748 



REGIONS AND MUSCLES OF THE CRANIUM. 



fibres of the last named muscle, as well as of 

 the corrugator supercilii. The aponeurotic 

 slip before alluded to, situated in the middle 

 line, forms the internal boundary of each la- 

 teral portion. On the outside the fibres gra- 

 dually shorten and extend a very short distance 

 into the temporal region, over the temporal 

 fascia. Each portion presents a convex margin 

 above, which is inserted into the thin tendinous 

 aponeurosis, which extends over the middle 

 portion of the occipito-frontal region, correspond- 

 ing to the posterior margin of the frontal bone, 

 the fronto-parietal suture, internal portions of 

 the parietal bones, the sagittal and lambdoidal 

 sutures and part of the occipital bones, but se- 

 parated from them by the pericranium and by 

 some fine cellular tissue which connected the 

 aponeurosis to the last-named membrane. This 

 aponeurosis is called the cranial or epicrunial 

 aponeurosis : in some instances its fibrous cha- 

 racter is very distinct in all its extent ; but very 

 frequently it is most manifest in its posterior 

 third or half, the anterior part being little more 

 than condensed cellular membrane, excepting 

 near to the fleshy fibres of the frontal portion of 

 the muscles, where the aponeurotic structure 

 again becomes manifest. On the sides this 

 aponeurosis gradually degenerates into cellular 

 membrane without leaving any defined margin. 

 The aponeurosis in its whole extent adheres 

 closely to the superjacent subcutaneous cellular 

 tissue and to the subjacent pericranium through 

 the intervention of a fine cellular membrane 

 already referred to. Proceeding from before 

 backwards, we find that this aponeurosis ends 

 in affording insertion to the fibres which form 

 the posterior belly of the muscle. 



This portion of the muscle, also called the 

 occipital muscle, consists likewise of two lateral 

 portions which are attached inferiorly to the ex- 

 ternal part of the superior curved line of the 

 occipital bone, and to the mastoid portion of 

 the temporal. The fibres are parallel and 

 nearly vertical, inclining a little inwards, and 

 are inserted, as already described, into the pos- 

 terior margin ot the epicranial aponeurosis. 

 The attachment of the muscle to the occipital 

 bone is immediately above that of the slerno- 

 mastoid and splenius muscles. On the sides 

 the fibres gradually disappear over the mastoid 

 portion of the temporal bone, and the fleshy 

 belly of the muscle lies immediately over the 

 pericranium, some cellular membrane only in- 

 tervening ; its adhesion to the skin, however, is 

 less intimate than that of the frontal portion. 



This muscle is evidently destined to act upon 

 the integuments of the cranium : its influence 

 is most apparent upon the skin of the forehead 

 and eyebrows ; it distinctly raises the latter, 

 and throws the former into transverse wrinkles. 

 Under its influence the whole scalp may be 

 made to move backwards and forwards, but the 

 occipital portion of the muscle cannot create, as 

 the frontal does, wrinkles in its corresponding 

 integument, owing to the less firm adhesion of 

 the muscle to it. 



Subjacent to the anterior portion of the occi- 

 pito-frontalis is the corriigulor supercilii muscle. 

 It lies on the inner half or third of the orbital 



margin of the frontal bone. By its inner extre- 

 mity it is attached to the internal angular pro- 

 cess of the frontal bone ; the fibres pass thence 

 outwards, inclining a little upwards, and are 

 inserted into the integument of the eyebrow, 

 being mixed with the orbicularis and occipito- 

 frontalis muscle. This muscle evidently can 

 depress the eyebrow, and acting in conjunction 

 with its fellow, throw the integuments into 

 vertical wrinkles, approximating the eyebrows, 

 and occasioning the act of frowning. This 

 muscle lies on the supra-orbital nerve and 

 vessels. 



4. Nerves. The anterior part of the occi- 

 pito-frontal region is freely supplied with nerves 

 from those branches of the ophthalmic portion 

 of the fifth which originate within the orbit. Of 

 these the supra-orbital is the largest: imme- 

 diately after its emergence from the supra-or- 

 bital foramen this nerve divides into a series of 

 branches which pass up on the forehead, some 

 adhering to the pericranium, others distributed 

 to the muscle, and others becoming subcu- 

 taneous. Here, too, we find ramifications of 

 the supra-trochleator or internal frontal nerve, 

 chiefly distributed in the internal portion of the 

 muscle. At the external part of this frontal 

 region we find some filaments of the portio 

 dura. In the posterior or occipital region the 

 principal nerves are derived from the cervical 

 plexus; the auricular and mastoid branches of 

 this plexus distribute their filaments here; and 

 we also find ramifications from the posterior 

 branch of the first cervical nerve, accompany- 

 ing the subdivisions of the occipital artery. 



5. Arteries. In front we have ramifications 

 of the supra-orbital and superficial temporal 

 freely anastomosing with each other; and 

 deeper-seated, a few branches of the deep 

 temporal, distributed to the pericranium. In 

 the occipital region we have the occipital, 

 often of considerable size, and the posterior 

 auricular also sends some of its ramifications 

 to anastomose with the occipital branches. 

 Both in front and behind, the arteries of oppo 

 site sides inosculate with each other on the 

 middle line. 



6. Veins. Small veins accompany most of 

 the arteries; but the most remarkable vein is 

 one which is situated in the frontal region 

 nearly on the middle line ; it is the frontal 

 vein, or vena preparata, sometimes replaced 

 by two or three. Velpeau advocates the re- 

 vival of the ancient practice of bleeding from 

 this vein in head affections. It carries the 

 blood, as he observes, from all the anterior part 

 of the head to the root of the nose, whence he 

 argues that venesection practised on this vessel 

 would empty the whole of the scalp. How 

 often in practice do we see manifest advantage 

 from cupping the temples or some region of 

 the scalp, when little or no benefit had been 

 derived from other modes of practising the 

 detraction of blood ! 



7. Lymphatics. The lymphatics are very 

 few, and pass into the parotid ganglions, or 

 those behind the ear or in the superior part of 

 the neck. 



8. Pericranium. This fibrous tissue, pos- 



