Avian Anatomy Flashcards
Uncinate process
Extensions of bone that project caudally from the vertical segment of each rib.
Prevents excessive compression of the thorax.
Choanal slit
Connects the oropharynx with the nasal cavity.
Coracoid
Short bone extending from the sternum (acts as a wing strut).
Calamus
Proximal shaft.
Hollow inner portion of the feather shaft that lacks barbs and attaches to the skin.
Opening at the tip is the pathway for blood vessels.
Synsacrum
Fusion of the bones to decrease flight stress and wind resistance.
Usually consists of ilium, ischium, lumbar, sacral, and first 6 caudal vertebrae.
No ventral pelvic symphysis.
Rachis
Distal shaft. Vane and barb attach to it.
Furculum
Pair of clavicles; ”wishbone”.
Acts as a strut to brace the wings apart.
Preen gland
Surface gland found at the base of the tail that functions to secrete a mixture of waxes, lipids, and other organic compounds which the bird applies to its feathers.
Pygostyle
Fusion of the last few coccygeal vertebrae.
Acts as an anchor for the main tail feathers.
Cecal tonsil
Lymphoid tissue present at the most proximal part of the cecae.
Tibiotarsus
The largest bone in the leg.
Fusion of the tibia and proximal tarsal bones (drumstick).
Cloaca
The colon.
Receives waste from the large intestine and materials from the urinary and reproductive systems.
Syrinx
Muscular structure found at the tracheal bifurcation.
Responsible for vocalization.
Bursa of Fabricius
Where B-cells are programmed.
Off-white, fleshy structure.
Dorsal to the cloaca/colon.
Prominent in juvenile birds.
Involutes in sexually mature birds.
Crop
Out-pocketing of the esophagus that provides storage for consumed food.
Foodstuffs moistened and softened.
Lined with simple columnar epithelium.
Thin tunica muscularis.
Located on the right side of the neck.
Proventriculus
Glandular stomach where the first significant amount of digestive juices are added.
Mucosal ridges (look like papillae).
Simple columnar epithelium.
Large submucosal glands.
One type of glandular cell.
Gizzard
Mechanical stomach. A muscular organ used to grind and break up food.
May contain grit eaten by animal.
Lined by a thick keratinized layer but is not a keratinized epithelium.
Simple cuboidal to columnar epithelium. Amorphous substance is the pellicle.
Pellicle
Amorphous substance. Thin skin or film.
Meckel’s diverticulum
Junction between the jejunum and ileum. Remnant of the yolk sac.
What is Pneumatic bone? Give 2 examples.
Bone that is hallow, connected to the respiratory system.
Example: skull, humerus, clavicle, pelvic girdle.
What is Medullary bone? Give 2 examples.
Important source of calcium.
Example: tibia, femur, pubic bone, ribs, ulna.
What are the three parts of the pectoral girdle?
Clavicle
Coracoid
Scapula
How is the avian pelvis different from the mammalian?
Avians do not have a ventral pelvic symphysis.
Bird pelvic girdles have a lot of spine fused to the pelvic bones, where mammals lack any apparent vertebra in their structure.
In the bird, which bone is larger, the ulna or radius?
Ulna.
How many digits do birds have on the forelimb (wing) and the hind limb (leg)?
Forelimb (wing): 3
Hindlimb (leg): 4
What is the function of the pectoralis and supracoracoideus muscles in the bird?
Pectoralis: Pulls wings down
Supracoracoideous: Pulls wings up
Why is the body chamber of the bird known as the coelom?
Because they only have one body chamber; they have no separate abdomen, diaphragm, or thorax.
How is the avian trachea different from the mammalian?
Tracheal rings are complete, in mammals they are C-shaped.
Avian trachea is also longer and wider than that of a comparably sized mammal.
How are the avian lungs different from the mammalian?
Airflow in the lung is unidirectional.
Avian lungs do not expand or contract.
What are the 8 air sacs found in chickens?
Cervical (1)
Clavicular (1)
Cranial thoracic (2)
Caudal thoracic (2)
Abdominal (2)
= 8 total.
What is the site of gas exchange in the bird’s lung?
Air capillaries (homologous with mammalian alveoli).
What are the four steps of the avian respiratory cycle? Know the details of where air moves in each step.
- First inhalation
Air passes into paired bronchi.
50% goes through the lungs and into
caudal air sacs.
50% goes into lungs. - First expiration
Lungs fill with air from the caudal air
sacs.
Air from lungs and cranial air sacs empty
through the trachea. - Second inhalation
Stale air (remaining 50% from 1st
inhalation) empties from the lungs into
the cranial air sacs. - Second expiration
Cranial air sacs expel air out of the body.
Which side of the body is the crop?
Located on the right side of the neck.
Which lobe of the liver is larger?
RIGHT lobe.
What are the 3 sections of the avian cloaca, and their respective functions?
Coprodeum
Receives waste from large intestine.
Urodeum
Receives urine from the kidneys via
ureter and sperm/eggs from the gonads.
Proctodeum
Temporarily stores and ejects material.
What nerve runs through the kidneys?
Sciatic nerve
Do birds have a renal pelvis? Urinary bladder?
No.
What is the nitrogenous waste product in birds?
Uric acid.
Which side of the reproductive tract in the female bird persists in maturity?
Left side persists in maturity.
What are the 5 parts of the female avian oviduct and their respective functions?
- Infundibulum
Funnel-like part of the oviduct that
receives the yolk.
Site of fertilization. - Magnum
2nd part of the oviduct.
Secretes albumen (thick white).
Largest part. - Isthmus
3rd part of the oviduct.
Adds the two shell membranes.
Non-glandular. - Uterus (shell gland)
4th part of the oviduct that secretes the
thin white, shell, and shell pigment. - Vagina
Last part of the oviduct.
Holds the egg until it is laid.
Egg then passes to the cloaca and then
out of body through vent.
Where is the bursa of Fabricius in relation to the colon?
Dorsal to the colon (cloaca).
How many chambers does the avian heart have?
Four chambers.
What are the different types of feathers birds have?
Contour feathers, Semiplumes, Down feather, Bristle feathers, Filoplume. (study diagram)
What are the three parts of the avian small intestine?
- Duodenum
- Jejunum
- Ileum
