Bone Structures Flashcards
Load bearing structures of the mammal
Bone structures and cartilage wherever bones articulate with other bones.
Where is cartilage located?
Transition between bone and other connective tissue such as points of insertion of ligaments and tendons.
AND bone and bone articulation
Bones provide
Support, levers for locomotion, and provide protection (cranium for example- protection for the brain delicate tissues)
Also to house haemopoeitic tissues (bone marrow main haemopoietic tissue in adult animals)
Bones also have an important function calcium homeostasis- imp. reservoir of calcium. Maintain constant level of Ca in blood- imp. for funciton of all cells in the body (used to convey signals from cell membrane to the nucleus and other parts of the cell), muscle contractility as well.
Bone classification- 3 main
other ways?
Long bones- major limb bones- humerus, radius, etc
Short bones- vertebrae
Flat bones- skull bones, scapula
Other ways:
Cortical and trabeculae component
Cortical bone is compact.
Trabeculae bone- network of trabeculae or rods and plates- porous network
Periosteum
Dense connective tissue that surrounds bones. Not at articular surfaces. Interupted by tendons and ligaments
Endosteum
All surfaces inside a bone.
Shaft
Diaphysis- comprised of cotrical bone. Cylinder of bone with empty space in the middle with bone marrow
Very end of bone
Epiphysis- thin shell of cortical bone but primarily trabecular bone- shape varies enormously between individual bones and species. But generally rounded
Point at which shaft of the bone gets narrower is called?
Metaphysis- shape varies enormously. Made up of trabecular bone that turns into bone marrow- thin shell of cortical bone gets thicker.
Trabecular bone is normally contained by?
Thin layer of cortical bone
Blood supply to bone
Multiple sources. Bone in a living animal is a dynamic living tissues. Bone is constantly being turned over by cells.
Major source of blood supply: nutrient artery (nutrient foramen) into the bone marrow- branches which pass into cortical bone- (diaphysis)- nutrient artery anastomose as well
Metaphyseal and epiphyseal arteries
Adult animal- arteries anastamose inside the bone.
If you didn’t have anastamose- large areas of bone would just die.
The anastamose does not happen until animals are fully grown, fully mature.
Medullary vein- (medulla is marrow)- veins leave the bone accompanying the nutrient artery accompanying the epiphyseal and metaphyseal.
Growth plate
Made of cartilage- can tell if adult bone or juvenile- not fully matured
How do the bones drain?
Veins leave the bone accompanying the nutrient artery and metaphyseal and epiphyseal vessels
Cortical bone of diaphysis drains to the periosteal veins
Centrifigal blood through the cortical bone of the diaphysis
Draining into the periostial venules
What is bone comprised of?
Connective tissue.
Extracellular matrix
Cellular component
What are the two components of the bone matrix?
Organic (type I collagen- fibres of type I which is THICK collagen fibres, glycoproteins mixed in, many of them are there because they have the capacity to bind Ca2+
inorganic component (mineral- hydroxyappetite- calcium and phosphate)
Both proteinaceous and mineral arranged in layers. Lamella bone- mature bone in which the bone matrix is arranged in layers.
When first formed in an embryo or in pathological process- they are randomly arranged, collagen not parallel- less organization. THIS IS CALLED WOVEN BONE.
Osteoblasts
Osteoblasts- cuboidal cells that have the function of synthesizing and secreting bone matrix
Situation where there is mature bone and they form lamilla bone- they secrete bone matrix on which they are adherent to.
Collagen type I and calcium binding proteins- called ostoid (?)
Within a few days ostioid is mineralized.
Successive layers of bone matrix deposited on bone surfaces. When osteoblasts mature they differentiate into osteocytes and are embedded into matrix.
Osteocytes
A bit shrunken compared to osteoblasts
Osteoblasts- Substantial RER because they are actively synthesizing proteins to secrete- as they diff. into osteocytes they become less active in synthesis and they shrink- less cytoplasm. But what they have is organized into multiple processes which extend out into channels in the bone called cuniliculi– the osteocytes located in the space within the bone called a lacuna. Extending out are multiple cuniliculi (sp)- osteocyte processes make contact with other osteocytes and form gap junctions. With osteoblasts as well.
