Joints Flashcards
What does hyaline cartilage do?
Provides low friction surfaces (elastic springy surface)
What does fibrocartilage do?
Provides resilient support
What do ligaments do?
Tie bones together
What do tendons do?
Tie muscles to bones
What does fascia do?
Wraps around to hold things in place
What does fat do?
Provides padding and reduces weight (think of floating on water– lighter packing material then tissue– as you go further down the limb weight becomes more important. Marrow of the bones- as animal gets older- bone marrow becomes fatty. Haematopoietic marrow is only retained in areas that don’t move as much- every time you move something it takes energy).
What are bones made of? (very basically)
Collagen stiffened with mineral
Aponeurosis
Sheet of fascia
What is cartilage made of?
Collagen filled with glycoproteins that hold water. When they come under load, it pushes the water out. If you hold a joint tight together for a length of time, it squeezes the water out into the joint sheath (joins the synovial fluid) and the cartilage becomes stiff and it is more likely to tear the collagen. (Think about sitting on your foot and it feels stiff).
What are ligaments and tendons made of?
Collagen +/- elastin aligned into ropes (collagen is springy so it can take a lot of stretching and recoil, store elastic energy, prevent sudden loads coming onto the skeleton. Bones don’t like being pulled, they are okay with being compressed.)
What are muscles made of?
Collagen bags of cells filled with contractile proteins. You can tell how they go into a bone because you can find the fossa, for example.
What is fascia made of?
Collagen not otherwise named (e.g. sheets wrapping limbs)
What is fat made of?
Collagen (fascia) + adipocytes stuffed with triglycerides
Why does the scapula have a serrated face?
Serrated because there are bits of bone and collagen- where you are left with collagen from the serratus ventralis was going directly into the bone.
What type of loads do muscles put on bone?
Compressive. NOT direct TENSILE loads. They SPREAD the load**** important concept
If you want to stabilize a joint that is sloppy, you put a support bandage, what is the analogous to?
Fascia
How do each part of the anatomy in locomotion act together?
Muscles provide movement, joint allow movement, posture of the body, length, position and stiffness in ligaments in tendons determine how the movement is directed. Elasticity within ligaments and tendons, along with connections between them– smooths movements and helps balance. e.g. wobbly on a bike- cerebellum has to learn a new control system.
Just having the Elastic recoil in ligaments and tendons does what?
Slows down the speed of the muscle effect on the bones. It makes the much more efficient BUT it slows them down fractionally. Ligaments evenly toned- uneven tension on ligaments causes inappropriate joint loading.
Muscles role in movement– ligaments and tendons play a part
Muscles contract and pull against ligaments. Tension surface- even a slight bump could crack the bone EXCEPT that there is an antagonistic muscle group. SO ONE SIDE RELAXES. A gradual change from one to the other. Ligaments also counteract muscle pull to provide posture. Large tendons counteracting forces- which reduces the requirement for muscle. * Muscles held contracted give a static posture and lead to generalized stiffening/ increased damage risk. * Muscles that balance ligament pull in an elasticm anner give a dynamic, efficient, posture.
Ligaments
Ligaments can only be stretched If never stretched- they passively contract become stiffer and maybe less strong. If continuously stretched- they lengthen and may become sloppy and cease to provide support. If used within an active balanced system- they will be elastic and strong and supportive.
Which posture is assisted by ligaments?
The second picture.
Balancing ligament tone allows spinal muscles to strengthen evenly. Unbalanced ligament tone means that certain muscles are overused and movement through the joints are no longer optimal. Joints then become painful and/or damaged which restricts joint movement and causes more imbalance in the system.
** horses exercised regularly and on varying terrain
What happens with uneven tension on ligaments?
Causes inappropriate joint loading
Where are fibrous joints found?
Skull sutures. Difficult to tell where the separations are. Do not have large movement. Fractions of mm. of movement- important in denistry.
Where are cartilagenous joints- where are they found? what are they made of?
Fibrocartilaginous between them. Ring of fibrous tissue either side- at the surface where bones meet. In the middle- globular mass- a remnant of the motor cord (nucleus palposes)– when there is undue pressure and the fibrous tissue (collagen) around the edge tears- it can produde up and put pressure ont the spinal cord.
****Found at the vertebrae (intervertebral discs)- symphyses (pubic and mandible), costochondral/sternal (inbetween sternum and ribs and lumbs on ribs)
(e.g. fused pubic symphyses- important in a female that is going to be breeding. Can fuse in either mandible or pubis)
Synovial joint- where?
Most limb joints. Wonderful place for bugs to grow- nice and warm with nutrition and protected to some extent from the immune system.
**synovial capsule keeps hyaline cartilage hydrated and provides nutrition to hyaline cartilage (it has no blood supply)- blood supply from bones??
Muscular joints- found?
E.g. pectoral girdle to trunk
Which joints have intrinsic support?
Fibrous and cartilaginous joints. When they heal end up with scar tissue.
Naming of joints
Proximal bone then distal bone. e.g. metacarpophalangeal joint between metacarpus and first phalanx
How is movement constrained in synovial hinge joints that flex and extend?
Contrained by shape of the bone surfaces at the joint, and/or ligaments that surround the joint and/or tendons that cross the joint.
What is tricky about flexion and extension in forelimb vs. hindlimb?
Hand and foot flex and extend in different ways
Stifle needs more ligaments.
what is the largest of the sesamoids?
Patella
Where does flexion mainly occur along the spine?
where does axial rotation occur?
lateral bending along the spine?
