CUTANEOUS NERVES. 21 



and frontal, come from the former ; whilst three, viz., the temporal, occi- 

 pital, and posterior auricular, belong to the latter. 



The supra-orbital artery (c) leaves the orbit through the notch in the 

 margin of the orbit, and is distributed on the forehead. Some of its 

 branches are superficial to the occipito-frontalis, and ascend to the top of 

 the head ; whilst others lie beneath the muscle, and supply it, the peri- 

 cranium, and the bone. 



The frontal branch (5) is close to the inner angle of the orbit, and is 

 much smaller than the preceding. It ends in branches for the supply of 

 the muscles, integuments, and pericranium. 



The superficial temporal artery (d) is one of the terminal branches of 

 the external carotid. After ascending above the zygomatic arch for 

 about two inches, the vessel divides on the temporal fascia into anterior 

 and posterior : 



The anterior branch runs forwards with a serpentine course to the fore- 

 head, supplying muscular, cutaneous, and pericranial offsets, and anasto- 

 moses with the supra-orbital artery : this is the branch that is opened 

 when blood is taken from the temporal artery. 



The posterior branch is larger than the other, and arches backwards 

 above the ear towards the occipital artery, with which it anastomoses. 

 Its offsets to the parts around are similar to those of the anterior, and it 

 communicates with the artery of the opposite side over the top of the 

 head. 



Occipital artery (a). The terminal part of this artery, after perforat- 

 ing the trapezius, divides into large and tortuous branches, which spread 

 over the back of the head and the occipito-frontalis muscle. Communi- 

 cations take place with the artery of the opposite side, with the posterior 

 part of the temporal, and with the following artery. Some offsets pass 

 deeply to supply the occipito-frontalis muscle, the pericranium, and the 

 bone. 



The posterior auricular artery (/) appears in front of the mastoid 

 process, and divides into two branches. One (mastoid) is directed back- 

 wards to supply the occipito-frontalis, and anastomose with the occipital 

 artery. The other (auricular) is furnished to the retrahent muscle and 

 the back of the pinna of the ear ; and an offset from this pierces the pinna 

 to be distributed on the opposite surface. 



The VEINS of the exterior of the head are so similar to the arteries, 

 that a full notice of each is not required. All the veins corresponding 

 with branches of the internal carotid artery enter the facial vein, whilst 

 the rest open into the jugular veins. These superficial veins communi- 

 cate both with the sinuses in the interior of the skull by means of small 

 branches named emissary, and with the veins occupying the spongy sub- 

 stance (diploe) of the cranial bones. 



The frontal vein is directed towards the inner angle of the orbit, where 

 it receives the supra-orbital vein, the two giving rise to the angular vein 

 of the face : near its ending it receives small veins from the eyebrow, and 

 from the upper eyelid and the nose. Both the superficial temporal and 

 posterior auricular veins open into the external jugular; and the occipital 

 joins the internal jugular vein. 



CUTANEOUS NERVES (fig. 2). The nerves of the scalp are furnished 

 from cutaneous offsets of both cranial and spinal nerves. The half of the 

 head anterior to the ear receives branches from three trunks of the fifth 

 cranial nerve, and a few twigs from the facial nerve. All the rest of the 



