Avian Skeleton

Question 1

Skeleton Functions

Answer 1

Support, protection, articulation of appendages, blood cell production, and calcium stores

Question 2

Axial skeleton

Answer 2

Head spine and tail

Question 3

Skull

Answer 3

Large orbits to accommodate large eyes for good sight

Question 4

Occipital condyle

Answer 4

One to articulate spine while mammals have 2

Question 5

Cranial kinesis

Answer 5

High ability to unhinged the jaw to swallow large prey

Question 6

Heterocoelius

Answer 6

Centrum in cervical vertebrae allows for a high degree of neck mobility; each vertebrae moves a little bit further

Question 7

Uncinate process

Answer 7

Fuses the ribcage together for flight rigidity and serves as an attachment point for scapula muscles; short in walking birds, intermediate in non specialists, and long in diving birds

Question 8

Synsacrum

Answer 8

Lumbar, sacral, and some caudal vertebrae fused into a solid structure which is fused to the pelvis; allows Legs to support the body

Question 9

Pygostyle

Answer 9

Fused causal vertebrae at the end of the reduced tail, attachment site for tail feathers

Question 10

Appendiculur skeleton

Answer 10

Appendages including pectoral girdle, wings, pelvic girdle, and legs

Question 11

Pectoral girdle

Answer 11

Forms a tripod of bones to transfer energy from wing thrust to the body

Question 12

Scapula

Answer 12

Runs along the spinal column bracing the shoulder against displacement from flapping

Question 13

Coracoid

Answer 13

Braces the sternum against compression resulting from contraction of the pectoralis, prevents the ribcage from collapsing

Question 14

Furcula

Answer 14

Wishbone; strut that braces the wings apart, acts as a spring aiding in the downstroke

Question 15

Wing

Answer 15

Highly modified forelimb that folds against the body in a z shape; the humerus is a shortened and broadened upper arm, reduced number of wrist hand and finger bones are fused

Question 16

Pelvic girdle

Answer 16

Lengthened and fused to the synsacrum forms a roof covering half of the body allowing the legs to support the body; pubis and ischium open ventrally to accommodate egg laying

Question 17

Legs

Answer 17

Spaced far apart by the fused pelvis; femur buried in the body, forward facing to support center of gravity and exposed tibiometatarsus

Question 18

Cnemial crest

Answer 18

Tibial extension at the knee joint well developed in divers, allows for oar like leverage from the legs for swimming and prevents splaying

Question 19

Tarsometatarsus

Answer 19

Elongated heel bone, typically the unfeathered leg piece connecting to 2 3 or 4 toes

Question 20

Bird musculature

Answer 20

Serves for posture, flight, and thermogenesis; shifted ventrally for aerodynamics supported by the fused vertebral column

Question 21

Flight muscles

Answer 21

Pectoralis powers up stroke, originates on the pectoral girdle and inserts on ventral humerus; supercorracoideus powers the downstroke originates on the sternum and passes through the triossial canal before inserting on dorsal humerus

Question 22

Slow tonic muscle fibers

Answer 22

Slow contracting fatigue resistant, low energy use and low power, highly aerobic red muscle

Question 23

Fast twitch glycolytic fibers

Answer 23

Fast contracting, fatigue rapidly, few mitochondria, white muscle

Question 24

Fast twitch oxidative glycolytic fibers (FOG)

Answer 24

Fast contracting, high levels of oxidative and glycolytic enzymes, high mitochondria levels, fatigue resistant intermediate muscles; most common in birds that fly a lot

Question 25

Shivering

Answer 25

Mechanism of heat production in birds; isometric antagonistic muscle groups exert equal and opposite force to limit surface disturbance

Question 26

Burst shivering

Answer 26

As temperature decreases amplitude and duration of shivering increases; cold acclimation leads to decreased amplitude in the same cold stress

Question 27

Non shivering thermogenesis

Answer 27

Heat production without shivering, done by brown fat in mammals; likely occurs in birds but method is unknown