as the superficial fascial muscles
• M. sphincter colli superficialis (ca)
  
  • Runing forwart along vental surface of the neck → mandibular space (fascia masseterica)
• M. cutaneous faciei
  
  • ​Ca, sus: in contact with m. platysma
  • Ru, eq: independent muscle
  • Passes forwad over the m. masseter → commisures of the lips
• M. sphincter colli profundus
  
  • ​Arise under m. platysma → lateral surface of head and neck
• M. frontalis (ru)
  
  • Fibers from m. sphincter colli profundus

Question 14

Cutaneous muscles

Neck region

Answer 14

• Cervical region
• M. sphincter colli superficialis
  
  • ​Envelopes the neck from ventrally to pectoral region
  • Fe: best developed
• M. platysma (ca, sus)
  
  • From nuchal and dorsal regions of the neck → fascial region
• M. sphincter colli profundus
  
  • ​Car: independent
  • Ventral aspect of neck
• M. cutaneous colli (ø ca)
  
  • Ventral aspect of neck

Question 15

Cutaneous muscles

Trunk

Answer 15

• M. cutaneous trunci
  
  • ​Part of m. pectoralis profundus
• M. cutaneous omobrachialis (eq, ru)
  
  • Covers the shoulder region
  • Base of scapula → elbow
• M. praeputalis (ø eq)
  
  • Cranial muscle: pull the prepuce forewards
  • Caudal muscle: retracts
  • Action: Extends and retracts prepuce
• Mm. supramammarii (female ca)
  
  • Cranial muscle: Originates from xiphoid → disappears in superficial fascia cranial to the angle of ilium
  • Caudal muscle: originates from muscle lying superficial in vulva and the inguinal mammary gland → angle of ilium