122 HEAD AND NECK 



each eyelid, sweep in gentle curves from the medial palpebral 

 ligament to the lateral palpebral raphe, gaining attachment to 

 both. They form a continuous layer of uniform thickness in 

 each eyelid, except near the free margins, where, close to the 

 bases of the eyelashes, there is a more pronounced fasciculus 

 termed the ciliary bundle. 



The orbital portion of the muscle passes upwards to the 

 forehead, laterally to the temporal region and downwards into 

 the cheek. Its fibres are relatively dark and coarse. They 

 all take origin medially from the medial part of the palpebral 

 ligament, the medial angular process of the frontal bone, and 

 the frontal process of the maxilla, and they sweep laterally 

 round the margin of the orbit in the form of a series of con- 

 centric loops. The pars lacrimalis of the orbicularis oculi 

 (O.T. tensor tarsi) will be described when the eyelids are 

 dissected (p. 140). 



Musculus Epicranius (O.T. Occipito - Frontalis). The 

 epicranius is a quadricipital muscle possessing two occipital 

 heads, the occipitales muscles, and two frontal heads, the 

 frontales muscles ; they are all inserted into an intermediate 

 aponeurosis, the galea aponeurotica (O.T. epicranial aponeur- 

 osis), which extends from the frontal to the occipital region 

 (p. 158). The lower part of each frontal head blends with the 

 orbicularis oculi, and from its medial border a small muscular 

 bundle, known as the musculus procerus (O.T. pyramidalis 

 nast), descends to the dorsum of the nose. At present only 

 the frontalis and the procerus are to be displayed. 



The Frontalis becomes apparent immediately above the 

 upper border of the orbicularis oculi. As it is cleaned care 

 should be taken to avoid injury to the branches of the supra- 

 orbital nerve which pierce it. It has little or no attachment 

 to bone. Below, its fibres either blend with the fibres of the 

 orbicularis oculi or they are attached to the skin of the eye- 

 brows. Above, they terminate in the galea aponeurotica in the 

 region of the coronal suture. The lateral border is attached 

 to the temporal ridge by aponeurotic fibres, and the medial 

 border blends with its fellow of the opposite side for a short 

 distance above the root of the nose. Above the union the 

 medial fibres of opposite sides diverge, and below it they pass 

 downwards over the nasal bones as the proceral muscles. 



Musculus Procerus (O.T. Pyramidalis Nasi). The proceral 

 muscles are often absent ; when present, each springs from 



