174 



CRANIAL GROUP. 



Fig. 105.* 



1. Cranial group. Occipito-frontalis. 



Dissection. The occipito-frontalis is to be dissected by making a Ion 



gitudinal incision along the vertex of the 

 head, from the tubercle on the occipital 

 bone to the root of the nose ; and a 

 second incision along the forehead and 

 around the side of the head, to join the 

 two extremities of the preceding. Dis- 

 sect the integument and superficial fascia 

 carefully outwards, beginning at the an- 

 terior angle of the flap, where the mus- 

 cular fibres are thickest, and remove it 

 altogether. This dissection requires care ; 

 for the muscle is very thin, and, without 

 attention, would be raised with the in- 

 tegument. There is no deep fascia on 

 the face and head, nor is it required ; for 

 here the muscles are closely applied 

 against the bones upon which they de- 

 pend for support, whilst in the extremities 

 the support is derived from the dense 

 layer of fascia by which they are invested, and which forms for each a 

 distinct sheath. 



The OCCIPITO-FRONTALIS is a broad musculo-aponeurotic layer, which 

 covers the whole of the side of the vertex of the skull, from the occiput to 

 the eyebrow. It arises by tendinous fibres from the outer two-thirds of 

 the superior curved line of the occipital, and from the mastoid portion of 

 the temporal bone. Its insertion takes place by means of the blending of 

 the fibres of its anterior portion with those of the orbicularis palpebrarum, 

 corrugator supercilii, levator labii superioris alseque nasi, and pyramidalis 

 nasi. The muscle is fleshy in front over the frontal bone and behind over 

 the occipital, the two portions being connected by a broad aponeurosis. 

 The two muscles, together with their aponeurosis, cover the whole of the 

 vertex of the skull, hence their designation galea capitis ; they are loosely 

 adherent to the pericranium, but very closely to the integument, particu- 

 larly over the forehead. 



Relations. This muscle is in relation by its external surface from be- 

 fore backwards, with the frontal and supra-orbital vessels, the supra-orbital 

 and facial nerve, the temporal vessels and nerve, the occipital vessels and 



* The muscles of the head and face. 1. The frontal portion of the occipito-frontalis. 

 2. Its occipital portion. 3. Its aponeurosis. 4. The orbicularis palpebrarum, which 

 conceals the corrugator supercilii and tensor tarsi. 5. The pyramidalis nasi. 6. The 

 compressor nasi. 7. The orbicularis oris. 8. The levator labii superioris aloeque nasi , 

 the adjoining fasciculus between numbers 8 and 9 is the labial portion of the muscle 

 9. The levator labii superioris proprius; the lower part of the levator anguli oris is seen 

 between the muscles 10 and 11. 10. The zygomaticus minor. 11. The zygomaticua 

 major. 12. The depressor labii inferioris. 13. The depressor anguli oris. 14. The 

 levjtuf labii inferioris. 15. The superficial portion of the masseter. 16. Its deep por- 

 tion. 17. The attrahens aurem. 18. The buccinator. 19. The attollens aurem. 20. 

 The temporal fascia which covers in the temporal muscle. 21. The retrahens aurem 

 22. The anterior belly of the digastricus muscle ; the tendon is seen passing through 

 its aponeurotic pulley. 23. The stylo-hyoid muscle, pierced by the posterior belly of the 

 digastricus. 24. The mylo-hyoideus muscle. 25. The upper part of the sterno-rnastoid. 

 5t'. The upper part of the trapezius. The muscle between 25 and 26 is the splenius 



