K 



502 THE MUSCULATURE 



ig) To constrict the aditus and vestibule of the larynx: aryepiglotticus, 



thyreo-ary tenoideus . 

 (h) To widen the aditus and vestibule of the larynx: thyreo-epiglottideus 



6. Muscles acting on the tongue (see Section IX). 



(a) To elevate it: stylo-glossus (especially along the sides), glosso-palatinus, 

 glosso-pharyngeus, and the elevators of the hyoid bone. 



(6) To depress it: genio-glossus (in the centre), hyoglossus (at the sides), 

 chondroglossus, and the depressors of the hyoid bone. 



(c) To protrude it: genio-glossus (middle and inferior portions). 



(d) To retract it: genio-glossus (anterior portion), stylo-glossus, chondro- 



glossus. 



(e) To shorten it and make it bulge upwards: longitudinalis superior and 



inferior. 

 (/) To narrow it and make it bulge upwards: transversus linguse. 

 (g) To flatten it: verticalis linguse. 

 When the muscles work symmetrically, these movements are symmetrical; when they 

 do not work symmetrically, the tongue is moved from side to 

 side, rotated, etc. 



7. Muscles acting on the palate and pharynx (see Section IX). 



(a) To narrow the pharyngeal opening of the tuba auditiva (Eustachian tube) : 



levator veli palatini. 



(b) To widen the isthmus of the tuba : levator veli palatini. 



(c) To open the tube: tensor veli palatini, pharyngo-palatinus. 



(d) To raise and shorten the uvula: m. uvulae. 



(e) To depress the soft palate: glosso-palatinus, pharyngo-palatinus. 

 (/) To make tense the soft palate: tensor veli palatini. 



(g) To lift the soft palate: levator veli palatini. 



Ih) To approximate the glosso-palatine arches (anterior pillars of the fauces) : 



glosso-palatinus . 

 {i) To approximate the pharyngo-palatine arches (posterior pillars of the 



fauces): pharyngo-palatinus, superior constrictor of the 



pharynx. 

 ij) To constrict the pharynx: superior, middle, and inferior constrictors. 

 (A;) To widen the pharynx: stjdo-pharyngeus and the muscles which protract 



the hyoid bone. 

 (Z) To elevate the pharynx: stylo-pharyngeus, pharyngo-palatinus. 



8. Muscles acting on the head. 



(a) To flex it: the supra- and infrahyoid muscles, rectus capitis anterior, longus 

 capitis, rectus capitis lateralis. 



(6) To extend it: sterno-cleido-mastoid, trapezius, splenius capitis, longissimus 

 capitis, semispinalis capitis, obliquus capitis superior, rectus 

 capitis posterior major and minor. When the hyoid bone and 

 lower jaw are fixed by contraction of the hyomandibular and 

 infrahyoid muscles, the posterior belly of the digastric aids the 

 extensors of the head in opening the mouth. 



(c) To bend it laterally: sterno-cleido-mastoid, rectus capitis lateralis, splenius 



capitis, longissimus capitis, semispinalis capitis, obliquus 

 capitis superior. 



(d) To rotate it: sterno-cleido-mastoid, trapezius, splenius capitis, longissimus 



capitis, semispinalis capitis, obliquus capitis superior and in- 

 ferior, rectus capitis posterior major. 



9. Muscles acting on the spinal column. 



(a) To flex it: sterno-cleido-mastoid, longus colli, longus capitis, psoas major 

 and minor, scaleni, rectus abdominis, obHquus abdominis 

 externus and iuternus, the crura of the diaphragm, levator ani, 

 and the coccygeus. 

 ^ (6) To extend it: splenius capitis, splenius cervicis, spinalis, sacro-spinalis, 

 ^ semispinalis dorsi, cervicis and capitis, multifidus, rotatores, 



intcrspinales, intertransversarii, levatores costarum, quadratus 

 lumborum. 



(c) To bent it laterally and extend it: quadratus lumborum, splenius, ihocostalis, 



longissimus dorsi, cervicis and cajntis, seniispinales, multi- 

 fidus, rotatores, levatores costarum, intertransversarii. 



(d) To bend it laterally and flex it: scalene, sterno-cleido-mastoid, obliquus 



alidoniiriis externus and internus, intercostales, psoas major 

 and minor. 



When the arm and shoulder girdle are fixed the trapezius, 

 levator scai)ul:i', latissinnis dorsi and rhomboids aid abduction. 



(e) To rotate it to the right: r. internal ol)li(juo, 1. external ol)lique, r. splenius, 



1. stern()-(;l(!i(io-niast()id, r. longissimus capitis, r. ilio-costalis 

 1. seniis|jinalis, 1. nuiltifidus, 1. rotatores (except the lumbar.' 

 longiiH colli (r. above, I. below), 1. serratus anterior and rhom 

 boids, r. levatores costarum. 



ill 



