Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

TIIE SKULL FROM THE SIDE (norma later...

Online Encyclopedia
Originally appearing in Volume V25, Page 197 of the 1911 Encyclopedia Britannica.
Spread the word: del.icio.us del.icio.us it!

TIIE See also:

SKULL FROM THE See also:SIDE (norma lateralis)  . On looking at the accompanying ,figure (fig.'s) it will be seen that the calvaria or See also:brain Fr, Frontal See also:bone . Pa, Parietal . SO, Supra-occipital . Sq, Squamous-temporal . MT,Mastoid-temporal . Ty, Tympanic . St, Styloid-temporal . As, All-sphenoid . E, Os planum of ethmoid . L, Lachrymal . N, Nasal .

See also:

case forms all the upper See also:part, while the See also:face is below the anterior See also:half . Taking the' ealvaria first the See also:side view of the frontal bone (fig, 2, Fr) is seen extending back as far as the coronal suture (cs) . Just above Fr is an' See also:elevation on each side, the frontal See also:eminence, better seen in See also:female than in male skulls . The junction between the frontal and See also:malar (Ma) at the See also:outer margin of the See also:orbit has already been referred to as the See also:external angular See also:process and is an important 2.—See also:Profile of the See also:Skull . Mx, See also:Superior maxilla . Ma, Malar . Mn, Mandible . bh, Basi-hyal . th, Thyro-hyal . ch, Cerato-hyal . em, External meatus. cs, Coronal suture . ls, Lambdoidal suture. ss, Squamous suture .

landmark for measurements, and from it a curved See also:

line (the temporal See also:Crest) runs back See also:crossing the coronal suture to reach the parietal bone (Pa, fig . 2); as it runs back this line divides into two . Below the crossing of the temporal crest the coronal suture is less serrated than above, and here it becomes obliterated first . The See also:quadrilateral outline of the parietal bone is seen as well as its articulations; above it touches its See also:fellow of the opposite side; in front, the frontal (Fr) ; below the See also:great wing of the sphenoid or alisphenoid (As), the squamous part of the temporal or squamosal (Sq) and the mastoid part of the temporal (MT), while behind it articulates with the supra-occipital (SO), through the lambdoid suture (Is) . All four angles of the parietal are points of See also:special See also:interest ; the anterosuperior See also:angle or bregma has been already noticed, and it will be seen to See also:lie nearly above the See also:ear opening or external auditory meatus in the temporal bone (em) . The antero-inferior angle where the frontal, parietal and alisphenoid meet is the pterion and is the site of an occasional Wormian bone (epipteric) . The posterior superior angle is the lambda and will be better seen on the norma occipitalis, while the posterior inferior angle, where the parietal, supra-occipital, and mastoid temporal bones meet, is known as the asterion and marks the lateral sinus within the cranium . A little above and behind the See also:middle of the parietal bone, and just above the superior temporal crest, is the parietal eminence where ossification starts . The squamous part of the temporal bone overlaps the parietal at the squamous suture, while from its See also:lower part the zygomatic process projects forward to articulate with the malar . At the See also:root of this process is the glenoid cavity where the condyle of the lower See also:jaw articulates, and just behind this the external auditory meatus is seen (em) . Behind this again the mastoid temporal is prolonged down into a nipple-shaped swelling, the mastoid process (MT), containing See also:air cells and only found in the adult human skull, while just in front of the external auditory meatus is the styloid process (St), connected with the hyoid bone by the stylo-hyoid See also:ligament (clotted) . In the side view of the face the nasal and maxillary bones are seen, and from this point of view it will be noticed that just below the nasal See also:aperture the maxillae, where they join, are produced forward into a little See also:spur, the anterior nasal spine, which is a purely human characteristic .

At the side of the maxilla the malar or jugal (Ma) bone is placed, and its See also:

lozenge-shaped outline is apparent; it forms the anterior part of the zygomatic See also:arch . When the mandible is disarticulated and removed the posterior part of the maxilla is seen, and behind it the external pterygoid See also:plate of the sphenoid . Between these two bones there is a See also:vertical slit-like opening into a See also:cave, the spheno-maxillary fossa, which communicates with the orbit through the spheno-maxillary fissure, with the nasal cavity through the spheno- See also:palatine foramen, with the See also:cranial cavity through the foramen rotundum, and with the mouth through the posterior palatine See also:canal, as well as having other smaller openings . The side view of the mandible or lower jaw shows the See also:body, already seen from in front, and the See also:ramus projecting up from the back part of it at an angle of from i Io° to 120° in the adult . Before the See also:teeth come and after they are lost theangle is greater . The point just above ch (fig . 2) is known as the angle of the jaw . At the upper part of the ramus are two projections; the most anterior is the coronoid process for the See also:attachment of the temporal muscle, while posteriorly is the condyle which articulates with the glenoid cavity of the temporal See also:hone .

End of Article: TIIE SKULL FROM THE SIDE (norma lateralis)
[back]
TII
[next]
TILBURG

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click and select "copy." Paste it into a website, email, or other HTML document.