The musculoskeletal anatomy of the reindeer (Rangifer tarandus): fore- and hindlimb

Abstract

Reindeer are numerous and widespread across the northern Holarctic. They are eYcient long distance migrants and are able to cope with variations in substrate, such as ice, snow, uneven forest Xoor, wetland and Xat grassland. However, as with the vast majority of quadrupe- dal vertebrates, no quantitative musculoskeletal anatomical information exists for these animals making it diYcult to analyse the biomechanics of their locomotor behaviour. In this paper, we describe the gross anatomy of the limb mus- culature and quantify muscle and tendon morphology. Reindeer show slight hindlimb dominance in muscle and tendon mass, with muscle mass primarily proximally situ- ated and tendon distally situated. Extensor muscles are heavier than Xexors, but tendon mass is broadly similar in both extensors and Xexors. The only complete quadrupedal data sets available for comparison are for hares and grey- hounds making it diYcult to identify general patterns. There are no obvious body mass eVects and reindeer often comes out as intermediate between hare and greyhound. However, greyhound seem less hindlimb dominated in terms of muscle but both greyhound and hare have much higher masses of tendon compared to reindeer, particularly in their hindlimbs. All these quadrupeds show the com- monly observed trait of much larger tendons and less mas- sive muscles in distal limb segments; this reduces the inertial cost of accelerating the limbs. Generally, there is a dearth of available quantitative anatomical data of complete animals. This lack of information is hindering attempts to gain a better understanding of musculoskeletal function in quadrupeds.