HEAD. 85 



Accessory organ — orbital cavity. — Formed by 

 the orbital process, the frontal, laclirymal, zygomatic 

 bones, and part of the zygomatic process of the tem- 

 poral. It is closed by the ocular sheatli, a fibrous en- 

 velop attached on the orbital hiatus and forward on 

 the internal face of the orbit, and surrounding the 

 seven muscles of the globe of the eye. 



1. Posterior rectus or retractor-oculi — Attach- 

 ments: Rourid.tlie optic foramen, external face of the 

 sclerotic. Action : Pulls the globe backwards. 



2. Superior, inferior, external and internal rec- 

 ti. — Attachments: In the bottom of the ocular sheath, 

 and external surface of the sclerotic. Action : Turns 

 the pupillary opening upwards, downwards, outwards 

 or inwards. 



3. Great oblique or obliquus superior oculi. — 

 Attachments : The bottom of the orlnt and the ex- 

 ternal surface of the sclerotic. Action : Pivots the 

 •eye inwards and upwards. 



4. Small oblique or obliquus jnferior oculi. — 

 Attachments : The lacrymal fossa and external face of 

 the sclerotic. Action : Pivots the eye outwards and 

 downwards. 



Eye-lids. — One superior, and one inferior. They 

 have two surfaces, and are lined internally by the con- 

 junctiva forming the conjunctival sinus ; they have 



