Veterinary Technician Anatomy: Chapter 7 - Skeletal System

-os / -osteo

Bone

Bone producers

Osteoblasts

Harden

Ossification

Matrix

Calcium and Phospherous. Bone is composed of a sparse population of cells embedded in a hard intercellular substance called this. Osteoblasts also harden this.

Ossification

Osteoblasts harden the matrix through a process called this.

Osteocytes

Trapped hardened bone cell in the ossified matrix called lacunae

Basic function of bone

Support the animals body.

Bone Function

Support
Protect
Leverage
Storage
Hematopoiesis

Leverage

Skeletal muscles move body. Attachment of skeletal muscles to bones via the tendons allow the muscles to move the joints.

Protection

Their firm strength protects many delicate vital organs and tissues by surrounding them partially or completely.

Storage

Bones act as "banks" for calcium. They enable the body to deposit and withdraw calcium as needed to control its level in the bloodstream precisely.

Role of bones in calcium homeostasis

It is regulated by two calciotropic hormones, each of which has effects on bone. when the level of calcium in the blood begins to rise too high, the hormone calcitonin is secreted by the thyroid glands. When it is too low parathyroid hormone is released from the parathyroid glands.

Calcium

Substance that bone stores, makes muscles contract, clots blood, milk secretion, and skeleton formation and maintenance. Also helps prevent hypercalcemia

Hematopoisesis

Blood Cell Formation

Bone Structure: 2 main types

Cancellous and compact

Light spongy bone. The spaces between the spicules are occupied by bone marrow. It is light but strong and helps reduce the weight of bones of the skeleton w/out reducing their strength

Cancellous

Heavy dense bone. Makes up the shafts of long bones and the outside layer.

Compact

Filling of spongy (cancellous) bone

Spicules
Bone Marrow

Composes shaft of long bones and all outer layers

Compact Bone

Tiny tightly packed Cylinders of hard bone

Haversian systems

Haversian Bone Contents

Blood Vessels and Nerves that supply the osteocytes. The osteocytes are located at the junctions between the layers of bone that make up each _____ system.

Canaliculi

Allows osteocytes to contact each other and exchange nutrients and wastes.

Periosteum

Outer surface of bones. Contains an inner layer of bone forming cells the enables bones to increase in diameter

Endosteum

Membrane lining of hollow bone interior

Bone Cells

Osteoblasts
Osteocytes
Osteoclasts

Osteoblasts

Cells that form bone. they secrete the matrix of bone and then supply the minerals necessary to harden it.

Osteoclasts

Remove bone. Allow the body to withdraw calcium from the bones when it is needed to raise the calcium level in the blood.

Blood supply to bone

Comes from tiny vessels that pass through tiny channels in the bone matrix called Volkmanns's canals.

Bone Formations

Endochondral
Intramembrane

Endochondral bone formation

bones in the body develop by this. Body creates cartilage template to replace bone

Primary Growth

In long bones, bone begins developing in the shaft or diaphysis of the cartilage rod

Bone developing in the ends or epiphyses of the bone

Secondary Growth

Epiphyseal plates or growth plates

Cartilage on end of bones for when bones grow. new bone allows long bones to lengthen as the animal grows. Remain as cartilage when animal is born

Bone Shapes

Short
Long
Flat
Irrecular

Occurs only in certain skull bones. Flat bones form within fibrous tissue membranes

Intramembraneous bone formation

End of long bone

Epiphyses (Cancellous bone covered in compact)

Main shaft of long bone

Diaphysis (Hollow centered compact bone)

Short Bone Composition

Spongy covered by Compact

Flat Bones Composition

Spongy bone between 2 compact layers

Flat Bones

Ex. Scalpulae , Shoulders

Short Bones

Ex. Carpus and Tarsus

Irregular Bones

Ex. Vertebrae

Bone Marrow Types

Yellow and Red

Red Bone Marrow

Hematopoietic. makes up the majority of the bone marrow of young animals but represents only a small portion of the marrow of older animals.

