Avian Comparative Anatomy Flashcards
The wing of the bird is it’s ____
forelimb
What are the articulations of the pectoral girdle of the bird?
scapula
clavicle
coracoid
What is the canalis/foramen triosseum?
foramen at the junction of the articulations of the pectoral gurdle
tendon of the supracoracoideus (flight muscle) passes through here
Describe the scapula of the bird
flat rod, laying lateral and parallel to the vertebral column
extended caudally to the pelvis
Describe the coracoid of the bird
acts as a brace between the vigorous up-down strokes of the wing
Describe the clavicle of the bird
two clavicles fuse ventrally
forms the furcula
What is the function of the furcula?
braces the pectoral girdle against the axial skeleton
Describe the humerus of the bird
pneumatized bone with a pneumatic foramen
Describe the radius and ulna of the bird (the antebrachium)
the ulna is thicker and longer than the radius
What bones comprise the proximal row of the avian carpus?
radial and ulnar carpal bones
Describe the distal row of the avian carpus
fused with the metacarpals
forms the carpometacarpus
What is the synsacrum in the avian species?
fused thoracic, lumbar, sacral and caudal vertebrae
allows birds to stand erect
Do the hip bones of birds meet in a ventral symphysis?
no (except in the ostrich)
What part of the avian hindlimb is considered the “drumstick”?
tibiotarsus which is longer than the femur
fused tibia and proximal tarsal elements
Describe the fibula in birds
feebly developed
Describe the tarsal joint of the bird
tarsal bones merge with metatarsals II-IV forming the tarsometatarsus
Describe the tarsometatarsus in the bird
extends to the ground and gives rise to 4 digits
digit 1 is usually plantar
What is the vertebral formula for the avian species?
C 14 (varies with species)
T 7
LS 14
Cd 6
How many cervical vertebrae are present in small birds? swans? chickens?
small birds: 8
swans: 25
chickens: 14-17
Why is division of the vertebral regions difficult in the avian species?
extensive fusion
Describe the thoracic vertebrae of birds
complete ribs and connect with the sternum
the first 3-5 fuse - form the notarium
Describe the atlas of the bird
ring shaped
articulates by a depression in its ventral arch with a single occipital condyle
Describe the tail of birds
synsacrum is followed by 5-6 free caudal vertebrae - allowing free movement of the tail
pygostyle (most caudal segment)
Describe the pygostyle in the avial tail
most caudal segment
several fused rudiments
gives support to the flight feathers of the tail
What bone makes up the sternum of birds?
keel
large, unsegmented bone
How does the keel bone vary between avian species?
prominent in strong fliers
deep in weak fliers (chickens)
Where do the muscles of flight insert?
onto the keel
Which muscle of flight is responsible for downward stroke of the wings?
pectoralis muscle
aka superficial pectoral
aka pectoralis major
Which muscle of flight is responsible for the upward stroke of the wings?
supracoracoideus muscle
aka deep pectal
aka pectoralis minor
Which muscle of flight is responsible for drawing the wing caudally/folding up the wing?
latissimus dorsi muscle
Describe the oropharynx of the avian species
combined cavity
extends from the beak to the esophagus
Describe the roof of the avian oropharynx
composed of the hard palate NO SOFT PALATE
choana = opening
infundibular cleft = smaller opening, caudal to the choana
Describe the floor of the avian oropharynx
mandible, tongue, laryngeal mound
What is the laryngeal glottis in the avian species?
median slit on the laryngeal mound that opens to the larynx
What is the organ of phonation in the avian species?
synrinx
Describe the mucosa of the avian oropharynx
many openings for salivary glands
more in granivorous birds
Which side of is the avian esophagus on within the cervical region?
right side
Describe the crop
expansion of the ventral wall of the esophagus at the thoracic inlet
used to store food for short periods of time
What are the two parts of the avian stomach?
proventriculus and ventriculus
Proventriculus =
glandular stomach
Ventriculus =
muscular stomach
gizzard
Describe the proventriculus
spindle shaped
mucus-secreting columnar epithelium
numerous papillae and collecting ducts (glands) secrete HCl, pepsin, and mucus
Describe the ventriculus
lens shaped
two thick masses of muscles - insert on tendinous centers, one on each side
cuboidal epithelium with tubular glands, screte Kaolin (carbohydrate-protein complpex) which hardens and protects the gizzard
Where do the intestine open into in the avian species?
open into the cloaca
What is the vitaline/meckel’s diverticulum?
small outgrowth marking the former connection with the yolk sac
persists for a few days to nourish the hatchling
also serves as a marker for the beginning of the ileum
How many ceca are present in herbivorous birds?