Osteocytes are thought to transmit signals within the bone.
Bones are responsive to mechanical loading and they adapt their structure to forces they are exposed to.
Bone lining cells
Bone surfaces in general are covered with one type of cell or another. Active cell formation then osteoblasts. Esp in adult animals- there are few osteoblasts. Vast majority are covered in bone lining cells- capacity to differentiate into osteoblasts
Osteoclasts
Small proportion. Changes depending on level of bone turnover taking place.
Multinucleate
Capacity to resorb bone (dissolve bone matrix)
Old bone with small cracks in it can be removed and replaced by new bone.
They are also important in new growth- keep removing bone on inside so marrow cavity can expand.
They do that by adheringt o bone surfaces by ceiling zone- forms a ring around the outside between the osteoclasts and the bone surface- seals off an microenvironment. Described as apical surface- the osteoclasts secrete hydrogen ions to acidify the microenvironment which provides the right conditions for lysosomal enzymes secreted into micro environment. These enzymes are proteolytic break down collagen fibres and the bone.
Osteoclasts are the only cells taht can resorb bone and degrade the bone matrix.
Where is bone marrow? What is it made up of?
Diaphysis hollow cylinder.
Haemopoeitic tissue.
Also adipose tissue
Trabecular bone
No blood vessels, except some large species because they are actually really thick and need it. Generally gets it blood supply from vessels from the marrow supply.
How is trabecular bone structured?
Network of plates and rods
Homogenous pink stain- bone tissue (osteocytes scattered) amongst bone marrow
Bone in 3D- lumbar vertebrae- microcomputertomography- mouse bone- you can see the plate like structures connected by rod like structures- connected
Cortical bone- structure
Osteon (Haversian system)- longitudinal cylinders of bone tissues consisting concentric bone lamilae arranged around central canal containing a blood vessel (arteriole and venule) AND nerve branches.
(note the transverse canals connecting vessels- Volkmann’s canals)
**Concentric layers of collagen fibres surrounding Haversian canal- arranged at right angles to each other– enormous strength of osteons.
Spider like structures- osteocyte lacuni. Cuniliculi extending out from them- osteocytes to osteocytes and their gap junctions.
Osteons are different sizes. Dark profile. Volkman’s canal connecting two Haversian canal. You can also see the tiny cuniliculi.
Cortical bone
Dense, compact. You can see some blood vessels and osteocytes. You can also see osteoblasts if immature (or damaged). Some trabecular bone scattered amongst bone marrow.
Mesenchymal stem cell
Capacity to diff. to adipose, cartilage, muscle, fibroblasts, or osteoblasts, osteocytes or bone lining cells
* Adult stem cells- persist in adult animals- they cannot diff into all diff tissues but still many of them- predominantly muscle
Osteoblast Differentiation
Active osteoblasts- synthesize and secrete bone matrix (ostioid)
3 possibilities:
- terminal differentiation into osteocytes and retained within bone tissue
- Apoptosis- if excess of osteoblasts
- Bone lining cells- no requirement to form new bone but could if needed. Resting cells. Form barrier between bone matrix sufrace and surrounding tissues.
Intramembranous ossification
The way the flat bones develop
e. g. skull
1. Condensation of embryonic mesenchymal cells- (condensation means- accumulation of mesenchymal cells close to each other happens through prolif and cell migration)
2. As they condense they diff. into osteoblasts
3. Then they secrete ostioid
4. Then it starts to mineralize
Bottom picture- you can see growing trabecular matrix. Edges of pre-existing spicules- new ostioid being deposited. Gradually expand. They start to fill in trabecular and gradually form thin cortical shell.
