106 DISSECTION OF THE NECK. 



Dissection. To see the stylo-pharyngeus muscle, the posterior belly of 

 the digastric, and the stylo-hyoid muscle, should be detached from their 

 origin and thrown down. The trunk of the external carotid artery is to 

 be removed by cutting it through where the hypoglossal nerve crosses it, 

 and by dividing those branches of it that have been already examined; 

 the veins accompanying the arteries are to be taken away. In cleaning 

 the surface of the stylo-pharyngeus muscle, the glosso-pharyngeal nerve 

 and its branches, and the stylo-hyoid ligament may be prepared. The 

 side of the jaw is to be drawn forwards on the face. 



The STYLO-PHARYNGEUS MUSCLE (levator pharyngis externus) resem- 

 bles the other styloid muscles in its elongated form. The fibres arise 

 from the root of the styloid process on the inner surface, and descend be- 

 tween the superior and middle constrictors to be inserted partly into the 

 pharynx, and partly into the upper border (hinder border, Merkel 1 ) of the 

 thyroid cartilage. 



The muscle lies below the stylo-glossus, and between the carotid arte- 

 ries ; and the glosso-pharyngeal nerve turns over the lower part of its fleshy 

 belly. 



Action. It elevates and draws outwards the part of the pharynx above 

 the hyoid bone, making the tube ready for the reception of the morsel to 

 be swallowed. From its attachment to the thyroid cartilage it will raise 

 the larynx ; and by its position it will control the movement forwards of 

 the air tube. 



The stylo-hyoid ligament is a fibrous band, which extends from the tip 

 of the styloid process to the small cornu of the os hyoides. Its position is 

 between the stylo-glossus and stylo-pharyngeus muscles, and over the in- 

 ternal carotid artery ; whilst the lower end is placed beneath the hyo- 

 glossus muscle. To the posterior border the middle constrictor muscle is 

 attached below. It is frequently cartilaginous or osseous in part of, or in 

 all its extent. Occasionally a slip of fleshy fibres is continued along it. 



The INTERNAL CAROTID ARTERY supplies parts within the head, viz., 

 the brain, the eye and orbit, and the nose ; and takes a circuitous course 

 through and along the base of the skull before it terminates in the brain. 



The arterial trunk in the cranium, and its offset to the orbit, have been 

 already examined ; but the portion in the neck and the temporal bone re- 

 mains to be dissected. The branches of the carotid to the brain are 

 examined with the encephalon. 



Dissection. For the display of the cervical part of the artery (fig. 25) 

 there is now but little dissection required. By detaching the styloid pro- 

 cess at the root, and throwing it with its muscles to the middle line, the 

 internal carotid artery and the jugular vein may be followed upwards to 

 the skull. Only a dense fascia conceals them, but this is to be taken away 

 carefully, so that the branches of the nerves may not be injured. 



In the fascia, and directed inwards over the artery, seek the glosso- 

 pharyngeal nerve and its branches near the skull, and the small pharyn- 

 geal branch of the vagus lower down ; still lower, the superior laryngeal 

 branch of the vagus, with its external laryngeal offset crossing beneath the 

 carotid. Between the vein and artery, close to the skull, will be found 

 the vagus, hypoglossal, and sympathetic nerves ; and crossing backwards, 

 over or under the vein, the spinal accessory nerve. External to the ves- 



1 Anatomic und Phisiologie des Menschlichen Stimm und Sprach Organs. Leip- 

 zig, 1857. Von Dr. Merkel. 



