Wael Khamas and Josep Rutllant The anatomy of gamebirds (quail, partridge, and pheasant) is briefly presented in this chapter. Any term not recognized by Nomina Anatomica Avium [1] will be avoided. Areas of clinical interest are emphasized, along with comparisons to other avian species, including the chicken, one of the most studied avian species. Both mature and immature animals will be described. Body regions are used to describe the locations of certain structures and draw the attention of the clinicians to the site of infection or injury. Therefore, the body can be divided into head and neck, thoracic, wing, abdominal, pelvic, and pelvic limb regions. The natural orifices on the head are the eyes, external acoustic meatuses, nasal openings, and mouth. The ornamental structures on the head include cere, comb, wattles, and ear lobes when present. The appearance of orifices and ornamental structures is frequently used by clinicians to identify illness in birds. In chickens, the ornamental structures differ in size between sexes, being larger in males even at an early age. The same is true in pheasants. The regions of the head and neck include nasal, orbital, suborbital, forehead, crown, auditory, dorsal cervical, lateral cervical and ventral cervical (Figure 4.1a). The ventral aspect of the wing region includes the chest, abdomen, shank, upper arm, propatagium, forearm, and hand (area of major and minor metacarpals) (Figure 4.2). This region can be used for examination of the bird to detect external parasites and determine feather conditions [2]. Figure 4.1 (a) Male partridge. 1. Nasal, 2. Orbital, 3. Suborbital, 4. Forehead, 5. Crown, 6. Auditory, 7. Dorsal cervical, 8. Lateral cervical, 9. Ventral cervical. (b) Male partridge, face and cervical regions. 1. Superior eyelid, 2. Inferior eyelid, 3. Operculum, 4. Superior (maxillary) beak, 5. Inferior (mandibular) beak, 6. External nares, 7. Maxillary rictus. (c) Male pheasant. 1. Nasal opening, 2. Culmen, 3. Tomium, 4. Periorbital wattle, 5. Mandibular rictus, 6. Auditory orifice. Ornaments vary among different gamebird species as well as between sexes of the same breed. These ornamental appendages, mentioned before, can be affected by the early nutritional status of the bird. Differences in growth conditions during early life have been suggested to cause long‐lasting changes in the morphology and quality of adult birds, including their ornaments (Figures 4.1 and 4.2). Because of this factor, females may choose ornamented mates that are superior at handling early nutritional stress [3]. The skin of gamebirds is typically white in color, but pigmentation can change based on a variety of factors. For example, coloration of the shank and beak of the chukar partridge results from dietary pigments. The skin of birds is very thin and composed of two layers of epidermis and dermis. The epidermis is thin stratified squamous epithelium with different degrees of keratinization. Most notably, skin on the legs will form scales and is highly keratinized compared to other regions. The thin skin of birds is one of the modifications that aids in decreasing body weight for facilitation of flight. The spur is a highly keratinized outgrowth of the hindlimbs of some birds. It is usually located at the distal tarsometatarsal region (Figure 4.3). It is well developed in mature males, and less so in female and immature birds. The main function of the spur is defense. Spurs are well developed in pheasants and are often used for aging. They are rudimentary in partridge and absent in quail. Spurs can be removed at an early age with electrocautery. Figure 4.2 (a) Pheasant ventral view. 1. Chest, 2. Abdomen, 3. Shank, 4. Upper arm, 5. Propatagium, 6. Forearm, 7. Hand region (area of major and minor metacarpal). (b) External features showing wing feathers on adult pheasant. a. Alula, b. under covert primary feathers, c. under covert secondary feathers, d. under wing feathers, e. Contour feathers (chest), f. Contour feathers (abdomen). Primary feathers: 1. Alula, 2. II primary, 3. IV primary, 4. VI primary, 5. VIII primary, 6. X primary. Figure 4.3 Male pheasant feet detail. 1. Tarsometatarsal, 2. Spur, 3. Digit I, 4. Metatarsal pad, 5. Digit II, 6. Digit III, 7. Digit IV, 8. Digital pads, 9. Claw. Uropygial, preen, oil, rump, caudal, or perunctum gland are all names for the same gland. It is a bilobed gland situated above the caudal rump region. It is relatively large in pheasants (Figure 4.4). In rock partridge, the location varies from the first caudal vertebra or end of synsacrum to the last 3–4 caudal vertebra. The elevation at the tip of the gland is where the two lobes open and the oil can be accessed by the bird. The gland can be described as simple tubular with a holocrine mode of secretion. The gland in Japanese quail is elongated and described as heart‐shaped, consisting of two active lobes. The gland has a very deep septum between the lobes [4]. Figure 4.4 (a) Pheasant, caudal‐dorsal region. 1. Levator caudae m., 2. Uropygial (bilobed) gland, 3. Papilla where the duct open, 4. Gastrocnemius m., 5. Fibularis longus m., 6. Iliotibialis lateralis m. (b) Pheasant, caudal‐ventral region. 