e.g. mouse skull would just be cortical bone structure
Cartilage purposes
Support where flexibility is required
Shock absorption
Articular cartilage- smooth articular surface- bones move in relation to each other within synovial joints
Composed of cells and extracellular material
Hyaline Cartilage (one of three types)
Growth plates
Articular surfaces
e.g. Tracheal cartilage (rapidly growing lamb)- picture
Perichondrium- dense connective tissue surrounding cartilage
As cartilage grows and get larger- they separate
Trachea- randomly arranged cells
Growth plate- they are not randomly arranged- chondrocytes are in an organized columnar structure
Hyaline cartilage- has a high ratio of fibres!! It looks homogenous there is SO MUCH. (Glycosaminoglycans)
Blood in Cartilage
Avascular in normal adult mammal
Tracheal cartilage is usually avascular
There are exceptions- esp. in large animals with large masses of cartilage there will be blood vessels
Mostly related to articular cartilage
Chondrocyte
Only cell present in healthy cartilage
Present encased in lacuni
Normally fill lacuna
Individual chondrocytes would be on their own. Interstitial growth is possible in cartilage- grows through prolif. of chondrocytes. So they congregate if this is going on.
Cartilage Extracellular Matrix
Synthesized and secreted by chondrocytes
Made up of fibres and amorphous material
Fibres are composed of collagen type II- only present in cartilage and almost no other locations.
Fibres forming teh skeleton of the cartilage structure- packed in amongs fibres is the amorphous EC material. Proteoglycans and Hyaluronan.
Proteoglycan and Hyaluronan- purpose? structure?
Many proteoglycan molecules linked to hyaluronan molecules.
Side chains are negatively charged- hydrophilic- attract water- packed in amongst collagen fibres- swelling against the pressure of the compression of the collagen fibres. This provides the shock absorption
Elastic cartilage
External ear and epiglottis
Places where more flexibility is required
Elastic fibres in the matrix
Perichondrion
Fibrocartilage
Intervertebral discs, TMJ, manisci (sp?) at attachments of ligaments and joints Also in the cardiac skeleton as well
Providing structural transition between rigid hard tissue of bone and the flexible tissue of ligament or tendon
If you had a sudden transition from flexible to rigid in some locations this would result in stresses and damage of soft tissue
(lower ratio of glycosaminoglycans- fibres to collagen fibres- for that reason- you can see the fibres in the fibrocartilage. Chondrocytes are arranged in rows and columbs between the fibres)
Endochondral ossification
ALL bones develop this way except for flat bones. (Long bones and short bones)
Involves formation of cartilage model
Generalized mesenchyme- instead of cells diff. directly. They undergo condensation. They then diff. into chondrocytes- synthesize cartilage matrix. And then they go on and form the model of the future bone.
Basic shape- chondrocytes of the future diaphysis start to undergo hypertrophy. The lacuna around them expands (they digest away) creates signals that lead to the deposition of a thin layer of bone around the outside of the midshaft of the bone:
Periostial bone collar- forms around the outside. Once the PBC is there. Diff. of osteoblasts around the outside of cartilage model which lay down bone. Again after the PBC, all of the necessary cell types start to invade into the spaces that the hypertrophic chondrocytes created. Osteoclasts come in and start to break down cartilage matrix freeing up path for osteoblast and bone marrow precursors to invade.
If chondrocytes are flattened- they have just recently proliferated– as they mature a bit then they start to secrete cartilage matrix and they start to separate from each other. They will die– empty lacuni where the blood vessels and osteoclasts can get into.
Endochondral ossification
- Cartilage model
- Invasion of primary centre of ossification
- Once it forms- it gradually expands towards each end of the bone with proliferation of chondrocytes in the remaining cartilage. Bone expands in length and at the same time primary centre of ossification is expanding. Remanants of cartilage- osteoblasts deposit bone on. Continues to lengthen the bone throug prolif of chondrocytes.
- Most long bones formation of secondary centre of ossification at both ends. through similar process to primary ossification. NOT in SHORT BONES. Don’t need the longitudinal growth- just widening. When you get the secondary centre there is still cartilage left- THIS IS WHAT IS CALLED THE GROWTH PLATE. The Growth plate continues to take over the growth plate cartilage. Cartilage loses the race, give up, and the metaphyseal bone takes over and fuses to the epiphysis. This is when bone growth ceases (gradual process). (growth plate gets thinner and thinner as animals get older- secondary ossification centre first forms it is thick, but gets thinner fairly rapidly– animal approaching puberty- quite thin)
- Mature bone- just articular cartilage left at the end on the surface.
