Skeletal System Flashcards
TUBEROSITY/TROCHANTER/TUBERCLE
PROTUBERANCES ON BONES, WHICH ARE USUALLY FOR THE ATTACHMENT OF MUSCLES
TROCHLEA
BONY STRUCTURES THROUGH OR OVER WHICH TENDONS PASS. THEY ARE USUALLY GROOVES IN THE BONE
CONDYLE
A ROUNDED PROJECTION ON A BONE, USUALLY FOR ARTICULATION WITH ANOTHER BONE
EPICONDYLE
A PROJECTION OF THE BONE ON THE LATERAL EDGE ABOVE ITS CONDYLE
FORAMEN
AN OPENING OR PASSAGE INTO OR THROUGH A BONE E.G. TO ALLOW THE PASSAGE OF BLOOD VESSELS AND NERVES
FOSSA
A HOLLOW OR DEPRESSED AREA ON A BONE
TENDON
ATTACHES MUSCLE TO BONE
LIGAMENT
ATTACHES BONE TO BONE
What are the functions of the skeleton?
- Support and Protection (soft tissues and organs within)
- Articulations (permit movement via muscles)
- Storage (stores essential calcium and phosphate)
- Haemopoiesis (manufactures blood cells in red bone marrow)
What makes up the axial skeleton?
Skull Vertebral Column Sternum Ribs Mandible
Describe the make up of the vertebral column
Cervical (7), thoracic (13), lumbar (7), sacral (3 fused together) and coccygeal (about 20 - depends on breed)
What does the appendicular skeleton consist of?
Scapula, Pelvis and the Limbs
What is the make up of the Splanchnic skeleton? Give examples
Composed of bones that are not attached to the rest of the skeleton. E.g. Os Penis and Fabellae (sesamoid bone behind the stifle)
What is a sesamoid bone and give an example
A bone that develops within a tendon or a ligament. E.g. patella. They serve to change the angle at which the tendon passes over the bone and reduces wear and tear.
Name the 2 methods of bone development and what bones are formed by each
- Intramembranous (Flat bones are formed this way)
2. Endochondral/ Interchondral (Long bones)
Describe the process of intramembranous ossification
The osteoblasts lay down new bone between the 2 layers of fibrous connective tissue. There is no cartilage template. Osteoblasts convert soluble salts of magnesium and calcium into insoluble salts such as calcium phosphate.
When does an osteoblast become an osteocyte?
When the osteoblast becomes surrounded by bone matrix.
What are osteoprogenitor cells?
They are mitotic cells that divide into 2 daughter cells. The are responsible for maintaining the population of osteoblasts.
What is an osteoclast responsible for and where is it found?
It is responsible for destroying or remodelling bone and is found in the Haversian Canal
What is endochondral ossification?
Involves the replacement of a hyaline cartilage model by bone i.e. the cartilage becomes calcified and is replaced by bone. The process starts in the developing embryo but is not completed fully until the animal reaches maturity and growth is ceased.
Describe the steps of endochondral ossification
- Cartilage model exists in the embryo
- Ossification begins in the diaphysis (shaft) in the primary ossification centre. The cartilage is replaced as the osteoblasts lay down bone , which gradually extends towards the ends of the bone.
- Secondary ossification then begins in the epiphysis
- Osteoclasts start to remove bone from the centre of diaphysis in to form the marrow cavity, whilst the osteoblasts continue to lay down new bone at the outer edges.
- The first growth plate fuses and marrow cavity extends
- Proximal growth plate fuses and growth ceases
What is the growth plate and why does it exist?
A band of cartilage between the epiphysis and diaphysis. Allows the bone to lengthen whilst the animal is growing, once it reaches its final size it ‘closes’ and is replaced by bone.
What type of tissue is bone? What are the two types of bone?
Connective Tissue
- Compact Bone 2. Spongy/Cancellous Bone
Where is compact bone found?
On outer surfaces of bones
Describe the structure of Compact Bone
Made up of Haversian Canal Systems (contain blood vessels, lymphatics and nerves).
Surrounded by plates of bone called Lamellae. The spaces between the lamellae are called lacunae (contain osteocytes and lymph).
Canaliculi are fine channels between the lacunae and Haversian canals - they carry lymph.
Describe what makes up Compact Bone Tissue?
Calcium, Collagen Fibres, Osteocytes and mucopolysaccharides (ground substance)
What covers all bones?
A tough, fibrous membrane called Periosteum - it helps provide blood to the bone and is very sensitive to pain
What is the nutrient foramen?
A small opening in the cortex in the shaft of long bones. Where blood vessels enter and nutrients are supplied
What are articular bone irregularities? Give an example
Smooth projections of bone where joints are formed. E.g. Head of femur fits into acetabulum of pelvis to form hip joint
E.g. trochlea of humerus fits into the trochlear notch of the ulna
What are non-articular bone irregularities? Give an example
Rough projections where muscles and ligaments attach. (The stronger the muscle, the larger and rougher the projection)
E.g. Anconeal process of the Ulna
which sits within the olecranon fossa when the elbow is extended)
Describe the structure of spongy/cancellous bone?
Haversian systems are spread more widely and the spaces between are filled with Red bone marrow (fat and blood cells). Found where mechanical stress is low e.g. at the ends of long bones
What 3 parts is the skull made up of?
The cranium, the maxilla and the mandible
What is the cranium?
The caudal part of the skull which provides the bony ‘case’ in which the brain sits.
What bones make up the base of the brain box?
One behind the other at the midline of the skull - the sphenoid bone (closer to nose) and occipital bone (forms framework around the foramen magnum)
What is the foramen magnum?
A hole in the bony skull where the muscles that support the head and neck attach and where the spinal cord passes through
Where does the 1st cervical vertebrae (the atlas) join the skull?
At the occipital condyles
What bone protects the tympanic bulla? What is the tympanic bulla?
Temporal Bone. A small bony chamber that contains the middle ear - the exit from the tympanic bulla to the external ear is the external auditory meatus
What does the sphenoid bone join with (apart from the occipital bone)?
Sphenoid bone is continued on either side nearer the nose by a frontal bone
What is the ethmoid bone? What passes through it?
A sieve-like bone which separates the cranial cavity of the nose from the cranium. The olfactory nerve passes through its perforations.
What makes up the maxilla?
The Nasal chambers, lacrimal bone and zygomatic bones
What separates the nasal cavity?
Nasal septum which attaches to the middle of the ethmoid bone
What forms the walls of the nasal cavity?
Incisive bone, nasal bone, maxilla, palatine bone and ethmoid bone
What are turbinates?
Tiny, thin scrolls of bone that are attached to inside walls of nasal cavity