Skeletal system (7), Test yourself

Besides supporting tissue, what does the bones do?

Protecting organs and tissue, act like levers for the skeletal muscle to move, stores minerals (calcium) and hematopoiesis.

Hematopoiesis

Sites for blood cell formation, happens in the bone marrow

What happens if the calcium level is too low? What if it’s too high?

Too low - parathyroid releases from the parathyroid glands, and inhibits calcium deposition into the bones, encourages osteoclaster to withdraw from bones. Lastly. it decrease the amount of calcium going into the kidney.

Too high - calcitonin secretes into the thyroid glands and encourage calcium to deposit into the bones by osteoblasts, inhibits bone reabsorption by osteoclaster and increase the amount of calcium excreted by the kidney into urine.

What’s the 3 kinds of bone cells?

Osteoblaster, osteocytes and osteoclaster

Osteoblaster

Form the bones. Secrete the matrix of bones and supply the necessary minerals to harden it.

Osteocytes

The hardened version of osteoblasts, but can be reversed into them if needed.

Osteoclasts

Eats the bone and makes it able to remove calcium if the body is low on it.

What’s the matrix of bone made of?
What makes it hard?

The matrix is made of collagen fibers, gelatinlike ground protein substance and polysaccharides. It’s secreted by osteoblasts and hardens through ossification.

Ossification

Calcium and phosphate (hydroxyapatite crystals) infiltrate the matrix and produce lacunae (ossified matrix)

What’s the structural difference between cancellous bone and compact bone? Why’s both types needed?

Cancellous bone (spongy bone) looks like a sponge, in the holes are bone marrow. It makes the bones lighter without making it weaker.

Compact bone is heavy and dense, but strong. It’s the outside layer of bones and the shaft of long bones. It has tiny, tightly compacted cylinders of bone, (Haversian system).

The different bones are used to lighten the weight, but still remain as strong as possible. The difference is also about their ability and responsibility in the body.

Haversian system

Tiny, tightly compacted cylinders of bone. Lays lenght wise to the bone.

It consists of multilayered (laminated) cylinders composed of concentric layers of ossified matrix around a central Haversian canal.

Haversian canal

Consists of blood vessels, lymph vessels and nerves that supply osteoblasts.

What’s the difference between a Haversian canal and a Volkmann’s canal?

The Haversian canal is focused to supply osteoblasts, while the Volkmann’s canal is used to supply the Haversian canal.

Volkmann’s canal

Supply Haversian canal with blood and nutrients, it lays horizontal in the bone (90^o for Haversian canals)

Which mechanism of bone formation happens before an animals’ born? How does it happen?

Endochondral bone formation, the body makes a cartilage “template”. It starts as cartilage rods and is replaced in developing fetus.

The femur begins developing in the shaft/diaphysis of the cartilage rod (primary growth center). The cartilage is gradually removed as the bone form.

What’s the difference between the primary growth center and the secondary growth center?

The primary growth center happens in the shaft/diaphysis, while the secondary growth center is developed in the ends/epiphyses of the bone.

Where’s the epiphyseal plate? What would it be doing?

It’s found at the ends of long bones. In young animals they can also be called growth plates, as it’s where they grow from as the animal is growing.
It’s divided into the proximal and distal epiphysis.

What’s bone marrow?
What’s the difference between red and yellow bone marrow?

Bone marrow fills spaces within the bone.

Red bone marrow is hematopoietic tissue - forms blood.
Yellow bone marrow is fat. It can revert into red bone marrow if needed, but itself doesn’t produce anything.

Name the skull bones that make up:
External bones of the cranium

The occipital bone, the interparietal bones, the parietal bones, the temporal bones and the frontal bones.

Occipital bone

Forms the caudo-ventral portion of the skull, where the spinal cord exits and the skull bone that articulates with atlas.

