Musculoskeletal: Directions, intro, tissues, histology Flashcards
Tissue: definition and types?
A group of similar cells and intercellular material specialised to carry out specific activity. Epithelial, connective, muscle, nervous.
Organ: definition?
Discrete portion of the body composed of two or more tissue types.
Long axis
Imaginary line through centre of an organ or structure of the body
Median plane
divides the head, body or limb longitudinally
into equal left and right halves
Sagittal plane
- paramedian
- passes through the head, body or limb
parallel to the median plane but located
further lateral
Transverse plane
Any plane perpendicular to the long axis of
the body, organ or part
Dorsal plane
Any plane that is parallel to the dorsal
surface
Dorsal
Ventral
Dorsal: toward the back and corresponding
surface of the head, neck and tail
Ventral: toward the belly and the corresponding
surface of head, neck and tail
Cranial
Caudal
Rostral
Cranial: toward the head
Caudal: toward the tail
Rostral: toward the tip of the nose
Proximal
Distal
Proximal: relatively near to the main mass (or trunk)
Distal: away from the main mass (or trunk)
Front/back directional terms for:
- Proximal segment (limb)
- Distal segment (thoracic limb)
- Distal segment (pelvic limb)
- Proximal segment (limb)
- Cranial, caudal
- Distal segment (thoracic limb)
- Dorsal: applies to the upper or front surface of the carpus and digits
- Palmar: aspect of forepaw that contacts the ground of the standing animal
- Distal segment (pelvic limb)
- Dorsal: applies to the upper or front surface of the tarsus and digits
- Plantar: aspect of hind paw that contacts the ground of the standing animal
Distal segment of limb:
- Axial
- Abaxial
Midline (axis) taken between digits 3 & 4:
- Axial: Direction towards midline
- Abaxial: Direction away from the midline
Directional terms bones:
- Proximal
- Distal
- Proximal: towards the tunk
- Distal: towards the ground
Directional terms bones:
- Cranial
- Caudal
- Cranial: surface closer to the head
- Caudal: surface closer to the tail
Directional terms bones:
- Lateral
- Medial
- Lateral: away from midline of body
- Medial towards midline of body
To describe the position of a structure in the body or in a hollow organ use:
- External
- Internal
- Superficial
- Deep
- External: Structure is away from the hollow centre of an organ
- Internal: Structure is near the lumen of an organ
- Superficial: Structure is relatively near the surface of the body or the surface of a
solid organ - Deep: Structure is relatively near the centre of the body or the centre of a
solid organ
To describe position of certain
structures in the head use:
- Anterior
- Posterior
- Superior
- Inferior
- Anterior
- Posterior
- Superior
- Inferior
These terms replace:
- Cranial
- Caudal
- Dorsal
- Ventral
But only for specific areas on the head
Regions of the body:
Head
Neck
Trunk
Limbs
Tail
- Head (caput)
- Neck (collum)
- Trunk (truncus)
- Limbs (membra)
- Tail (cauda)
Steps: processing tissue for histology
- Place fresh sample in ______. Why?
- Embed in ________ after dehydration in _______. Why?
- Cut thin tissue sections (____μm) on microtome. Why?
- Collect tissue sections on glass slide, ____, and
place coverslip over tissue. Why?
- Place fresh sample in formalin fixative.
- stops cell metabolism and autolysis
- kills microbes
- Hardens tissues (protein denaturation and crosslinking)
- 10% neutral buffered formalin
- Embed in paraffin wax after dehydration in alcohols
- Removes water and hard substance can be cut into slices
- Cut thin tissue sections (5-7 μm) on microtome
- Thin to allow light of microscope to shine through
- Approx. one cell thick so cells aren’t overlapping
- Collect tissue sections on glass slide, stain and place coverslip over tissue to preserve
Haematoxylin stains [basophilic/acidophylic] structures e.g. ______________. It is ____ in colour.
Haematoxylin stains basophilic structures e.g. nucleus (DNA/RNA)
Most common histological stain type?
haematoxylin and eosin
Eosin stains [basophilic/acidophilic] structures e.g. _____. It is ____ in colour.
Eosin stains acidophilic structures e.g. cytoplasm. It is pink in colour.
What is an artifact? Examples?
Artifacts are abnormalities seen in the histology that are due to processing rather than disease.
E.g.
