Skull

Figure 653 Lateral projection of skull with teeth shadows excluded for clarity.

A Atlas

B Axis

C Stylohyoid bone

D Epihyoid bone

E Ceratohyoid bone

F Basihyoid bone

G Thyrohyoid bone

1 Incisive bone

2 Nasal bone

3 Frontal bone

4 Parietal bone

5 Osseous tentorium of the cerebellum

6 Interparietal bone

7 Occipital bone

7(a) External occipital protuberance or ‘nuchal crest’

8 Occipital condyle

9 Jugular process of occipital bone

10 Petrous temporal bone or temporal bone-petrosal part

11 Tympanic bulla of temporal bone or temporal bone-tympanic part

12 External acoustic meatus of temporal bone

13 Zygomatic process of temporal bone or temporal bone-squamous part

14 Retroarticular process of temporal bone

15 Mandibular fossa of temporal bone

16 Palatine process of maxilla. The vomer lies dorsally.

17 Palatine bone. Rostrally the palatine process of maxilla is included.

18 Sphenoid sinus of presphenoid

19 Cribriform plate of ethmoid bone. Rostral limit only is visible.

20 Ethmoidal fossa

21 Ethmoidal conchae

22 Dorsal nasal conchae

22(a) Dorsal nasal meatus

23 Middle nasal conchae

23(a) Mass of conchae attached to the ethmoid bone, from the dorsal and middle conchae. Seen as a radiopaque region and must not be mistaken for a foreign body.

24 Ventral nasal conchae

24(a) Ventral nasal meatus

25 Dorsal orbital margin

26 Basisphenoid bone

27 Frontal sinuses

28 Mandibular body

29 Mandibular ramus

30 Coronoid process of mandible

31 Condyloid or articular process of mandible

32 Angular process of mandible

33 Mandibular foramina

34 Mandibular canal

35 Mental foramen

36 Lamina dura

37 Soft palate

38 Nasopharynx

39 Epiglottis

Figure 654 Lateral projection of skull to demonstrate details of teeth excluded in Figure 653.

1 Upper incisors. Total of six.

2 Lower incisors. Total of six.

3 Upper canines. Total of two.

4 Lower canines. Total of two.

5 Upper premolars. Total of six.

6 Lower premolars. Total of four.

7 Upper molars. Total of two.

8 Lower molars. Total of two.

Note that the term ‘upper’ can be replaced by ‘superior’ and ‘lower’ by ‘inferior’.

Figure 655 Dorsoventral projection of skull. British Domestic Short Haired cat 1 year old, neutered male. (Approximately 150% of original size.)

Figure 656 Dorsoventral projection of skull with teeth shadows excluded for clarity.

A Atlas

B Axis

C Cartilaginous ear canal

D Pinna

1 Incisive bone

2 Maxilla or maxillary bone

2(a) Maxillary teeth obscuring bony shadows of maxillary bone (lamina dura seen as radiopaque lines)

3 Vomer and nasal septum (the osseous part of the nasal septum contributes to the radiopaque line)

4 Temporal process of zygomatic bone

5 Frontal process of zygomatic bone

6 Zygomatic process of frontal bone

7 Zygomatic process of temporal bone. Forms zygomatic arch with (4).

8 Frontal sinuses

9 Sphenoidal sinuses

10 Cribriform plate of ethmoid enclosing ethmoidal fossa

11 Ethmoturbinates and dorsal nasal concha (dorsal nasal concha is not seen clearly on this projection)

12 Border of choanae formed by palatine bone

13 Medial wall of orbit

14 Ventral margin of orbit

15 Lamina dura

15(a) Mandibular lamina dura

15(b) Maxillary lamina dura

16 Mandibular body

17 Coronoid process of mandibular ramus

18 Angular process of mandibular ramus

19 Condyloid or articular process of mandibular ramus

20 Retroarticular process of temporal bone

21 Tympanic bulla of temporal bone

22 External acoustic meatus of temporal bone

23 Internal acoustic meatus of temporal bone

24 Jugular foramen

25 Petrous temporal bone

26 Mastoid process of petrous temporal bone

27 Occipital condyle

28 Nuchal crest

29 Hamulus of pterygoid bone

30 Osseous tentorium of cerebellum

31 Foramen magnum

Figure 657 Dorsoventral projection of skull to demonstrate details of teeth shadows excluded in Figure 656.

1 Lower incisors. Total of six.

2 Upper incisors. Total of six.

3 Lower canines. Total of two.

4 Upper canines. Total of two.

5 Lower premolars. Total of four.

6 Upper premolars. (The 1st premolar in this cat appears to be present, making a total of eight instead of six. This is unusual.)

7 Lower molars. Total of two.

8 Upper molars. Total of two.

Note that the term ‘lower’ can be replaced by ‘inferior’ and the term ‘upper’ by ‘superior’.

Temporomandibular joints, single relaxed lateral projection: Figures 658–659

Figure 658 Relaxed lateral skull centred on temporomandibular joint. British Domestic Short Haired cat 2 years old, neutered female. (Approximately 220% of original size.)

Figure 659 Relaxed lateral skull centred on temporomandibular joint.

A Temporomandibular joint of recumbent side

B Temporomandibular joint of non-recumbent side

1 Body of mandible

2 Angular process of mandible

3 Condyloid or articular process of mandible

4 Coronoid process of mandible

5 Mandibular fossa of temporal bone

6 Retroarticular process of temporal bone

7 Tympanic bulla of temporal bone

8 External acoustic meatus of temporal bone

9 Cribriform plate

10 Petrous temporal bone

11 Cranial base

12 Occipital condyle

13 Atlas

14 Stylohyoid bone

15 Epihyoid bone

16 Ceratohyoid bone

17 Basihyoid bone

18 Thyrohyoid bone

19 Soft palate

20 Epiglottis

21 Rostral limit of arytenoid cartilage

22 Nasopharynx

23 Oropharynx

Tympanic bullae, single oblique projection: Figures 660–661

Figure 660 Rostroventral–caudodorsal oblique (open mouth) projection of skull centred on tympanic bullae. British Domestic Short Haired cat 2 year-old, neutered female. (Approximately 160% of original size.)