Lymph Nodes of the Head, Neck and Shoulder Region of Swine L

Volume 25 | Issue 3 Article 3

1962 Lymph Nodes of the Head, Neck and Shoulder Region of Swine L. I. Saar Iowa State University

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Recommended Citation Saar, L. I. (1962) "Lymph Nodes of the Head, Neck and Shoulder Region of Swine," Iowa State University Veterinarian: Vol. 25 : Iss. 3 , Article 3. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol25/iss3/3

This Article is brought to you for free and open access by the Journals at Iowa State University Digital Repository. It has been accepted for inclusion in Iowa State University Veterinarian by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. Lymph Nodes of the Head, Neck and Shoulder Region of Swine

L. I. Saar, Dr. med. vet. R. Getty, D.V.M., M.S., Ph.D.*

I. Introduction 1914). Titze (1911-1914) tried to investi A review of various textbooks and other gate the lymph flow of swine by injecting publications concerned with the lymph bovine tuberculosis cultures subcutane system, clearly indicated a great variety of ously but his experiments failed. The first terminology used to group the lymph nodes known research paper published about the of 'swine in region of the head, neck and location of the lymph nodes was done by shoulder. Probably the statement made by Gregor (1914), on swine fetuses approach Baum (1912) was true that, "the group ing term. In 1927/28 Postma confirmed ing of the lymph nodes is basically very Gregors results and pointed out the differ uncertain and will always depend upon the ences found between the lymph flow of individual viewpoint of the author." Never swine compared to the ox. In 1929 Baum the less, an attempt will be made to clarify re-examined the location of the lymph the controversies found in literature about nodes and introduced a new terminology the descriptive information and terms for ,the lymph node groups of swine as used. found in the region of the head, neck and shoulder. Baum's terminology was adopted II. Review of the Literature by von Ostertag (1932); Egehoj (1934- Before 1914 it was generally assumed 37); Zietzschmann (1939); Grau (1938, that the patterns of the flow of lymph of 1943); Klimow-Akajewski (1950); SchOn swine were probably similar to the ox berg-Zietzschmann (1958). Some text (Titze, 1914). This opinion was mainly books, however, like Sisson-Grossman based on viewpointS' expressed by Bartels (1938, 1953) remained firm on terminol (1909), that evidently there was basic ogy and descriptive information used be similarity in distribution of the lymph ves fore 1914. Sisson's influence was reflected sels and the lymph nodes in mammals and in publications of the V.S.D.A. Circular man. In fact, however, before 1914 the ox No. 866 (1951) and St. Clair (1958). was the only animal in which the location Some authors, like Thornton (1949, 1957) of the lymph nodes and their drainage preferred to keep an "intermediate" posi are a s were systematically examined tion by mentioning in part some of Baum's (Baum, 1912). At that time, the descrip and Egehoj's results, but otherwise stating tive information found in textbooks about that, "the nodes of the head and neck are the lymph system of swine was kept at a numerous and somewhat difficult to group minimum (Chauveau 1902; von Ostertag, satisfactorily. " 1904; Ellenberger-Baum, 1908; Sisson, It should be stressed here that Baum's (1929, 1938); Egehoj's (1934-1937) and • From Iowa State University. Ames. Iowa; where Zietzschmann's (1939, 1958) research re Dr. Saar is with the Department of Veterinary Anat· omy and Dr. Getty is Professor and Head of the sults on lymph flow, were obtained mainly Department of Veterinary Anatomy. College of Veteri· nary Medicine. from experiments conducted on nonliving

120 Iowa State University Veterinarian animals. Most (1927) recommended to dicate that the description given by the explore the possibilities for research on the author may be considered as vague. Fur lymph system on living ( anesthetized) thermore, a question mark ( ? ) in an animals, and he referred to his work per empty rubic designates that an equivalent formed in 1908 on rabbits and guinea pigs. term for Baum's (1929) classification was Postma (1928) criticized his own methods not given. Occasionally some of the terms of using dead piglets by saying, "However were marked with one or two "stars" (*) the direction of the lymph flow on 'a living ( * * ) bringing to attention that terms animal will still remain a hypothesis." Ac marked by the same number of stars repre cording to Rusznyak et. al. (1960), "all sent together one group only. [See Table I, data of the earlier literature that are based column 4, (Ostertag, 1904): middle cerv an application of injection techniques cal glands (* ).J should be revised by means of autoinjec It can be observed from tables given that tion of the lymphatic system with lymph," all the authors listed were in agreement performed on living animals. In fact regarding the descriptive information Egehoj (1934) demonstrated that differ about the Lnn. mandibulares (Submaxil ences may be found on lymph flow on lary nodes) and the Lnn. cervicales super dead and live oxen, which results in turn ficiales dorsales (Prescapular nodes), al influence the terminology used to group although a number of synonyms were the lymph nodes. used. (C .... mpare the upper (first) and the First, however it seemed proper for the lower, t14th) horizontal group through authors to re-examine the terminology of tables (I) to (IV). the lymph nodes of swine as sited in pre The Ln. retropharyngicus medialis sent literature. (Baum, 1929; Engehoj, 1936; Grau, 1943; Klimow-Akajewski, 1950; Zietzschmann, III. Terminology of the lymph nodes of 1958), corresponds with the "retropharyn the head, neck and shoulder region geal glands" of von Ostertag, 1904; Ellen of swine. berger-Baum, 1908, 1915. These nodes In the tables I through IV the classifi were called by Sisson (1914, 1953); "Cir cation of the lymph nodes of the past are cular No. 866" (1951) and 8t. Clair arranged according to the descriptive in (1958) as the "suprapharyngeal lymph formation and illustrations given by vari nodes." The other synonyms noted were: ous authors. In table I, the first column ganglions retropharyngiens, or cervicaux lists the terms given by Baum (1929). superieurs (Montane, 1920); "deep cervi They were compared in chronological cal lymph node" (Jossifow, 1932); the order with those which existed before and superior cervical glands (Castor, 1938); after Baum's classification. The continu the internal retropharyngeal lymph nodes ous horizontal lines indicate the corre (Thornton, 1957). Some (earlier) authors sponding regions of the lymph nodes de considered the latter nodes as being part scribed by various authors. The dotted of a larger group of lymph nodes. (E.g. the horizontal lines were drawn as "guide "glandulae tracheales superiores" (Franck, lines" thus allowing the reader to compare 1871); the "pharyngeal glands" (Chau the different terms presented in the tables veau, 1902); the "upper cervical lymphatic I through IV. glands" (Leighton, 1927). It can be observed in tables I through IV Comparing the descriptive information that various authors of the past have given for the "posterior cervical or pre grouped the lymph nodes into a variable pectoral lymph glands" (Sisson, 1914, number of groups; ranging from 4 (Chau 1953; "Circular" No. 866, 1951) it ap veau, 1902) to eleven (Postma, 1928). peared that the following terms were con On a number of occasions the lymph node sidered as being synonymous: "Glandulae groups described by Baum (1929) cor tracheales inferiores, or the "glandulae respond in part only with the classification cervicales profundae inferiores (Franck, given by the other authors. The question 1871); the "lower or caudal cervical lymph marks (?) placed after a term should in- glands, (von Ostertag, 1904); the '1ym-