- Tears
- Folds
- Stain residue
- Shrinkage
- Structure loss
Why do veterinarians need to understand histology?
- Need to know normal cells and tissues of the body
- Must understand disease processes at this level to beable to diagnose animal illness correctly
- Need to be able to interpret histopathology reports of samples collected from patients
- Need to explain this information to the owners
- Future pathology or research careers
SKELETON TOPOGRAPHY
- Cranial
- Postcranial
- Axial
- Appendicular
- Cranial: skull and mandible
- Postcranial: all the rest
- Axial: head, vertebral column, tail
- structures oriented along the midline
- Appendicular: limbs
Functions of bone (5)?
- Support
- Locomotion
- System of levers
- Protection
- Storage
- Esp. calcium, phosphate
- Haemopoiesis
- Manufacture of red blood cells
Classification of bones (4 types): shape, number of centres of ossification, example
- Long bones
- a bone that is longer than it is wide
- three centres of ossification
- e.g. humerus, tibia, fibula
- Short bones
- a bone that is as wide as it is long
- single centre of (endochondral) ossificaiton
- e.g. carpal bones, tarsal bones
- Flat bones
- sandwich of two plate-like layers of compact bone with trabecular bone between
- intramembranous ossification
- e.g. scapula, frontal, parietal
- Irregular bones
- number of ossification centres varies
- e.g. vertebrae
Special types of bone (3) with description and examples?
- Sesamoid bones
- found within tendons
- change direction of force, protect structures from excessive pressure and friction
- e.g. patella
- Splanchnic bones
- develop in soft organs
- e.g. os penis (baculum)
- Pneumatic bones
- bones containing air spaces
- e.g. certain skull bones and avian long bones
Describe and give the terms for (in a long bone):
- Compact bone
- Spongy bone
- Periosteum
- Medulla
- Articular cartilage
- Compact bone (yellow):
- cortical bone (outer layer of diaphysis, thin layer over epiphysis)
- hard, dense tissue (heavy)
- Spongy bone (blue):
- cancellous/trabecular bone
- open, porous, 3D thin bony network of struts
- allows room for blood vessels and bone marrow (esp. red)
- ends (epiphyses) or long bones
- Periosteum (red):
- loose connective tissue covering the bones with the exception of the articular surfaces
- Medulla:
- central cavity in long bone
- contains adipose tissue (yellow marrow) and some red marrow
- Articular cartilage:
- covers articular surfaces of bones
- smooth hyaline cartilage
- blends with periosteum and joint capsules
Label the forces:
Forces produce stresses resulting in strain
Gross anatomy of skeletal muscle: Label and describe these structures
- Muscle belly
- also called the head
- enveloped in connective tissue sheath
- Tendon
- Attaches muscle to bone or aponeurosis
- dense regular fibrous connective tissue
- Origin
- Proximal attachment
- Insertion
- Distal attachment
Skeletal types based on fibre orientation: label and describe with example
- Strap:
- long, parallel fibres and have relatively broad attachments
- force of contraction weak
- e.g. omotransversarius
- Fusiform:
- their fibres lead into narrow tendons at the ends of a muscle belly
- force of contraction is concentrated on a smaller area and therefore stronger
- e.g. biceps brachii
- Pennate:
- short, diagonally arranged fibres
- Unipennate
- attached to one side of tendon
- e.g. flexor digitorum profundus (ulnar head)
- Bipennate
- attached to both sides of a centrally located tendon
- e.g. infraspinatus
- multipennate
- attached to more than one tendon
- more muscle fibres produce more force
- e.g. subscapularis
- Circular and Sphincter
- bands of muscles that contract concentrically
- circular e.g. orbicularis oris
Muscle contraction:
- Concentric
- Eccentric
- Isometric
- Concentric (a)
- muscle shortens under tension
- bones move closer together
- Eccentric (b)
- muscle elongates under tension
- bones move away from each other
- Isometric (c)
- no visible motion - static
Explain what the following terms mean applied to muscles:
- Agonist
- Antagonist
- Synergists
- Agonist (prime mover)
- produces the desired motion at a joint
- Antagonist
- opposes the action of the agonist
- Synergists
- help the agonist to perform the desired motion
Label this diagram of a long bone:
What are some advantages of having hollow rather than solid bones?
