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Comparative Anatomy > Musculoskeletal System > Flashcards

Musculoskeletal System Flashcards

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1
Q

What are the functions of ligaments?

A

Transmit load from bone to bone

Hold the skeleton together

Some flexibility

Provide stability at joints

Maintain joint alignment

Limit freedom of movement

Prevent excessive motion by being a static restraint

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2
Q

What are the functions of tendons?

A

Force transmission between muscle and bone

Sustain high tensile stresses

Store energy during locomotion

Enables the muscle belly to be at a convenient distance from the joint

Act as a lever arm, reducing the need for large muscles

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3
Q

What are the 7 main components of tendon/ligament structure?

A
  1. Collagen muscle
    - Gly-X-Y repeats
  2. Collagen microfibril
  3. Collagen fibril
  4. Collagen fibre
    - Intrafascicular tenocytes
  • Crimp
  1. Fascicle
    - Fascicular matrix (FM)
  2. Fascicle Bundle
    - Interfascicular tenocytes
  3. Whole tendon
    - Interfascicular matrix (IFM)
    - Vasculature
    - Peritenon
    –> Epitenon
    –> Paratenon
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4
Q

Describe, in brief, the structure of tendons/ligaments:

A

Multiple hierarchical levels of collagen

Proteoglycan matrix binding

Interspersed with cells (tenocytes/ligamentocytes)

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5
Q

Describe the 5 steps of the evolution of tendons in vertebrates:

A
  1. Formation of linear tendons
  2. Fibrocartilaginous pad forms in compressed regions
  3. Sesamoid bones form in highly compressed regions
  4. Tendons store energy to reduce the cost of locomotion
  5. Tendons calcify in response to tensile load
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6
Q

What are the components of Cyclostome Tendons?

A

Protractor tendon

Teeth

Cartilage

Retractor tendon

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7
Q

Describe the tendons of Chondrichthyes:

A

Tendinous myosepta between muscles

Linear tendons in jaw/pharyngeal muscles

Fibrocartilaginous pad in compressed region as the tendon changes direction
- Proteoglycan (blue)
- Fibrous regions (pink)

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8
Q

Describe the tendons of Osteichthyes:

A

Linear tendons
- Similar in appearance to mammalian tendon
- Presence of fascicles

Fibrocartilaginous pads
- Similar to Chondrichthyes

Development of sesamoid bones
- Urohyal bone
- For the mouth opening

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9
Q

Describe the tendons of amphibians:

A

Broadly similar morphology to mammalian

In frogs, tendon collagen fibril diameter varies between species
- Forelimb flexor tendon
- Related to function

Presence of fibrocartilaginous patella

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10
Q

Describe the tendons of reptilians:

A

Few studies on reptillian tendon structure
- Short, wavy tendons

Ossified patella in lizards and tuataras

Specialised musculotendinous anatomy in reptilian hindlimbs
- 2 tendinous insertions from caudofemoralis longs
- Allows muscles to work synergistically

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11
Q

Describe the structure of avian tendons:

A

Similar structure to mammalian tendon
- Few studies have looked in detail

Highly loaded hindlimb tendons calcify
- Not pathological
- Tendons become much stiffer

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12
Q

What is the overall structure of the mammalian tendons?

A

Multiple hierarchical levels of collagen

Proteoglycan matrix binding

Interspersed with cells (tenocytes)

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13
Q

What is the more in detail structure of mammalian tendons?

A

Collagen molecules
- Cross linked together to build fibrils

Fibrils
- Surrounded by decorin-rich matrix
- Matrix links adjacent fibrils to build fibres

Fibres
- Interspersed by cells
- Surrounded by non-collagenous matrix builds fascicles

Fascicles
- Surrounded by interfascicular matrix, bound together to make tendon

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14
Q

What specialisation of the tendons have horses adapted?

A

Passive stay apparatus

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15
Q

Which mammalian species have adaptation of the tendon interfascicular matrix?

