ANT 350 Lecture Notes - Lecture 5: Shoulder Girdle, Knuckle-Walking, Brachiation
Document Summary
Coccyx no caudal vertebrae (tail) on all hominoids. Pectoral girdle form broad thorax, posterior, and lateral placement of the scapula on all hominoids. But bones are shaped differently to position the muscles differently. Apes: brachiators, modified quadrupeds: brachiation: suspensory locomotion propelled by the arms through the trees. Humans: obligate bipeds: humans still retain brachiation abilities and apes can walk bipedally. The difference is a question of adaptive focus. Limb proportions: apes: long arms (pectoral limbs) for brachiation and long, powerful hands for powerful flexion. Modified quadrupedalism: knuckle walking: humans: long legs (pelvic limbs) for bipedal locomotion. Vertebral column: apes: single arch from pelvis to shoulder (suspension bridge, humans: balance/weight support problems. Vertebral lordosis (wedging in intervertebral disks and vertebral bodies, especially lumbar. Lumbar lordosis begins with orientation of the sacroiliac articular surface (os coxae sacrum) Lumbar vertebrae 5 in humans but 4 in apes. Sacrum 5 lumbar verts in humans and 6 in apes.
