Hyoid bone

forensic medicine

1. Dr Nikita Prabhakaran Junior resident Dept of Forensic Medicine GMC, Trivandrum

2. Name Shape: “U” shaped Letter ‘upsilon’ in Greek ~ hyoideus

3. History chipmunks Neanderthals Adult man

4. Anatomy Horizontally Superior to the larynx At the level of C 3

5. Independent Interface floor of the oral cavity larynx pharynx

6. Parts Horizontal  body Lesser horns Greater horns

7. Surface marking 3 cm below angle of mandible 1.5 cm outer to midline Connecting a line 3 cm 1.5 cm

8. Joints Fibrous joint Sometimes with synovium Gets calcified only > 40 yrs Often confused with fractures

9. Development 2 nd pharyngeal arch ~ 7th 3 rd pharyngeal arch ~9th

10. Ossification centres 2 centres for the body 4 centres for each cornua Greater cornua  complete ossfn (20-30 yrs ) Fuses completely with the body at 40-60 yrs 10 m IU 20-30 yrs 16 yrs Just after birth

11. Calcification Young age – cartilagenous joints mobile >30 yrs - ends of the horns calcify becomes more brittle hence < 30yrs - less chance for # ↓ common in females – calcifies only at old age

12. Muscle attachments Body upper border anterior surface posterior border Greater horn medial surface lateral surface Lesser horn

13. Upper border of the body

14. Anterior surface-body Geniohyoid Mylohyoid hyoglossus

15. Lower border of the body

16. Greater Cornua : Medial border Digastric pulley Middle constrictor Lateral border Thyrohyoid Lesser Cornua : stylohyoid

17. Ligaments attached Stylohyoid ligament  Lesser horn Thyrohoid memberane Hyoepiglottic ligament Medial surface of greater horn

18. Hyoid fractures According to Displacement of fractured ends Inward / lateral compression # Outward (AP) compression # One side inward & other side outward Mechanism of fracture Direct pressure: outward inward Avulsion

19. Inward /lateral compression fractures Force- inward Eg : throttling Fingers of the grasping hands  squeeze the greater horns posterior fragment – displaced inwards U/l or B/L Periosteum~ torn  outer side Fragment can be seen lying medially

20. Outward /Anteroposterior compression # Force – inward Eg : hanging /ligature strangulation Hyoid forced backwards Fixed on to the vertebrae ↑ divergence of the greater horns Periosteum – torn on inner side DD: RTA runover ( multiple #) blows on the front ~ other signs

21. One side inward and other side outward During violent neck violence Backwards and sideways One end gets caught up between the paravertebral structures So that end- inward # Other –outward #

22. According to the mechanism of fracture Direct pressure ~ outward inward Avulsion ~ muscular stretch or overactivity  usually in hanging hyoid is drawn up and held rigid sudden suspn ~ downward displacement of TC traction through TH lig usually outward

23. Demonstration of the fracture Palpatory method ~ body held stable in one hand distal fragment between index and thumb assess its mobility antemortem ~ infiltration Advanced putrefaction  hard to determine the type periosteum is completely destroyed

24. Tests 1% tolidene blue Leave for 15 sec Clean with water Under stereomicroscope: # end stains blue

25. Semi-microradiography Method to visualise Soft tissue structures of neck To diagnose microtrauma Focal spot 1*1 mm 125 cm special photoelectronic printers

26. X ray and CT ~ best &most certain not feasible

27. Medicolegal importance Hanging Strangulation Throttling Blow to the neck RTA ~ runover injuries Identification~ skeletal remians

28. Case study 35 year old man h/o strangulation * 12 days back Persistent neck pain Tenderness+++ USG and X-ray  WNL

29. Flexible nasal endoscopy: right vocal cord hematoma CT was advised ???

30. Thank you

31. References: Krogman , W. M. and Iscan , M. Y. Human Skeleton in Forensic Medicine. 2nd Edition, Charles C. Thomas, Springfield, 1986. Langmanns textbook of osteology Poddar’s handbook of osteology, 13 th edition Grays anatomy for students 3 rd edition Gradwohl’s legal medicine Guharaj’s forensic medicine Anil Aggarwal’s textbook of forensic medicine B Umadathen’s textbook of forensic medicine Essentials of forensic medicine by KS Narayana Reddy