What causes longitudinal Growth of Bones??
Proliferation of chondrocytes!!
Matrix of chondrocytes and hypertrophy of chondrocytes as well
Point out some structures
Note columns of chondrocytes. At the base= hypertrophy= and even further down they die. Cells of ossification front below that
Some places you start to lose transverse struts of chondrocyte lacuni- but in the vertical ones stay intact. Vertical struts provide structure for osteoblasts to deposit bone matrix. Also vessels in there.
Pale staining in the middle of trabecular- vertical remnants of vertical struts. Bone matrix that osteoblasts have laid down on top of vertical struts.
Regulation of endochondral ossification
Behaviour of chondrocytes is key.
Circulating hormones and locally secreted factors. Growth hormone is really imp. Acts in 2 ways. Stim secretion of insulin like growth factor 1- acts on receptors on chondrocytes. Chondrocytes also secrete IGF 1- stim. proliferation. BMPs- stim. chondrocyte prolif in growth plate.
Important break that is acting at the same time- ensure it doesnt get out of hand. Provided by fibroblast growth factors (inhibit proliferation)
Thyroid hormones from the thyroid gland regulate the hypertrophy of the chondrocytes. Also stim. release of IGF1 and fibroblast growth factors. Also add to chondrocyte hypertrophy. Inhibit release of parathyroid hormone (PTHrP)- closely related to thyroid hormone. Produced localled by chondrocytes- inhibits hypertrophy.
Cartilage matrix secretion regulation- need nice solid cartilage structure for stable growth plate- also stimulated by IGF 1 and BMPs
Hypertrophic chondrocytes secrete factors that regulate behaviour of ossificiation front- chondrocytes that are closest to the front- secrete vascular endothelial growth factor- factor that stimulates angiogenesis. blood vessels are the first structures that invade ahead of the osteoclasts- clear a path and ensure appropriate nutrition for bone cellst aht follow them
RANKL- factor that is essential for osteoclast differentiation. Hypertrophic chondrocytes secreting RANKL- stim. differentiation and activity of osteoclasts on the ossification front.
BMPs- Also stim. osteoblast differentiation and bone matrix synthesis.
Only works properly in normal animals- stimulation and BRAKE. Appropriate balance.
Mutations in any regulatory factor leads to?
Skeletal dysplasia- abnormal growth of the skeleton. Chondral dysplasia (dysplasia of growth cartilage).
Range of genes that can mutate and cause pathology: Genes encoding cartilage matrix proteins, hormones, growth factors, or growth factor receptors, or the mediators.
e.g. Bulldog dwarfism (in calves)- severe, short legged phenotype (Dachshunds- considered chondrodysplasia)- Fibroblast growth factor 4- fibroblast growth factors suppress chondrocyte proliferation
Proximal
Structures that lie towards the junction with the body
Distal
Structures further away from the junction of the limb with the body
Cranial and caudal of the limb
The front and the back of the limb if proximal to the carpus or tarsus
Dorsal and palmar
the front and back of the forelimb from the carpus distally
Dorsal and plantar
The front and back of the hindlimb from the tarsus distally
Axial and abaxial
Towards the axis or midline of the limb; away from the axis of the limb
What is a ventrodorsal projection or view of the abdomen, for example?
The beam enters the abdomen ventrally and exits dorsally. The animal will be lying in dorsal recumbency (on its back).
When radiographed, an animal in left lateral recumbency produces what? And how are they lying?
Right side up, left side down.
Produces left lateral projection
Dorsal flexion
Some joints such as the metacarpophalangeal and metatarsophalangeal joints in the dog are in a state of overextension or dorsal flexion at rest. In these joints, flexion will increase the dorsal angle of this joint and extension will decrease the angle. Further or hyperextension of this joint is also referred to as dorsi- or dorsal flexion.
What is the metacarpo or metatarsophalangeal joint commonly known as in the horse?
Fetlock joints
Hyperextension
Movement beyond the normal range of extension
Abduction
A movement that pulls a structure away from the midline of the body
Adduction
A movement that pulls a structure towards the midlne of the body
Circumduction
When an extremity is moved in the curved plane of the surface of a cone- the joint that allows this motion must therefore allow abduction, adduction, flexion, and extension.
