1. ANTERIOR TRIANGLE OF THE NECK II
Dr. Ahmed Fathalla Ibrahim

2. CAROTID TRIANGLE BOUNDARIES: FLOOR:
Superiorly: posterior belly of digastric
Inferiorly: superior belly of omohyoid
Posteriorly: sternomastoid
FLOOR:
Anteriorly: hyoglossus & thyrohoid muscles
Posteriorly: middle & inferior constrictors of pharynx C

3. CAROTID TRIANGLE

4. CAROTID TRIANGLE

5. CAROTID TRIANGLE

6. CONTENTS OF CAROTID TRIANGLE
CAROTID SHEATH:
A condensation of deep fascia that contains:
Common & internal carotid arteries: (medially)
Internal jugular vein: (laterally)
Vagus nerve: between & a little posterior to arteries & vein

7. CONTENTS OF CAROTID TRIANGLE
ARTERIES:
Termination of common carotid: at level of disc between C3 & C4 (level of upper border of thyroid cartilage)
Proximal part of external carotid
Proximal part of internal carotid
Five branches of external carotid: superior thyroid, ascending pharyngeal, lingual, facial & occipital

8. CONTENTS OF CAROTID TRIANGLE
VEINS:
Internal jugular vein
Five tributaries to internal jugular veins: common facial, lingual, superior thyroid, middle thyroid, pharyngeal veins

9. CONTENTS OF CAROTID TRIANGLE
FIVE NERVES:
TWO NERVES RELATED TO CAROTID SHEATH:
Ansa cervicalis (anterior rami of C1,2,3): embedded in the anterior wall of sheath
Sympathetic trunk: embedded in the posterior wall of sheath

10. CONTENTS OF CAROTID TRIANGLE
THREE NERVES BETWEEN INTERNAL JUGULAR VEIN & INTERNAL CAROTID ARTERY:
Vagus (10th cranial) nerve: descends between internal jugular vein & common carotid artery
Spinal part of accessory (11th cranial) nerve: crosses internal jugular vein, passes deep to sternomastoid to reach posterior triangle
Hypoglossal (12th cranial) nerve: crosses internal & external carotid arteries, passes deep to posterior belly of digastric to reach digastric triangle

11. CONTENTS OF CAROTID TRIANGLE
DEEP CERVICAL LYMPH NODES: embedded in the anterior wall of sheath, along the internal jugular vein

12. MUSCULAR TRIANGLE BOUNDARIES: Anteriorly: midline of neck
Superiorly: superior belly of omohyoid
Inferiorly: sternomastoid M

13. MUSCULAR TRIANGLE CONTENTS: THE INFRAHYOID MUSCLES Superficial layer:
Sternohyoid: medially
Omohyoid: laterally
Deep layer:
Thyrohyoid: above
Sternothyroid: below

14. MUSCULAR TRIANGLE

15. MUSCULAR TRIANGLE

16. MUSCULAR TRIANGLE FLOOR: PRETRACHEAL FASCIA
STRUCTURES IN THE INFRAHYOID PART OF MEDIAN REGION OF FRONT OF NECK:
Thyrohyoid membrane
Thyroid cartilage
Cricothyroid ligament & muscle
Cricoid cartilage
Cricotracheal ligament
Trachea
Structures in front of trachea: jugular arch, inferior thyroid vein, isthmus of thyroid gland

17. INFRAHYOID MUSCLES (SUPERFICIAL LAYER)
Sternohyoid:
Origin: back of manubrium sterni
Insertion: hyoid bone
Action: depression of hyoid bone
Omohyoid:
Superior belly: hyoid bone
Inferior belly: upper border of scapula
Insertion: intermediate tendon (deep to sternomastoid) attached to clavicle

18. INFRAHYOID MUSCLES (DEEP LAYER)
Thyrohyoid:
Origin: oblique line of thryroid cartilage
Insertion: hyoid bone
Action: depression of hyoid bone, elevation of larynx
Sternothyroid:
Origin: back of manubrium sterni
Insertion: oblique line of thryroid cartilage
Action: depression of larynx

19. INFRAHYOID MUSCLES NERVE SUPPLY:
All muscles are supplied by ansa cervicalis (anterior rami of C1,2,3) EXCEPT: thyrohyoid (by anterior ramus of C1)