forensic medicine

1. Hyoid bone
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

7. •Independent
•Interface
floor of the oral cavity
larynx
pharynx

8. Parts
• Horizontal body
• Lesser horns
• Greater horns

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

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

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

13. 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

14. 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

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

16. Upper border of the body

17. • Anterior surface-body
• Geniohyoid
• Mylohyoid
• hyoglossus

18. Lower border of the body

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

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

21. 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

22. 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

25. 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

26. 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 #

27. 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

28. 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

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

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

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

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

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

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

37. Thank you

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