Neck and lumbosarcal joints
Axial rotation- top of the head (tilted neck)
Lateral bending in neck and some in rib cage
Atlanto axial joint movement in a quadruped
rotational, flexion, extension- one ear down or the toher.
Why would you want a ligament to snap into straight?
So it is stable when you land on it.
How many fibrocartilaginous plates are found in how many joints in the body? What are they called?
Femur or temporal bone
Tibia or mandible
*Only 4 joints in the body with a fibrocartilaginous plate in the center
left and right stifle (medial and lateral menisci), left and right temporalmandibular joints (single meniscus)
** Periosteum gets thicker- goes around to make a joint sheath
Lining the joint sheath is the synovial membrane
Synovial membrane
Thin layer of membrane that produces synovium lines the inside of the joint sheath up to the edge of the cartilage.
It is sensitive and secretory. Over the collagen NOT over the cartilage. Secretes synovial fluid.
in the elbow joint, what constrains movement mostly? What breaks in the elbow joint if breakage occurs?
- Bone constrains movement.
- Anconeal and two coronoid processes fracture.
What gets into trouble in the stifle if breakdown occurs?
Ligaments tying the bones together.
Two joints at the stifle?
Femoropatellar and Femoraltibial
What are the stabilizing and supporting structures in the stifle?
Menisci, sesamoids, and ligaments and tendons
Where do sesamoids occur?
Where a tendon crosses a joint in such a way that it would be pulled against the bone ends
Only sesamoids if they are actually bone, if they are still fibrocartilage plaque (enlargement of the tendon as it crosses the surface)
** patellar
Where do menisci occur?
A pair of menisci in each femorotibial joint and a single meniscus in each temporomandibular joint
You can tell in an X-ray based on the space
What is a bursa?
Bursa is the same as a synovial membrane between fibrocartilaginous plaque (or scutum) and a bone
Where do fibrocartilagenous plaques occur?
Where compression is not as focussed. e.g. biceps tendon at the bicipital bursa; proximal, middle and distal scutums in the equine digit.
Scutum- synonymous with fibrocartilaginous plaque.
What are these?
Superficial Deep Digital flexor tendon
and Deep Digital Flexor Tendon
Ligaments that are extracapsular?
Joint capsule thickenings e.g. collateral ligaments, other supporting ligaments, e.g. sesamoidean ligaments.
Ligaments that are intracapsular?
Cruciate ligaments of stifle joint
Meniscal ligaments.
Fascial thickening example
Annular ligaments (retinaculi)
Ligaments that span many joints examples
Nuchal ligament, sacrotuberous ligament, interosseous ligaments
What are these? What do they do? What joints do not have them?
Ligaments of the hindlimb. They confine the limb to flexion and extension- one plane. Hip joint is an ex. of a joint that does not have ligaments because of its much larger range of motion
Which one is which?
Medial condyle has the higher point- because cranial cruciate going up to the femur. The caudal attaches more caudally and more laterally onto the tibial plateau.
Solid blue is cranial cruciate ligament
and caudal cruciate ligament is clear
5 large ligaments holding the femur to the tibia
What ligaments are these in a horse?
Patellar ligaments have 3 parts
b- is a strong piece of fibrocartilage which helps tether it more
What ligaments in a horse?
Much more directly connected in dogs.
Sacroiliac ligaments.
Most limb muscles are what as levers?
3rd order levers. They act on joints (the fulcrum or pivot)
1st is simple lever- push on one end and the weight is on the other.
Wheel barrow is a 2nd order
3rd order- distance/ speed multiplier– attachment site is the “effort” and the joint is the fulcrum. The rest of the limb is the weight.
Muscle contraction can be?
What can help determine muscle function?
Isometric or isotonic or a mixture of both
Balanced either side of bones to prevent bending (agonist + antagonist)
Determining muscle function: cross sectional area (power) or the whole muscle; length (range) of whole muscle. Size, relative length, and direction of muscle fibres. Position relative to the skeleton. Points of attachment- form and strength. Other attachments or constraints (ligaments, tendons, fascia, etc.)
** As a muscle gets bigger- the more fasicles- the larger the volume of contractile protein- the more it can pull. ACCORDING TO THE CROSS SECTIONAL AREA
** Distance it can move depends on the alignment of fasicles. V alignment vs. longitudinal alignment. Muscles strength lies in the collagen and alignment of the collagen
Power depends on the cross sectional area and how much contractile protein it has. Distance it can move depends on the alignment of the fibres and their orientation based on the direction. Each muscle fibre can only contract a certain portion, if you angle them, you decrease the distance it can move the muscle but you increase its strength.
Where does muscles strength and power, and distance it can move come from?
Muscles strength lies in the collagen and alignment of the collagen
Power depends on the cross sectional area and how much contractile protein it has.
Distance it can move depends on the alignment of the fibres and their orientation based on the direction. Each muscle fibre can only contract a certain portion, if you angle them, you decrease the distance it can move the muscle but you increase its strength.
Isometric vs. Isotonic
Isometric- keeps the same position (sitting in a squat position). Muscle does not change length but there is power.
Isontonic- keeping the same tone but moving it through space
** most movements are a combination of both
Know three muscle groups in the spine
How are muscles aligned? One consideration
Most muscles are aligned to put compressive loads on bones- where they are not aligned this way they are spread out quite a bit so they can put a more compressive load vs. tensile load
If you have a sudden movement and a muscle contracts, what happens? What happens if you had a sudden contraction without the other?
Antagonistic muscle relaxes and ligaments counteract muscle pull to help provide posture and large tendons reduce the requirement for muscle (MUSCLE IS HEAVY!). If this didn’t occur you could crack the bone with even a slight bump.