- trabeculae enable resistance of compressive force in multiple directions (increase in strength)
- decrease weight of bone at joint while maintaining strength
- lower structure and higher surface ares and number of active osteoblasts increases bone turnover potential: good for rapid release and building/remodelling
- space for hematopoeisis
What is found in the spaces between spongy (trabecular) bone?
Red bone marrow: site of haematopoeisis
Connective tissue cells originate from the ____chymal cells of the embryo, which are derived from the ____derm. Connective tissue is composed of cells, _______ (ECM), and g____________.
Connective tissue cells originate from the mesenchymal cells of the embryo which are derived from the mesoderm. Connective tissue is composed of cells, extracellular matrix (ECM), and ground substance. The ECM characteristics define the properties of the connective tissue.
Describe some of the properties of fibroblasts
- Found in fibrous connective tissue
- Pale, oval nucleus
- elongated shape
- protein-producing organelles
- may have contractile properties (actin) for cound healing ‘myofibroblasts’
Fibrocytes are ________ cells that are located amongst the c______ _________.
Fibrocytes are mature cells that are located amongst the collagen fibres.
ECM:
Elastin: what are some of its properties and where is it found?
- Protein with elastic properties that allows stretch and recoil to original position
- 5x more elastic than rubber
- Elastic fibres have cross-links
- Found in varying amounts in:
- arteries
- lungs
- elastic cartilage ie ears, nose
- some ligaments/ tendons ie nuchal
- dermis of skin
ECM:
Collagen: What are some of its properties and what is it composed of?
- Most abundant protein in the body
- Collagen is arranged in fibres composed of smaller subunits called fibrils
- Fibrils are composed of collagen molecules which are a triple helix of α-chains
Identify the structures labelled in this transmission electron micrograph of fibrous connective tissue ECM
Collagen (C), elastin (E) and ground substance around fibroblasts (F)
TENDON
Identify the structures shown in this histological sample
TF= tendon fascicle Ent= endotendineum
Tendon fibre fascicles/bundles are surrounded by endotendineum.
What cell type is present in cartilage below the perichondrium (fibrous connective tissue layer around the edge of cartilage) and can regenerate the ECM after damage?
Chondroblasts
In hyaline cartilage, chondrocytes are found in spaces called L_______. Alteration in the matric around these referred to as c_______.
In hyaline cartilage, chondrocytes are found in spaces called lacunae. Alteration in the matric around these referred to as capsules.
Hyaline cartilage is made up of 15% p_______-h______ ____ complexes.
These are extrememly hydro______ and thus hold water within the cartilage matrix to provide compression resistance.
Hyaline cartilage is made up of 15% proteoglycan-hyaluronic acid complexes.
These are extrememly hydrophilic and thus hold water within the cartilage matrix to provide compression resistance.
A______________ refers to hyaline cartilage found in joints.
Articular cartilage refers to hyaline cartilage found in joints.
See image:
AC= articular cartilage
SB= spongy bone (sometimes referred to as subchondral bone in this location)
BV= blood vessels
M= marrow cavity
What role does weight bearing play in providing nutrition for hyaline cartilage at the joints?
- Cartilage is avascular
- Hyaline cartilage nutrition is via diffusion from blood vessels in subchondral bone and nutrients in synovial fluid
- Weight bearing squeezes the fluid out of matrix and the proteoglycan molecules attract water back into the matrix again causing a net movement of nutrients into the tissue matrix and nourishing the chondrocytes
Label these parts of the synovial membrane:
Two types of synoviocytes:
One produces the transudate and looks like a fibroblast and the other is like a tissue macrophage
As well as joints, also line some tendon sheaths forming a ‘synovial sheath’ for the tendon to slide through, protected from other structures
Name and describe the two types of adipose tissue and their functions.
- Yellow fat
- insulation
- energy source suring starvation as triglycerides
- padding of vital structures - shock absorption
- found under skin, in diaphysis of adult bones, in connective tissue, in digital and metacarpal/tarsal pads
- primary cell type: adipocytes
- Brown fat
- heat production in hibernation and newborns (around neck and back)
- Abundant mitochondria and small lipid droplets within cells
Brown fat (L) and yellow fat (R)
The bone ECM produced by osteoblasts is composed primarily of
- O_________
- C__________ 15%
- G__________ 10%
- C________ h_________ 75%
- Osteoid (unmineralised protein matrix)
- Collagen (type 1) 15%
- Ground substance/organic martix 10%
- Calcium hydroxyapatite 75%
- provides strength & resists compression
What are osteoclasts and what are their function?
