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A&P. Skeletal System

Terms

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"osteo"
= bone
Ossification
mineralization or hardening of bone
Lacunae
spaces in the ossified matrix that the osteoblasts become trapped in
Canaliculi
tiny channels through the matrix of bone
Functions of Bones
Support: strength & structure
Protection: surrounds organs
Leverage: levers for skeletal muscles to move the body
Storage: minerals


Hematopoiesis
blood cell production
Cancellous Bone
light, spongy bone.
tiny spicules of bone, spaces full of bone marrow.
found in epiphyses of long bones

Compact Bone
heavy, dense, strong.
found in diaphyses of long bones & outside layer of all bones.
Haversian Canal
contains blood vessels, lymph vessels & nerves that supply the osteocytes.
run up & down in long bones
Osteology
study of bones that make up the skeletal system
Bone Matrix
organic = 1/3 bone composition.

Support of Bones
Ligaments & Tendons
Protection of Bones
-CNS by skull & vertebral column
-heart & lungs by rib cage
Leverage of Bones
attachments to muscle
Storage
Ca & P reservoir
Periosteum
membrane that covers outer surfaces of bones except on articular surfaces.
outer layer = fibrous tissue
inner layer = osteoblasts

Endosteum
membrane that lines the hollow interior surfaces (marrow cavity) of bones. contains osteoblasts.
Osteoblasts
young bone cells.
cells that produce bone.
Osteocytes
adult/mature bone cells. ossified osteoblasts

Osteoclasts
remodel/remove bones
Bone Cells
-increase bones diameter
-critical in healing fractures
-determines size of marrow cavity
-determine the thickness of the diaphyseal cortex


Volkmann Canals
channels through bone matrix that contain blood vessels, run 90 degrees in bone (left & right)
Nutrient Foramina
channels in many large bones.
contains large blood vessel, lymp vessles, nerves
carries blood in/out of the marrow.

Endochondral bone formation
cartilage to bone. grows into & replaces cartilage.
Intramembranous bone formation
membrane. develops from fibrous tissue membranes
Primary Growth Center
bones develop in diaphyses.
endochondral bone formation.
cartilage makes a template & is removed as bone is created.

Secondary Growth Center
develops in the epiphyses of the bone.
endochondral bone formation
how much can an adult bone be stretched before breaking?
0.5%
what happens the bone reaches its full size?
the epiphyseal plates completely ossify
4 types of bone shapes?
Long
Short
Flat
Irregular


Long Bones
proximal/distal end.
support & leverage.
limb bones

Short Bones
phalanges
metacarpals/metatarsals
Flat Bones
ribs, skull, scapula
Irregular Bones
unpaired bones, vertebrae
Bone Marrow
fills the spaces within bones.
red -> yellow -> white
Red Bone Marrow
forms blood cells.
majority of bone marrow in young animals.
only small portion in older animals.
specific locations in older animals.


Yellow Bone Marrow
primarily adipose connective tissue.
majority of bone marrow in adults.
can revert to red bone marrow only if animal is undergoing huge stress or hardship

White Marrow
aged animals. nonfunctional. hard, fatty tissue. CANNOT revert back to yellow or red marrow.
Articular Surfaces
joint surfaces.
condyle, head, facet.
condyle
large, round articular surface
head
spherical articular surface on the proximal end of a long bone
facet
flat articular surface
processes
projections (lumps, bumps) off a bone surface. name of the process depends on the location.
foramen
a hole in the bone.
may contain blood vessels & nerves.
Fossa
a depressed/sunken area on the surface of a bone.
axial skeleton
skull. hyoid bone. spinal column. ribs. sternum.
Skull
37-38 bones.
Sutures: joints of the skull bones.
Mandible: connected to skull by synovial joint.
Maxilla: different in ruminant & monogastric


Suture
joints of the skull bones
Mandible
bottom portion of skull.
connected to skull by a synovial joint.
Upper Jaw
Maxilla, incisive bones
External Bone of Cranium
Frontal Bones = 2
big bone in front/on top of skull
Hyoid Bone
aka hyoid apparatus.
composed of several portions of bone united by cartilage
bones of ear
= 6
how many bones in the face?
11-12
how many internal bones of the face?
= 9
Vertebrae
consists of a body, an arch & processes
intervertebral disk

cartilage separating bodies of adjacent vertebrae
3 types of vertebral processes?
spinous, transvers, articular
Cervical Verterbrae
C1 = atlas
C2 = axis
what are the vertebral regions?
cervical (C)
thoracic (T)
lumbar (L)
sacral (S)
coccygeal (Cd)



Ribs
flat bones, lateral walls of thorax.
dorsal heads of the ribs articulate with thoracic vertebrae
Costal Cartilage
ventral ends of the ribs
Xiphoid Process
most caudal bone of the sternum
Costochondral Junction
area where costal cartilage meets bony rib
Floating Ribs
cartilage does not join anything at all
Sternum
breastbone. forms floor of throax. composed of sternebrae (fuse with age).
Manubrium Sterni
most cranial sternebra
appendicular skeleton
bones of the limbs.
pectoral limb: thoracic limb or forelimb
pelvic limb: hind limb

