Avian Anatomy Gross Anatomy 2

Avian Anatomy

• Gross Anatomy 2 was lectured by Dr. Cristian Martonos.
• Previous lecturer was Dr. Melissa Kehl.
• Images of various bird species are shown.

Learning Objectives

• Understand anatomical adaptations specific to birds in integument, cardiorespiratory, gastrointestinal, musculoskeletal, urogenital and immune systems.
• Understand and apply clinical applications of avian anatomy.
• Recognize diseases and conditions unique to birds and their anatomical adaptations.
• Understand the anatomical position of the avian skeleton.
• Identify external structures during a physical examination.
• Differentiate between types of feathers.
• Identify soft-tissue organs (respiratory, gastrointestinal, immune, and urogenital tracts).

Integument: Skin

• Very thin skin.
• Poor blood vessel and nerve supply.
• No sweat glands.
• Feather tracks are present.
• Easily bruises.
• Scales on feet and legs are cornified epidermis.
• Beaks are derived from skin.
• Uropygial gland is present.

Integument: Uropygial gland/preen gland

• Located at the base of the tail.
• Dorsal to the caudal vertebrae.
• Important for waterproofing and insulating submerged body parts in waterfowl.
• Absent in most ratites and some amazon parrots.

Integument: Ornamental Features

• Comb
• Wattle
• Snood or frontal process
• Ear lobes

Integument: Skin - Patagium

• Triangular area between shoulder, elbow, and wrist joints.
• Increases surface area of wings.
• Composed of skin and elastic tissue, including patagial ligament.
• Important for flight aerodynamics.

Integument: Feathers

• Pteryla: tracts in skin where feathers grow.
• Apteria: featherless skin between pterylae.
• Contour feathers: externally visible feathers, covering the down feathers and defining the body shape and wings.
• Down feathers: lack barbules, under contour feathers, conserving heat and being abundant in waterfowl.

Skeletal System

• Skull: lower jaw articulates with upper jaw via quadrate bone; upper jaw is movable relative to the cranium; large orbits separated by interorbital septum; single occipital condyle.

• Pneumatic bones (hollow) include humerus and femur.

• Bones are strong but brittle and open fractures common.

• Thin cortex

• Trabeculae for strength

• Notarium: fusion of dorsal spinous processes of most thoracic vertebrae.

• Keel and Sternum: support internal organs, respiration, body conditioning; good for radiography positioning.

• Synsacrum: fusion of last two or three thoracic, all lumbar, all sacral and first few caudal vertebrae.

• Pygostyle: fusion of most caudal vertebrae (3-4 in most birds).

• Wing feathers (remiges): responsible for flight and include primary and secondary flight feathers.

• Tail feathers (rectrices): known as tail feathers.

• Clavicles (wishbone): fused and form the furcula.

• Coracoids: form a brace supporting the wing strokes.

• Forelimb/wing: modified for flight.

• Three metacarpals instead of digits for a wing.

• Pelvic limb: important for locomotion on the ground.

• Hip bones (ilium, ischium, and pubis): fused dorsally with the synsacrum.

• Tarsal bones fused with metatarsal bone = tibiotarsus.

Muscular System

• Pectoralis: more superficial, powerful downstroke of the wing.
• Supracorocoideus: smaller, used for take-off.
• Pectorals and supracoracoideus originate on the keel of the sternum, insert on the humerus. Having opposing functions.

Respiratory System

• Lungs: in contact with vertebral ribs, constant volume.

• Air sacs: external to lungs, 8 in Chickens: cervical, clavicular (interclavicular), and paired cranial thoracic and caudal thoracic; abdominal air sacs.

• Syrinx: vocal apparatus at tracheal bifurcation.

• Air sacs allow for unidirectional airflow through the lungs

Circulatory System

• Heart structure is similar to mammals but isn't covered by lungs.
• Heart apex is covered by the liver.

Venipuncture Sites

• Jugular vein (right larger than left).
• Medial plantar metatarsal vein (medial side of the tibiotarsus).
• Cutaneous ulnar vein (branch of brachial)..

Gastrointestinal System

• Lack a soft palate.
• Hard palate contains the choana.
• Choana connects the oral and nasal cavities.
• Choana lined with caudally directed papillae.
• Salivary glands and taste buds are poorly developed.
• More developed in birds that eat dry diets (seeds).
• Esophagus (down the right side of the neck).
• Crop: diverticulum of the esophagus.
• Some birds, like chickens and turkeys, have a crop to store food.
• Proventriculus (glandular stomach): secretes digestive enzymes.
• Ventriculus (muscular stomach): breaks up larger food.
• Duodenum, jejunum, ileum; intestinal tract.
• Cysticoenteric duct: from gall bladder.
• Hepatoenteric duct: from left lobe of liver.
• Vitelline diverticulum (Meckel's) : remnant of the embryonic yolk sac.
• Paired ceca: (10)
• Descending colon: (11)

Urogenital System

• Paired kidneys with elongated 3 lobes (cranial, intermediate, caudal).
• Urinary bladder is absent (urates instead of urea).
• Males have paired testes inside the abdomen (no scrotum).

Egg Production

• Infundibulum: 7 cm long, thin coating of dense albumen, collects egg from ovary.
• Magnum: 30 cm long, albumen production.
• Isthmus: 8 cm long, primarily shell membranes.
• Shell gland: 8 cm long, shell formation.
• Vagina: (7): passage of egg seconds.

Immune System

• Palpable lymph nodes absent (in mammals).
• Thymus and bursa of Fabricius regress early in life.
• Spleen at the junction of proventriculus/ventriculus; enlarged with diseases (e.g., chlamydiosis).

Test your knowledge on avian anatomy as covered in Gross Anatomy 2 with Dr. Cristian Martonos. This quiz explores various anatomical adaptations specific to birds, including their integument, cardiorespiratory, and gastrointestinal systems. You will also learn to recognize diseases unique to birds and apply clinical knowledge effectively.