Lecture 5: Skeletal System Flashcards
Fuctions of skeletal system
protection, support, leverage, Storage, blood cell formation
Fuctions: Protection
- CNS protected by skull and vertebrae
- heart and lungs protected by rib cage
- internal urogenital system by pelvis
Fuctions: Support
- giving rigitdity and form to body
- maintain upright posture
- gives basis for external structure
- apperance of most animals
Functions: Leverage
- mechanism that augments speed of movement or force
- levers are mainly the long bones of the body and the axes are joints where bones meet
- aids in locomotion, defense, offence, and grasping
Fuctions: Storage
-Minerals like calcium and phosphorus
Functions: Blood cell formation
aka hematopoiesis takes place in the cavities of bone(bone marrow) and in fat
Compact bone/Cortical Bone
- hard layer of bone
- solid, strong, resists bending (cortex and surrounds spongy bone)
- covers most bone
- forms most entire surface of long bone
Cancellous bone/Spongy bone
- composed of spicules
- arranged to form a porous network filled with marrow
- located in epiphysis, metaphysis and right outside the medullary cavity
epiphysis
either extremity/end of long bones
diaphysis
cylindrical shaft of long bone stituated between the two epiphysis
metaphysis
the most recently form bone at area on either end of the diaphysis, filled with spongy bone, right before epiphysis
epiphysis cartilage
- layer of hyaline cartilage separating the epiphysis and diaphysis of a immature bone
- site of bone growth
articular cartilage
thin layer of hyaline cartilage that covers the articular surface of bone
articular projections: head
-spherical projection, ie head of femur
articular projections: condyle
cylindrical/rounded process of bone that articulates with another bone
ie. distal end of femur
articular projections: trochlea
pully-like articular mass
ie. distal end of femur or humerus
articular projections: facet
small, flat, smooth surface of bone, generally an articular surface
ie. articular facet of adjacent carpal bones
non-articular projection: process
general term for a bony projection/prominenece
ie spinous process of vertebrae
non-articular projection: tuberosity
- large, non-articular projection
- or a raised section of bone to which a ligament, tendon, or muscle attaches
- usually created or enlarged by the stress of the muscle’s pull ont that bone during growth
non-articular depressions: Fossa
large, non-art. depression; shallow depression or hollow
ie. atlantal fossa ventral to wing of atlas
non-art. depression: fovea
small non-art. depression
ie. head of femur
non-art. depression: foramen
- hole in which bone through which nerves or vessels pass
ie. foramen magnum
nonart. depression: spinal canal
tunnal through one or more bones
-ie. spinal canal
articular depression: glenoid cavity
shallow articular cavity
-ie articular surface of scapula
art depression: cotyloid cavity
deep art cavity
ie acetubulum of hip
art depression: notch
articular indentation
ie semilunar notch of the ulna
Long Bones
- greater in one dimension
- grows in length ONLY at epiphyseal cartilage
- functions as levers, support, locomotion, grasping
- ie humerus, radius, ulna, metacarpal
Short Bones
-equal in all dimensions
-interior filled with marrow space
functions as shock absorbers
located in complex joinst
ie carpals and tarsals, consists mainly of spongy bone covered with a thin layer of compact bone
function to allow movement, provide elasticity, flexibility, and shock absorption
Flat bones
relatively thin, expanded in two dimensions
protect vital organs
provides attacment site for muscles
ie Ribs, ilium, sternum, and scapula
consist of two layers of compact bone, with spongy bone and marrow in between
Sesamoid bones
resemble sesame seeds
short bone embedded within a tendon or join capsule
ie patella/kneecap; function to alter the angle of insertion of muscle
Pnematic bones (aka air bones)
contain air spaces or sinuses that communicate with exterior
ie frontal bones and maxillary bones of skull
axial skeleton
skull, vertebrae, ribs, not-limbs
skull
protects the brain
supports many sense organs
forms passages for beginning of digestive and respiratory systems
Vertebral column
-median, unpaired, irregular bones