Thoracic Limb
scapula, humerus, radius, ulna, carpus, metacarpal, phalanges
scapula
flat, triangular bone.
forms portion of shoulder joint.
Glenoid Cavity
shallow, concave articular surface on scapula
humerus
long bone of brachium. forms parts of shoulder & elbow joints
Tubercles
processes where shoulder muscles attach
Olecranon Fossa
indentation above the condyle
Epicondyles
non-articular
Ulna
Olecranon process. point of elbow. site for tendon attachment of triceps brachii muscle.
Trochlear Notch
concave articular surface on ulna
Radius
main weight bearing bone of antebrachium. articulates with humerus & ulna
Carpus
2 rows of carpal bones.
metacarpal bones
extend distally from carpal bones to proximal phalanges.
dogs & cats = metacarpal 1: dewclaw
Splint Bones
2 smaller vestigial metacarpal bones on metacarpals of horse. non weight-bearing
Metacarpal - cattle
2 fused metacarpal bones: bones 3 & 4
long pastern bone =
1st or proximal phalanx
short pastern bone =
2nd or middle phalanx
coffin bone =
3rd or distal phalanx
Pelvic Limb
pelvis (ilium, ischium, pubis), femur, tibia, fibula, tarsus, metatarsus, phalanges
-connected to axial skeleton at SI joing
Pelvis
3 fused bones: ilium, ischium, pubis
pelvic symphysis
carilaginous joint between the 2 halves of the pelvis
ilium
dorsocranial direction.
forms SI (sacroiliac) joint with sacrum
ischium
caudal-most pelvic bone.
forms caudal portion of pelvic floor
pubis
forms cranial portion of the pelvic floor
Femur
proximal ends form part of hip joint.
Trochanters
processes where hip & thigh muscles attach
femur articular surfaces
2 condyles, trochlea
trochlea
articular groove containing the patella
patella
large sesamoid bone. protects tendon. formed in distal tendon of the quadriceps femoris muscle
fabellae
2 small sesamoid bones in proximal gastrocnemius muscle tendons of dogs & cats. not in cattle or horses
tibia
weight bearing bone of lower limb. forms stifle joint
fibula
parallel to tibia. not weight bearing. muscle site attachment.
Tarsus
hock. 2 rows of tarsal bones.
calcaneal tuberosity
point of attachment for the tendon of the gastrocnemius muscle
metatarsal in animals
dogs & cats = 4 bones (2,3,4,5)
horses = 1 large (cannon), 2 small (splint)
visceral skeleton
bones that form in organs
3 types of Joints
1. fibrous - immovable
2. cartilaginous - slightly movable
3. synovial - freely movable

Fibrous Joints
synarthroses, united by fibrous tissue. ex: skull sutures, splint bones
Cartilaginous Joints
amphiarthroses. slight rocking movement. ex: pubic symphysis, intervertebral disks
Synovial Joints
diarthroses. freely movalbe, articular surfaces on bones covered by articular cartilage (hyaline), fluid filled joint cavity enclosed by joint capsule
synovial joint movements
flexion, extension, adduction, abduction, rotation, circumduction
Flexion
decrease angle b/w 2 bones
Extension
increase angle of 2 bones
Adduction
come together, towards medial plane
Abduction
opposite, apart
Rotation
twisting movement of a part on its own axis
Circumduction
movement of an extremity so that the distal end moves in a circle
Synovial Joints (4 types)
hinge, gliding, pivot, ball & socket
Hinge Joints
ginglymus joints,2 joint surface swivels around another.
only flexion & extension. ex: elbow


Gliding Joints
arthrodial joints. rocking motion of 1 joint surface on the other. primarily flexion & extension. abduction & adduction possible. ex: carpus
Pivot Joints
trochoid joints. 2 bone pivots (rotates) on another. only rotation. ex: atlantoaxial joint
Ball & Socket Joints
spheroidal joints. all joint movements. ex: shoulder/hip joints
Fracture
a break in the continuity of a bone
Simple Fracture
skin over the fracture site is unbroken
Open/Compound Fracture
wound from exterior contacts the bone at the point of the fracture
Greenstick Fracture
1 side of bone is broken/splintered. other side is bent. typically young animals
Complete Fracture
bone is broken entirely across
Episyseal Fracture
at junction of the epiphysis & diaphysis of a bone. typically young animals. dangerous because of growth plates
Comminuted Fracture
bone was splintered or crushed producing small fragments
What causes pathologic conditions of bones?
infections, tumors, endocrine disturbances, nutritional imbalances, genetic abnormalities
Osteomyelitis
inflammation of the bone & bone marrow. usually caused by bacteria (staphylococcus or streptococcus)
Osteoma
bone tumors. benign = slow growing, not harmful. malignant = grow rapidly, harmful.
Rickets
nutritional imbalance. disease of young bones that affects the growing areas of bone
Osteomalacia
adult rickets. affects entire bone. due to lack of vitamin D and/or imbalance or lack of calcium and/or phosphorus
what type of tissue is red bone marrow?
Hematopoietic Tissue
Foramen Magnum
the center of the occipital bone, where the spinal cord exits the skull
Occipital Bone
base of skull
Frontal Bones
forehead region of the skull.
Pituitary fossa
houses the pituitary gland. in the sphenoid bone
Intervertebral disk
cartilaginous disk located between the bodies of adjacent vertebrae. shock absorber for vertebrae
Brachium =
upper arm
antebrachium =
"forearm" (ulna & radius)
what are digits made of?
phalanges (singular bones)
Obturator foramina
2 large holes in the pelvis, purpose is to lighten it
acetabulum
socket portion of the ball & socket hip joint. formed at junction of ilium ,ischium & pubis.

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