• Anterior triangles 

A) Submental triangle contents -

1. Submental lymph nodes (drain mental region , tip of tongue , inferior lip , incisor teeth)

2. Submental vein

3. Commencement of Anterior jugular veins

B) Submandibular (Digastric) triangle contents -

(Digastric triangle is subdivided into anterior and posterior parts by stylomandibular ligament )

Anterior part of triangle contents - 

1. Submandibular salivary gland 

2. Submandibular lymph nodes 

3. Hypoglossal nerve

4. Facial vein (lies superficial to gland)

5. Facial artery (lies deep to gland)

6. Submental artery

7. Mylohyoid nerves & vessels

Posterior part of triangle contents -  

1. External carotid artery

2. Carotid sheath and its contents

3. Structures passing between external carotid artery and internal carotid artery (Deep part of parotid gland , Styloid process , Styloglossus muscle , Stylopharyngeus muscle , Glossopharyngeal nerve , Pharyngeal branch of vagus nerve)

C) Muscular triangle contents -

1. Infrahyoid muscles (Sternothyroid , Sternohyoid , Thyrohyoid)

2. Thyroid gland 

3. Trachea 

4. Esophagus

D) Carotid triangle contents  -

1. Arteries - Common carotid artery , Internal carotid artery , External carotid artery & branches of External carotid artery 

{ Anterior branches - Superior thyroid artery , Lingual artery , Facial artery      

  Medial branch - Ascending pharyngeal artery 

  Posterior branch - Occipital artery }

2. Carotid sinus & Carotid body

3. Carotid sheath

4. Veins - Internal jugular vein , Common facial vein , Lingual vein

5. Nerves - Vagus nerve , Hypoglossal nerve , Spinal accessory nerve , Ansa cervicalis , Cervical part of sympathetic chain

6. Deep cervical lymph nodes

• Posterior triangles 

(Subdivided by inferior belly of Omohyoid into following 2 triangles)

A) Occipital triangle contents (above omohyoid) - 

1. Occipital artery 

2. Occipital lymph nodes

3. Lesser occipital nerve (C2)

4. Spinal accessory nerve

5. 3rd & 4th Cervical nerves providing branches to Levator scapulae & Trapezius muscle

6. Dorsal scapular nerve (C5)

7. Four Cutaneous branches of Cervical plexus (initial parts)

8. Uppermost part of Brachial plexus

9. Superficial transverse cervical artery

10. Supraclavicular nerves (C3 & C4)

11. Nerve to rhomboids

12. Great auricular nerve (C2 & C3)

B) Subclavian / Supraclavicular / Omoclavicular triangle contents (Below omohyoid) -

1. 3rd part of Subclavian artery 

2. Subclavian vein

3. Trunks of Brachial plexus

4. Terminal part of External jugular vein

5. Superficial ( Transverse ) Cervical artery

6. Suprascapular artery , Suprascapular vein , Suprascapular nerve , Suprascapular lymph node

7. Dorsal scapular artery

8. Nerve to serratus anterior / Long thoracic nerve

9. Nerve to subclavius 

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