Issue, No.3, 1962-63 121 ...... t-:> t-:> ~COLUMN1 2 3 4 5 6 o U Baum. 1929 Fr 8 Chauveau, 1902 v. Ostertag. 1904 Ellenberger-Baum, Sisson, 19141 P (Baum-Grau, 1938) anck, 1 71 (Engl. ed.) (Engl. ed.) 1908 ~~~~on,Grossman,

Lnn. Old. Submaxillary, or Submaxillary Lgl. Mandibular 1 mandibu1ares: submaxillaris subglossal @"lands p;lands" submaxillaris lymph glands

TABLE I 2' Lnn. Gld. maxillares Terminology applied parotidei posteriores or _ '- ' r - - - -- L_I-r------to the lymph nodes Ln. Gld. subauricu- Parotid lymph of head, neck and 3 retropharyngeus lares glands (*) shoulder region of , ...... ;.,... - _ r- _ _ ~ _ _ :- ~: subparotid. swine from 1871 to ~ gland (Sisson) 1960. Remarks for 4 ';;l Cranial. Lymphatic glands Lnn. retro- tables I thru IV: I-- b Group ______I- _ _ pharyngicus Ln. Lymphonodus; = • ~ Middle Lgl. lateralis (Baum)? Lnn. = Lymphonodi; Gld. = Glandulae; Lgl 5 ~. Group subparotideae = Lymphoglandulae; r--- u'i:! -- .t- -- -t- -- I- -- (?) = placed after a 6 S 8. Caudal Middle cervical. term indicates that the ~ iii Group lymph glands (_) description given by ------an author may be Lnn. Glandulae Uoper cervical. Parotid lymph 7 mandibul~stracheales Pharyngeal. glands gland (*) considered as "vague" .. , superiores _ _ _ glands _ or in an empty rubric Lnn. cervical.es . it shows that an 8 superficiales Middle cel'Vl.cal "' Middle cervical ..... elluivalent term for medii glands (?) (*) • lymph glands (**) o Baum's (1929) dassi ------~ Inn. Retropharyngeal Lgl. Suprapharyngeal !:l cation was not given 9 ~:~~~geus glands retropharyngesles lymph glands CI) In a column term .... marked with the same -- -r- -- !:l Lnn. cervicale~ Lgl. rvi 1 .... m f (1) number of "stars,' 10 di .ce caes Q) pro un craniales "other small represent one lymph I-- 'il craniales --- Middle cervical. nodes around - ~ node group only (1) ::;. 't! Lnn.cervicales Gld.tracheales glands (*) trachea" (See also text!) 11 J:; profundi v. cervi cales LItheg • cervicales (1) .,:8 ;;';'r!tf m;'t!i"A 'f?' mediae ;;; r--- U s:: .... •.e Lnn. cerv. 1 ~ 12 s:: 0 prof caudaJ.es G d. tracheales oSto ( i i) inferiores, Gld. Prepectoral. Lower or caudal Posterior cerv. ~ me an cervical.es glands (includes cervical lymph Lgl. cervical.es or prepectoral. _ ~ 13 Lnn. cerv~~.cau:dales profundae also the !.nn. glands caudaJ.es IymPh glands ;::t lat. (Axi s inferiores sternales, Baum) " ;:! rimae COg !:l IT .nn. cervicales Prescapular or ::I. 14 ~~.erficiales Gld. cervicalell Prescapular superficial. Lgl. cervicales Prescapular § "D~""-"l•• superf'iciales glands cervical. 1Z1ands superficial.es lymph glands .... '" G '";:: COLUMN 7 8 9 10 11 12 I .<1:> R 0 Gregor, 19].4 Z (cited by Postma. Ellenberger- Montane- Ellenberger- U Martin. 1923 Leighton. 1927 ? P '28 and Baum. 129) Baum. 191$ Bourdelle. 1920 Baum. 1926 C.:l

