Maharashtra Board Class 11 Animal Science And Technology Chapter 10 Poultry Anatomy And Physiology PDF Download

10. Poultry Anatomy And Physiology

Can you recall? Functions of Skeletal system, Digestive system, Respiratory system, Reproductive system and Endocrine system.

10.1 Skeletal System

The skeletal system of fowl consists of axial and appendicular skeleton.

10.1.1 Axial Skeleton

It consist of skull, vertebral column, ribs and sternum.

1. Skull: Skull is small and conical. The anterior extremity is elongated and ends into a pointed beak. The posterior extremity articulates with atlas.

2. Vertebral Column: The vertebral column of fowl consists of - a) Cervical vertebrae, b) Thoracic vertebrae, c) Lumbar and sacral vertebrae and d) Coccygeal vertebrae.

a. Cervical vertebrae: They are 14 in number. Atlas is the first cervical vertebra which is thin and ring like. Axis, second vertebra, is short.

b. Thoracic vertebrae: They are seven in number. The first and sixth vertebrae are free where as second to fifth are fused with first lumbar vertebra.

c. Lumbar and Sacral vertebrae: They are 14 in number. They fuse to form lumbo-sacral mass.

d. Coccygeal Vertebrae: They are six in number. The first coccygeal vertebra is fused with lumbo sacral mass. The last two or more vertebrae unite to form a three sided pyramid like structure called as Pygostyle.

3. Ribs: There are seven pairs of ribs. They form lateral wall of thoracic cavity. They articulate above to the thoracic vertebrae and below to the sternum.

4. Sternum: It is also called as breast bone. It is quadrilateral curved plate of bone. It forms the floor of thoracic cavity and part of the abdominal cavity.

Teacher's Note

The bird skeleton is very light and strong like an airplane. Birds can fly because their bones are hollow.

Exam Trick

Remember: C14 T7 L+S14 Cy6. This is the vertebral formula. Count 14 neck bones, 7 chest bones, 14 lumbar-sacral bones, and 6 tail bones.

Points to Remember

Skull is small and pointed like a beak.
Cervical vertebrae are 14 in number in the neck.
Pygostyle is the last bone that looks like a pyramid.
Ribs form the side wall of the chest.
Sternum is also called breast bone.

10.1.2 Appendicular Skeleton

Appendicular skeleton of fowl consists of bones of pectoral and pelvic limbs.

1. Bones of Pectoral Limb

a. Pectoral girdle: It comprises Clavicle, Coracoid and Scapula. Clavicle is slightly bent, thin rod of bone. Coracoid is long, three sided, rod shaped bone. Scapula is thin elongated bone.

b. Humerus: The bone articulates with the scapula and the coracoids proximally and with the radius and the ulna distally.

c. Radius and Ulna: The radius is placed external to the ulna. Radius and ulna are separated by a wide interosseous space. These bones articulate with the humerus proximally and with carpus distally.

d. Carpals: There are two bones, namely radial carpal and ulnar carpal in the proximal row. The distal row bones are fused with the metacarpal bones.

e. Metacarpals: There are three metacarpal bones. The first metacarpal is a small projection while the second and third are fused at both extremities.

f. Digits: There are three digits in fowl. The first and second digits have two phalanges while the third digit has one.

Teacher's Note

Wings are like human arms. Pectoral girdle holds the wing to the body just like our shoulder holds our arm.

Exam Trick

Remember: Wings have 3 digits just like birds have 3 fingers. Legs have 4 toes like they walk on 4 things.

Points to Remember

Pectoral girdle connects the wing to the body.
Humerus is the upper arm bone.
Radius and ulna are forearm bones.
Metacarpals are hand bones.
Digits are fingers or toes with phalanges.