1. Pectoralis m., 2. Abdominal mm., 3. Puboischiofemoralis m. (reflected)., 4. Iliotibialis cranialis m., 5. Puboischiofemoralis m., 6. Flexor cruris medialis m., 7. Ischiadic vein, artery, and nerve. Feathers develop embryologically as buds from the skin during the early stages of embryonic development. Feathers do not cover the entire body of the bird but follow specific lines, depending on the region of the body. The line with feathers is called the pteryla (pl: pterylae) while the line without feathers is called the apteryla (pl: apterylae). The feathers of birds have many classifications. The first classification discussed is flight. Flight feathers are either remiges or rectrices. Remiges are the flight feathers of the wing and rectrices are those of the tail. The remiges can be divided into primary, secondary, and tertiary. The wing has 10 primary, 13–21 secondary and 3–4 tertiary remiges. Birds typically have between 12 and 22 rectrices. Other feathers include the contour feathers, which are on the outer surface of the body. Contour feathers include the covert feathers, which cover the bases of flight feathers (Figure 4.2). Although feathers have many different classifications, they have the same general structure. Feathers consist of a shaft, also known as the quill, and a vane (Figures 4.5–4.7). The shaft has two parts: the calamus and the rachis (Figure 4.7). The calamus is the proximal portion that is implanted into the skin. The rachis is the distal portion of the shaft. Barbs are singular strands of keratin that extend from the rachis. Barbs are either pennaceous or plumulaceous. Pennaceous barbs have interlocking barbules, and plumulaceous barbs do not. Barbules are made by further branching of barbs. On either side of the shaft, the interlocking of the pennaceous barbs is known as the vane. The vane is what forms the smooth surface of the feather [5]. Figure 4.5 Pheasant feathers. (a) Primary, (b) Allula, (c) Secondary covert, (d) Secondary, (e) Tail. Figure 4.6 Adult pheasant contour feathers. (a) Lateral thoracic, (b) Neck, (c) Dorsal thoracic, (d) Ventral abdominal. Figure 4.7 Pheasant primary feather of adult male. Dorsal view (left image), ventral view (right image). (a) Inferior umbilicus, (b) Remnant of feather sheath, (c) Calamus (quill), (d) Posterior barbs, (e) Anterior barbs, (f) Rachis. Primaries do not have any freedom of movement relative to the bones to which they are rigidly attached. Secondaries, on the other hand, are able to hinge up and down relative to the ulna through flexible attachment. When the elbow and wrist joints are fully extended, primaries spread out and secondaries are pulled downward by the tightening of the postpatagial tendon, which results in an increase in the camber of the wing [6]. Feathers are shed in intervals through a process called molting. Flight feathers are usually replaced annually while secondary feathers are replaced with less frequency. Many factors may affect the shedding of feathers including hormones, light, diet, and weather. The male pheasant is one of the most colorful birds and has long tail feathers while the female has brown mottled plumage and a short tail. In contrast, male and female chukar partridges are almost identical in appearance of the feathers but differ in size, with males being larger. In bobwhite quails, males have white coloring of the head that is absent in the female. The color of the feathers is due to pigments from three different groups: carotenoids, melanin, and porphyrine. Oxidation variability of a pro‐pigment leads to the development of different types of melanin. For example, black and dark brown pigments are called eumelanin, while red, light brown, and yellow pigments are called phaeomelanin. Male and female birds differ in feather color because of the response of the feathers to hormones and genetic factors [7]. However, no details of this response are described in the literature. The skull of Aves has a number of fused bones and a larger orbit than that of mammals (Figure 4.8). The vertebral column also has many points of fusion, providing increased support for the entire body. The fusion of bones in the vertebral column, synsacrum, and unfused pubic bone allows for the passage of relatively large eggs. The fusion of the last few caudal vertebrae forms the pygostyle, which supports the tail feathers (Figure 4.9). Relative to body size, birds are lighter than mammals, and much of this is due to adaptations of the skeleton. This is done by the introduction of air into large bones such as the humerus, femur, coracoid, and sternum (Figures 4.10 and 4.11). These are known as pneumatic bones. Gamebirds are not highflyers, but their bones are similar to other birds with respect to pneumatization. Sexual dimorphism is obvious in pheasants, with the male being heavier than the female. Figure 4.8 Pheasant skull. (A) Lateral view. (B) Dorsal view. (a) Maxillary bone, (b) Maxillary process, (c) Mandible, (d) Lacrimal bone, (e) Interorbital