...... Ganglions sous- (0 1 Mandibular Lgl. maxillaires ou Lgl. mandibulares Lnn. Submaxillary m lymph node submaxillaris snu: _ ..1n""i"n" (submaxillares) mandibulares lymphatic glands ~ 2 Inn. Ganglion pre- Lgl. parotidea Inn. C.:l paroUdei parotidien parotidei - - - uang.Ll.on -m-. - - - 3 ilJaramastoidien ~ retropharyn- Ln. ! (pre-atlo1dien) Lgl. geus lateralis I- G> ~ retropharyngeus --- tropharyngeae - ~ - - - 4 lateral1s ...~ laterales Gangl10ns i ItOther lymphatic Lgl. parot1deae ~ post- . I- glands It - Po parot1diens - 5 I:: ] OUIference not a Lgl. cervicales I- - available) -- :a - mediae - ~. cerv. - - - 6 fj superficiales ~uperf1ciales 0 - ~entrales - Upper cervical 1 Upper cervical Lgl. cerv. prof. Inn. mandibulares lymph node Ganglions- cranialls accessorii lymphatic glands(*) cervicaux moyens Lnn. cervicales au jugulaires (*) Lgl. cerv. prof. Middle cervical 8 (1) superfici~~) ~ - mediales (*) ventrales 1 glands (1) - Gangl. retro-p~ar.ynLgl. retropharyn- In. 9 Lgl, glens. au cervicaux retropharyngeus ~ - retroDharvn2eales sup_eneurs gea medialis medialis - Upper cervical - 10 Lgl. cervi cales Lnn. cervicales craniales Gangl10ns craniales lymphatic ~ (Reference not cervicaux moyens Lgl. cerv. prof. glands (*) - available) au jugulalres (*) mediales (*) - 11 Lgl. cervlcales Lnn. cervicales mediae I--- - - medii Inn. cervicales I 12 Gangl. pre-pecto- Lgl. cervicales caudales ~ - I-caudales - raux; auxi11aire • ~l.cerv' Lower cervical - au de l'entree prof. caudales Inn, lymphatic glands l 13 de In poitrine axi11ares I ;:)uperficial Lgl. cervicales Gangl. pre-scapu- Inn. cervicales ..... 14 cervical lymph laires au cervicaux Lgl. cervicalis superficiales Prescapular I.\:l superficiales node __ superficial1s glands W inferieul'S dorsale~ - -- -~ ..... t-.:l G >1>0 COLUMN 15 16 17 18 R 13 14 0 U v. Ostertag, v. Ostertag, 1934 Castor in: Postma, 1928 Jossifow, 1932 Egehoej I 1936 P 1932 (Engl. ed.) Edelmann, 1938 submaxillary Ln. Ln. Lgl. submaxillaris Lnn. Submaxillary 1 ~phatic gland mandibulares lymph glands mandibularis mandibularis anterior (In. mandibularis) Parotid lymphatic TABLE 1 Ln. Ln. Lgl. parotidea Lnn. 2 superior gland; parotid parotidei Terminology applied -parotideus parotideus 1_nnnnn;t,,11 Parotid lymph. -I to the lymph nodes Lgl. parotidea Lateral retro- Lnn. retropharyngei glands of head, neck and 3 Ln. retropharyn- pharyngeal lympho- geus lateralis inferior (?) lateralis ! shoulder region of r-- Lnn. ~orluli swine from 187I to retropharyngei - - - 1960. Remarks for 4 laterales tables I thru IV: Ln. = Lymphonodus; Lnn. cervicales "Superficial - Ventral super- Inn. cervicales - - - Lnn. = Lymphonodi; 5 Lnn. cervicales super!:iciales cervical lymph fidal cervical superficiales Gld. = Glandulae; Lgl. medii super- ventrales - node" (?) lymphonoduli ventrales - = Lymphoglandulae; - ficiales - Middle cervical. (?) = placed after a 6 glands (*) term indicates that the Accessory description given by Ln. cervicalis Lnn. Lgl. submaxillaris Lnn. mandibulares Anterior an author may be 7 cranial.is mandibulares posterior mandibular accessorii cervical (?) considered as "~'ague"; accessorii ~V1TIPhonoduli or an empty rubric Ln. cerv. prof. Lnn. cervi cales Median supf. cerv. in Inn. cervicales Deep cervical it shows that an 8 medii, "Ln. under superficiales (?) lymph nodes (m~~ia equivalent term for brachiocephalicus medii cervical glands sup!. medii glands (?) o Baum's (1929) classi Ln. "!Jeep cerv:l.CIU. l'leCllaJ. O)upenor Cerv1CaL -~ Lnn. retropharyn- In. retropharyn- retropharyngeus lymph node" (Lgl. retropharyngeal glands (Retro- and >::l catiou was not given. 9 In a colullln terms medialis geus medialis retropharyngea) lymphonoduli geus medialis parapharyngeal) .,..,.en marked with the same ~nt..cerv.J.ympn >::l number of "stars," 10 III Lnn. cerv. rodes (tJpper III Lnn. cerv. ~ Q) cranial.es .c craniales represent one lymph cerv. gland) ~ Middle cervical c::: r-- Lnn. tracheales - ~ u ;:: node group only. u - - - glands (*) - ;:;;. (See also text!). 11 Lnn. cerv. t [Median cerv. Lnn. cerv. (1) medii '2 IJ-ymphonoduli ta medii ta - (?) U III U 5=: o§ - - -ri'tl ::> ~. "Several small .....Lnn. cerv. lPosterior cerv ..... Lnn. cerv • 12 t lii ~ nodes at the caudales Q)r-I ~ymphonoduli caudales .., ~t t}!>D ]~ Inferior cervical -.:::: r" (1) LOwer glands (pre- - .,..,. cerv1cal or (1) 13 Lnn. cervical.es Lnn. axillares Lgl. primae prepectoral; or Ln. axillaris pectoral glands) .... profundi caudales primae costae costae axillary primo msta primae costae E" >::l In. cervicalis Prescapular lympha~ .... 14 In. cervicalis Lgl. cervi calis glands; dorsal supf Ln. cervicalis Prescapular lymph s" superficialis superficialis centralia supt. dorsalis glands ;:! dorsalis cerv. lymphonoduli G -'" R COLUMN '" 1Q 20 21 22 23 24 ~ 0 Klimow-Akajewski, U U.S.D.A.: z p 1950; and Grau in: Circular No. 866 iThornton, 19S1 St. Clair, 1958 Zietwschmann, 19S8 Grau and Sl E11enberger-Baum,'4 1951 Boessneck, 1960 cv Lnn. Mandibular lymph ~ubmaxillaryMandibular Ln • Lnn...... 1 (0 mandibulares glands ~ymnhnode lymnh nodes mandibularis mandibulares Ol If Inn. Parotid lY'/ll!lh Ol 2 Parotid lymoh node Ln. Lnn. CV parotidici inode Parotid lymph parotidiclls parotidici nodes 3 Lnn. retropharyn- Ln. retrooharyn- Lnn. retropharyngici later ales gicus lateralis gici laterales - - -I- - - 4 I] I] Cranial Q) Q) Group _ ~~escapular -I- - '01'01 - - ~Anterior and - - 0,.. - Inn. cervicales ymph nodes (*) (?) Middle Lnn. cervicales 5 s uperfic1ales Middle cervical. superficiales 'E~Group ventrales ~lymph plands (*) _ Q» ventrales - - - - 0 . - - ~osteriorcervical; .... Caudal 6 prepectoral nodes(* go. Group - - ...:l~ Lnn. mandibulares ~nterioror upper In. mandibularis Inn. mandibulares 1 accessorii cerviciil(a~~es~~~accessorius accessorii Isubmaxi Larv no Middle cervical SUpplementary 1Lnn.cervi cales ?rescapular lymph nodes (**) Ln. cervicalis Lnn. cervicales 8 cervicat Isup!'. medii glands 1Fh - ~ymphnodes (*) (1) sup!'. medius sup!'. medii Ln. Ln. retropharyn- suprapharyngeal. Internal retro- Suprapharynp,eal retro- Lnn. retrooharyn- 9 pharyngeal lymph pharyngicus gius medialis lymph glands nodes lymph nodes medialis gici mediales ., Lnn. cerv. I] Ln. cerv. I] 10 Q) Lnn. cerv. Q) cranial.es Anterior and ,!l cranialis craniales 'al fMtddle cervical • Middle cervica1 • 'al I-- u Middle cervical '"0 u Lnn. cerv. lymph nodes lymph nodes (**) ~ Ln. cerv. Lnn. cerv. n lymph glands (*) ,....-1 medii Q)"CI medius E:amedii E:a U § U c: I--- U § ....Lnn. cerv • .... Ln. cerv. .~ Lnn. cerv. 12 caudales Prepectoral or ~[ caudalis caudeles .§[ posterior Prepectorals or Posterior cervica1 ]~ cervical lymph p.ower cervical or prepectora1 JLnn. axillares lymoh nodes lymph nodes (*) Ln. axillaris Lnn. mcillares 13 j;>rimae costae glands primae costae pri:nae costae IIll. CervlCa.i1s Ln. Ln. cervicalis ?res c apular Prescapular Prescapular or cervicalis ...... Isuperficialis stmerficialis 14 lymph glands lymph nodes posterior super!'• superficialis t.:l borsalis I cerv. Ivrnnh nodes dorsalis CJl dorsalis .- phoglandulae cervicales caudales," (Ellen Grossman (1953) were in general agree berger-Baum, 1908, 1915); the "ganglion ment with Ellenberger-Baum (1908, pre-pectoraux; auxillaire ou de l'entree 1915), except the lymph nodes situated at (Montane, 1920). In Ellenberger-Baum the posterior ventral edge of the parotid (1926) the "prepectorals" were divided salivary gland were named as the "middle into two distinct groups, namely the Lnn. cervical lymph glands" which included cervicales caudales and the Lnn. axillares. also the Lnn. cervicales superficiales medii Postma (1928) described the "prepector (Baum, 1929). In Montane-Bourdelle als" as composed of "several small nodes (1920) and in Ellenberger-Baum (1926) at the thoracic entrance" and of the Lnn. the parotid lymph nodes were divided into cervicales profundi caudales. In 1929, three groups of w.hich 1) the ganglions Baum concluded from his research that preparotidien (Montane, 1920) corre those "prepectorals" should be described as sponded with the Lnn. parotidei (Ellen composed of the Lnn. cervicales profundi berger-Baum, 1926); Ln. parotideus caudles (mediana) and the Lnn. cervicles (Postma, 1928); Lnn. parotidici (Grau, profoundi caudales (laterales). The lat 1943); 2) The ganglions paramastoidien ter lymph nodes were considered by Baum (pre-atloidien) by Montane (1920) were as representing the Lnn. axillares primae synonymous with the Ln. retropharyngeus costae of the ox. In 1932, von Ostertag lateralis (Ellenberger-Baum, 1926; Baum, adopted Baum's terminology, but unfor 1929; Grau, 1943); while the Ln. retro tunately, in the English translation of pharyngeus lateralis, described by Gregor the same book (1934), the term "Lnn. (1914), Martin (1923) and Postma axillares primare costae" was translated (1928) corresponded with the "Subparo as being synonymous with the "lower cer tid gland" (Sissqn, 1914, 1953); 3) The vical or prepectoral lymph nodes" (Sisson, ganglions post-parotidiens (M 0 n tan e 1914; Leighton, 1927). This has caused 1920) were synonymous with the Lnn. confusion in the English literature, due to cervicales superficiales ventrales (Baum, the fact that the Lnn. axillares primae 1929). Martin (1923) referred to those costate (Baum) presented only a part of nodes as the Lgl. cervicales mediae super the "prepectorals" (Sisson, 1914). Accord ficiales (Table II, column 10). St. Clair ing to St. Clair (1958) the prepectorial (1958) considered the posterior-ventral lymph nodes included the following groups group of the Lnn. cerv.supf. ventrales described by Baum (1929, 1938); 1) Lnn. (Baum, 1929) as being part of the "pre cervicales profundi caudales, 2) Lnn. axil pectoral" nodes (Table IV, column 22). lares primae costae and 3) the caudal According to Baum (1929) the pre group of the Lnn. cervicales superficiales scapular lymph nodes of swine form 3 ventrales. groups (dorsal, ventral and medial) of Most controversial 'and confusing was which all of them present the superficial the terminology and descriptive informa cervical lymph nodes. The "prescapular tion given for the parotid lymph nodes. lymph nodes" (Chauveau, 1902); Sisson, The difficulties involved were due to group 1914; Montane, 1920; Thornton, 1957) ing the Jymph nodes situated along the were the "dorsal superficial cervical" posterior border of the parotid salivary lymph nodes (Baum, 1929); while the gland. (See illustration No.1). Ostertag nodes located at the posterior border of ( 1904) referred to these nodes as the the parotid salivary gland were considered "lymphatic glands"; and Leighton (1927) by Baum as the ventral supf. cervical called them "other lymphatic glands." In lymph nodes (See table I, column 1). The Ellenberger-Baum (1908) these nodes medial superficial cervical lymph nodes were described as the "lymhoglandulae (Lnn. cervicales superficiales medii; subparotidea" and in 1915 the latter term Baum, 1929), were called by Postma was ohanged by the same authors into ( 1928) as the Ln. cervicalis profundus "lymphoglandulae parotideae." It included medii, or as "the lymph nodes located also the Lnn. mandibulares accessorii under the brachiocephalicus muscle," and (Baum,1929). Sisson (1914) and Sisson- were probably the "deep cervical glands"

