Lecture 1: Osteology, Myology, Anthrology Flashcards
7 primary functions of the bone
- Support the weight of the body
- Movement in concert with muscles
- Protection of internal organs
- Growth
- Storage of minerals (phosphorous and calcium)
- Storage of fat within yellow marrow cavities
- Blood cell formation within red marrow cavities
What is the real term for blood cell formation?
hematopoiesis
Where is red marrow found in adults?
Flat bones
Two divisions of the skeleton
Axial
Appendicular
Axial skeleton
Bones of the axis of the body
Skull, thorax, vertebral column
Appendicular skeleton
bones of the appendages and limbs
5 types of bone
Long Short Flat Sesamoid Irregular
How do we classify a long bone?
The length of the bone is greater than its diameter
Where are long bones found?
In the appendages
How many ossification centers do long bones have
Multiple (3 - 2 epiphasis, 1 diaphysis)
Ossification center
Where ossification first begins
The site of the earliest bone formation via accumulation of osteoblasts within connective tissue (intramembranous ossification) or of earliest destruction of cartilage before onset of ossification (endochondrial ossification)
Endochondrial ossification
- A cartilage model
- Mesenchymal cells become chondroblasts which produce a cartilage model which is later replaced by bones
What kind of ossification happens with long bones?
endochondrial ossification
Diaphysis
long, straight main body of a long bone
Epiphysis
End regions of the bones
Metaphysis
Region of the bone lying between the diaphysis and epiphysis
Metaphyseal growth plate
located between epiphyses and diaphysis in young animals. Composed of cartilage
Short bones have approx. ______ dimensions
Equal
How many center of ossification do short bones have?
1
Therefore, no growth plates
When are flat bones present?
When either extensive protection or large muscle attachment area is necessary.
Diploe
Cancellous tissue enclosed by two thin layers of cortical bone.
In certain areas of the skull, this is absorbed to form air sinuses
How are irregular bones formed?
Both endochondral ossification and intramembrous ossification
Intramembrous ossification
Bone formation without a cartilage model
Mesenchymal cells become osteoblasts directly rather than becoming chondroblasts
Sesamoid bones
Small, seed-like bones that are embedded in muscle tendons
All sesamoid bones are short bones, but
not all short bones are sesamoid bones
Three purposes of sesamoid bones
- Eliminates tendon shear
- Redirects line of force
- Increases torque
Periosteum
- Lines outer surface of the bone
- Source of osteoblast progenitor cells (healing fractures)
- Rich in nerves and blood vessels; extremely sensitive
Osteoblasts
Cells that lay down bone
Endosteum
lines inner surface of bone
Medullary Cavity
Location of bone marrow (red or yellow)
Younger animals will have more _____ marrow
red
Most bones are formed by
endochondrial ossification
What bones are formed by intramembrous ossification
Flat bones, including the bones of the calvaria (top of the skull) and face
Why is the growth plate clinically relevant
Often the primary site for infection, metastisis, fractures, and effects of endocrine disorders
What results in dwarfism?
Achondroplasia
chondrodystrophy
Chondrodystrophy
- Cartilage maldevelopment
- Genetic conditions
- Causes arrested growth of long bones
- Results in disproportionate dwarves
Bone blood supply
- Nutritional vessels enters the diaphysis and epiphysis
- The majority of long bones have a single nutrient foramen that accommodates a nutrient artery that enters the bone mid-diaphysis
What supplies the outer, cortical bone?
Periosteal blood vessels
Wolff’s Law
Normal bone remodels in response to the stress placed upon it
If a load in a particular area of the bone increases,
The bone will remodel to become stronger to resist the force
Myology
The study of muscles
Three types of muscle
smooth, skeletal, cardiac
Smooth muscle
- In organs and blood vessels
- ANS
Skeletal muscle
- Attached to the skeleton
- Voluntary
Cardiac muscle
- Muscle of the heart
- ANS
The locomotor system (apparatus) includes
all structures that provide the body with:
- stability (skeleton)
- independent movement (muscles/joints)
- the basis for the characteristic conformation of individual species
The musculoskeletal system is divided into two components:
The muscular system - Active
The skeletal system - Passive
The muscular (active) component
- Consists of muscles that move parts of the individual body such as the limbs, the trunk, and the head
- Provides the individual with means of locomotion
Skeletal muscle fibers are made to
actively contract
Three layers of connective tissue surrounding skeletal muscle fibers
Epimysium
Perimysium
Endomysium
Epimysium
outermost connective tissue surrounding the muscle belly
Perimysium
extend from epimysium into the muscle; divides muscle into smaller units called musclefascicles
Endomysium
Extends from the perimysium to envelop individual fiber muscle cells
7 criteria for muscle nomenclature
- Shape
- Size
- Relative position/direction
- Origin and insertion
- Function
- Structure
- Combo of above
Muscles attach to bones via
tendons
Tendon of origin
- May originate from bone, another muscle, or skin
- Usually the more proximal or fixed point of a muscle attachment
Tendon of insertion
- Inserts on bone, another muscle, or skin
- Usually distal or movable part of the muscle
Aponeurosis
A sheet-like tendon that allows muscles to have broader attachments
Three associated structures that ease the effect of excessive pressure or friction associated with tendons
- Sesamoid bones
- Synovial subtendonous bursa
- Synovial sheath
Ligaments attach
bone to bone
5 arrangements of muscle fibers
- Parallel to the long axis (strap-like)
- Fusiform (spindle-shaped)
- Pennate (angled to one side)
- Bipennate (angled to the inside)
- Mulitpennate (multiple different angles)
More fibers, more cross sectional area =
more powerful
Arrangement of muscle fibers in biceps brachii, triceps brachii, quadriceps femoris, ect.