C=cervical/neck, T=thoracic/chest, L=lumbar/loin, S=Sacral/pelvis (fused), LS=fused lumbar and sacral (fowl), CD=caudal/tail
vertebral formula
cow: C7, T13, L6, S5, CD18-20
human: C7, T12, L5, S5, CD4
Sternum and ribs
sternum form floor of bony thorax
gives attachment site to costal cartilages of sternal (true) ribs
forms place of origin for pectoral muscles
appendicular skeleton
pectoral limbs, including scapula
pelvic limbs, including pelvic bones
composition of bone
2/3 inorganic components deposited within organic framework
mainly calcium and phosphorous salts
gives hardness and rigidity
altered composition of bone
INORGANIC=RIGIDITY
‘minus’ inorganic component=original shape is retained but flexible enough to tie into a knot
ORGANIC=TOUGHNESS
‘minus’ organic component=original shape but becomes very brittle and easily broken
Ossification
process of bone formation
osteoblasts lay down osteoid tissue
calcified under influence of phosphatase
centre of ossification is the localized area of bone formation
Types of ossification
dependent on environment
- heteroplastic ossification
- intramembranous ossification
- endochondral/intracartilagenous ossification
heteroplastic ossification
bone formation in tissues other than skeleton
ie os penis in dog, os cardis in bovine heart, pathological ossification
intramembranous ossification
bones that originate between sheet-like layers of connective tissues, ie. broad flat bones of skull
-membrane like layers of primitive connective tissue appear at sites of future bones
-primitive connective tissue cells arrange around blood vessels in these layers
-connective tissue cells differentiate into osteoblasts, forming spongy bone
osteoblasts become osteocytes when bony matrix completely surrounds them
Osteoblasts form _____ and become…..
form spongy bone
become osteocytes when bony matrix completely surrounds them
intramembranous ossification process
- connective tissue on surface of each developing structure forms a periosteum
- osteoblasts on the inside of the periosteum form compact bone over the spongy bone
endochrondral ossication
- bone is preformed in cartilage in the fetus
- most LONG BONE is developed this way
- the cartilage becomes mineralized and replaced by bone tissue
- the long bone can continue to grow in length if the cartilage between the epiphysis and diaphysis continues to grow
- when all this cartilage has changed to bone, increase in lengthis impossible
endochondral ossification growth in diameter
- long bones increase in diameter by producing new bone from the periosteum
- as new bone is laid down, portion of deeper bone are removed to increase the marrow cavity
- most notable in fetus’ cartilage pattern being replaced by bone
growth of an endochondral bone/long bones
- bones grow in length at the epiphyseal plates, the junction of diaphysis and epiphysis. these junctions are known as metaphyses
- cartilage cell multiplication in the zone of growth will force the epiphysis away from the diaphysis, thus lengthening the epiphysial plate
- subsequent removal of cartilage and deposistion of bone in the zone of ossification in turn will lengthen the diaphysis
- diameter increases from activity of the osteogenic cells in the periosteum
epiphyseal plate divides into
zone of growth
zone of cartilage formation,
zone of ossification
Bone matrix of osteoid tissue
- highly sensitive to environmental changes like pressure, blood supply, and nutrition
- can decrease/increase in size
- capable of withstanding tension (stretching), compression, bending, and tortion
Bone Fractures: types
fracture is a break in the continuity of a bone
includes simple, green stick, compound, epiphyseal, and comminuted
simple bone fracture
skin over fracture site unbroken
green stick fracture
one side of bone is broken and other side is intact, often seen in young animals
compound fracture
a wound from the exterior contacts the bone; bone pierces the skin
epiphyseal fracture
fracture at the junction of epiphysis and diaphysis; common in young animals
comminuted fracture
number of small fragments formed at fracture site
fracture healing
- fractures destroy blood vessels carrying nutrients to osteocytes, initiating repair sequence (early fracture to inflammatory phase)
