Introduction to the Neck 20 Transaxial MRI Images of the Neck These images start at the maxilla and continue inferiorly to the apices of the lungs. Like the upper thorax many students find it easier to start at the bottom and work upward, which is how these images are presented. There is a good deal of repetition in the neck and not all the anatomy is repeatedly identified on every image. Nevertheless, be certain you can identify reoccurring structures on every image. First page number in parenthesis is Netter’s 3rd edition Second page number in parenthesis is Netter’s 4th edition Introduction to the Neck

Another Look: Upper Thorax MRI 4 3 2 1 5 6 8 7 1. Trachea 2. Esophagus 3. Rt & Lt internal jugular veins 4. Rt & Lt subclavian vein 5. Rt & Lt subclavian artery 6. Rt subclavian artery 7. Lt common carotid artery 8. Lt subclavian artery Although it may look quite different than the CT study of the thorax, this MRI section is at a similar cut level to image 2 of the CT images. Click for the legend. Another Look: Upper Thorax MRI

3 4 MRI study of the Neck Reference 5 6 7 1. Trachea 2. Esophagus* 3. Rt internal jugular vein 4. Lt internal jugular vein** 5. Rt & Lt common carotid arteries 6. Rt & Lt vertebral arteries 7. Rt & Lt thyrocervical trunks*** (233, 410) (237, 427) 8. Rt sternocleidomastoid muscle (23, 24) (27,28) 9. Rt & Lt external jugular veins 10. Thoracic vertebral body 11. Thoracic nerve root & ganglion (163)(170) 12. Branch of the thyrocervical trunk 13. Lt lobe of thyroid gland. (70, 71)(74,75) * On this patient the esophagus has deviated to the Lt side of the trachea as they approach the thoracic outlet. ** The appearance of the Lt jugular vein in these images is due to the slow moving venous blood returning a weak MRI signal. There is not a thrombus as it might appear. ***These trunk vessels are short, and quickly branch into cervical and thyroid arteries as seen in #12. 5 6 7 1 2 9 8 13 9 10 12 11 Images 20 & 19

Images 20-17

1 1 3 2 5 4 6 1. Rt & Lt external jugular veins* (66) (70) Reference 1 1. Rt & Lt external jugular veins* (66) (70) 2. Spinal cord 3. Cerebrospinal fluid in the subarachnoid space (163) (170) 4. Rt internal jugular vein 5. Rt common carotid artery 6. Rt. trapezius muscle 2 3 5 4 6 Images 18 & 17

1 Reference 2 1. Trachea 2. Esophagus 3. Lt sternocleidomastoid muscle 4. Rt internal jugular vein 5. Rt common carotid artery 6. Lt lobe of the thyroid gland 7. Lt vertebral artery* (130) (136) 8. Spinous process * Although the transverse processes of C-7 have foramen through them, the vertebral arteries do not enter there. They enter at C-6. On image 16 the vertebral arteries are at the anterior edge of the vertebral body, and in front of the transverse processes. On image 15 they appear to be in the transverse processes, which is evidence that this is C-6. See the lizard (bearded dragon) in #15? His eyes are the vertebral arteries, his tongue is the spinal cord 5 6 3 4 7 8 Images 16 & 15

Images 16-13

1 2 5 4 3 1. Cricoid cartilage (59, 73) (63, 77) Images 14 & 13 1 Reference 2 1. Cricoid cartilage (59, 73) (63, 77) 2. Lt anterior jugular vein* (27) (31) 3. Lt inferior horn of the thyroid cartilage (73) (77) 4. Lt external jugular vein** 5. Rt carotid sinus (or bulb)*** (65) (69) * Look for these bilateral vessels that have been visible on every image so far. ** The externals have also been visible on every image. They move laterally as they ascend. ***Netter does not label the carotid sinus (or carotid bulb, though we can see on plate 65 the widening of the common carotid as it approaches the bifurcation of the internal and external arteries, which typically occurs around the C-4 C-5 interspace. On image 13 the right sinus is evident. The left is not as obvious, and the internal and external carotids are not seen as clearly as the right until image #10. Because this area is prone to accumulation of athromas, referring to it is as the sinus or bulb is significant to imaging. 5 4 3

1 2 6 4 3 5 8 7 1. Rt vocal cord (ligament)* (74) Reference 6 1. Rt vocal cord (ligament)* (74) 2. Lt. vocal fold** (59, & a plate deleted from the 3rd and 4th edition which is found 3 slides forward) (63) 3. Glottis*** 4. Rt external carotid artery 5. Rt. internal carotid artery 6. Rt internal jugular vein 7. Submental vein and branches (66) (72) 8. Thyroid cartilage**** * Not well seen, but we know it is on the edge of the folds ** Tissue lateral to vocal cords *** Space between cords, covered by the epiglottis during swallowing ****Not well seen on this or previous image due to the weighting of these MR images, but there is thyroid cartilage there 4 3 5 8 7 Images 12 & 11