septum, (f) Quadrate bone, (g) Postorbital process, (h) Occipital bone, (i) External nares, (j) Intermaxillary process of the nasal bone, (k) Craniofacial hinge. Figure 4.9 Synsacrum of an adult pheasant. (A) Dorsal view. (B) Ventral view. (a) Apex of pubis, (b) Wing of ischium, (c) Dorsolateral iliac crest, (d) Iliosacral canal, (e) Preacetabular tubercle, (f) Preacetabular wing of the ilium, (g) Caudal recess of renal fossa, (h) Shaft of pubis, (i) Ilio‐ischiadic foramen, (j) Perforation of acetabulum, (k) Obturator foramen, (l) Iliosacral synostosis, (m) Preacetabular tubercle, (n) Lateral iliac crest. Aves have a large number of muscles in a unique and complex arrangement. Muscles of the chest and thoracic limb (wing) are enlarged to assist in flight. Since the primary function of the thoracic limb is flight, the musculature of the pelvic limb compensates by development of muscles specialized for walking, jumping, and hunting. A general view of the medial aspect of the wing and the thighs is presented in Figure 4.12. Additional major muscle groups, including the superficial group (major pectoral), help depress the wing and, although smaller than the pectoralis, the supracoracoideus muscle is the primary elevator of the wing. The supracoracoideus muscle is active during upstroke, particularly at slow to moderate speeds and during hovering [8]. These muscles are best known as flight muscles and they originate on the keel bone (Figures 4.11 and 4.12a). Figure 4.10 All bones are from an adult pheasant. 1. Scapula and coracoid: (a) Blade of scapula, (b) Coracosternal surface, (c) Pneumatic foramen, (d) Shaft of coracoid, (e) Coracohumeral surface. 2. Humerus: (f) Humeral head, (g) Pneumatic foramen, (h) humeral condyles. 3. Femur: (i) Head of femur, (j) Neck of femur, (k) Pneumatic foramen, (l) Intercondylar fossa, (m) Medial condyle. 4. Tibiotarsus and fibula: (n) Tibial plateau, (o) Fibula, (p) Shaft of tibia, (q) Fused proximal row of the tarsal bones with the tibia. Figure 4.11 A pheasant sternum. (a) Lateral surface of keel, (b) Sternal keel (carina), (c) Carinal apex, (d) Rostrum of sternum, (e) Sternocoracoidal process, (f) Costal margin, (g) Thoracic process, (h) Caudal lateral process. Figure 4.12 (a) Pheasant, ventral view. 1. Crop, 2. Pectoral m., 3. Keel (white line), 4. Abdominal m., 5. Iliotibialis lateralis m., 6. Iliotibialis cranialis m., 7. Fibularis longus m., 8. Gastrocnemius m. (medial). (b) Pheasant, dorsal view. 1. Thymus, 2. Scapulohumeralis m., 3. Latissimus dorsi m., 4. Longissimus dorsi m., 5. Levator coccygeus m., 6. Sartorius m., 7. Tensor fascia lata m., 8. Superficial part of biceps femoris m. (iliofemoralis caudalis), 9. Uropygial gland. (c) Pheasant, wing ventral muscles. 1. Alular mm., 2. Ventral interosseus m., 3. Deep digital flexor m., 4. Flexor carpi ulnaris m., 5. Superficial and deep pronator m., 6. Basilic vein, 7. Superficial ulnar vein, 8. Propatagium, 9. Triceps m., 10. Biceps brachii m. The breast muscles of most gamebirds are a mixture of red and white fibers, while chickens have mainly white. In the pelvic limbs, the gastrocnemius and the peroneus longus (Figure 4.12) are strongly supported by the flexor muscles of the toes (three front and one hind). These muscles are actively involved in perching. The nasal openings (external nares) vary among birds. They are two oval openings at both sides of the base of the beak (Figure 4.1b,c). In some species they are covered by a soft flap of tissue (cere) to protect the entrance of the nasal cavity (Figure 4.1b). In some species, the flap is cartilaginous (operculum). During physical examination, increased or abnormal secretions can be observed in this region if the animal is unhealthy. The nasal cavity is divided into left and right cavities by the nasal septum. The nasal septum is perforated by a small opening at the level of the internal nares [9]. Rostral, middle, and caudal nasal conchae are described in birds. In the Japanese quail, the caudal nasal concha is the largest, while the cranial one is smallest. Caudally, the caudal nasal concha communicates with the single well‐developed paranasal sinus (infraorbital) [10]. The caudal end of the nasal cavity communicates with the pharynx. There are three laryngeal cartilages: cricoid, procricoid, and arytenoid. The cricoid is the largest cartilage in the quail [11]. It is longer ventrally than dorsally. The glottis is a small slit‐like opening supported by the arytenoid cartilage on both sides of the entrance into the larynx. Papillae are observed caudal to the tongue and caudal to the glottis in all gamebirds (Figure 4.13b). Generally, the pharynx and larynx in gamebirds are like other bird species.
4
Gamebird Anatomy
4.1 Introduction
4.2 Body Regions
4.2.1 Head and Neck Regions (Figure 4.1)
4.2.2 Thoracic Region and Wing
4.3 Integument: Skin and Feathers
4.3.1 Ornaments
4.3.2 Skin
4.3.3 Spur
4.3.4 Uropygial Gland
4.3.5 Feathers
4.3.6 Color of Feathers
4.4 Skeletal System
4.5 Muscular System
4.6 Respiratory System
4.6.1 Nasal Cavity
4.6.2 Larynx
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