126 Iowa State University Veterinarian (Castor, 1938) or the "supplementary cer kg. body weight were used. Within the vical lymph glands" (V.S.D.A.; Circular, limitations, the "mixed breeds" may be 1951). In Martin (1923) these nodes classified as: 6 "Chester White" (4 female, were described as being part of the "me 2 castrated males); 3 "Duroc" (2 female, dial deep cervical" lymph nodes (See table 1 castrated male); 10 "Hampshire" (8 fe II, column 10). According to von Oster male, 2 castrated males); 5 "Berkshire" tag, (1904); Sisson, 1914, 1953); Leigh (3 female, 2 castrated males) and one ton, (1927); St. Clair, (1958); those "Spotted Poland China" (female). Eleven nodes were probably included into the of the animals 'showed a minor degree and "middle cervical lymph nodes." two a marked degree of "chronic rhinitis." The Lnn. mandibulares accessorii Three swine presented an umbilical hernia (Baum, 1929) were synonymous with the and one animal a scrotal hernia. One ani "upper cervical glands" (von Ostertag, mal exhibited an abscess the size of a base 1904; Gregor, 1914; Thornton, 1957); the ball on the left ventral side of the neck. Lgl. cervicalis prof. cranialis (Martin, Five of the swine were considered as "with 1923); the Ln. cervicalis cranialis (Postma out clinical symptoms" which did not ex 1928); and the Lgl. submaxillaris poster clude slight "stiffness." Twenty of the ior (Jossifow, 1932). In Montaine-Bour swine showed arthritis to a lesser or delle (1920) those nodes were described greater degree on one or several joints. as being part of the ganglions cervicaux Furthermore, all of the swine showed on moyens, ou jugulaires, and St. Clair postmortem pathological changes in the (1958) referred to them as the "middle lungs, indicating flu, chronic pneumonia, cervical lymph nodes." or parasitic conditions. A short review of the grouping of the lymph nodes and the terms used showed· B. Method that the problems involved were not solely The 25 swine described under "mater due to choice of different terms used, but ials" were used for investigations con frequqently the same terms were used to ducted on the lymph flow of live animals describe different lymph node groups. placed under anesthesia, by using the in Furthermore the number of lymph node jection dye T-1824*. A detailed report groups differed greatly and thus the termi about the method, technique and results nology frequently overlapped. The ques will be published in another article to fol tion, who's terminology and grouping dow. In short, however, it may be said should be preferred, can be answered only here that after lY2-1% hours following through a thorough knowledge of the af injection the animals were sacrificed while ferent and efferent lymph vessels, and by under the anesthesia either by exsanqui taking into consideration the general view nation through the femoral blood vessels points outlined by the comparative anat (9 swine) or by giving an overdose of the omy and standards set by the Internation anesthetic (16 swine), thus leaving the Anatomical Nomenclature Committees blood vessels intact. After removal of the (LA.N.C.). viscera the specimens were placed for 24 However, in order to compare previous hours in a cooler at 34° F. By routine dis results published about the lymph flow of section the lymph vessels and the lymph the non-living swine, with experiments nodes were exposed. In this article, the conducted on living animals, placed under location of the lymph nodes will be de anesthesia; the terminology used by Baum scribed only. (1929), Egehoj (1934-1937) and Zietz schmann (1958) was adopted. C. Results a) General Observations IV. Location of the lymph nodes of the Ins swine the neck is relatively short head, neck and shoulder region of swine. compared to the horse, dog, cow and A. Material sheep; thus, the structures involved in this For the dissection purposes 25 swine of * "Evans Blue," Allied Chemical Co., New York, "mixed breeds" of approximately 45-70 N. Y.

