120 OSTEOLOGY. 
the lesser wings, and terminates anteriorly in a ragged edge, which articulates with 
the cribriform: plate of the ethmoid, and has often projecting from it, mesially, a 
pointed process, the ethmoidal spine. The /ateral aspects of the body are fused 
with the great wings, and in part also with the roots of the pterygoid processes. 
Curving along the side of the body, superior to its attachment to the great wing, 
is an We shaped groove, the carotid groove (sulcus caroticus), which ‘marks the 
position and course of the internal carotid artery. Posteriorly, the hinder margin 
of this groove, formed by the salient outer edge of the posterior surface of the 
body, articulates with the apex of the petrous portion of the temporal bone, and 
is hence called the petrosal process; just above this, on the lateral border of the 
dorsum sell, there is often a groove for the sixth nerve. 
The anterior surface of the body displays a vertical mesial sphenoidal crest 
(crista sphenoidalis), continuous above with the ethmoidal spine, and below with 
the pointed projection called the rostrum. This crest articulates in front with the 
perpendicular plate of the ethmoid. On either side of the middle line are seen the 
irregular openings leading into the sphenoidal air sinuses, the thin anterior walls 
of which are in part formed by the absorption of the sphenoidal turbinated bones 
with which in early life they are in contact. With the exception of a broad groove 
leading downwards from the apertures above mentioned, which enters into the 
formation of the roof of the nasal fossa of the corresponding side, the lateral 
aspects of this surface of the bone are elsewhere in articulation with the lateral 
masses of the ethmoid and the orbital processes of the palate bones. The rostrum 
is continued mesially for some distance along the inferior surface of the body, 
where it forms a prominent keel which fits into the recess formed by the ale of 
the vomer. The edges of the latter serve to separate the rostrum from the incurved 
vaginal processes at the roots of the internal pterygoid plates. Posteriorly the 
under surface of the body of the sphenoid is rougher, and covered by the mucous 
membrane of the roof of the pharynx; here, occasionally, a median depression may 
be seen which marks the position of the inferior extremity of a foetal channel, 
called the canalis cranio-pharyngeus. 
The lesser or orbital wings (ale parvee) are two flattened triangular plates of 
bone which project forwards and outwards from the fore and upper part of the 
body of the bone, with which they are united by two roots, enclosing between them 
the optic foramina (foramina optica) for the transmission of the optic nerves and 
ophthalmic arteries. Of these roots, the posterior springs from the body just wide 
of the olivary eminence, separating the carotid groove behind from the optic foramen 
in front; externally this root is confluent with the recurved posterior angle of the 
lesser wing, which here forms the projection known as the anterior clinoid process 
(processus clinoideus anterior), which overhangs the fore part of the body of 
the bone. The anterior root, broad and compressed, unites the upper surface of 
the lesser wing with the fore and upper part of the body. Externally the outer 
angle terminates in a pointed process which reaches the region of the pterion and 
there articulates with the frontal, and may come in contact with the great wing. 
The superior aspect is smooth, and forms in part the floor of the anterior cranial 
fossa. The inferior surface forms part of the posterior portion of the upper wall 
of the orbit, and also serves to roof in the sphenoidal fissure which separates the 
lesser from the greater wings below. The anterior edge is ragged and irregular, 
and articulates with the orbital plates of the frontal. The posterior margin, 
sharp and sickle-shaped, separates the anterior from the middle cranial fossa, and 
corresponds to the position of the Sylvian fissure on the surface of the cerebrum. 
The greater or temporal wings (ale magne), as seen from above, are of a 
somewhat crescentic form. If the inner convex edge of the crescent be divided 
into fifths, the posterior fifth extends backwards and outwards beyond the body of 
the bone, presenting a free posterior edge, which forms the anterior boundary of the 
foramen lacerum medium. This border ends behind in the horn of the crescent, 
from which a pointed process projects downwards, called the alar or sphenoidal spine 
(spina angularis), which is wedged into the angle between the petrous and squamous 
parts of the temporal bone. The inner surface of the posterior border and spine is 
furrowed for the cartilaginous Eustachian tube (sulcus tube), whilst on the inner 
