Exam 1: Osteology, Myology, Arthrology Flashcards
Long Bones
- The length of the bone is greater than its diameter.
- Multiple ossification centers (growth plates)
- EX: locted in the appendages such as humerus, radius, ulna, femure, tibia, fibula, metacarpals/tarsals
Anatomy of long bones
Note: Metaphyseal growth plate is compromised of cartilage in young animals
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Short bones
- Have approimate equal dimensions (cube shaped)
- EX: carpal bones, sesmoid bones (don’t articulate with other bones)
- Only one ossification center
- NO growth plates
Ossification center
- Site of earliest bone formation via accumulation of osteoblasts with connective tissue (intramembranous ossification)
- Earliest destruction of cartilage before onset of ossification (endochondral ossification)
Flat bones
- Present when either extensive protection or attachment area is necessary
- EX: scapula, bones of the skull
- Contain a lot of active red marrow; which is why we take bone marrow bx from these sites
- Diploe: cancellous tissue enclosed by two thin layers of cortical bone (seen in certain areas of the skull)
Irregular bones
- Can’t be classified under any other category
- Short bones with multiple processes
- EX: vertebrae
- Formed by endochondral ossification (body of bone) and intramembranous ossification (bony processes)
Sesamoid bones
- Small, seed-like bones that are embedded in muscle tendons
- ALL sesamoid bones are short bones but all short bones are NOT sesamoid bones
- EX: proximal sesamoid bones of the manus and pes, patella (largest)
- Purposes: 1) eliminate tendon shear (occurs when we have sharp angles between bones) 2) redirects lines of force and 3) increases torque
Periosteum
- Source of osteoblasts (healing fractures)
- Rich in nerves and blood vessels; extremely sensitive
Endosteum
Lines inner surfce of bone; has similar cell types as in periosteum
Medullary cavity
Location of bone marrow (red or yellow)
Bone development
- Most bones form via endochondrial ossification (ossification of a cartilage model)
- Flat bones are formed via intramembranous ossification
Chondrodystrophy
- Cartilage maldevelopment
- Genetic condition (basset hounds and dauschunds)
- Causes arrested growth of long bones
- Results in disproportionate dwarves
Bone blood supply
- Nutritional vessels enter the diaphysis and the epiphysis
- Majority of long bones have a single nutrient foramen that accomodates a nutrient artery that enters the bone mid diaphysis
- Periosteal blood vessels supply the outer, cortical bone
Wolff’s Law
- Normal bone remodels in response to stress placed upon it
- If load on a particular area increases, the bone will remodel to become stronger to resist those forces (muscle building, weight gain)
- Accounts for the variation of bony prominences observed from the specimens in lab
Locomotor system (apparatus)
- Includes all those structures that provide the body with 1) stability, 2) independent movement; mucles and joints 3) basis for the characteristic conformation of the individual species
- Muscular system: ACTIVE componenet of the locomotor system (skeletal muscles
- Skeletal system: PASSIVE component of the locomotor system (bones and joints)
Skeletal muscle components
- Epimysium: outermost connective tissue envelope surrounding the muscle bell
- Perimysium: extends from the epimysium into the muscle; divides the muscle into smaller units or muscle fascicles
- Endomysium: extends from perimysium to envelop individual muscle fibers (CELLS)
Skeletal muscle diagram
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Tendon of origin
- Proximal or central attachment
- May originate from bone, another muscle, or skin (cutaneous muscles)
- Usuall more proximal and or fixed point of muscle attachment
Tendon of insertion
- Distal or peripheral attachment
- Insertion on bone, another muscle, or skin
- Usually distal or moveable point of muscle attachment
Aponeurosis
- Sheet like tendon
- Allows muscles to have broader attachment
Associated structures that ease the effect of excessive pressure or friction associated with tendons
- Sesamoid bones
- Synovial subtendinous bursa : synovial fluid filled bag positioned between a tendon an a bony process
- Synovial sheath: synovial fluid filled bag that wraps around a tendon
Muscle fibers parallel to the long axis
- Result in strap like muscle