Issue, No.3, 1962-63 127 area are somewhat closer together. After marize differently named lymph node reflecting the skin, the underlying heavy groups which in fact represent a larger fat deposits and the cutaneous muscles common functional unit. (Platysma and the M. cutaneous colli) the large three-cornered parotid gland is vis b) The Lymph Nodes of the Head ible. It extends from near the base of the The lymph nodes of the head form three ear along the posterior border of the man lymph centers [Lymphocentra (Lcc.)] of dible and continues up to the incisura which in swine the parotide lymph center vasorum. Its posterior border covers to a (Lc. parotidicum) includes the lympho greater part the M. brachiocephalicus (M. nodi (Lnn.) parotidici only; while the cleidooccipitaIis) and ventral, the parotid mandibular lymph center (Lc. mandibu gland extends up to the ventral edge of thE lare) is composed of the Lnn. mandibu M. sternohyoideus. A number of lymph lares and the Lnn. mandibularesaccess nodes are found along the anterior and the orii. The retropharyngical lymph center posterior border of the parotid gland, (Lc. retropharyngicum) presents the Lnn. being partly or completely covered by the retropharyngici lateralis and the lympho latter gland. nodus (Ln.) retropharyngicus medialis. In swine the lymph nodes usually fonn clusters (conglomerations) of nodes, of 1) The Parotid Lymph Center (Le. paro which their number is often difficult to de tidieum) (Illust. 1; and Fig's. 1,2,3) tennine. For that reason they were re The Parotid lymph nodes (Lnn. paroti ferred to as presenting one "lymph node" dici) are situated ventral to the mandibu (Ln). However, when in a certain region lar joint at the posterior border of the M. several conglomerations of lymph nodes masseter forming an elongated group of were found or when ;single lymph nodes lymph nodes of 2.5 to 5 cm. in length and were clearly distinguished from each 0.5 cm. to 1.5 cm. in width. Thus the other, then they were termed "lymph lymph nodes are located lateral to the V. nodes" (Lnn). maxillaris interna and extend dorsal and The color of the lymph nodes varied ventral to the latter vein. The Lnn. paro from gray-white to tan-grey in animals tidici may be composed of 2 to 8 lymph sacrificied during anesthesia by exsanqui nodes, being partly or completely covered nation or by an overdose of anesthetic. laterally by the anterior edge of the paro This is in contrast to the reddish-brown tid gland. color of the parotid lymph nodes seen in animals killed at abattoirs. 2) The Mandibular Lymph Center (Le. The lymph nodes, show!! in illustration mandibulare) ( 1) may be described as the "superficial The mandibular lymph nodes (Lnn. lymph nodes." The "deep lymph nodes" mandibulares) (Illust. 1; and Fig's 1,2,3) are related to the trachea from the jugular are covered laterally by the cutaneous process down to the thoracic entIance and muscles and the parotid salivary gland. include the Lnn. cervicales profundi and They are located at the caudoventral the Ln. retropharyngicus medialis. [They border of the mandible, on the lateral side are not shown in illustration (1)]. The of the M. sternohyoideus. They are found latter classification, however, is somewhat ventromedial to the angle of the mandible empirical, because often it is difficult to and anterior to the mandibular gland. Us decide which of the lymph nodes should ually the lymph nodes are located ventral be considered as being "deep" or "super to the V. maxillaris externa, but often they ficial." In the following the lymph nodes extend to the dorsomedial side of the lat will be grouped as: 1) the lymph nodes ter vein fonning one or two conglomera (Lnn.) of the head, 2) the Lnn. of the tions of lymph nodes of 2 to 3 cm in neck and 3) the Lnn. of the thoracic limb. length and 1 \12-2\12 cm. in width. The term lymphocentrum (Lc.) as intro The accessory mandibular lymph nodes duced by Baum (1926) and discussed by (Lnn. mandibulares accessorii) (Illust. 1; Saar-Getty (1962) will be applied to sum- and Fig's 1,2,3,4) are found ventral to the