two ceca at the ileocolic junction - function for bacterial breakdown of cellulose
attached via ileocecal folds
Describe the cloaca
common to the digestive and urogenital systems
opens to the exterior at the vent
What are the regions/parts of the cloaca
cuprodeum - where feces are stored
urodeum - where the ureter opens
proctodeum - most caudal, related to the reproductive system
Which lobe of the avian liver is larger? Why?
right lobe - carries the gallbladder
Which species of bird lacks a gallbladder?
pigeons
What color is the avian liver?
dark brown
yellow for the first 2 weeks after hatching due to yolk pigment
How many bile ducts are present in the avian species?
two
only the right one is attached to the gallbladder
Where are the nostrils located in the bird?
located at the base of the beak - covered by operculum
Name the nasal conchae present in the avian species?
rostral, middle and caudal conchae
Describe the caudal nasal conchae in the avian species
encloses a diverticulum of the infraorbital sinus - communicates with the nasal cavity via a narrow duct
What is the nasal/salt gland in birds? Describe it
extends from the dorsal part of the orbit in the lateral wall of the nasal cavity and opens into the cavity at the level of the rostral concha
secretes hypertonic sodium chloride solution - allows seabirds to drink saltwater
Describe the trachea of birds
composed of tightly stacked, complete cartilaginous rings
Describe the syrinx in birds
responsible for sound production - lateral and medial walls of the bronchii are membranous and cause sound when caused to flutter
formed by the terminal part of the trachea and the beginning of the primary bronchi
Where are the avian lungs located?
dorsal in the body cavity
Describe the avian lungs
roughly quadrilateral
relatively small
inelastic and non-expansible
Describe the primary bronchus in birds
enters the lung
continuous with the abdominal air sac
Describe the secondary bronchii in birds
named according to the general area of the lung they supply
essential to the passage of air through the lungs
Describe the parabronchi in birds
where gas exchange takes place
arise from the mediodorsal and medioventral secondary bronchi
form loops - make up 3/4 of the lung
Describe the paleoplumo parabronchi
functional unit of gas exchange
anastomose with air capillaries, intertwine with blood capillaries
What are air sacs? Describe them
blind, thin-walled enlargements of the bronchial system
extend beyond the lung
airflow is multidirectional
Which air sacs are the largest?
abdominal sacs
Which side of the avian female reproductive system develops? Which species are the exception?
left side
exception: birds of prey and kiwi bird
Describe the avian ovary
resembles a truss of grapes of various sizes - several thousand follicles
yellow
What is the function of the avian oviduct?
conducts fertilized ovum to the cloaca
add nutrients (albumin)
protection
conveys spermatozoa to the ovum for fertilization
storage of spermatozoa for later use
What are the parts of the avian oviduct?
infundibulum
magnum
isthmus
uterus/shell gland
How long does the ovum stay in the avian infundibulum?
15 minutes
What occurs within the avian infundibulum?
chalaziferous layer is formed
How long does the egg stay in the magnum for?
~3 hours
What is unique about the magnum?
largest segment
What occurs in the magnum?
deposits albumin, calcium, sodium and magnesium
What is unique about the isthmus?
thinner than the magnum
most narrow part
How long is the egg in the isthmus for?
~1 hour
What occurs in the isthmus?
secretes more albumin
forms the homogenous membranes between albumin and the shell
Describe the shell gland
uterus
thinner-walled, slightly enlarged chamber
What occurs in the uterus of birds?
watery albumin is added
deposit shell, shell pigments and outer cuticle
How long does the egg remain in the avian uterus?
~20 hours
Describe the avian vagina
muscular
s-shaped
How long does the egg stay in the avian vagina?
completed egg passes in seconds when laid
Describe the testis of the avian species
paired, bean shapped, relatively small
Where are the avian testis located?
located symmetrically against the cranial ends of the kidneys
What is unique about the epididymidis of the avian species?
not divided into head, body and tail
Describe the deferent duct of the avian species
arises from the caudal part of the epididymidis
accompanies the ureter
opens on a low papilla on the lateral wall of the urodeum
Describe the avian phallus
located at the ventral lip of the vent
parts: lymphatic fold, lateral phallic fold, median phallic fold/tubercle, paracloacal vascular body
Where are the avian kidneys located?
lodged in the renal foosae of the synsacrum and pelvic girdle
make contact eith the lung cranially
What are the parts of the avian kidneys?
cranial, middle and caudal parts
Does the avian urinary system have a renal pelvis, bladder or urethra?
no
ureters go straight from the kidneys to the dorsal wall of the urodeum
Describe the blood supply to the avian kidneys
three renal arteries
one for each division of the kindey
Describe the renal portal system of the avian species
cranial and cuadal renal portal veins
receive blood from the caudal body parts via external iliac vein