A

Horse

Rodent

Humans

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16
Q

What 3 groups can we compare the anatomy of the rotator cuff tendons?

A

Quadrupeds

Marsupials

Primates

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17
Q

What distal limb adaptations do horses have?

A

Elongated distal limbs

Muscle bellies situated proximal to carpus/tarsus

Very long tendons that insert onto the phalanges

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18
Q

What is the stay apparatus in horses?

A

System of muscles, ligaments and tendons supporting/locking equine limb

Allows horse to conserve energy and sleep while standing

Present in both forelimb and hindlimb

Structures are different in the proximal limb

Structures are the same in the distal limb

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19
Q

What are the muscular adaptations of the forelimb stay apparatus?

A

Increased collagen content

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20
Q

What are the tendon and ligament adaptations in the forelimb stay apparatus?

A

Long tendons/ligaments on cranial and caudal aspects of the limb

Provide passive support

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21
Q

What are the key structures in the proximal forelimb stay apparatus?

A

Biceps brachii

Lacertus Fibrosus

Deep digital flexor

Superficial digital flexor

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22
Q

What are the components of the distal limb stay apparatus?

A

Similar in forelimb and hindlimb

Sesamoidean ligaments

Suspensory ligament

Deep digital flexor tendon

Superficial digital flexor tendon

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23
Q

What are the key components in the hindlimb stay apparatus?

Study These Flashcards
A

Deep digital flexor

Superficial digital flexor

Tendons of the distal limb (same as the forelimb)

24
Q

What are the two additional mechanisms in the hindlimb stay apparatus?

