DISTRIBUTIOX OF CUTANEOUS BRANCHES 821 



THE DISTRIBUTIOX OF THE CI'TAXEOUS BRAXCHES OF THE 

 SEXSORY AXD MIXED XERVES 



The ciitani^vms filaments of the sensory and mixed nerves are distril)uted to 

 definite regions of the surface of the l)ody which are known as " cutaneous areas." 

 Each cutaneous area has one special nerve of supply and the central part of the 

 area receives that nerve alone, but wherever the borders of two areas meet they 

 reciprocally overlap, therefore each margin of every cutaneous area receives two 

 nerves of supply, its own nerve and that of an adjacent area, and of these sometimes 

 one and sometimes the other preponderates. 



The Cutaneous Areas of the Scalp 



The limits of the cutaneous areas in the scalp region are indicated in Figs. 469a, 

 469b, but in general terms it may be said that the skin of the scalp in front of the 

 pinna is supplied by four cutaneous nerves, the mesial part b}" the supratrochlear 

 and the supraorbital l)ranches of the first division of the fifth cranial nerve, and 

 the lateral part by the temporal branch of the second division, and the auriculo- 

 temporal In'anch of the third division of the same nerve. 



The portion of the scalp behind the pinna also receives four cutaneous nerves; 

 laterally it is sui)plied by the great auricular and small occipital branches of the 

 cervical plexus which contain filaments from the second and third cervical nerves, 

 and mesially it receives the great and smallest occipital nerves which are derived 

 from the internal divisions of the posterior primary branches of the second and 

 third cervical nerves respectively. 



The Cutaneous Areas of the Face 



^^'itll tlie exception of the skin over the posterior part of the masseter muscle 

 the whole of the skin of the face is supplied by the branches of the fifth cranial 

 nerve. The nose is supi^lied mesially by the supratrochlear, the infratrochlear, and 

 the nasal branches of the first division, and laterally by the infraorbital branch of 

 the second division. The upper eyelid is supplied by the supratrochlear, the supra- 

 orljital, and the lachrymal branches of the first division; the lower eyelid by tlie 

 infratrochlear liranch of the first division and by the infraorbital and the malar 

 l)ninches of the second division. The skin over the upper jaw and the malar Ijone 

 i:s supplied by the infraorbital and malar liranches of the second division, that over 

 the buccinator muscle by the buccal branch of the third division, and that over tli(^ 

 lower jaw, from before backwards, by the mental, Iniccal, and auricnlo-temporal 

 branches of the third division, except a small part near the posterior border which 

 receives its supply from the great auricular nerve. 



The Cutaneous Areas of the Pinna 



The upjier two-thirds of the outer surface of the pinna are supplied by the 

 auriculo-temporal branch of the third division of the fifth cranial nerve, and tlic 

 lower third by twigs of the great auricular nerve. The cranial surface of the pinna 

 is supplied in the lower part of its extent l»y the great auricular nerve, and in the 

 upper part by the small occipital nerve. The posterior surface of the external 

 auditory meatus receives filaments from the auricular Ijranch of the tenth cranial 

 nerve. 



The Cutaneous Areas of the Xeck 



The skin over the anterior part of the neck is supplied by the superficial cervical 

 branch of the cerx-ical plexus, which contains filaments of the .second and thinl 

 cervical nerves, and in the lower part of its extent by the suprasternal l)ranch, 

 which conveys twigs of the third and fourth cervical nerves (fig. 469a). The lateral 

 part of the neck receives filaments from the second, third, and fourth cervical nerves 