What is an example of a joint and circumduction? In your index finger?
Ball and socket joints- e.g. humerus or carpometacarpal joint
Sliding and Gliding in joints
Joint surfaces slide transversely across the opposing surface. Most synovial joints- range normally restricted by ligaments stabilizing the joint
Rotation
Circular movement of a part such as a bone around its long axis- e.g. in a quadruped when tilting its head to one side- chiefly involves the atlanto axial joint (upper part of the neck between the first and second vertebrae- the atlas and axis)
Pronation
Inward rotation of the forepaw that allows the palmar surface to face outwards
Supination
An outward rotation of the forelimb so that the palmar surface faces inwards
Eversion
The plantar surface of the hindlimb is turned to face laterally (outwards)- requires both pronation and abduction of the metatarsus
Inversion
The plantar surface of the hindlimb is turned to face medially (inwards)- requires supination and adduction of the metatarsus
Fibrous joints- 3 types
Type 1: Syndesmosis
Lots of intervening connective tissue e.g. connection of the hyoid to the skull in the dog
Fibrous joints- 3 types
Type 2: Suture
Mostly occur within the skull
Fibrous joints- 3 types
type 3: Gomphosis
The implantation of a tooth in its socket
Cartilaginous: 2 types
Hyaline- usually temporary such as the epiphyseal plate (growth plate), but also costochondral junctions that remain cartilaginous through life
Fibrocartilaginous- e.g. pelvic and mandibular symphyses
Synovial
These joints have a joint cavity containing synovial fluid, a joint capsule (outer fibrous and inner synovial membrane), and articular cartilage. A synovial joint may be simple: has two articular surfaces e.g. the shoulder joint OR compound: has more than two articular surfaces within the same joint capsule e.g. elbow, stifle.
a. Incisive bone
b. Nasal bone
c. Lacrimal bone
d. Orbit
e. Frontal bone
f. Parietal bone
g. Occipital bone
h. Occipital condyles
i. External auditory meatus
j. Temporal bone
k. Sphenoid complex
l. Zygomatic bone
m. Maxilla
a. basisphenoid bone
b. presphenoid bone
c. Palatine bones
d. External acoustic meatus
e. Tympanic bulla
a. Temporal line
b. Temporal fossa
c. Sagittal crest
d. Zygomatic process
a. Sagittal crest
b. External occipital protruberance
c. Nuchal crest
d. Occipital condyle
e. Mastoid process
f. Temporal fossa
g. Lacrimal fossa
h. Paracondylar (jugular) process
A. Zygomatic process
B. Mandibular fossa
C. Retroarticular process
D. Squamous part of the temporal bone
A. Tympanic bulla
B. External acoustic meatus
C. Mastoid process (Cleidomastoideus and sternomastoideus mm. insert here)
4? 8? 10? 12?
- Oval foramen
- Jugular foramen
- Hypoglossal canal
- Foramen magnum
2? 5 (3)? 7? 10?
- Infraorbital foramen
- Optic canal, orbital fissure, rostral alar foramen
- Retroarticular foramen
- Stylomastoid foramen
ID the cartilages in this image
A. Epiglottis
B. Thyroid
C. Arytenoid (paired)
D. Cricoid
a. Stylohyoid
b. Tympanohyoid cartilage
c. Thyroid cartilage
d. Arytenoid cartilage
e. Thyrohyoid
f. Cricoid cartilage
g. Epihyoid
h. Ceratohyoid
a. Stylohyoid
b. Tympanohyoid
c. Epihyoid
d. Thyrohyoid
e. Ceratohyoid
f. Basihyoid
a. Lingual process
b. Basihyoid
c. Stylohyoid
d. Thyrohyoid
e. Thyroid cartilage
f. Cricoid cartilage
Which bones of the hyoid apparatus can you ID in this image?
Epihyoid, Ceratohyoid, Basihyoid
What is this image showing?
