64 DISSECTION OF THE NECK. 



2. The Hyoid Bone lies just anterior to the larynx. 

 Determine its shape by feeling through the muscles 

 covering it. The body is a short transverse bar of 

 bone, and from it two horns — posterior cornua — 

 may be felt passing posteriorly to the thyroid cartil- 

 age of the larynx. Two longer anterior horns pass 

 to the base of the skull to be attached to the temporal 

 bone. 



3. The Sterno-mastoid Muscles form a pair of broad 

 muscular bands arising from the anterior end of the 

 sternum, and passing obliquely forward, diverging 

 from each other, to be inserted into the mastoid por- 

 tion of the temporal bone. 



Cut these imtscles at the sternal insertion, and re- 

 flect them forward. 



4. The Sterno-hyoid Muscles, one on each side, lie 

 along the ventral mid-line of the neck. Separate the 

 two along the mid-line, and the trachea will be ex- 

 posed. Each is a flat band arising from the anterior 

 end of the sternum and the ist rib, and inserted into 

 the hyoid bone. 



Ciit the sterno-hyoids at the anterior end and reflect 

 backwards. 



5. Sterno-thyroid Muscles, one on each side of the 

 neck. Each is a slender band of muscle arising from 

 the anterior end of the sternum with the sterno-hyoids, 

 and passing obliquely forward to be inserted into the 

 side of the thyroid cartilage of the larynx. 



Ciit the stcrno-thyroids at the anterior end and re- 

 flect backwards ; the trachea will be. fully exposed. 



6. The Thyroid Glands are two oval bodies lying 

 one on each side of the trachea just posterior to the 

 larynx. Usually these are entirely separated from each 

 other (differing in this respect from the same struct- 