2. Bones of Pelvic Limb

a. Pelvic girdle: It comprises of ilium, ischium and pubis or lay bone. The ilium is the largest pelvic bone and is fused with sacrum. The ischium is smaller than ilium. The pubis is thin bone and has a tendency to straighten out when a bird is in production. The acetabulum is large, deep and perforated.

b. Femur: This long bone articulates with pelvic girdle proximally and with tibia-fibula distally.

c. Patella: It is thin triangular bone.

d. Tibia: The proximal end is attached to fibula. The distal end is fused with proximal row of the tarsus.

e. Fibula: It is thin, rod shaped bone. The proximal end has a massive head for articulation with femur. The distal end is pointed and extends up to lower third of the tarsus.

f. Tarsals: They are not found separately in the adult birds. The tarsal bones of the proximal row are fused with the tibia to form tibio-tarsus. The tarsal bones of distal row are fused with metatarsal bone to form tarso-metatarsus.

g. Metatarsal: It is a single large bone in adult fowl. The proximal end is irregular and fused with tarsus. The distal end articulates with second, third and fourth digits.

h. Digits: There are four digits (toes) in fowl. The first and second digits have three phalanges. The third has four phalanges and the fourth has five phalanges.

Teacher's Note

Legs of a chicken are like our legs. Femur is thigh bone, tibia is shin bone, and we see this in chicken curry at dinner.

Exam Trick

Remember: Legs have 4 toes. First toe has 3 bones, second has 3, third has 4, fourth has 5. Count like this: 3, 3, 4, 5.

Points to Remember

Pelvic girdle is the hip bone of the bird.
Ilium is the largest pelvic bone.
Femur is the thigh bone in the leg.
Tibia and fibula are shin bones.
Tarsus and metatarsus are foot bones.

10.2 Digestive System

The digestive system of fowl consists of mouth, oesophagus, stomach, small intestine, large intestine, cloaca and associated glands viz liver and pancreas.

10.2.1 Alimentary Canal

1. Mouth: It is triangular in shape closed by upper and lower jaw forming the beak. The shape of tongue is like the barbed head of an arrow. Mouth is directly continuous with the pharynx. The main functions of mouth are prehension and deglutition.

Do you know? Mouth in birds is characterised by absence of cheeks, lips and teeth.

2. Oesophagus: It is thin walled elastic tube. It begins at pharynx and terminates at proventriculus. It is a passage for food.

3. Crop: It is an enlargement of the oesophagus. It is simple, oval, musculo-membranous pouch. It stores food material. It also secretes mucus which lubricates and softens food material. It sends food to the proventriculus.

4. Stomach: It consists of two parts viz. proventriculus and gizzard.

a. Proventriculus: It is also called as glandular stomach. It is located 2-3 inch beyond the crop. It is an oval thick walled tube. It passes food from the crop to gizzard. It secretes gastric juice and some acids. It helps in further softening of the food material.

Remember... Very little digestion take place in poultry through bacterial action. They can digest small amount of fibre than any other class of farm livestock.

b. Gizzard: It is also called as muscular stomach. It is located just behind the proventrilculus. It is larger than proventriculus. It is reddish green in colour. It is composed of two thick, powerful muscles. Its main function is crushing or grinding of ingested food. It acts as a filter for food material.

Do you know? Gizzard is the largest single organ of the body.

5. Small Intestine: It extends from the gizzard to the caeca and about 2.5 ft long in mature bird. It consists of three parts namely duodenum, jejunum and ileum. The duodenum begins from gizzard and forms a loop. The bile and pancreatic ducts open near each other at the termination of duodenum. The jejuno-ileum is arranged in the form of coils. Gastric digestion together with some pancreatic digestion takes place in duodenum. It secretes intestinal juice which helps in digestion of food material. It acts as an organ for absorption of the digested food material.

Teacher's Note

The digestive system of a chicken is like a food factory. Food goes in, gets broken down, and useful parts are taken out.

Exam Trick

Remember: Mouth - Oesophagus - Crop - Proventriculus - Gizzard - Small Intestine. This is the path food takes. Just memorize: Mouth to Gizzard for grinding food.

Points to Remember

Crop stores food like a bag.
Proventriculus is the glandular stomach that makes juice.
Gizzard grinds food with strong muscles.
Small intestine has three parts: duodenum, jejunum, ileum.
Gizzard is the largest organ in the bird body.

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