- Bone matrix degrading macrophages
- Origin is in blood cell lineage not the mesenchyme
- Multinucleated cells (4-10 nuclei)
- Acidify the bone matrix to dissolve hydroxyapatite
- Enzymatically degrade proteins
- Normal bone turnover
- Repair damaged matrix
- Release calcium into blood
Label this histological sample of bone tissue
STRUCTURE OF COMPACT BONE
- Bone is arranged in dense concentric layers ‘L______’
- These cylinders of layered bone are called ‘O_______’
- Centre of osteon is a blood vessel within the c_____ (Haversian) canal
- Bone is arranged in dense concentric layers ‘lamellae’
- These cylinders of layered bone are called ‘osteons’
- Centre of osteon is a blood vessel within the central (Haversian) canal
HC= Haversian canal L= lacunae with osteocyte IL= interstitial lamellae
- Osteocytes located in L_______ (spaces) in compact bone lamellae in osteons
- C_______ (small channels) allow connection of all osteocytes via cytoplasmic processes - communication
- Allows passage of extracellular fluid with nutrients to reach these living cells
- Osteocytes located in lacunae (spaces) in compact bone lamellae in osteons
- Canaliculi (small channels) allow connection of all osteocytes via cytoplasmic processes - communication
- Allows passage of extracellular fluid with nutrients to reach these living cells
Label this image of compact bone
Perforating V______’s canals connect central
(Haversian) canals. Their role is to carry blood supply
from the ______ & ________ arteries.
Perforating Volkmann’s canals connect central
(Haversian) canals. Their role is to carry blood supply
from the nutrient and periosteal arteries.
Trabeculae are surrounded by _____ bone marrow and a______ cells. No blood supply within trabeculae - diffusion of nutrients - so limitation on thickness. Ability for high bone turnover by _________ and ________.
Trabeculae are surrounded by red bone marrow and
adipose cells. No blood supply within trabeculae - diffusion of nutrients - so limitation on thickness. Ability for high bone turnover by osteoclasts and osteoblasts.
Label this diagram of bone cell types
Steps in intramembranous ossification:
- Development of ossification centre - o________ sheet producing matrix
- Calcification of matrix (h_______ laid down after o______)
- Formation of cortical plates with internal t_______
- Development of p_________
- Growth is _________ to increase size during maturation
Steps in intramembranous ossification:
- Development of ossification centre - osteoblast sheet producing matrix
- Calcification of matrix (hydroxyapatite laid down after osteoid)
- Formation of cortical plates with internal trabeculae
- Development of periosteum
- Growth is appositional to increase size during maturation
Label this histological sample of flat bone structure
* Compact bone may be deposited in flat lamellae (layers) in flat bones, rather than in cylindrical osteons as in the diaphysis of long bones
Development: Long bones will have a ______ at each end between the epiphysis and metaphysis.
This ______ cartilage allows long bones to increase in _______ in growing animals.
Development: Long bones will have a physis at each end between the epiphysis and metaphysis.
This physeal cartilage allows long bones to increase in length in growing animals.
Label the histological cones of the physis:
- ?
- ?
- ?
- ?
- ?
- Resting zone of chondrocytes
- Proliferative (growth) zone
- Chondrocytes multiply- columns of cells
- Hypertrophic cartilage zone
- Chondrocytes enlarge and matrix shows beginnings of mineralisation
- Calcification of cartilage zone
- Calcium is deposited in the cartilage
- Cartilage matrix is removed by chondroclasts
- Osteoblasts and blood vessels enter
- Ossification zone
- Cartilage is fully replaced by bone
What happens during growth plate fractures?
Cause abnormal bone development due to lack of longitudinal growth of bone at location of damage
Good prognosis –> poor prognosis
Label this diagram of long bone growth
Label this diagram of the blood supply to a long bone.
All the arteries anastamose. Why?
- Epiphyseal arteries
- Metaphyseal arteries
- Nutrient artery
- Enters via nutrient foramen in diaphysis of long bones
- Periosteal arteries
- All anastamose to ensure blood supply
For bone healing to occur there must be:
- _____ bridging
- Adequate/little blood supply
- No/movement
- No/infection
- No/weight bearing
For bone healing to occur there must be:
- Gap bridging
- Adequate blood supply
- No movement
- No infection
- Weight bearing - pain management