- callus-specialized repair tissue binds broken ends of fracture together (well formed callus/reparative phase)
- fracture hematoma-blood clot occurs immediately after the fracture, then reabsorbed and replaced by callus (remodelling phase)
- callus then becomes mineralized
- reorganization of callus and formation of bone shaft and marrow cavity completes the repair
Pathological bone conditions
tuberculosis: bacterial infection
osteomyelitis: inflammation of bone and marrow
osteoma: bone tumor; ie. exostoses, chondroma, fibroma, osteoclastoma
rickets
achondroplasia
Joints
Articulation between bones
- binds part of skeleton together
- allows bone growth
- permits parts of the skeleton to change shape during childbirth
- enables body to move in response to muscle contractions
classification of joints (by degree of movement)
- synarthrotic: immovable
- Amphiarthrotic: slightly movable
- diathrotic: freely movable (consists of articular cartilage, a joint capsule and synovial membrane); limb joints
class of joints (by type of tissue binding bones): fibrous joins
united by fibrous tissue
contains no joint cavity
syndesmosis: amphiarthrotic splint bones of horse
suture: synarthrotic bones of skull
gomphosis: synarthrotic articulations of teeth in jaw sockets
cartilaginous joints
united by cartilage, contains no joint cavity
synchondrosis: synarthrotic hyaline cartilage joints; the union of diaphysis and epiphysis of immature ebone
symphysis: amphiarthrotic pelvic bones and vertebrae
Synovial (diarthrodial) joints
surrounded by thick flexible membrane forming a sac filled with lubricant for joints
articular surfaces, articular cartilages, articular cavity, joint capsule, and ligaments make them up
structure of synovial joint: articular cartilage
resists wear and minimizes friction when compressed as the joint moves
synovial joint: subchondral plate
bone beneath the articular cartilage (cancellous-spongy bone), somewhat elastic and absorbs shocks
synovial joint: joint capsule
outer fibrous connective tissue
-helps bind the articular ends of bone together
synovial membrane
inner layer of joint capsule of loose connective tissue
secretes and reabsorbs fluids
synovial cavity
closed sac surrounded by synovial membrane
secretes clear synovial fluid that moistens, lubricates, and supplies nutrients to articular cartilage
synovial joint: menisci (fibrocartilage)
disks of fibrocartilage located between articular surfaces
absorbs shock and provides cushioning
synovial joint: bursae
closed, fluid filled sacs
types of joint movement
gliding, angular, rotation, and circumduction
gliding
simplest type of joint motion
one surface moving over another without rotary or angular motion
exists between two adjacent surfaces
angular movment
decreases or increases the angle between two adjoining bones
includes flexion, extension, hyperextension, abduction and adduction
angular motion: flexion
decrease in angles, ie bending of arm or leg
angular motion: extension
increasing angles: straightening or unbending of leg or arm
angular motion: hyperextension
angle between segments beyond a straight line, like fetlock joint in horses
angular motion: abduction
moving and extremity away from body (wings up)
angular motion: adduction
bringing extremity towards body (wings down)
Rotation movement of joints
movement in which bones move around a central point without being displaced
ie; turning the head from side to side
circumduction
movment of the hips and shoulders
Other types of joint motion: pronation and supination
pronation: turning downward; placing palm down
supination: turning upward; placing palm up
other joint motion: eversion and inversion
eversion: turning sole of foot outward
inversion: turning sole of foot inward
Joints of axial skeleton: skull
mainly sutures which ossify with age, fontanel of baby’s skull
symphysis of mandible
sychondrosis: junction of sphenoid and occipital bone at base of skull
joints of axial skeleton: first movable joint
the temporomandibular joint
injuries and pathological dirorders of joints
dislocation: stretching or tearing of ligaments, tearing of join capsule
subluxation: partial dislocation
arthritis: inflammation of joints
fractures involving joints
thoroughpin: swelling of digital flexor tendon
laminitis: inflammatory disease of hooves
