Anterior triangles of neck

Dr, Kathirvel Gopalakrishnan
M.D.S (OMFS)
Presentation on Anterior triangles of neck which helps for a quick refresh.
Applied aspects described well and all slides will be informative with lot of image based examples

1. ANTERIOR TRIANGLES OF NECK Presented by Dr.Kathirvel.G MDS (OMFS)

2. Contents: Triangles of the neck Anterior triangle of Neck Submental triangle Submandibular triangle Carotid triangle Muscular triangle Journal Club discussion

3. TRIANGLES OF NECK: Anterolaterally, neck is quadrilateral in shape Boundaries: Anteriorly : Midline of neck Posteriorly : Anterior border of trapezius Superiorly : Inferior border of mandible Inferiorly : Clavicle

4. Sternocleidomastoid muscle: Passes obliquely upwards and backwards Origin : Clavicle and sternum Insertion : Mastoid process and occipital bone Sternocleidomastoid muscle divides the quadrilateral area into two triangle Anterior triangle Posterior triangle

5. ANTERIOR TRIANGLES OF NECK: B oundaries: Anteriorly : T he midline of the neck Posteriorly : T he anterior border of the sternocleidomastoid muscle Superiorly/ Base : T he inferior border of the mandible B.D.Chaurasia – Human anatomy – Fifth edition – Volume 3

6. Divisions: 3 paired and 1 unpaired. Unpaired triangle: Submental triangle P aired triangles: Submandibular triangle C arotid triangle M uscular triangle Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

7. SUBMENTAL TRIANGLE: Boundaries: Anteriorly : Midline of neck Posteriorly : Anterior belly of digastric Base / Inferiorly : B ody of the hyoid bone F loor : Mylohyoid muscle B.D.Chaurasia – Human anatomy – Fifth edition – Volume 3

8. Contents: Submental lymph nodes S mall veins anastomose to form the anterior jugular vein. As the anterior belly of the digastric muscle can present with variable anatomy or even be absent, the submental triangle can be distorted or absent. Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

9. Two accessory bellies originated anteriorly to the intermediate tendon of the digastric muscles Appeared fused along the midline and inserted on the medial surface of mandible

10. Applied aspects: Any odontogenic infection in anterior teeth, u sually appear as an abscess or fistula on the skin in the chin area. Occasionally, they can spread out into the submental space and form an abscess. The risk of the incision is low because structures within the triangle are sparse and include no arteries. Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

11. Submandibular triangle: Area between body of the mandible and hyoid bone Boundaries: A nteriorly : Anterior belly of digastric muscle Posteriorly : P osterior belly of digastric muscle Superiorly : I nferior border of the mandible F loor : M ylohyoid muscle B.D.Chaurasia – Human anatomy – Fifth edition – Volume 3

12. Contents: Nerves: Marginal mandibular branch of the facial nerve N erve to the mylohyoid H ypoglossal nerve Arteries and veins: T he facial and lingual arteries and veins Others: S ubmandibular gland L ower pole of the parotid gland L ymph nodes . Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019 Marginal mandibular nerve Mylohyoid nerve Hypoglossal nerve Facial artery and vein Submandibular gland Parotid gland

13. Layers: Superficial structure: Platysma Facial vein Marginal mandibular branch of facial nerve After removal of superficial layer Submandibular gland

14. Remaining structure Facial artery Lingual nerve Lingual artery Hypoglossal nerve

15. Applied aspects: The attachment of the mylohyoid muscle onto the mandible is more inferiorly in the anterior region and more superiorly in the posterior region of the triangle. Infection from lower molar tooth could easily spread below the mylohyoid muscle into the submandibular space. Submandibular lymph nodes are clinically very important because of its wide range of drainage. Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

16. Applied aspects: The submandibular incision to access to this triangle should be inferior to the MMB. A n incision two fingers-breadth below the inferior border of the mandible would provide safer access to the submandibular triangle than the 2 cm line below the inferior border of the mandible in order to avoid injury to the MMB. Davies et al; Evaluation of Clinically Relevant Landmarks of the Marginal Mandibular Branch of the Facial Nerve; Clinical anatomy; 2016

17. Two small triangles are included : Lesser’s triangle Pirogov’s triangle  Tubbs Et al; Three nearly forgotten anatomical triangles of the neck: triangles of Beclard , Lesser and Pirogoff and their potential applications in surgical dissection of the neck. Surgery Radiol ogy anatomy;  2011

18. Lesser’s triangle: Named after the G erman surgeon Leon Lesser Also called the lingual triangle. Boundaries: Anteriorly : Anterior belly of digastric muscle Posteriorly : P osterior belly of the digastric muscle Superiorly : H ypoglossal nerve F loor : Hyoglossus muscle L ingual artery is found beneath it

19. Applied aspects: Tubbs et al. reported that Lesser's triangle was present in 30 out of 34 . When it was absent, the hypoglossal nerve coursed inferior to the digastric muscle. It is an ideal location for accessing the lingual artery . Tubbs et al; Three nearly forgotten anatomical triangles of the neck: triangles of Beclard , Lesser and Pirogoff and their potential applications in surgical dissection of the neck; Surgery radiology anatomy; 2011

20. Pirogov’s triangle: Named after Russian surgeon Nikolai I. Pirogov This triangle is the posterior part of Lesser's triangle. Boundaries: Superiorly : Hypoglossal nerve Inferoposteriorly : I ntermediate tendon of the digastric muscle Anteriorly : P osterior border of the mylohyoid muscle Van et al; Pirogoff’s Triangle revisited: an alternative site for microvascular anastomosis to the lingual artery; International journal of Oral and maxillofacial surgery; 2000