128 Iowa State University Veterinarian v. maxillaris externa where the latter vem stoideus. Usually the medial retropharyn terminates into V. jugularis externa. The gical lymph node presents an oval con lymph nodes are located on the ventro glomeration of lymph nodes of 2 to 3 cm. lateral side of the M. sternomastoideus and in length and 1 to 1 Y2 cm. in width. Oc posterior to the mandibular salivary gland, casionally one or two small lymph nodes being completely covered and partially em of 0.5 and 1.0 cm. in length may accom bedded by the ventral edge of the parotid pany the main node, being situated pos salivary gland. Usually there is found an teriorly or ventrally to the latter lymph oval conglomeration of two or four vari node. able sized lymph nodes of 0.5 cm. or 11;2 cm. in length. In one case (out of 25) on c) The Lymph Nodes of the Neck the left side and in 3 cases (out of 25) on The lymph nodes of the neck form two the right side, the latter lymph nodes were lymph centers (Lcc.) of which in swine not clearly distinguished from the Lnn. the superficial cervical lymph center (Lc. cervicales ventrales. In these exceptional cervicale superficiale) includes three cases, the lymph nodes were located ven lymph node groups (Lnn. cervicales super tral to the V. juglaris externa, 1-2 cm. pos ficiales dorsales, ventrales and medii); and terior to the termination of the maxillary the deep cervical lymph center (Lc. cervi veins into the V. jugularis externa, being cale profundum) which is composed of situated anterio-medial to the posterior three lymph node groups (Lnn. cervicales group of the Lnn. cervicales superficiales profundi craniales, medii and caudales). ventrales. 1) The Superficial Cervial Lymph Center 3) The Retropharyngical Lymph Center (Lc. cervicale superficiale). (Lc. retropharyngicum) The dorsal superficial cervial lymph The lateral retropharyngical lymph nodes (Lnn. cervicales superficiales dor nodes (Lnn. retropharyngici laterales) (11- sales) (IlIust. 1; and Fig's. 1,2,3) are situ lust. 1; and Fig. 1) form a group of 1-2 ated craniodorsal to the shoulder joint, lymph nodes along the dorsal, posterior just anterior to the scapular portion of the border of the parotid gland; thus, being deep pectoral muscle, being located on the situated caudal to the V. auricularis M. serratus ventralis. The dorsal third of magna and dorsal to the V. maxillaris in the conglomerate of lymph nodes is cov terna on the M. brachiocephalicus (M. ered by the M. trapezius, while the ventral cleidomastoideus). Those lymph nodes portion extends under the M. omotrasver are partly or completely covered by the sarius. Generally there is only one oval posterior border of the parotid gland and shaped conglomerate lymph node present often they are not clearly distinguished of a variable size of 1-4 cm. in length but from the anterior group of the Lnn. cervi occasionally one or two smaller lymph cales superficiales ventrales. nodes of 0.5-1 cm. in width are found The medial retrophanJngical lymph ventral to the main group, covered by the node (Ln. retropharygicus medialis) (Fig's. M. omotransversarius. 2,3) is found on the dorsolateral side of The ventral superficial cervical lymph the pharynx muscles; located dorsal to the nodes (Lnn. cervicales superficiales ven A. carotis communis, V. jugularis intern a trales) (Illust. 1; Fig's. 1,4) form a row of and the vago-sympathetic trunk. The lymph nodes on the ventrolateral side of lymph node is found just posterior to the the M. cleidooccipitalis and on the lateral hyoid bone and it extends 2 cm. ventro side of the M. cleidomastoideus along the medial to the wing of the atlas, reaching posterior border of the parotid gland. They posteriorly to the lateral side of the M. represent a chain of lymph nodes extend longus capitis. Laterally the lymph node ing from the lateral retropharyngical is covered by fat, and the thymus when lymph nodes caudoventral along the anter present, and by the tendon of the M. ster ior edge of the brachiocephalicus muscle. nomastoideus, which structures in turn Usually the lymph nodes seem to form 2 are covered laterally by the M. cleidoma- or 3 groups which may be distinguished as

