DISSECTION OF THE HEAD AND NECK. 159 



cesses and neural arches, and (2) those connecting the adjacent vertebral 

 bodies. 



Ligaments of the Processes and Neural Arches : 



The Ligamentum Nuclue.—This. has already been dissected. 

 ^ The Inter spinmts Ligaments.—These are composed of yellow elastic 

 tissue. Each consists of two narrow parallel bands stretching between 

 adjacent superior spinous processes. 



Capsular Ligaments of the articular processes. 



Ligamenta suhflava. — For these two series of ligaments, see page 135, 

 where the corresponding ligaments of the back and loins are described. 

 In the neck these ligaments differ from those of the other regions in 

 being composed of yellow elastic tissue. 



Ligaments of the Bodies : — 



The Svperior Common Ligament lies on the floor of the spinal canal, 

 and terminates in front at the axis. See page 135. 



The Intervertebral Substance. — See page 136. 



Movements of the cervical part of the spinal column. These are 

 flexion, extension, lateral inclination, rotation, and circuTndnction, the last 

 being a combination of the first three. In flexion the vertebrae are 

 carried downwards in a vertical plane, and extension is the opposite 

 movement. Rotation is the twisting, or turning, of a vertebra round a 

 longitudinal axis passing through its body. In consequence of the 

 thickness of the intervertebral substance, and the feeble development of 

 the transverse and spinous processes, all these movements have here a 

 greater range than in the back or loins ; and within the cervical region 

 the greatest range of movement is permitted in the posterior joints. 



the external ear (fig. 19). 



The organ of hearing consists of three divisions : the external, the 

 middle, and the internal ear. Only the first of these will now be 

 examined. The middle and the internal ear, which are cavities within 

 the petrous temporal bone, are described at page 267. The external ear 

 comprises the external auditory process of the petrous temporal bone ; 

 three cartilages — conchal, scutiform, and annular ; muscles which move 

 these cartilages ; vessels ; and nerves. 



Directions. — An incision through the skin is to be begun a few inches 

 behind the summit of the occipital bone, and carried down the middle 

 line as far as the supraorbital process. It is here to be carried outwards 

 along the supraorbital process, and then backwards along the zygomatic 

 arch. On reaching the articulation of the jaw, the incision should be 

 ' carried along the edge of the vertical ramus, and inwards to the middle 

 line. All the skin mapped out by this incision is to be removed, the 

 conchal cartilage being also denuded of its outer covering. This will 

 expose not only the parts of the external ear, but also the parotideal 



