第十一期 规模蛋鸡场长培训班 12月 下旬 将在山西举办

鸡的器官与支气管

鸡的鼻甲壳（旁切面）

鸡鼻鼻甲水平处的鼻腔横切面和鸡鼻甲壳中部的鼻腔横切面

鸡喉、鳃裂器官和舌头的解剖关系

鸡的喉部软骨（示意图）

鸡的鸣管（示意图）

鸡的肺脏

鸡的左右肺叶

鸡的气囊（背视图）

鸡的气囊（侧视图）

第十一期 规模蛋鸡场长培训班 12月 下旬 将在山西举办

Nasal cavity (cavum nasi)

The nasal cavity is situated to the left and right of the median nasal septum (septum nasale).

The position of the nostrils (nares) varies considerably between species. In the chicken they are located at the base of the beak. The nares can also be surrounded by feathers and may be tubular in structure.

In some species, including the chicken and turkey, a cornified plate known as the operculum projects from the dorsal border of the nares. In pigeons, the operculum is covered by the fleshy cere (see Chapter 17 ‘Common integument’). The left and right ceres may coalesce dor sally and, in many breeds of pigeon, are quite pronounced.

In the duck and goose, the nasal septum is perforated by asmall opening at the level of the nares.

Most birds have three nasal conchae (conchae nasales)(Figure 7.2). In contrast to mammals, they are arranged ina rostrocaudal, rather than dorsoventral, sequence.

They are composed of the:

• the presence of both a larynx and a syrinx,

• ossification of the tracheal rings,

• a relatively constant lung volume,

• the absence of pleura post-hatching and

• the presence of air sacs

7.1 Relationship between the air sacs and the bronchial system in the chicken (schematic).

• rostral nasal concha (concha nasalis rostralis),

• middle nasal concha (concha nasalis media),

• caudal nasal concha (concha nasalis caudalis).

In the chicken, a cartilaginous lamella arises from theventral border of the nostril, in front of the rostral nasal concha. The nasolacrimal duct (ductus nasolacrimalis)

opens into the nasal cavity between the rostral and middlenasal conchae. Its course is described in Chapter 15 ‘The eye’ (Figure 15.43).

The cranial portion of the nasal cavity (nasal vestibule; regio vestibularis) is lined with non-glandular mucosa.

This transitions caudally, in the respiratory region (regio respiratoria), into a pseudostratified ciliated epithelium containing goblet cells (respiratory epithelium). In the olfactory region (regio olfactoria) the epithelium con tains neurosensory cells (olfactory epithelium) (Figures

7.2 to 7.4). Its histological structure is similar to that of mammals.

In chickens and waterbirds, the typically yellowish olfactory region consists of a small circumscribed area on the caudal nasal concha and the caudal nasal septum. The avian olfactory mucosa, like the olfactory bulb, is usually limited in extent and function. Development of the olfac tory apparatus is generally greater in fish- and meat-eatin birds than in grain-eating species.

The nasal cavity communicates with a single paranasal sinus. Termed the infraorbital sinus (sinus infraorbitalis),

this occupies a relatively large, triangular space situated immediately under the skin, rostroventral to the eye. It is surrounded almost entirely by soft tissue. Near the nasal angle of the eye, the infraorbital sinus communicates with the cavity of the caudal nasal concha. The infraorbital sinus is clinically significant and can be accessed for paracentesis (see Chapter 18 ‘Clinical examination’).