16 ANATOMY OF THE HEAD AND NECK. 



part of the superior curved line of the occipital bone, and 

 from the mastoid portion of the temporal bone to form a 

 rounded and flat belly, which terminating in an aponeu- 

 rosis, passes forward to join the frontal portion lying upon 

 the frontal bone; this, broader and thinner than the 

 occipital, confounds itself with the orbicularis palpebra- 

 rum, pyramidalis nasi and corrugator supercilii muscles, 

 and is inserted into the nasal bones and the superciliary 

 ridge of the frontal bone. Anteriorly the muscular bellies 

 of the two sides blend together ; posteriorly they are sepa- 

 rated by an interval completed by an aponeurotic expan- 

 sion. 



It might seem better, perhaps, to describe the occipito- 

 frontalis as two muscles instead of one single digastric 

 muscle ; each being inserted into the epicranial aponeurosis. 

 This would be suggested by its action, it being a muscle of 

 expression, and is the manner in which it is described by 

 some authors. The aponeurosis connecting the two por- 

 tions of the occipito-frontalis is firmly connected with the 

 skin, though but loosely attached to the pericranium. It 

 expands over the vertex without any separation into lateral 

 parts, and upon the sides of the head is thin and amounts 

 to little more than cellular tissue. 



Upon the posterior belly of the occipito-frontalis muscle 

 will be found the occipitalis major nerve, a posterior branch 

 of the second cervical nerve, and the occipital artery, a 

 branch of the external carotid. The artery is tortuous, and 

 supplies the muscle, integument, and epicranium ; it anasto- 

 moses with the temporal artery, and sometimes gives off the 

 posterior auricular branch to the external ear. The nerve 

 accompanies the artery only in a part of its course, and is 

 distributed chiefly to the integument. 



The PYRAMIDALIS NASI is a slip of the occipito-frontalis 

 passing downward upon the bridge of the nose. Its out- 

 line is usually confused, and it is inserted into the nasal 

 bone and the compressor muscle of the nose. Properly, it 

 should be considered as a pillar of origin of the frontal 

 belly of the occipito-frontalis. 



The ORBICULARIS PALPEBRARUM surrounds the eye, and 

 is seen by dissecting the integument from the eyelids, upon 

 which it expands, as it also does upon the circumference of 

 the orbit ; it is a thin muscular plane, difficult to dissect, 

 owing in a degree to the want of fixedness in the parts upon 

 which it rests. Its fibres are well marked, and it arises from 