Articular Surfaces

Joint surfaces in contact with bones. Smooth areas of compact bone where bones come in contact withe each other to form joints.

Yellow Bone Marrow

Adipose (fat). Moat common type of marrow in adult animals. Does not produce blood cells but can revert to red bone marrow if the body needs to produce larger than normal numbers of blood cells.

Articulation

Reduce friction and protect joints

Condyle

Large , round , articular surface
(Occipital). Located on distal end of humerus and femur.

Head

Sphere-shaped articular surface
on end of long bone. form the ball portion of the ball and socket shoulder and hip joints

Facet

Provides rocking motion to the joint

Processes

Any lump , bump, or projection on a bone

Foramen

Hole in bone where blood vessels pass

Fossa

Sunken bone area where muscles attach to a bone

Bones of a Skeleton

Head
Trunk

Trunk

Bones of the limbs

Axial

Bones of head and trunk

Components of Axial Skeleton

Skull
Hyloid
Spine
Ribs
Sternum

Skull divisions

Cranium
Ear
Face

Sutures

Jagged immovable joints

Only mobile skull bone

Mandible

Internal

Cannot be seen without disassembling

External Bone

Visible on surface of intact skull.

Occipital Bone

Form base of skull

Most caudal skull bone that forms joint with vertebrae

Occipital

Frontal Bones

Form orbit and front sinus

Large hole for entering and exiting of spinal cord through the occipital bone

Foramen Magnum

Sphenoid

Ventral cranium rostral to occipital

Ethmoid

Rostral to sphenoid with bony olfactory plates

3 Middle Ear Bones
(Ossicles)

Malleus
Incus
Stapes

Incisive (Incisor) Bones

House upper incisors

Upper Jaw

Maxillary

Maxillary Bone

House Upper Canine
Hard Palate

Medial aspect of orbit
(Glasses holder)

Lacrimal bones

Zygomatic Bones

Cheekbones

Zygomatic Arch

Above mandible, through ear

Shaft

Horizontal portion of mandible

Ramus

Vertical portion of mandible

Cercival Vertebraes

7

Atlas

First Cervical Vertebrae

Joint between atlas and axis

Dens Joint

Internal bones of the face

Palatine bones
Pterygoid bones
vomer bone
turbinates

Palatine bones

Two make up the caudal portion of the hard palate which separates the mouth from the nasal cavity.

Pterygoid Bones

two small bones that support part of the lateral walls of the pharynx(throat).

Vomer bone

Single bone located on the midline of the skull and forms part of the nasal septum.

Turbinates

also called nasal conchae. four thin scroll like bones that most of the space with in the nasal cavity.

Spinal column 5 regions

Cervical(neck), Thoracic(chest), lumbar(abdomen), sacral(pelvis), and coccygeal(tail).

Ischium

The caudal most pelvic bone.

Pubis

smallest of the three pelvic bones.

Femur

Long bone of the thigh

Patella

Kneecap and is the largest sesamoid bone in the body.

Scapula

most proximal bone of the thoracic limb. Flat Triangular bone

Humerus

Long bone of the upper arm or brachium

Ulna

forms a major portion of the elbow joint with the distal end of the humerus.

Pelvic limb

directly connected to the axial skeleton through the sacroiliac joint

Tibia

Main weight bearing bone of the lower leg. It forms the stifle joint with the femur above it and the hock with the tarsus below it.

JOINTS

junction between bones

Fibrous joints

immovable in that the bones are firmly united by fibrous tissue. Synarthroses.

Cartilaginous Joints

capable of only a slight rocking movement. Amphiarthroses.

Synovial Joints

Freely moveable joints. Diarthroses. Types: hinge, gliding, pivot, ball and socket

Intervertebral disk disease

normal discs have soft center of gelatinous material called the nucleus pulposus. this disease occurs when one or more discs degenerate. Clinical signs: pain numbness weakness and paralysis