Large Animal Anatomy - Openings in the Skull

Question 1

Interincisive Canal

Answer 1

Major palatine A. (a single artery originating from the anastomosis of both Major Palatine Aa.)
Present only in the dog and horse.

Question 2

Infraorbital foramen

Answer 2

Rostral opening of the infraorbital canal
Infraorbital A. (branch of Maxillary A.)
Infraorbital V.
Infraorbital N. (branch of maxillary N.)

Question 3

Maxillary foramen

Answer 3

Caudal opening of infraorbital canal

Infraorbital A., V., & N.

Question 4

Sphenopalatine foramen

Answer 4

Opening between the pterygopalatine fossa and the nasal cavity
Sphenopalatine A. & V.
Caudal Nasal N.

Question 5

Caudal Palatine Foramen

Answer 5

Caudal opening of the Major (greater) palatine canal

Major Palatine A. & N.

Question 6

Major Palatine Foramen

Answer 6

Rostral opening of the major (greater) palatine canal

Major Palatine A. & N.

Question 7

Fossa for Lacrimal Sac

Answer 7

Absent in the pig

Lacrimal Sac sits in fossa

Question 8

Lacrimal Foramen & Lacrimal Canal

Answer 8

The lacrimal canal is part of the nasolacrimal canal within the lacrimal bone.
Nasolacrimal duct passes through

Question 9

Infratrochlear incisure

Answer 9

-infratrochlear N.

The infratrochlear N. (sensory) can be blocked at this location.

Question 10

Where can the infratrochlear N. be blocked?

Answer 10

Infratrochlear incisure

Question 11

Infratrochlear N. motor or sensory?

Answer 11

Sensory

Question 12

Supraorbital Foramen (eq)

Answer 12

Supraorbital A. & V.
Frontal N.
Frontal N. emerges through the supraorbital foramen/canal ONLY IN THE HORSE.

Question 13

Supraorbital Canal (su & Ru)

Answer 13

Supraorbital A. and V.

NO FRONTAL N. HERE IN SU and RU

Question 14

Ethmoid foramen

Answer 14

External ethmoidal A. & V. and Ethmoid N.
The A., V., and N. enter the cranial cavity through the ethmoid foramen and then pass through the lamina cribrosa to enter the nasal cavity.

Question 15

Optic canal

Answer 15

Optic N. (= cranial N. II)

Located in presphenoid bone

Question 16

Orbital fissure

Answer 16

Oculomotor N. (= cranial N. III)
Trochlear N. (= cranial N. IV)
Ophthalmic N. (a branch of the trigeminal N. (CN V))
Abducens N. (=cranial N. VI)
-present in the carnivores and the horse
-in the majority of horses, the trochlear N. passes through a small foramen, the trochlear foramen located on the pterygoid crest

Question 17

In majority of horses, where does the trochlear N. pass?

Answer 17

Trochlear foramen located on the pterygoid crest

Question 18

Round foramen (= foramen rotundum)

Answer 18

Maxillary N. (a branch of the trigeminal N)

• Present in carnivores and horse
• opens into the alar canal in the dog and the horse

Question 19

Foramen Orbitorotundum

Answer 19

Oculomotor N. (= cranial N III)
Trochlear N. (= cranial N IV)
Ophthalmic N. (branch of trigeminal N. (cranial N V))
Maxillary N. (branch of trigeminal N.)
Abducens N. (= cranial N. VI)
**Cranial Nerves 3-6 pass through here**

Question 20

Oval foramen (= foramen ovale)

Answer 20

Mandibular N. (a branch of the trigeminal N.)

-Present in ruminants and carnivores

Question 21

Rostral alar foramen

Answer 21

Maxillary A. & N.
(maxillary N. is branch of trigeminal N.)
-Present ONLY in dog and horse, it is the rostral opening of the alar canal

Question 22

Small alar foramen

Answer 22

Rostral deep temporal A.

-present only in the horse, it opens into the alar canal

Question 23

Caudal alar foramen

Answer 23

Maxillary A.

• Present ONLY in dog and horsrse
• it is the caudal opening of the alar canal

Question 24

Internal Acoustic Meatus

Answer 24

Facial N. (= cranial N. VII)
Vestibulocochlear N. (= cranial N. VIII)
-Internal opening of the facial canal

Question 25

Stylomastoid foramen

Answer 25

Facial N. (= cranial N. VII) | The external opening of the facial canal

Question 26

Foramen Lacerum

Answer 26

Internal Carotid A. (carotid incisure) Mandibular N. (Oval incisure) Middle meningeal A. (spinoud incisure) -Present ONLY in the horse and pig -the carotid incisure is not present n the pig -foramen lacerum connected b/w carotid incisure proximally and jugular foramen distally

Question 27

Jugular foramen

Answer 27

``` Glossopharyngeal N. (= cranial N. IX) Vagus N. (= cranial N. X) Accessory N. (= cranial N. XI) Internal carotid A. (Su & Ru) -Located between the occipital bone and the petrous part of the temporal bone (just distal to foramen lacerum) ```

Question 28

Canal for the Hypoglossal Nerve

Answer 28

Hypoglossal N. (= cranial N. XII) | -Hypoglossal N. innervates all extrinsic and all intrinsic muscles of the tongue

Question 29

Condylar Canal

Answer 29

``` Condylar sinus (venous) -present in carnivores and ruminants ONLY ```

Question 30

Mandibular Foramen

Answer 30

Inferior alveolar A. & V. (branches of the maxillary A. & V.) Inferior alveolar N. (branch of the mandibular N.) -Mandibular foramen is the caudal opening of the mandibular canal

Question 31

Mental Foramen

Answer 31

Mental A & V (branches of the inferior alveolar A. & V.) Mental N. (a branch of the inferior alveolar N.) -Mental foramen is the rostral opening of the mandibular canal