Mandibular symphysis- a site or line of union
Atlanto-occipital joint
atlanto-occipital aperture- this space between the caudal skull and the first cervical vertebra is a site that allows access to the cerebromedullary cistern (subarachnoid space) for collection of cerebrospinal fluid.
What region of the spine is this vertebrae?
THORACIC
a. Lamina
b. vertebral arch
c. vertebral body
d. Spinous process
e. Pedicle
f. Transverse process
g. Vertebral foramen
Note the intervertebral foramen
They allow the spinal nerves (except for cervical spinal nerve 1 and first 2 sacral nerves) to emerge from the vertebral canal to supply the body
What kind of vertebrae is this? What is the transverse foramen for?
Cervical vertebrae
A transverse foramen is present in C1-C6- this accomodates the passage of the vertebral artery
What is C1?
Atlas.
a. Lateral vertebral foramen
What is this?
What is the arrow?
Atlas
Favea for dens
What is the part with hidden labels?
Axis
a. Spinous processes
b. Dens
Which thoracic vertebrae in a dog is the anticlinal? Why?
T-11
The upright vertebra, usually T11, where the incline of the spinous processes change from cranial to caudal
a. wing
b. auricular surface
c. promontory
d. dorsal sacral foramina
What are these?
Caudal vertebrae
Intervertebral fibrocartilaginous joint
The intervertebral disc compises a pulpy nucleus (nucleus pulposus) within a fibrous ring (annulus fibrosus) and lies in the intervertebral space between the bodies of each adjacent vertebra (except for between C1 and C2).
a. Head
b. Neck
c. Tubercle
d. costochondral junction
e. costal cartilage
Which ribs are sternal in the dog and which are asternal? Which rib is floating?
Which ribs form the costal arch?
First 9 ribs are sternal
Last 4 ribs are asternal
13 is the floating rib
The costal arch is formed by costal cartilages of the 10, 11, and 12th- they unite with the cartilage of the last sternal rib (the 9th)
How many costovertebral joints are there?
Where are they?
What are they called
2
One between the head of the rib and the costal foveae of the thoracic vertebrae and the second between the tubercle of the ribe and the transverse process of the thoracic vertebra
Sternocostal- the joint between the costal cartilages and the sternebrae
Costochondral- the joint between the rib bone and the costal cartilage
Where does the tubercle lie in relation to the head of the same rib?
Tubercle lies above (dorsal) to the head of the rib- on the dorsal aspect connecting to the spinal column (thoracic vertebrae)
Sternocostal joint- between the costal cartilages and the sternebrae
3rd rib?
4th sternebrae?
a. Subscapular fossa
b. Glenoid cavity
c. Serrated face
d. Coracoid process
e. Supraglenoid tubercle
f. Supraspinatous fossa
g. Notch
h. Acromion
i. Spine
j. Infraspinatous fossa
Humerus
- Head
- Lesser tubercle
- Greater tubercle
- Shaft
- Olecranon fossa
- Lateral epicondyle
- Trochlea
- Medial epicondyle
- Lateral epicondyle
- Coronoid fossa
- Deltoid tuberosity
- Intertubercular groove
unnumbered- Capitulum
This is the craniocaudal (beam enters cranially and exits caudally) view of the humerus- belonging to which side of the animal?
Left side
Which side of the limb is the styloid process of the radius
Medial side of the limb
- Trochlear notch
- Anconeal process
- Styloid process
- Olecranon
- Coronoid process
- Interosseus space
- Head
- Neck
- Radial tuberosity
- Medial coronoid process
- Trochlear notch
- Lateral coronoid process
- Radial notch
What is the glenohumeral joint?
Shoulder joint
Elbow joints (3)
Classify the elbow- what 3 bones have to do with it?
Humeroradial, humeroulnar, proximal radioulnar joints
Humerus, ulna, and radial bones form the joint. The lower end of the humerus has two rounded knobs (the lateral and medial condyles)- with a hole called the supratrochlear foramen. The radius and ulna basically act as one bone- as they are held tightly together by ligaments.
Hinge joint, synovial joint
What movement does the radioulnar joint allow?
3 joints are termed the elbow joint and they share a common joint cavity. The elbow is a hinge joint that allows movement in one plane.