Muscles arise by two, three, or four heads that merge into one tendon of insertion
Arrangement of muscle fibers in digastricus, brachiocephalicus, ect
Two or more fleshy regions are separated by an intermediate tendon forming digastric or polygastric units
Arrangement of muscle fibers in Orbicularis occuli, orbicularis oris, external anal sphincter
Muscle fibers arranged into rings that surrounded natural openings
Synovial bursa
- One-sided protection of muscle tendons
- Can be subcutaneous, subtendinous, or intertendinous
Synovial tendon sheaths
Synovial fluid-filled sacs that surround muscle tendons
Fascia
- Allow muscles to function as units
- Divided into superficial and deep
Superficial fascia
Usually loose connective tissue
Deep fascia
- Dense collagenous connective tissue from which some muscles may originate or insert; attaches to bone
- Surrounds and compartmentalizes muscles; distinct fascial septa separate groups of muscles from one another and result in fascial planes
Clinical relevance of understanding fascial planes?
Understand the spread of infection -will spread to the area of least resistance
Arthrology
The study of the structure and function of joints
Joint
- A point of contact, or articulation, between two or more bones/cartilage
- Provides support and movement to the skeleton
- Keep in mind that not all joints are moveable
Two types of classification of joints
- Functional
- Structural
Functional classification of joints
Physiological classification -based on the amount of movement permitted
Structural classification of joints
Anatomical classification
Based on structure, which is based on the type of connective tissue present between bones
Three types of functional classification of joints
- Synarthroses
- Amphiarthroses
- Diarthroses
Synarthroses
- Immovable joints
- Includes: synostosis
Amphiarthroses
- Semimovable joints
- Includes: suture, syndesmosis, synchondrosis
Diarthroses
- Freely movable joints
- Includes: Synovial joints
Three types of structural classification of joints
- Fibrous
- Cartilaginous
- Synovial
Fibrous joint
- Strong fibrous connective tissue (dense irregular) between articulating bone
- Little to no movement
- In some cases, bones can fuse resulting in a bony joint (synostosis)
Cartilaginous joint
-Cartilage, either hyaline or fibrocartilage, between articulating bones = limited movement
Synovial joint
-Joint cavity between articulating bones lined with synovial membranes = free movement
Three types of fibrous joints
Suture
Syndesmosis
Gomphosis
Suture joint
- Seams (interdigitation) of the bones and the skull
- Gradually eliminated via ossification (results in synostosis)
Gomphosis
- Tooth in alveolus, united by periodontal ligament
- Not technically a joint by classic definition because teeth are technically not considered bones
Syndesmosis
Bones joined by interosseous ligaments (radius/ulna and tibia/fibula)
Two types of cartilaginous joints
Synchondrosis
Symphysis
Synchondrosis
- Hyaline cartilage union
- Ex. Coastal cartilage connecting ribs to sternum, growth plates
Symphysis
- Occurs in the midline of the body where articulating bones are connected via a flat disc of fibrocartilage
- Ex. pelvic symphysis, intervertebral disc
Synovial joint classification types
- Number of bones
- Shape
Structure of a synovial joint
- Joint capsule consists of an outer fibrous layer and an inner synovial membrane
- The outer fibrous layer blends with the periosteum and is thickened in some joints to form ligaments
Inner synovial membrane of a synovial joint
Highly vascularized, has nerves, and the synoviocytes produce synovial fluid for lubrication and nutrition of the bone surfaces
Three accessory structures of the synovial joint
- Meniscus
- Ligament
- Fat pads
Meniscus
Fibrocartilage located within the synovial cavity
Ligaments
- Extracapsular: located outside of the joint capsule
- Intracapsular: occur within the joint capsule, but are excluded from the synovial cavity by folds of the synovial membrane
Fat pads
Between fibrous and synovial layers, may protrude into joint cavity
Ways synovial joints can be classified
By number of articulating bones -Simple joint -Compound joint How well bones fit together -Congruent joint -Incongruent joint Shape
Simple vs Compound synovial joints
Simple - formed by two bones
Compound - formed by more than two bones
Congruent vs incongruent synovial joints
Congruent - two articular surfaces fit together
Incongruent - two articular surfaces do not fit together
Shape of a joint determines
Permitted motions around the joint
Hinge synovial joint
Permits angular motion in one plane
Spheroidal synovial joint
- Ball and socket
- Permits rotation and other movement
Plane synovial joint
Permits angular motion in one plane
Condylar synovial joint
formed by two condyles of one bone fitting into concavities of another bone
Pivot synovial joint
permits rotation around the longitudinal axis of a bone
Ellipsoidal synovial joint
oval surface nestles within a depression in the opposing surface
Saddle synovial joint
articular surfaces of the two articulating bones are concave
7 synovial joint shapes
Saddle Ellipsoidal Pivot Condylar Plane Spheroidal Hinge
Two kinds of motion of synovial joints
Gliding/translation
Angular motion
Gliding/translation
two surfaces slide past each other
11 Angular motions of synovial joints
- Flexion
- Extension
- Hyperextension
- Adduction
- Abduction
- Circumduction
- Left/right
- Lateral rotation
- Medial rotation
- Pronation of the forearm
- Supination of the forearm
Flexion
Decreasing angle between bones
Extension
Increasing angle between bones to approx. 180 degrees
Hyperextension
Increasing angle past anatomical position
Abduction
Moving away from median plane
Adduction
Moving towards median plane
Circumduction
Movement circumscribing a cone shape
Left/Right
Head movement
Pronation
Palmar surface rotated to touch ground
Supination
Palmar surface faces medially
Purpose of intra-articular injections
- Anesthetics for lameness evaluations
- Treatment for osteoarthritis
