SECTION XIII 



CLINICAL AND TOPOGRAPHICAL 



ANATOMY 



Revised for the Fifth Edition 

 By JOHN MORLEY, Ch.M., F.R.C.S. 



HONORARY SURGEON, ANCOAT'S HOSPITAL, MANCHESTER; LECTURER IN CLINICAL 

 ANATOMY, MANCHESTER UNIVERSITY 



THE HEAD 



IN describing the clinical and topographical relations, the divisions of the body 

 will be successively considered in the following order: head, neck, thorax, 

 abdomen, pelvis, back, upper and lower extremities. 



The bony landmarks of the head will first be considered, followed by a separate 

 description of the cranium and the face. 



Bony landmarks. — These should be studied with the aid of a skull, as well as 

 on the living subject. Beginning in front is the nasion, a depression at the root of 

 the nose, and immediately above it, the glabella, a slight prominence joining the 

 two supraciliary arches. These points mark the remains of the frontal suture, and 

 the junction of the frontal, nasal, and superior maxillary bones and one of the sites 

 of a meningocele. In the middle line, behind, is the external occipital protuber- 

 ance, or inion, the thickest part of the vault, and corresponding internally with 

 the meeting-point of six sinuses. A line joining the inion and glabella corresponds 

 to the sagittal, and occasionally the frontal, suture, the falx cerebri, the superior 

 sagittal sinus, widening as it runs backward, and the longitudinal fissure of the 

 brain. From the inion the superior nuchal lines pass laterally toward the upper 

 and back part of the base of the mastoid processes, and indicate the first or so- 

 called horizontal part of the transverse (lateral) sinus. 



This vessel usually presents a varying curve upward and runs in the tentorium. The second 

 or sigmoid portion turns downward on the inner surface of the mastoid, then forward, and lastly 

 downward again to the jugular foramen, thus describing the double curve from which this 

 part takes its name. In the jugular foramen the vessel occupies the posterior compartment; 

 its junction with the internal jugular is dilated and forms the bulb. A line curved downward 

 and forward from the upper and back part of the base of the mastoid, reaching two-thirds of 

 the way down toward the apex, will indicate the second part of the sinus. The spot where it 

 finally curves inward to the bulb would be about 1.8 cm. (f in.) below and behind the meatus. 

 The two portions of the transverse sinus meet at the asterion laterally; at the entry of the 

 superior petrosal sinus medially. The right transverse sinus, the larger, is usually a continua- 

 tion of the superior sagittal sinus, and, therefore, receives blood chiefly from the cortex of the 

 brain; the left, arising in the straight sinus, drains the interior of the brain and the basal ganglia. 

 Each transverse sinus receives blood from the temporal lobe, the cerebellum, diploe, tympanic 

 antrum, internal ear, and two emissary veins, the mastoid and posterior cond}4ar. 



About 6.2 cm. (2| in.) above the external occipital protuberance is the lambda, 

 or meeting of the sagittal and lambdoidal sutures (posterior fontanelle, small and 

 triradiate in shape). It is useful to remember, as guides on the scalp to the above 

 two important points, that the lambda is on a level with the supraciliary ridges, 

 and the external occipital protuberance on one with the zygomatic arches. 



Below the external occipital protuberance, between it and the foramen magnum, an occip- 

 ital, the commonest form of cranial meningoceles, makes its appearance. It comes through 

 the median fissure in the cartilaginous part of the squamous portion of the bone. 



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