Interparietal bones

2 small bones on the dorsal midline between the occipital bone and the parietal bones. Fuses together in adults

Parietal bones

2 bones that form the dorso-lateral walls of the cranium.

Temporal bones

2 bones located ventral to the parietal bone, forming the lateral walls of the cranium.

Contains the middle and inner ear structure and forms the temporomandibular joints.

Frontal bones

The forehead, is rostalt to the parietal bones.

Name the skull bones that make up: Internal bones of cranium

Sphenoid bone and ethmoid bone

Sphenoid bone

Forms the ventral part of the cranium and contains the pituitary fossa (important endocrine gland).

Ethmoid bone

1 bone located rostal to the sphenoid bone.
It has the sievelike cribriform plate.

Name the skull bones that make up: External bones of the face

The incisive bones, the nasal bones, the maxillary bones, the lacrimal bones, the zygomatic bones and the mandible

Incisive bones

The premaxillary bones, layes the most rostal.

Nasal bones

2 bones that form the brigde of the nose, dorsal of the nasal cavity.

Maxillary bones

2 bones that make the upper jaw. Houses the upper teeth, the upper cheek teeth and the maxillary sinuses.
Also form the rostal part of the hard palate - bony seperation between the mouth and nasal caavity.

Lacrimal bones

2 small bones that form part of the medial portion of the orbit of the eye.

Zygomatic bones

Malar bones, 2 bones that form a portion of the orbit of the eye and joins with the temporal bones to form zygomatic arches.

Mandible

Lower jaw. houses the lower teeth and is movable.

Name the skull bones that make up: Ears

Ossicles (malleus/hammer, incus/anvil and stapes/stirrup)
Transmits vibrations from the tympanic membrane into the cochlea.

Name the skull bones that make up: Internal bones of the face

Palatine bones, pterygoid bones, vomer bone, turbinates

Palatine bones

2 bones that make the caudal portion of the hard palate.

Pterygoid bones

2 bones that support part of the lateral walls of the pharynx (throat)

Vomer bone

Located on the midline of the skull and forms part of the nasal septum.

Turbinates

Nasal conchae, 4 tin, scroll like bones that fill most of the space in the nasal cavity.

Where’s the bone? Cribriform plate

In the ethmoid bone - internal bone of the cranium

Where’s the bone? External acoustic meatus

The temporal bone, and is the only visible ear structure from the outside.

Where’s the bone? Foramen magnus

Rostral on the mandible

Where’s the bone? Frontal sinus

Among the frontal bones, in horned animals its under the horns and is later fused together.

Where’s the bone? Lacrimal sac

In the lacrimal bone, and is part of the tear drainage system of the eye.

Where’s the bone? Lower teeth

On the mandible, dorsalt

Where’s the bone? Pituitary fossa

In the spehnoid bone, it is a depression that houses the pituitary gland

Where’s the bone? Upper incisor teeth

Inside the incisive bone. Only carnivores have it.

Where’s the bone? Upper cheek teeth

In the maxillary bone,

Would a fracture to the mandible or occipital bone be worse for an animal?

The occipital bone is the place of the spinal cord and where the cranium and cervical meet. A deadly place to get a fracture.

The mandible is the lower part of the jaw, with it broken an animal wouldn’t be able to eat properly or at all.

Which groups of vertebrae make up the spinal column dorsal to: the abdomen

The lumbar vertebrae

Which groups of vertebrae make up the spinal column dorsal to: the neck

The cervical vertebrae

Which groups of vertebrae make up the spinal column dorsal to: the pelvis

The sacral vertabrae

Which groups of vertebrae make up the spinal column dorsal to: the tail

The coccygeal vertebrae

Which groups of vertebrae make up the spinal column dorsal to: the thorax

The thoracic vertebrae

What’s the 3 kinds of processes found on vertebrae, and what’s their characteristics?

The single, dorsally projecting spinous process and 2 laterally projecting transverse processes.
Both act as sites for muscle attachment and provide leverage to move the spine and trunk.