The radioulnar joint allows a pivoting movement of the ulna around the radius which accounts for the rotation that is possible at the elbow joint.
What are the boundaries of the pelvic inlet and the pelvic outlet?
Pelvic inlet- cranial opening- bounded by the sacrum, ilium and pubis (rigid boundary)
Pelvic outlet- caudal boundary- perineum (region and a wall)-spot under the dog’s tail- area between the anus and vulva or scrotum
What are some differences between the humerus and femur?
Main difference is size
Stifle Joint- what 3 bones? What sesamoids?
What are A, B, and C?
3 bones: Femur, Patella, and Tibia
Sesamoids: Patella, Fabellae (medial and later), and Popliteal sesamoid
A & B are fabellaes
C would be the popliteal sesamoid
* The Grastocnemius muscle has two tendons of origin within each of which a sesamoid bone (fabella) develops
* The smallest and most distal sesmoid is located within the tendon of origin of the popliteus muscle adjacent to its muscle fibres and it articulates with the lateral condyle of the tibia
* The most proximal sesamoid bone develops in the tendon of insertion of the quadriceps femoris muscle and it is called the patella which articulates with the trochlea of the femur
*
What view of the hindlimb is this?
What 3 structures help you answer this question?
Tibia is the thicker bone, while the fibula is the thin bone that is caudal to the tibia. You cannot see the fibula
The calcanean tuber (point of hock) is the large bony process.
Talus bone
A- Medial condyle
B- Cranial border (tibia crest)
C- Medial malleolus
D- Fibula
E- Tibia
F- Popliteal notch
G- Caudal intercondylar area
A- Lateral condyle
B- Intercondylar eminence
C- Head of fibula
D- Tibial tuberosity
E- Lateral malleolus
F- Cranial intercondylar area
The Metatarsals, phalanges, and sesamoids of pes- what are they like? What is one difference?
Similar to the manus except for the bones of digit I, this digit may be present or absent or variable in its anatomy- if it is present it is referred to as the dewclaw.
Sacroiliac joint- what is the name given to the articulating surface of both the sacrum and the ilium in this joint?
Ilial wing and the sacrum- “auricular sufaces” of both (shape)
Synovial joint
What is the pelvic symphysis?
Comprises the pubis symphysis and ischiatic symphysis
What is the coxofemoral joint?
Hip joint
What is the stifle?
(hint: 2 joints)
What of the joints has two menisci- why is this important? where do they lie?
Comprises the femoropatellar and femorotibial joints
* there are two fibrocartilagionous menisci (two pads of fibrocartilagionous tissue which serve to disperse friction in the knee joint between the lower leg (tibia) and the thigh (femur)) in the femorotibial joint that lie between the femoral and tibial condyles. These accomodate the mismatched shapes of the femoral and tibial condyles and act to spread and dissipate forces through the joint.
Name the articulations at A, B, and C
A- Sarcoiliac joint
B- Coxofemoral joint
C- Femorotibial joint
Name the articulations occurring at D
Distial tibiofibular joint, tarsocural joint, proximal intertarsal joint, distal intertarsal joint, intratarsal joint, tarsometatarsal joint
Dog femur enchondral ossification (slightly different than other bones- they are larger) example- timing of femoral head, greater trochanter, lesser trochanter, and distal epiphysis- secondary ossification centres
Variation in timing- has to do with how large the animal will be.
A turning into B. initial woven bone spicules have been filled in by osteoblastic activity. Thin cortex surrounding trabecular activity in the middle.
Simple situation with flat bones as shown.
Larger diaphysis- add on bone around the outside- osteoblastas all the way around the outside of the periosteal surface. It doesn’t go all the way up
Epiphysis in a 2 week old dog becomes the metaphysis in a 6 month old dog. So you also need bone resorption to allow for the shaping of the bone
Underneath the growth plate- metaphyseal trabecular being formed.
Marrow cavity needs to be expanded- so that the growing animal has appropriate amount of bone marrow. Resorption to enlarge it.
Growing tibia from a rat.
Blue box- what was metaphysis being resorbed so that it can be thinned to achieve appropriate diameter
What are the black arrows?