Issue, No.3, 1962-63 129 the cranial, the middle and the caudal ens and the V. jugularis externa. Occa group. sionally (4 out of 50 cases) some of the The caudal group was found in all the lymph nodes extended caudally along the cases examined (25 swine) to be the larg dorsal or lateral side of the V. jugularis est compared to the other two groups. It externa and thus it becomes difficult to forms a conglomeration of lymph nodes of distinguish the medial superficial cervical 2-3 cm. in length 'and 1-1Y2 cm. in width. lymph nodes from ·the "split off" lymph The middle group may be described as nodes of the Lnn. axillares primate costae. composed of smaller lymph nodes of less than 0.5 cm. to 1 cm. in size. Occasionally 2) The Deep Cervical Lymph Center (Lc. some of the latter lymph nodes were found cervicale profundum). to cover an area dorsally on the M. cleido The deep lymph nodes of the neck (Lnn. occipitalis reaching up to the dorsal border cervicales profundi) are related to the of the M. omotransversarius; thus being trachea !ranging from posterior to the located close to the dorsal superficial cervi larynx, downward to the thoracic inlet. cal lymph nodes. In swine they were relatively small and The cranial group of the ventral super inconsistently found and of less import ficial cervical lymph nodes were repre ance compared to the numerous and well sented by 2-5 variable sized lymph nodes developed superficial cervical lymph nodes of up to 2 cm in length. Quite frequently in this animal. The deep cervical lymph they were not clearly distinguished from nodes form three groups which may be the lateral retropharyngical lymph nodes. distinguished as the cranial, middle and The classification of the ventral super the caudal group. ficial cervial lymph nodes into the "cran The cranial deep cervical lymph nodes ial," "middle" and "caudal" group is rather (Lnn. cervicales profundi craniales) are empirical but it serves a practical purpose situated in the region between the larynx for describing the afferent and efferent and the thyroid on the first and second lymph vessels. tracheal ring, ventral to the V. jugularis The medial superficial cervical lymph interna. In 17 out of 25 swine examined nodes (Lnn. cerviales superficiales medii) these lymph nodes were found to be absent (Illust. 1; Fig's. 1,2,3,4) may be described on both sides of the head. In two cases, 3 as two inconsistantly found groups of lymph nodes of less than 0.5 em. were lo lymph nodes, of which the first group is cated on the left side and 2 lymph nodes of represented by one or two small lymph 0.25 cm. on the right side. In 3 cases, nodes varying in size from 0.5 cm. to 1 three lymph nodes were present on the left cm. in length. They were found to fol side, and 2 lymph nodes on the right side low the course of the V. cervicales ascen of varying sizes of less than 0.25 cm. and dens down to the termination of the latter up to 0.5 cm. in length. Finally in 2 vein into the V. jugularis externa. Some cases, one lymph node of 0.25 em. was of the dorsally located lymph nodes can present on the right side and none were not clearly be distinguished from the dor found on the left side. sal superficial cervical lymph nodes. The middle deep cervical lymph nodes The second group is 'situated dorsal to (Lnn. cervicales profundi medii) are situ the course of the V. jugularis externa, ated just dorsal to the thyroid gland, thus being covered laterally by the M. cleido ventrolateral to the trachea in the region occipitalis and M. cleido-occipitalis and M. of the latter gland. Of 25 swine examined, cleidomastoideus. The lymph nodes can these lymph nodes were found to be absent not always be clearly distinguished anter in 20 animals and in five cases 1 to 3 iorly from the ventral superficial cervical lymph nodes of approximately 0.25 cm. in lymph nodes. Usually (34 times of 50 size were located near the posterior exten cases) 1 to 3 (seldom 4) small lymph sion of the thyroid gland. nodes of less than 0.5 cm. or up to 1.0 cm. The caudal deep cervical lymph nodes in lengtJh were located anteriorly at the (Lnn. cervicales profundi caudales) (Fig. angle formed by the V. cervicalis ascend- 4) form an unpaired group of lymph nodes

130 Iowa State University Veterinarian located posteriorly to the thyroid gland onyms and controversies were present. The being situated ventral to the trachea in an research papers dealing with the lymph angle fonned by the common jugular flow were based mainly on tenninology veins. These lymph nodes were found to introduced by Baum (1929). be present in all cases examined (25 In this report only the location of the swine). The caudal deep cervical lymph lymph nodes was described and illustrated nodes present usually a scattered group of by one drawing and 4 photographs. An 3-8 small lymph nodes of less than 0.25 article to follow will describe the experi cm. up to approximately 0.75 cm. in size. ments conducted to date on the lymph Laterally the lymph nodes were covered by flow in the living (anesthetized) swine. the thymus. The latter gland when pre REFERENCES sent) separates the caudal deep cervical 1. Baum, H.: Betrachtungen liber die Arbeit Vun lymph nodes from the Lnn. axillares pri Postma "Oas Lymphgefass.System des Sehwein es." Z. f. Fleisch- u. Milchhyg., 39, (January 15, mae costae. 1929): 133-140. 2. Baum, H. und Grau, H.: Oas Lymphgefass-Sys tern des Schweines. Verlagsbuchhandlung Paul Parey, Berlin, (1938): 15-52. d) Lymph Nodes of the Thoracic Limb. 3. Castor, T.: In: Edelmann. R.: Text-Book of Meat Hygiene, Lea & Febiger, Philadelphia 1) Lnn. axillares primae costae (1939) :60. In swine there are no lymph nodes 4. Chauveau, A.: The Comparative Anatomy of the Domesticated Animals, 2. English edit., D. Ap found on the "free" thoracic limb. The pleton and Company, New-York, (1902): 713-724. 5. Egehoj, J.: Untersuchungen tiber das VerhaJten Lnn. axillares primae costae (Illust. 1; einiger Lymphknoten am Kopf und am Halse des Schweines, Deutsche Tierarztl. Wschr. 44, (April Fig's. 3,4) fonn a conglomerate of small 11, and April 25, 1936) :287-289; 319-322. 6. Egehoj, J.: Das Lymphgefass-System des Seh lymph nodes located anterior to the first weines, Z. f. Flcisch- u. Milchhyg., 47, (May 1, 1937): 293-298. rib, and lateral to the thymus, and ventral 7. Ellenberger, W. und Baum, H.: Handbuch der to the axillary veins. The term given for verglcichenden Anatomic der Haustiere, 13. and 14. edit., Verlag August Hirschwald, Berlin, these lymph nodes appears to be too long (1908):762-773, and (1915):725-753. 8. Franck. Ludw.: Handbuch der Anatomie der and thus the term Lnn. costoaxillares is Hausthiere. Verlag von Eber & Seubert, Stuttgart, 1871. suggested, (Cos to-axillary lymph nodes). 9. Grau, H.: Oas Lymphgefass-System, In. Ellen berger-Baum, Handbuch der vergl. Anatomie der The size of the conglomerate of these Haustiere, 18. edit., Springer-Verlag, Berlin, lymph nodes varies from 1.0 to 2.5 cm. in (1943): 746-808. 10. Grau, H. und Boessneck, .T.: Der Lymphapparat. length and occasionally one or two smaller In: Ktikenthal, W.: Handbuch der Zoologic; 8. Band/25. Lieferung. WaJter de Gruyter & Co.; lymph nodes of 0.5 em. or less in size may Berlin, (1960): 1-74. 11. Gregor, P.: Lymphknoten und Lymphbahnen am be found anteriorly to the main group, Kopf und Hals des Schweincs. Inaug. Disserta tion. Berlin, 1914 (Cited in Postma, C., 1928). along the lateral or ventral side of theV. 12. Jossifow, J. M.: Das Lvmphgefass-System des jugularis externa. Thus, it is sometimes Schweines, Anat. Anz., Vol. 75, (November 7, 1932):91-104. difficult to distinguish the latter lymph 13. KJimow, A. i. Akajewski, A.: Anatomija Domas zich Ziwotnych, Vol. 2., Gosundarstwiennoje nodes from the Lnn. cervicales superfi Izdatielstwo Sjelskochozjastwiennoj Literatury, Moskwa, 1950. ciales medii of which some may be situ 14. Leighton, G.: The Principles and Practice of Meat Inspection. William Hodge and Company, ated near (around) the termination of the Edinburgh and London, (1927): 142-153. 15. Martin. P.: Lehrbuch der Anatomie der Haus V. cervicalis aseendens. Sometimes, the tiere. 4. Band. Verlag von Schickhardt & Ebner, latter the lymph nodes can not be distin Stuttgart, (1923): 95-97. 16. Miller, A. R.: Meat Hvgiene. 2. edit., Lea & Fe guished clearly from the Lnn. cervicales biger. Philadelphia, (1958) :53-75. 17. Montane et Bourdelle: Anatomie Regionale des profundi caudales. This is especially true Animaux Domcstiques. III, Pore. Librairie J.-B. Baillicrc et Fils. Paris, (1920):112, 142, 184. in older animals in which the thymus has 18. Most, A.: Zur Darstellung der Chylusgefa.se in vivo, Anat. Anz., Vol. 64, (November 2, 1927): been reduced in size. 119-128. 19. von Ostertag, R.: Handbook of Meat Inspection. William R. Jenkins, New York, (1904): 177-181. V. Summary 20. von Ostertag, R.: Lehrbuch der Schlaehtvieh- und Flcischbeschau, F. Enke Verlag, Stuttgart, The terminology and the descriptive in (1932):242-272, and (1955):233-265. 21. von Ostertag, R.: Textbook of Meat Inspection. formation of the lymph nodes of the head, Bailliere, Tindall and Cox, London, (1934): 52- 84. neck and shoulder region of swine were re 22. Postma, C.: tiber das Lymphgefass-System an 24 Kopf, Hals und Schulter beim Schwein. Z. f. viewed, compared and evaluated in Fleisch-u. Milchhyg., Vol. 38, (October I, 1927): publications, and were arranged in 4 1-2. 23. Postma, C.: Das Lymphgcfass-System des Sch tables in chronological order, dated from weines. Z. f. Fleisch- u. Milchhyg., Vol. 38, (July 15, 1928):354-362. 1871 to 1960. 24. Saar, L. 1. and Getty, R.: The Lymphatic Sys It was found that a great variety of syn- i4~lJl~·U. Veterinarian, Vol. 24, No.3, (1952):-

