GOUGH'S CAVE AXIAL SKELETON 

 Table 6 Dimensions (mm) of ribs 2-4. 



R2 



L2 



R3 



L3 



R4 



Neck length' 

 Proximal thickness (M- 

 Proximal height (M-l) 

 Shaft thickness 3 

 Shaft height 1 



11.2 

 7.3 



12.2 

 7.1 



(11.7) 4 (12.3) 4 



8.4 

 8.3 



(27.9)- 

 8.9 

 9.3 



7.7 



(7.1) 4 (7.3) 4 11.7 10.1 7.7 



'Distance from the middle of the head to the middle of the articular tubercle. 

 2 Head unfused, measurement taken from middle of epiphyseal surface for head. 

 'Rib thickness (internal-external diameter, measured in the plane of rib curvature) 

 and height (supero-inferior diameter, taken perpendicular to the plane of curvature of 

 the rib) at the point where the M. iliocostalis line meets the inferior edge of the rib. 

 4 Taken 1 cm distal of where proximal thickness and height were taken. 



RIB 3 



The right-side third rib is represented by a 154.7 mm-long fragment 

 from mid-neck to just proximal of the anterior angle. The left third 

 rib is preserved as a 171 .7 mm-long fragment from the distal end of 

 the posterior angle to just proximal of the sternal end. 



The M. iliocostalis line 1 in the right rib is not pronounced (a 

 feature of all of the Cheddar Man's ribs). A small portion of the M. 

 iliocostalis line is preserved proximally in the left-side rib, and it 

 looks to have been more strongly developed than in the right (how- 

 ever, the rib itself is somewhat slighter). The right rib shows a 

 discernable attachment for M. levator costae and both ribs have a 

 distinct sulcus on the superior edge of the rib in the vicinity of the 

 posterior angle (ca. 30 mm long) for the intercostal muscles. There is 

 no discernable subcostal groove on the right rib, and the left side 

 shows a weak subcostal groove for only a few centimeters distal of 

 the posterior angle. The left rib has a supero-inferior flare to the body 

 about 45 mm proximal of the anterior angle, reflecting perhaps a 

 healed fracture. The articular facet on the right side is dorsoinferiorly 

 directed and measures 9.5 mm (proximodistally) by 7.8 mm (supero- 

 inferiorly). 



Rib 4 



The right fourth rib is a 1 27.0 mm-long fragment preserved from the 

 head to somewhere proximal of midshaft. The proximal end of the 

 rib is intact. The left fourth rib is a 1 56.8 mm-long fragment of the rib 

 body, from somewhere distal of the posterior angle to the region of 

 the anterior angle. 



On the right side, the surface of the head is rough and irregular, 

 likely representing the subchondral surface of the unfused secondary 

 centre of ossification for the head. There is a small and superiorly 

 directed tubercle on the neck, and from this a crest runs distally along 

 the superior margin of the bone past the non-articular tubercle, most 

 likely representing the attachment of the superior costotransverse 

 ligament. The M. iliocostalis line is not pronounced. The articular 

 tubercle is large (9.0 mm proximodistally by 11.5 mm internal- 

 external) and is primarily inferiorly directed. The subcostal groove is 

 weakly developed on both ribs. In the right rib there is a strong bend 

 at the posterior angle (the angle between the head-neck axis and the 

 proximal costal body is approximately 90°). 



Rm5 



The right fifth rib is preserved as a 190 mm-long fragment, intact 

 from the head down to the anterior angle, and missing only a portion 

 of the sternal end. The left rib is represented by a 210 mm-long 



fragment, also intact from the head down to the anterior angle and 

 missing only a part of the sternal end. 



The secondary centres of ossification for the heads are only 

 partially fused (and portions are missing) on both sides. As in the 

 right fourth rib. the fifth ribs present small superiorly directed 

 tubercles on the neck that continue distally as crests running along 



Table 7 Dimensions (mm) of ribs 5-7. 



R5 



L5 



R6 



L6 



R7 



L7 



Rib length (M-4) - >200' 



External arc (M-3) - >323' - 



Neck length 2 (27.3) 3 (28.5)-' (23.9)' (25.3) 1 - (26.9) 5 



Proximal thickness (M-2) 9.2 8.3 8.0 8.6 - 8.9 



Proximal height (M-l) 8.6 8.7 10.0 12.0 - 9.3 



Shaft thickness 4 9.3 9.6 8.6 8.7 9.7 9.3 



Shaft height 4 13.0 14.5 14.4 13.6 13.5 



Chord 5 - (213)' 



Subtense 6 (77)' 



Transverse width 7 8.2 



'Rib is missing a small portion of the sternal end. 



^Distance from the middle of the head to the middle of the articular tubercle. 



'Head unfused, measurement taken from middle of epiphyseal surface for head. 



J Rib thickness (internal-external diameter, measured in the plane of rib curvature) 



and height (supero-inferior diameter, taken perpendicular to the plane of curvature of 



the rib) at the point where the M. iliocostalis line meets the inferior edge of the rib. 



'Distance from the distal margin of the articular tubercle to the proximal extent of 



the sternal end, following McCown and Keith (1939: fig. 75). 



''Maximum perpendicular distance from the chord to the external surface of the rib. 



following McCown and Keith (1939; fig. 75). 



'Internal-external diameter of the rib body at the intersection of the subtense. 



the superior margins of the bones past the non-articular tubercles. 

 These crests, most likely marking the sites of attachment of the 

 superior costotransverse ligaments, are more strongly developed 

 than that on the fourth rib. Both ribs also have a crest on the inferior 

 edge of the neck running from the head to the proximoinferior edge 

 of the articular facet. These crests may represent the attachments of 

 expanded accessory ligaments from the heads and necks of the 

 subjacent ribs (Williams & Warwick, 1980) or distal extensions of 

 the radiate ligaments binding the heads to the adjacent vertebra. The 

 nonarticular tubercles are bulbous and projecting, and the articular 

 tubercles are inferodorsally directed (measuring 7.9 mm PD by 10.3 

 mm SI on the right, and 7.2 mm PD by 10.5 mm SI on the left). The 

 M. iliocostalis lines are not very well developed and it is hard to make 

 out where the lines cross the inferior border of the rib. The subcostal 

 grooves are neither deep nor strongly developed but are clearly 

 visible along most of the body. The angle between the head/neck axis 

 and the axis of the body is about 1 17° on both sides. 



Rib 6 



The right sixth rib is preserved as a 165.3 mm-long fragment, 

 complete from the head to somewhere distal of midshaft. The left- 

 side rib is a 1 85. 1 mm-long fragment, complete from the head to the 

 area of the anterior angle. 



The centres of ossification of the heads are incompletely fused and 

 portions of them are missing. The ribs of both sides have short necks 

 with small tubercles on their superior surfaces for the superior 

 costotransverse ligaments. The ribs lack the crests (distal of the 

 tubercles) that are seen on the suprajacent ribs. The inferior edges of 



'The iliocostal muscles are the lateral-most extensions of the erector spinae {sacrospinal!: ) muscle. The M. iliocostalis lumborum inserts on the inferior borders of the lower six or 

 seven ribs, at the posterior angle (Williams & Warwick, 1980). M. iliocostalis thoracis arises from the superior borders of the angles of the lower six ribs and inserts on the superior 

 margins of the upper six ribs. M. iliocostalis cervicis attaches to the superior borders of the third to sixth ribs. Thus various combinations of these muscles, as well as the thoracolumbar 

 fascia, contribute to the formation of the iliocostalis lines on the external surface of the posterior angle of the ribs, and will be referred to throughout this description as the iliocostalis 

 muscle. 



