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Flashcards in The Equine Skeleton Deck (38)
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1

Define BONE

Bone is a type of connective tissue. Is is the largest part of the skeleton and has a blood supply.
It can be damaged or diseased but can also repair itself, as well as adapt to environmental strength (e.g. training horses on roads improves bone strength).

2

What is the structure of bone?

The outer layer of bone consists of a dense, ivory covered outer shell called compact bone. This is covered by a further layer called the periosteum. Small holes and channels carry blood vessels from the outer coating to the spongy interior, known as cancellous bone. It is filled with red marrow, which is responsible for the production of red and white blood cells, and yellow marrow, which is mainly fat and can be used as a last resort energy source.

3

What are the 5 types of bone?

Long, short, sesamoid, flat, irregular

4

Describe a long bone

They are often limbs e.g. radius, humerus and cannon bones. They are longer than they are wide.

5

Describe a short bone

They are approximately equal in all dimensions. They can absorb concussion and are therefore found in complex joints that have a lot of movement e.g. the carpus (knee) and tarsus (hock).

6

Describe a flat bone

They are made up of a flat sandwich of cancellous bones between layers of cortex. They are usually slightly curved, with no cavity for bone marrow. Main function is the protection of vital organs e.g. the skull protects the brain.

7

Describe an irregular bone

They are unpaired bones on the median plane e.g. vertebrae and hip bones.

8

Describe a sesamoid bone

They occur along the course of tendons to reduce friction, increase leverage or change direction of pull e.g. the patella (kneecap).

9

What are the functions of the skeleton?

- protection of organs
- vertebrates depend on levers made of bone attached to muscle that allow locomotion, defence, offence, grasping etc.
- provides storage for minerals such as calcium and phosphorus

10

What is each section of the equine skeleton called and how many bones in each?

34 bones in the skull
20 bones in each forelimb
20 bones in each hindlimb
37 bones in the ribcage
54 bones in the vetebral column

11

Define DENSE/CORTICAL (COMPACT) BONE

Compact bone is the hard layer that covers most bones and forms almost the entire shaft of long bones.

12

Define CANCELLOUS (SPONGY) BONE

Cancellous bone is composed of spicules (small, needle like structures) arranged to form a porous network. The spaces between are usually filled with bone marrow.

13

Define an OSTEON

An osteon is the basic unit of structure of compact bone, comprising of a Haversian canal and its concentrically arranged lamallae.

14

Define LAMALLAE

Lamallae is a thin layer, membrane, or plate of tissue, especially in bone. It is arrnaged concentrically within the osteon, around the central Haversian canal.

15

Define a HAVERSIAN SYSTEM

Haversian systems are formed when several osteons are put together.

16

Define the MEDULLARY CAVITY

The medullary cavity is the central cavity of bone shafts where red bone marrow/yellow bone barrow is stored.

17

Define PERIOSTEUM

Periosteum is a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.

18

Define LACUNAE

Lancunae are small cavities at junctions between lamallae that allow the exchange of nutrients, waste and chemicals.

19

How does bone growth occur?

There are two ways that bone growth can occur:
1. Adding layers on to the surface (increasing girth).
2. Longitudinal growth from the growth plate (made of cartilage) between the diaphysis and epiphysis.
At sexual maturity the growth plate thickens and fuses.

20

What are the 3 types of cells in bone?

Osteoclasts - break down old/damaged bone
Osteocytes - carry nutrients and waste products to and from blood vessels
Osteoblasts - repair damaged and build up new bone.

21

What is endochondral ossification and how does it occur?

It is an essential process during fetal development. #
1. Cartilage model develops
2. Primary ossification centre develops in the midshafts of long bones
3. Secondary ossification centres develop near the end of long bones
4. Osteoclasts remove bone while osteoblasts continue to lay it down
5. Narrow band of cartilage persists

22

What are the 4 classifications of joints based on range of movement?

Synarthrosis joint, synchondrosis joint, amphiarthrosis, disthrosis

23

Describe a synarthrosis joint

These are immovable, fixed joints with bones in very close contact. They are separated by a thin layer of fibrous connective tissue.
Example: the sutures of the skull

24

Describe a synchondrosis joint

These are connected/bound by hyaline cartilage membrane. Most are temporary but some are permanent. They are almost immovable.
Example: the spinal vertebrae

25

Describe an amphiarthrosis joint

These are slightly movable joints that are connecte by a wedge or pad of fibro cartilage. They are compressible and therefore good for shock absorption.
Example: hip bones

26

Describe a disrthrosis joint

These are freely movable joints at the ends of opposing bones. They are covered in hyaline cartilage and separated by a joint cavity.
Example: the elbow

27

What are the 5 types of synovial joint?

1. Hinge joint - folding movement
2. Sliding (plane) joint - sliding movement
3. Ball and socket joint - wide ranging, triaxial, multidirectional
4. Pivot joint - monaxial rotation movement
5. Ellipsoid joint - biaxial movement, knuckle shaped surface

28

What are intervertebral discs?

They are layers of cartilage separating adjacent vertebrae in the spine.

29

What is the structure of the equine rib cage?

First is the cervical section, which contains 7 vertebrae. Next come the 18 thoracic vertebrae which are connected to 18 pairs of ribs. Then, 6 lumbar vertebrae and 5 fused sacral vertebrae which form the sacrum that functions as a single bone. Finally comes the tail vertebrae.

30

Define CARTILAGE

Cartilage is a highly specialised type of connective tissue. It is firm but flexible, with no direc blood and nerve supply. Difficult to repair once damaged.