Issue, No.3, 1962-63 131 25. Saar, L. I. and Getty, R.: Nomenclature of the 30. Thornton, H.: Textbook of Meat Inspection. Bail Lymph Apparatus. I.S. U. Veterinarian, Vol. 25, liere, Tindall and Cox, London, (1949): 96-99 and No.1, (1962): 23-29. (1957): 95-98. 26. Sisson, S. : The Anatomy of the Domestic Ani 31. Titze, C.: Lage und Wurzelgebiete der Fleisch mals. 2. edit. W. B. Saunders Company, Phila lymphknoten beim Rinde und Schweine, Z. f . delphia and London, (1914):740-742. Fleisch- u. Milchhyg., Vol. 24, (September 1, 27. Sisson-Grossman: Anatomy of the Demestic Ani 1914) :525-529. mals. 4. edit., Press of W . B. Saunders Company, Philadelphia. (1953) : 760-762. 32. U.S. Dept. of Agriculture, Washington, D.C .• 28. Spira. Anneliese: Die Lymphknotengruppen (Lym Circular No. 866 : The Lymph Glands of Cattle, phocentra) bei den Saugern-ein Homologisier Hogs and Sheep, (January 1951) :2-14. ungsversuch. Inaug. Dissertation. Miichen. 1961. 33. Zietzschmann, 0.: Das Lymphsystem. In: 29. St. Clair, L. E.: Lymphatic Svstem. In: Dunne' s, Schonberg. F. und Zietzschmann, D.: Die Aus "Diseases of Swine." Iowa State College Press, fiihrung der tierarztlichen Fleischuntersuchung, Ames, Iowa, (1958):28-31. Paul Parey, Berlin und Hamburg, (1958): 1-30.

Legends (or figures I thru 4.

Lymph nodes: I. Mandibular, 2. parotid, 3. accessory mandibular, 4. lateral retropharyngical, 5. ven tral superficial cervical, 6. medial retropharyngical, 7. dorsal superficial cervical, 8. medial superficial cer vical, 9. caudal deep cervical, 10. axillares primae costae (costo·axillary).

lUl/sdes: A. masseter, n. brachiocephalieus, C. trapezius, D. omotransversarius, E. deep pectoral (seal" ular portion), F. omohyoideus, G. sternomastoideus, H. sternohyoideus, 1. scalenus primae costate, ]. ser ratus ventralis, K. scalenus supraeostalis, L. sternothyroideus (ventral portion), M. sternothyroideus (dor sal portion), N. hyothyroideus, O. deep pectoral (humeral portion).

Other structures: n. masseteric vein (v.); b. transverse facial v.; c. superficial temporal v.; d. cut por· tion o( the parotill gland; e. great auricular v.; f. internal maxillary v.; g. mandibular, gland; It. extemal maxillary v.; i. external jugular v.; k. ascending cervical v.; m. cephalic hlllneral v.; n. suprascapular v.; o. subscapular v.; p. brachial v.; q. external thoracic v.; r. first rib; .f. internal thoracic v.; t. thyroid gland; II. thymus; v. cricoid cartilage; w. thyroid cartilage; x. proximal end of the humerus; y. inter·tuberal groove.

Figure No. I: (Left side) Lateral view of the head, neck region. The cutaneous muscles, fat and the paro· tid gland have been removed.

132 Iowa State University Veterinarian Figure No.2: (Left side) The brachiocephalic muscle and the lateral retropharyngical and the ventral su perficial cervical lymph nodes have been removed.

Figure ~o. 3: (Left side) Lateral "iew of the head, neck and shoulder region. The thoracic limb has been removed.

Issue, No.3, 1962-63 133 Figure No.4: (Ventral view) The cervical region is dissected to illustrate the "deeper structures" from the larynx to the first rib.

o/ l.rW\.~lIIttfolK ./ "" ..M dIldoot_..... "" /' ./ ",,\M~ "" ./ ,"' .... _-',....,. ./ '" ",'" l.M ~ Mlll4f6clalft dOr1IGI-. ", ,,'" ,,' ~~sor ... /' "" """"Ill pee_all proflMldullllon ~ 0/ "I.-..-coIIa ...-rt- _ / // ,,'!/----~ ; ./

IIIlctacl.hlwel Illustration No.1: Lateral view of the head, neck region (left side). The cutaneous muscles have been re moved.

134 Iowa State University Veterinarian