HEAD AXD ANTERIOR CERVICAL STRUCTURES. 41 



Crico-thyroid membrane, 943. (922) 

 Crico-arytenoideus posticus, 945 ; Fig. 535. (924) 



Divide the thyroid cartilage by a vertical incision just to the right of the anterior median line ; 

 carefully raise the right portion of the cartilage; divide the ligaments and remove it, exposing the 

 structures underneath. 



Crico-arytenoideus lateralis, 945-6 ; Fig. 528. (924) 

 Thyro-arytenoideus muscle, 946-7; Fig. 528. (524-5) 

 Arytenoideus, 947; Fig. 528. (925-6) 



Aryteno-epiglottideus muscle. 

 Thyro-epiglottideus, 947; Fig. 528. (926) 



Carefully remove the crico-arytenoideus lateralis and the thyro-arytenoideus, and expose the outer 

 surface of the lateral portion of the crico-thyroid membrane and thyro-arytenoid ligaments. 



Crico-thyroid membrane, 943-4. (^922-3) 



True vocal cords or inferior thyro-arytenoid ligaments. 

 Superior thyro-arytenoid ligaments, 944, (923) 



Divide the crico-thyroid membrane and vocal cords on the right side by a vertical incision in the 

 median line of the lateral wall ; the interior of the larynx will now be exposed, and the vocal 

 cords, etc., of the left side should now be studied from within. The nerves and vessels can then 

 be followed on the left side. 



Nerves, 950; Fig. 535. (928-9) 



The superior laryngeal. 



Inferior laryngeal : 

 Anterior branch. 

 Posterior branch. 



Arteries. Veins. Lymphatics, 950. (929) 

 Lymphatics of the larynx, 692. (676) 



Laryngeal glands. 



Hyo-epiglottidean ligament. Periglottis, 942. (921) 

 Epiglottis, 941-2. (920) 



Internal Orbital Region. 



\Vith the saw cut through the frontal bone and the plate forming the roof of the orbit. Make two in- 

 cisions ; the outer one extending from the outer end of the sphenoidal fissure to the outer angle of the 

 orbit, and the inner one from a point just external to the optic foramen to the inner side of the orbit, 

 but external to the pulley of the superior oblique muscle. Beginning at the posterior border, raise and 

 tilt forward this triangular plate, exposing the orbital periosteum underneath. 



Fascia of the orbit, (T), (2), (3), 893. (873) 



Orbital periosteum, or periorbita, 894. (874) 



Divide the periosteum in the middle line of the orbit, and transversely at the anterior border of the 

 orbit. Reflect the fascia each way from the median incision and expose the structures within. 



Cavity of the orbit, general arrangement of its contents, 890-1. (870) 

 The frontal nerve, 796. (778) 



Trace the supraorbital and supratrochlear branches to the point of exit from the orbit. 



The supraorbital artery, 531. (522) 



Branches: Periosteal. Muscular. Diploic. Trochlear. Palpebral. 

 Lachrymal nerve, 796. (778) 

 Lachrymal artery, 5301. (521-2) 



Recurrent lachrymal. Muscular. Malar branches. Palpebral branches. 

 The lachrymal gland, 904-5. (883-4) 



Carefully raise the gland and tease out the thread-like ducts passing from the gland to the con- 

 junctival sac. 



Nerves of the orbit, 9001. (879-80) 

 Motor. Sensory. Sympathetic. 



A. Motor nerves. 



B. Sensory nerves. 



C. Sympathetic nerves of the orbit. 

 Fourth or trochlear nerve, 793-4, 900. (775-6, 880) 



4 