Study These Flashcards
A

Patellar locking mechanism

Reciprocal apparatus

25
What is the patellar locking mechanism?
Horse can lock stifle in extension and rest other hindlimb Patella has large cartilage on medial aspect (parapatellar cartilage) Femur has enlarged medial trochlear ridge 3 patellar ligaments rather than 1 Activity of vastus medialis needed to lock the patella in place Uses only 2% of muscle activity is no locking mechanism was in place
26
What is the reciprocal apparatus in the stay apparatus?
Peroneus tertius muscle on cranial aspect of limb Superficial digital flexor muscle on the caudal aspect of limb Span stifle and tibiotarsal (hock) joint Lack of muscular tissue - cannot contract/change length Stifle and tibiotarsal joints cannot move independently of one another Reciprocal apparatus and patellar locking mechanism work together - when the stifle is locked tarsus/hock joint is also locked
27
Can the stifle and tibiotarsal joints move independently of one another?
No
28
How do the reciprocal apparatus and patellar locking mechanism work together?
When the stifle is locked, the tarsus/hock joint is also locked
29
What is the interfascicular matrix?
Loose connective tissue matrix Highly cellular Collagen type III Elastin Proteoglycans (Lubricin)
30
How is the IFM adapted in the energy storing tendons of the horse?
IFM - interfascicular matrix - provides elasticity/extensibility in the superficial digital flexor tendon (SDFT) Allows fascicles to slide past one another, increasing the extensibility of the tendon Larger volume of IFM in SDFT compared to CDET Greater proteoglycan and elastin content Proteoglycans allow sliding, elastin enables recoil
31
Why does the superficial digital flexor tendon, SDFT, require adaptation of IFM in horses?
Experiences high stresses and strains 16% strains during gallop compared to around 3-5% in positional tendons (common digital extensor tendon; CDET) Conflicting demands between strength and elasticity Collagen-rich fascicles provide strength Elasticity/extensibility provided by interfascicular matrix (IFM)
32
How is IFM adapted in rodent tendon?
Absence of IFM in most rodent tendons EXCEPTION: Tail Tendon - Allows fascicles to slide past one another
33
What is the anatomy of the Achilles tendon?
3 sub-tendons from different muscle bellies Soleus Lateral gastrocnemius Medial gastrocnemius Subtendons connected by inter-subtendon matrix (equivalent to IFM) Similar anatomy in rodent and human Twisted structure leads to non-homogenous deformation - Generates compressive, tensile and shear stresses within the IFM
34
How are the subtendons in the Achilles tendon connected?
By the inter-subtendon matrix (equivalent to IFM)
35
What is the anatomy of the rotator cuff?
4 muscles and tendons: - Supraspinatus - Infraspinatus - Subscapularis - Teres minor Connects scapula to humerus, stabilises glenohumeral joint Tendon fibres fuse, forming a common insertion onto the humerus - transverse fibres hold tendons together Complex loading environment - tears are common
36
What is the rotator cuff anatomy in Quadrapeds and marsupials, new world monkeys and hominoids?
Q and M: Supraspinatus, infraspinatus and teres minor tendons insert separately onto the humerus New world monkeys Primitive rotator cuff Hominoids Fully formed rotator cuff Exception of Tree Kangaroo
37
What are the tendon differences withing and between individuals?
Range from long and narrow to short and wide Basic hierarchical structure remains the same Flexor and extensor tendons have different anatomy Achilles tendon anatomy varies between individuals
38
What do the ranges from long and narrow to short and wide tendons mean?
Long and narrow - Fine movement and allow distance between muscle and insertion Short and wide - Efficient force transfer
39
What is the anatomy of extensors?
Flattened Smaller cross-sectional area Purely positional function
40
What is the anatomy of Flexors?
Round/Oval Larger cross-sectional area May have energy storing function - Human achilles - Equine superficial digital flexor tendon
41
How can human achilles tendon vary between individuals?
Large variation in Achilles tendon anatomy between individuals Length and cross-sectional area Size of sub tendons Degree of twist
42
What are muscles and tendons for (bike terminology)?
Motor Transmission Gearing Braking Shock Absorption Elastic recoil
43
Why does the size of the muscle matter?
Because size relates to time, time relates to power, and muscle power is costly or constraining
44
How do large animals tend to be compared to small animals?
Large animals tend to be more upright
45
How do small animals tend to be compared to large animals?
Small animals tend to be more crouched than large
46
What does geometric scaling result in?
Larger animals being disproportionately challenged to support body weight Weight = L^3 Strength = L^2
47
What does the geometry of upright postures allow?
High muscle effective mechanical advantage
48
Why are smaller animals not also upright, enjoying - Less massive limbs - Higher safety factors? Why allow muscles to be loaded by body weight at all?
Prevent uneconomical factors Upright at a small size = uneconomically high muscle activation to provide brief bursts of power Crouched at a big size = uneconomical mechanics: Wasteful stop/start
49
What are the observations of small biped locomotion compared to large?
The walk-run transition is not discrete Vertical GRF profiles are skewed early
50
What is flap bounding?
When birds fly by flapping wings and then holding wings against body intermittently
51
What do you know about size and power/work dynamics?
Too small: - Excess power demand Intermediate size: - Fastest - Minimally constrained by power or work Too big: - Excess work demand
52
What are two tricks to achive low LIMB work?
1. Vertical-axis joints (sprawled posture) 2. Linkages, with links going over at least 2 joints
53
What do we know about linkages?
4-bar linkages are pretty good Legs have to be flexed at midstance
54
What do bicycle spokes do? (Metaphor for muscles and tendons)
Are tension struts; they automatically align material with force - "Anti-buckle" Automatically take turns in taking the load Result in horizontal velocities, while Supporting body weight (vertical loads) while NOT changing length when under load
55
What can muscles be?
Agonists or antagonists Act as flexors or extensors - or both
56
What are legs like?
Vehicles Avoid mechanical work demand like bikes
57
What are the four things that legs as linkages do?
Avoid mechanical work demand from the leg: Keep force perpendicular to the velocity Avoid mechanical work supply from muscles: Keep loaded muscles isometric Simplify control: Let changes in geometry load and unload muscles Perform mechanical work economically: Minimise mass of muscle per joule; maximise contraction period

Comparative Anatomy (10 decks)

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