Images 12-9

Reference 1. Hyoid bone (59, 61, 64) (63, 65, 66) 2. Epiglottis (59, 73, 74) (63, 76, 78) 3. Lt sternocleidomastoid muscle 4 Lt internal jugular vein 5. Lt internal carotid artery 6. Lt external carotid artery 7. Rt external jugular vein 8. Rt & Lt piriform fossa* (recesses) (62) (66) 9. Tongue 10. Rt submandibular gland** (57, 65) (61, 69) * Two recessed folds of the laryngopharynx on the lateral sides of the upper trachea. Often seen on a barium swallow under fluoroscopy. Though not labeled, they first appear on image 10. ** The sublingual gland is between image 9 & 10, but just does not show on this exam. 1 6 5 4 2 7 3 10 9 1 2 8 Images 10 & 9

Deleted Plate of Laryngopharynx This plate was deleted from the 3rd edition of the Atlas. It provides an interesting perspective on the: Epiglottis Glottis Vocal cords (true cords) Vocal folds (false cords) Note the triangular shape the vocal cords form on inspiration. This is the shape seen on image 12.

1 6 7 5 4 2 3 10 7 9 8 1. Lt submandibular gland Reference 1 6 1. Lt submandibular gland 2. Rt sternocleidomastoid muscle 3. Rt internal jugular vein 4. Rt internal carotid artery 5. Rt external carotid artery 6. Mandibular symphysis (symphysis of the mandible) 7. Epiglottis 8. Rt & Lt vertebral arteries 9. Lt external jugular vein 10. Body of the Rt mandible 7 5 4 2 3 10 7 Images 8 & 7 9 8

Images 8-5

1 3 2 4 7 8 5 6 1. Alveolar process (crest) of the mandible* (13) (15) Reference 1. Alveolar process (crest) of the mandible* (13) (15) 2. Gonion (angle) of the Rt mandible** 3. Rt & Lt palatine tonsils (59, 60) (63, 64) 4. Rt masseter muscle (50) (54) 5. Rt parotid (salivary) gland*** (57) (61) 6. Cerebrospinal fluid (CSF) in the subarachnoid space 7. Ramus of the Lt mandible 8. Oropharynx**** * The black holes are sockets with the roots of the teeth in them, but the ridge of bone the sockets are in is the alveolar process. ** This is the first image that the most posterior part of the inferior mandible is clearly seen, making it the gonion (angle) of the mandible. ***First seen in image 6, the parotid enlarges as images continue superiorly. **** Boundaries between the naso, oro, and laryngopharynx are not distinct, but they are otherwise easy to identify. In this case the presence of the palatine tonsils, well above the epiglottis and below the hard and soft palate place this section around the middle of the throat, which is also the middle of the oropharynx. 1 3 2 4 7 8 Images 6 & 5 5 6

Another Look: Parotid Sialogram Prior to CT and MRI the only way to investigate the patency of the salivary ducts, which may be obstructed by stones, (calculi), was to inject them with iodinated contrast and take radiographs. Even in those days a sialogram was an uncommon exam. To localize the parotid papilla, (plate 47) (51), the patient sucks a lemon wedge, stimulating salivation. A tiny cannula is inserted and the duct (57) (61) is injected. If you are not familiar with a lateral radiograph of the skull, see plate 5. TMJ Parotid gland Parotid duct

Reference 3 1. Rt parotid gland 2. Uvula (of the soft palate) (48) (52) 3. Lt masseter muscle 4. Mandibular molars* 5. Maxillary molars 6. Lt retromandibular vein** (57) (61) 7. Ramus of the Rt mandible 8. Odontoid process (dens) of C2 9. Rt sternocleidomastoid muscle 10. Lt facial artery (56, 65) (60, 69) * Image 5 demonstrates the mandibular alveolar process. In 4 and 3 we see teeth: molars are evident. Image 2 again demonstrates alveolar process, which must be of the maxilla. Therefore, it is evident that image four is showing lower teeth, and 3 uppers. ** There is an anterior and posterior retromandibular vein that penetrates the parotid gland. In image 4 & 3, on the right side, the pair is seen. For testing purposes either one can be referred to as simply the retromandibular vein. 4 2 1 10 7 6 5 8 Images 4 & 3 9

Images 4-1

4 1 3 2 5 6 7 11 9 10 8 1. Alveolar process of the maxilla (3, 4) Reference 4 1 1. Alveolar process of the maxilla (3, 4) 2. Rt mastoid process 3. Lt parotid gland 4. Rt masseter muscle 5. Ramus of the Rt mandible 6. Incisive canal (6, 33, 35, 36) (6, 37, 39, 40) 7. Alveolar recess of the Lt maxillary sinus* (44) (48) 8. Base of occipital bone 9. Cisterna magna (posterior cerebellomedullary cistern) (103) (109) 10. Rt vertebral artery** (113) (119) 11. Lobule of Lt auricle (Lt ear lobe) (88) (94) * Seen on the left, but due to rotation of the image plane or asymmetry of patient (either are possible though rotation is most likely) the right side is demonstrating the bony floor of the maxillary sinus. **When the vertebral arteries emerge from the transverse foramen of C1 they enter the cranium at the anterior margin of the foramen magnum, in the anterior cerebellomedullary cistern (cisterna magna). 3 2 5 6 7 11 9 10 Images 2 & 1 8