Osteoclasts
What happens with high mechanical loading e.g. exercise? What surfaces remodel?
Stimulates osteoblasts and inhibits osteoclasts. Though sometimes the bone needs to change shape so some resorption will take place.
Modeling can occur: Periosteal surfaces, endosteal surfaces, or trabecular surfaces
E.g. TB horse example. Control group out in a paddock. TB trained for racing. Top bone more spaces. Bottom bone- Trabecular bone has almost turned into a cortical bone in response to mechanical loading. Converse occurs when bones are unloaded. Rapidly bone is resorbed if resting- even the TB race horses. More disorderly in the early stages after cessation of training.
Cortical bone remodeling
Leads to establishment of Haversian systems (osteon- fundamental functional unit of much compact bone– osteons are cylindrical structures). Osteoclasts drill longitudinal tunnel through the bone between I & II. Blood vessel following them. Surface of the cavity they created we have osteoblasts depositing lamellae (the concentic rings) bone. Last picture, leaves space for blood vessels in the middle. You can see the multiple concentric lamellae.
Fracture repair
Bone repair occurs in four stages
Inflammation, soft callus formation, hard callus formation and remodelling.
Fracture= bleeding and haematoma= Inflammation
- Inflammation- Inflammatory cells are attracted to the haematoma through responses to coagulation factors (thrombin for example have receptor mediated effect on cells and chemotactic for inflamm cells), also degran of platelets- granulocytes, macrophages, etc. they perpetuate the inflamm. state by releasing GFs and inflamm. cytokines and VEGF (vascular endothelial GF)- cause angiogenesis and attract mesenchymal stem cells from other tissues. Results in formation of granulation tissue.
- Soft callus formation- not all fractures go through this phase. Mesenchymal stem cells in the granulation tissue differentiate into chondrocytes and fibroblasts- create fibrocartilaginous- creates support for fracture. Cartilage that is formed then starts to undergo endochondral ossification- diff. of chondrocytes, secrete cartilage matrix, undergo hypertrophy then to hard callus formation on cartilage model.
- Hard callus formation- deposition of mineralized matrix. Need good blood supply. High oxygen tension! Osteoblasts need this (chondrocytes do not need this as much)
- Callus remodelling- Initial mineralization that you get is generally woven bone, but remodelling is resorption and then replacement by orderly lamellae bone by the osteoblasts.
Where are the flexor surfaces in the forelimb? Front or back?
Where are the flexor surfaces in the hindlimb?
What is the resting position of the distal interphalangeal joint?
What direction of movement when flexion occurs in the metacarpophalangeal joint?
In which direction will the claws move with hyperextension (dorsiflexion) of the distal interphalangeal joint?
- Slight curved position- straightened but not all the way- the distal interphalangeal joint is a saddle joint- combines two surfaces each maximally convex in one direction and maximally concave in the other direction.
- Toward the body- Think of the way the wrist curves.
- Away from the body- opposite of metacarpophalangeal joint
What is this showing?
Circumduction
Coxofemoral joint is the pivot. The hip joint allows flexion, extension, abduction, and adduction.
The hip joint is a ball and socket or spheroidal joint.
What do you have to do to the stifle and the flexed hock to rotate the femur (therefore its head) INWARDS?
Elevate the flexed hock and depress the flexed stifle
What do you have to do to the stifle and flexed hock to rotate the femur outwards?
Elevation of the flexed stifle and depression of the flexed hock.
How would you describe the position of all the fetlocks (metacarpo- and metatarsophalangeal joints)?
Flexion
How would you describe the carpuses and metacarpophalangeal joints?
Carpuses- extension
Metacarpophalangeal joints- hyperextension
How would you describe the position of all of the joints in the hindlimb at this point?
Extension
What is the asterix?
Calcaneal tendon (superficial digital flexor m. tendon)
There is reduced flexion in the stifle- what are some possibilities on why?
Oedema around the common calcaneal tendon and hock.
When she sits, she cannot bend the stifle joint properly- so it stays out in front of her.
Which joints are likely to be responsible for this abduction and rotation?
Hip joint is allowing abduction and rotation most likely. The stifle is flexed.
