648 



BLOOD-VASCULAE SYSTEM OF THE HORSE 



3. The tympanic artery is a very small vessel which passes along the Eusta- 

 chian tube to the petro-tympanic fissure and enters the middle ear. 



4. The middle meningeal artery (A. meningea media) arises beneath the buc- 

 cinator nerve, where the internal maxillary turns forward. It passes backward 

 across the temporal wing of the sphenoid to the antero-lateral part (foramen spino- 

 sum) of the foramen lacerum. Entering the cranium, it divides into branches which 

 course in the grooves on the temporal and parietal bones and supply the dura 

 mater. J^^ anastomoses with the posterior meningeal. 



The size of this artery is variable, and is in inverse ratio to that of the posterior meningeal. 



Fig. 565. — Sagittal Section of Head oe Horse, Cut a Little to the Right of the Median Plane. 

 I, Skin; ^, nasal bone; 5, frontal bone; 4, parietal bone; .4', tentorium osseum; 5, occipital bone; (?, sphenoid bone; 

 7, hard palate; 5, premaxilla; 9, mandible; 10, hyoid bone; 11, septum between frontal sinuses; 1^, alar cartilage; 

 IS, transversus nasi; 14, septum nasi with venous plexuses; 16, palato-Iabial artery; 16, 16', upper and lower 

 septal branches of 7,5; 77, septal branch of sphenopalatine artery and satellite vein; IS, septal branch of ethmoidal 

 artery; 19, sphenoidal sinus; 20, guttural pouch; 21, pharynx; 22, pharyngeal orifice of Eustachian tube; 23, posterior 

 naris; ;34, soft palate ; .25, palatinus muscle; i?5, pharyngeal muscles; ;i?7, oesophagus; ;?5, dotted line indicating posi- 

 tion of posterior pillar of soft palate; 29, lamina, 29', arch of cricoid cartilage; 30, arytenoideus transversus muscle; 

 31, epiglottis; 32, body of thyroid cartilage; 33, vocal process and cord; 34, arytenoid cartilage; 35, lateral ventricle 

 of larj'nx; 36, trachea; 37, ventral straight muscles of head; 38, longus colli; 39, atlas; 40, axis; 41, lig- nuchge; 4^t 

 dorsal spinal muscles; 43, muscles of external ear; 44, omo- and sterno-hyoideus; 45, tongue; 46, mylo-hyoideus; 47, 

 genio-hyoideus; 4^, genio-glossus; 49, longitudinalis inferior; 50, longitud. superior; 51, hj'po-epiglotticus; 52, chin 

 and mentalis muscle; 53, venous plexus of hard palate; 54, corpus callosum; 55, septum pellucidum; 56, fornix; 57, 

 thalamus; o5, pineal bodjs 55, corpora quadrigemina; 60, cerebral peduncle: 5i, corpus mammillare; 5:8, pituitary 

 body; 63, chiasma opticum; 64, intercarotid artery; 65, medulla oblongata; 66, interventricular foramen; 67, infun- 

 dibulum; ^5, third ventricle ; 5.9, cerebral aqueduct; 70, anterior medullary velum; 77, fourth ventricle; 7.9, posterior 

 medullary velum; 75, basilar artery; 74, spinal cord; 75, ethmoidal nerve; 75. septal branch of posterior nasal nerve; 

 76' , branch of same to vomero-nasal organ; 77, olfactory nerve to vomero-nasal organ; 78, nasal branches of palatine 

 arterj'. (After Ellenberger, in Leisering's Atlas.) 



5. The posterior deep temporal artery (A. temporalis profunda aboralis) 

 arises from the internal maxillary just before the latter enters the alar canal. It 

 passes upward and backward in the temporal fossa on the deep face of the temporalis 

 muscle, in which it ramifies. It sends a ])ranch outward to the masseter, and 

 anastomoses with the superficial temporal and middle meningeal arteries. 



In some cases the tympanic and middle meningeal arise from this artery. 



II. The second part lies in the alar canal, and is about an inch (ca. 2-3 cm.) in 

 length. It gives off two branches — the anterior deep temporal and the external 

 ophthalmic. 



1. The anterior deep temporal artery (A. temporalis profunda oralis) emerges 

 from the canal through the small alar or temporal foramen, and ascends in the 