21. Applied aspects: Tubbs et al reported that Pirogov's triangle was found in 30/34 sides When it was absent, the hypoglossal nerve coursed below the digastric muscle, as with Lesser's triangle. This triangle constantly included the lingual artery deep to the hyoglossus muscle . Tubbs et al; Three nearly forgotten anatomical triangles of the neck: triangles of Beclard , Lesser and Pirogoff and their potential applications in surgical dissection of the neck; Surgery radiology anatomy; 2011

22. CAROTID TRIANGLE: Boundaries: Superiorly : P osterior belly of the digastric muscle Anteriorly : S uperior belly of the omohyoid muscle Posteriorly : A nterior border of the SCM. F loor : Hyoglossus T hyrohyoid membrane I nferior and middle pharyngeal constrictor muscles. B.D.Chaurasia – Human anatomy – Fifth edition – Volume 3

23. Contents : Artery : C ommon carotid artery I nternal External carotid artery (ICA) carotid artery (ECA) Superior thyroid Lingual Facial Oc cipital A scending pharyngeal artery The anterior triangle of the neck; Harold Ellis, Vishy Mahadevan; Surgery 32:52; 2013

24. Variation in levels of bifurcation of the common carotid artery, related to the cervical vertebrae SURGERY 32:52; 2013

25. Superior Thyroid Artery Origin : Common carotid artery - 19 cases (47.5%) External carotid artery - 12 cases (30%) Carotid bifurcation - 9 cases (22.5%) When it arise from the external carotid artery, the distance of origin from the bifurcation ranged from 2 to 10.5 mm. The distance of origin from the common carotid artery to the bifurcation ranged from 2 to 10.7 mm. CROSS REFERENCE

26. Lingual Artery The distance of origin from the bifurcation ranged from 5 to 40 mm. In 8 cases the lingual artery shared a common trunk with the facial artery. Facial Artery The distance of origin from the carotid bifurcation ranged from 8 to 50 mm.

27. Veins: Superior thyroid L ingual F acial Ascending pharyngeal Occipital Nerve: H ypoglossal nerve External and internal branches of the superior laryngeal nerve The anterior triangle of the neck; Harold Ellis, Vishy Mahadevan; Surgery 32:52; 2013

28. Carotid body: Small cluster of chemoreceptors near the bifurcation of common carotid artery Detects changes in composition of blood passing through it, mainly Po2 It is also sensitive to changes in Ph and temperature

29. Carotid sinus Localized dilation at the origin of internal carotid artery Contains numerous Baroreceptors for maintaining blood pressure It is innervated by sinus nerve of hering , which is a branch of glossopharyngeal nerve

30. Beclards triangle: Named after the French anatomist Pierre A. Beclard Boundaries: Superiorly : Posterior belly of the digastric muscle Floor : P osterior border of the hyoglossus muscle Inferiorly : Greater horn of the hyoid bone

31. Applied aspects: Tubbs et al examined Beclard's triangle and found it in 28/34 sides (84%) With absent, the reasons were that the posterior belly of the digastric muscle did not attach to the hyoid bone, or directly located just above the greater horn of the hyoid bone. Beclard's triangle constantly included both the lingual artery and hypoglossal nerve . Convenient landmark for identifying both anatomical structures. Tubbs et al; Three nearly forgotten anatomical triangles of the neck: triangles of Beclard , Lesser and Pirogoff and their potential applications in surgical dissection of the neck; Surgery radiology anatomy; 2011

32. Farabeuf's Triangle N amed for the French surgeon Louis-Hubert Farabeuf B oundaries: Posteriorly : Internal Jugular Vein Anteroinferiorly : C ommon facial vein Anterosuperiorly : H ypoglossal nerve Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

33. Applied aspects: Tubbs et al. reported that Farabeuf's triangle was present in 75% (15/20 sides). This triangle was constantly located within the carotid triangle and included at least one of the branches of the common carotid artery on 14 out of 15 sides. Campbell et al., also mentioned that “this triangle is a helpful landmark in extensive dissections of the neck, especially in locating the IJV, the safety of which is best conserved by promptly exposing it.” Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

34. MUSCULAR TRIANGLE: Boundaries: A nteriorly : Midline of the neck Superiorly: Hyoid bone Inferiorly : Sternum I nferoposteriorly : Anterior margin of the Sternoclediomastoid P osterosuperiorly :Superior belly of the omohyoid muscle Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

35. Contents: Muscles - St ernohyoid S ternothyroid O mohyoid T hyrohyoid Artery - Superior thyroid artery Veins - Anterior jugular I nferior thyroid Nerve - Ansa cervicalis Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

36. Contents: Lymph nodes - A nterior cervical I nfrahyoid P relaryngeal T hyroid P retracheal P aratracheal Other - Esophagus T rachea Thyroid gland L ower part of the larynx Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

37. Applied aspects: Tracheostomy and thyroidectomy are invasive surgeries that access this triangle. Skin incision should be made parallel to Langer’s line to avoid scar During thyroidectomy, Injury of the superior thyroid artery can result in bleeding during surgery. Kikuta Et al ; Triangles of the neck: a review with clinical/surgical applications; Anatomy and Cell biology; 2019

38. THANK YOU