- Greater displacement
- Completed by very short tendons of attachment
- EX: brachiocephalicus
Fusiform muscle fibers
- Resulting in a spindle-shaped muscle
- EX Biceps brachii
Pennate muscle fibers
- Fibers that join tendons at an angle
- Pennate, bipennate, multipennate
- “pennatus” = latin for feather
- More fibers = more powerful
- EX: triceps brachii (long head), subscapularis
Flat muscle fibers
- Fibers form flat layers ending in broad tendinous sheets
- Aponeuroses
- EX abdominal muscles
Multiple heads for muscle fibers
- Muscle arises by two, three, or four heads that merge into one tendon of insertion
- EX: biceps brachii, triceps brachii, and quadriceps femoris
Muscle fibers arranged in units
- Two or more fleshy units are separated by an intermediate tendon forming digastric (two bellies) or polygastric units
- EX digastricus, brachiocephalicusm rectus abdominus
Muscle fibers arranged in rings
- Muscle fibers are arranged into rings that surround natural openings
- Eye, mouth, anus
- EX: orbicularis oculi, external anal sphincter
Fascia
- Allows muscles to function as units
- Divided into superficial and deep
- Superficial: loose connective tissue
- Deep: dense and collagenous tissue from which some muscles may originate or insert; attaches to bones
- Understanding fascial planes is clinically relebant in understanding the spread of infection
Muscle fiber arrangement diagram
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Synarthroses
- Immovable joints
- Includes synostosis
Amphiarthroses
- Semimoveable joints
- Includes: suture, syndesmosis, synchondrosis
Diarthroses
- Freely moveable joints
- Includes: synovial joints
Fibrous joint
- Strong fibrous connective tissues between articulating bones
- Little to no movment
- In some cases bones can fuse resulting in a bony joint (synsotosis)
Cartilaginous joint
- Cartilage, either hyaline or fibrocartilage between articulating bones
- Limited movement
Synovial joint
- Joint cavity between articulating bones lined with synovial membrane
- Free movement
Suture joint
- Seams of bones of the skull (interdigitation)
- Gradually eliminated via ossification (results in synostosis)
Gomphosis joint
- Tooth in aveolus, united by peridontal ligament
- Not technically a joint b/c teeth are not considered bones
Syndesmosis
- Bones joined by interosseus ligaments (radius/ulna, tibia/fibula)
Synchondrosis
- Hyaline cartilage union
- EX costal cartilages connecting ribs to sternum, growth plates
Symphysis
- Occurs in the midline of the body where areticulating bones are connected via a flat disc of fibrocartilage
- EX pelvic symphysis, intervertebral discs
Synovial joint diagram
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Acessory structures of the synovial joint
- Meniscus: fibrocartilage located within the synovial cavity; eg in the stifle
- Ligaments: extracapsular ligaments located outside the joint capsule (medial and collateral ligaments
- Intrascapsular ligaments: occur within the joint capsule but are excluded from the synovial joint cavity by folds of synovial membrane (ligament of the femoral head)
- Fat pads: between fibrous and synovial layers, may protrude into a joint cavity (parapatellar fat pads of the stifle joint)
Simple joint
- Formed by two bones
- EX: glenohumeral joint
Compound joint
- Formed by two or more bones
- Humerotadioulnar joint (elbow)
Congruent joint
- Two articular surfaces fir each other
- EX coxofemoral joint (hip)
Incongruent joint
- Two articular surfaces do not fit each other
- EX femorotibial joint (stifle)
Hinge joint
- Permits angular motion in one plabe
- EX humeroradiounar joint (elbow), metacarpophalangeal joint (fetlock)
Spheroidal joint
- Ball and socket
- Permits rotation and other movements
- EX glenohumeral (shoulder) and coxofemoral (hip)
Plane A joint
- Permits angular motion in one plane
- EX carpal, tarsal joints, vertebrae (dorsal articulation)
Condylar joint
- Formed by two condyles of one bone fitting into concavities of another bone
- EX femorotibial joint (stifle)
Pivot joint
- Permits rotation around the longitudinal axis
- EX atlantoaxial joint, radioulnar joint
Ellipsoidal joint
- Oval surface nestles within a depression in the opposing surface
- EX temporomandibular joint, antevrachiocarpal joint
Saddle joint
- Articular surfaces of two articulating bones are concave
- EX: distal interphalangeal joint