Forelimb Flashcards
In birds, what does the thoracic girdle consist of?
The scapula, clavicle, coracoid bone
In birds, where does the scapula lie?
In birds, what does a long scapula indicate and what does a wide scapula indicate?
Along the side of the rib cage
Long scapula = better flier
Wide scapula = strong swimmer
In birds, the left and right clavicle fuse to form the …
What is the purpose of this?
… furcula (wishbone)
Acts as a spring, storing energy on the down beat of the wings
What structure in birds hold the wings away from the sternum and stops the pectoral muscles from and crushing/ collapsing the ribs during contraction?
They have large coracoids
In birds, what 3 bones articulate with the humerus?
They create a foramen that allows the tendon of the supracoracoideus muscle to pass through, what is the foramen name?
Scapula, clavicle, coracoid
Triosseal foramen
What is the wing made up of in the bird?
Humerus
Ulna
Radius
Manus
- carpal bones
- carpometacarpus
- digits
In a bird, the humerus has a foramen which allows the lateral diverticulum of the clavicular air sack to pass through into the medullary cavity, what is the name of this foramen?
The pneumatic foramen
Why are the radius and ulna bowed in birds?
What type of feathers are attached to the ulna and carpometacarpus bones?
Bowed to aid the forces of flight
Primary flight feathers
Label the highlighted bones:
What is the purpose of the alular digit in a bird?
Can be raised to stop stalling at low speeds
In birds…
…what is pinioning?
…what is brailing?
Pinioning - cutting off manus to prevent flight (welfare issue - based in commercial farmed poultry)
Brailing - holding manus in flexed position with leather strap (was used with game farmers but also welfare issue)
What is the name of the wing extension (numerous elevation) muscle?
Where is its origin?
Insertion?
Supracoracoideus muscle
Origin - keel bone
Insertion - dorso-cranial aspect of humerous
What is the name of the wing flexion (downbeat) muscle?
Where is its origin?
Insertion?
Pectoralis muscle (Large: 15-20% of birds weight)
Origin - clavicle, keel and coracoclavicular membrane
Insertion - ventral surface of dorsal tubercle of humerous
In birds what is Oregon muscle disease?
Depp pectoral myopathy seen in heavy turkeys and broilers, ischaemic necrotic foci caused by excessive flapping (loss of blood flow)
In birds,
- what do the body wall muscles allow the humerus to do?
- what does flexion of the elbow allow?
- how are flight feather spread?
- there are two skin folds (one on leading edge and one on trailing edge) that alter shape depending on flight requirements, what are their names?
Protraction and retraction
Rotation of the antebrachium
Extension on the digits (not including alular)
Leading = larger propatagium
Trailing = smaller metapatagium
How do bird wings provide lift?
Convex dorsal surface and concave dorsal surface
Thick leading edge, tapered trailing edge
Drop in pressure as air passes over wing dorsal aspect
Fanning feathers on the pygostyle
What are the 4 movements that wings make each time they flap?
Forward + Downwards
Backwards + Upwards
How do birds hover?
Rotate wing 180º between up and down beat (maintains leading edge so lift with no thrust)
How can bird flight be prevented in an acceptable way?
Wing clipping
- always clip both wings
- must be even
- no welfare compromised
- should be done by specialist
What is endochondral ossification, primary method of bone growth?
What is intramembranous ossification?
When cartilage is replaced by bone
In flat bones the fibrous connective tissue differentiates into osteoblasts, forming osteoids, that mineralise to form bone
(Both main occur in the foetus)
There is a junction in growing animals bones where the growth plates/physis are, where is this?
Sits between the epiphysis and metaphysis
Once growth has finished, what happens to the physis?
Does the physis grow outward or upwards during enochondal ossification?
It is replaced by bone so no more growth can occur
Upwards, chondrocytes form at top of physis then shunted down to bone where there is blood and they become bone
Where are the 3 main sights of endochandral ossification post-natally?
When else would endochondral ossification occur if not for growth?
- Physis/growth plate
- Articular-epiphyseal cartilage complex (AECC)
- Cuboidal bones (tarsus and carpus)
During the healing of unstable fractures
Growth cartilage requires cartilage canals, what are these?
Blind ended channels within the cartilage that contain arterioles, venules and capillaries. The vessels come from the pericardium and run parallel to the articular surface.
Eventually they join with vessels in the ossification front.