The articular processes are on the cranial and caudal ends of the vertebral arches and help form the joints between adjacent vertebrael.

Where in the vertebra is the spinal cord located?

The spinal canal, provides place and protection

What’s the name of the first two cervical vertebrae?
What distinguished characters do they have?

Atlas (C1) - Doesn’t have a vertebra body, but has a ring for the spinal cord to pass through with 2 winglike transverse process sticking out laterally.

Axis (C2) - A large bladelike spinous process projecting dorsally and the peglike dens that help form the atlantoaxial joint.

What’s the difference between a sternal rib, asternal rib and a floating rib?

Sternal ribs make up the cranial part of the thorax.
Asternal ribs make up the caudal part of the thorax.
While floating ribs aren’t attached to anything, might end in the thoracic wall.

What’s the manubrium and xiphoid?

Manubrium is the first, most cranial sternebra. (breast bone)

Xiphoid is the last, most caudal sternebra.

Name the bones of the thoracic limb, proximal to distal.

Scapula, Humerus, Ulna & Radius, Carpus, Metacarpal & Splint bone, Metacarpal-phalangal joint, phalanx

What’s the anatomic name of the shoulder blades?

Scapula with spinal scapulaon it.

What’s the brachium and the antebrachium?
What bones form them?

Brachium is another word for the humerus bone.
Antebrachium is the ulna and radius bone.

Which bone is the olecranon process found, what is its purpose?

Forms the point of the elbow, the same place the triceps brachii muscle is attached.

What’s the anatomic names for the cannon bone and the splint bones in a horse?

The metacarpal bones,
1 large metacarpal and 2 smaller vestigial metacarpal bones

Which digit is the declaw on the front leg of a dog?

Metacarpal 1 on dogs.

What’s the common name for the distal sesamoid bone in the horse?

The navicular bone

Name the bones of the pelvic limb, distal to proximal.

Phalanges, Metatarsus, tarsus, fibula & tibia, fabellae, patella, femur and pelvis

3 bones make up the pelvis, what’s their name and region?

The ilium, the cranial part - hands on hip.
The ischium, the caudal-most part - sit on it, also form the caudal part of the pelvic floor.
The pubis, smallest and forms the cranial part of the pelvic floor

What’s the largest sesamoid bone in the animal body?

The patella

What’s a sesamoid bone?

A bone embedded within a tendon or a muscle

Does the tibia or fibula support the animal’s weight the most?

The tibia, it’s connected to the femur and tarsus completely, while the fibula serves as a muscle attachment site.

Where’s the calcaneal tuberosity found on the pelvic limb? What is its purpose?

It’s found among the tarsal bones.
It forms the point of the hock and act as a point of attachment for the tendon of the large gastrocnemius muscle.

Does 3/9 BCS to an animal mean it’s fat or skinny?
(body condition score)

In a 9-point scoring a 3/9 would mean the animal is too skinny, ideally it would be 5/9.

What’s the main characteristics of fibrous joints, cartilaginous joints and synovial joints?

The fibrous joint is immovable, the cartilaginous joint is slightly movable, and the synovial joint is fully movable.

What’s synovial fluid, and why is it important?

It’s produced by the synovial membrane, and lubricates the joint’s surface.

What’s the difference between a tendon and a ligament?

A ligament are bands of fibrous connective tissue, present in and around synvocial joints. They join bones together.

Tendons bonds muscle to bone,

Examples of synovial joint: Ball-and-socket joint

“Spheroidal joint”, found in the shoulder and hips

Examples of synovial joint: Gliding joint

“Arthrodial joint”, found in carpus/wrist

Examples of synovial joint: Hinge joint

“Ginglymus joints”, found in elbow and atlantooccitial joint.

Examples of synovial joint: Pivot joint

“trochiod joint”, a true pivot joint is atlantoaxial joint.