The Pectoral limb comprised bones of the Shoulder (Scapula), Arm (Humerus), Fore arm (Ulna and Radius), and Manus (carpals, metacarpals and phalanges). They contained morphological features resembled and differed from other domestic animals studied. The total number of pectoral limb bones in this species was investigated to be 75 as represented in Table 1.
The Scapula (Fig. 1) presented a flat somewhat D-shaped bone. The caudal border was straight in outline while the cranial border was straight proximally, convex at its middle and concave distally. The dorsal border also assumed a convex outline. The lateral surface presented a prominent bony structure, the scapular spine which originated from the dorsal border and ended with the formation of acromion process that consisted of a downward hamate process and a caudal suprahamatus process. The scapular spine divided the lateral surface into two almost equal parts; the cranial supraspinous fossa and caudal infraspinous fossa. On the ventral angle (Fig. 1), the bone presented the neck, glenoid cavity, supraglenoid tubercle laterally and coracoid process medially. The medial surface of the bone presented a shallow thin fossa, the subscapular fossa at the centre and a tiny ridge close to the cranial border. A nutrient foramen was noticed at the ventral angle medially.
The Humerus (Fig. 2) presented a long bone with two extremities (proximal and distal) and a shaft or body. The proximal extremity presented a caudally placed large convex head with a well-defined neck, lesser tubercle cranio-medially and greater tubercle caudo-laterally. An intertuberal groove separated the greater tubercle from the lesser tubercle medially. The greater tubercle was made up of two parts (cranial and caudal). The body presented a convex cranial and concave caudal surface. Towards the middle of the cranial surface, was a crest-like deltoid tuberosity that continues up to the lesser tubercle on the lateral surface. On its medial surface and adjacent to the deltoid tuberosity was the less prominent teres tubercle. The musculospiral groove was almost non-existent. On its distal third, it presented a distinct supracondyloid crest (ending at the lateral epicondyle) and supracondyloid foramen above the medial condyle. The distal extremity presented cranially the medial and lateral condyles, lateral and medial epicondyles and Olecranon fossa caudally.
The Ulna and Radius (Fig. 3) were fused proximally and distally creating an extensive interosseus space and a rather twisting appearance. Both bones presented proximal and distal extremity attached to a long shaft. The proximal extremity of the ulna bone presented a small Olecranon ending in a beak shaped anconeal process cranially above the sigmoid notch which was formed entirely by the ulna while the capsular fossa of the radius attached laterally to it. Coronoid process projected lateral and medial from the notch. The radius presented proximally, radial articular facet (capsular fossa), radial tuberosity cranially, lateral and medial eminence for muscular attachment. Distally, the ulna and radius presented lateral and medial styloid processes respectively. The bodies of the bones appeared similar in size however the ulna had a larger proximal extremity while radius had a larger distal extremity.
The Carpus (Fig. 4) presented seven bones arranged in two rows. The proximal row was made up of fused radial and intermediate carpal, ulna carpal and accessory carpal bone. The distal row comprised of first carpal bone, second carpal bone, third carpal bone and fourth carpal bone. The proximal row articulated with distal end of radius and ulna in the antebrachiocarpal joint while the distal row articulated with the metacarpal to form carpometacarpal joint. The fused radial and intermediate carpal bone was the largest among the carpal bones and it articulated with the distal part of the radius. The first carpal bone appeared small and attached to the first metacarpal bone at its most proximal aspect. The second carpal bone was larger than the first carpal bone and it was attached to the intermediate carpal bone proximally and distally with the first metacarpal bone. Third carpal bone was located on the proximal part of the second metacarpal bone and articulated with some part of the intermediate carpal bone, fourth carpal bone articulated with third carpal bone at its lateral side and with intermediate at its most proximal part and lastly with the ulna carpal bone dorsomedially. Ulna carpal bone attached to the fourth carpal bone at its ventral surface, accessory carpal bone which was the smallest amongst the carpal bone articulated with the ulna carpal bone and ulna bone.
Five (5) Metacarpal (Fig. 4) bones were present that anchored 5 digits. The first metacarpal was the smallest while the third and fourth metacarpal were the longest. The first digit comprised two phalanges while the rest (second to fifth) digits comprised three phalanges each. The third Phalanx (Fig. 5) had a characteristic appearance of a capsized boat with a wide convex cranial extremity and a caudal tubercle. The dorsal border was convex cranially before presenting an articular depression for the second phalanx articulation. A flat crescent plate (covered by a comma shaped claw in the live animal) projected ventrally from the open ventral border. Two sesamoid bones were located on the ventral surface and one on the dorsal surface of each Metacarpophalangeal joint.
Table 1
Number of bones of the pectoral limb of the Lion (Panthera leo)
Bones | Number |
Scapula | 2 |
Humerus | 2 |
Ulna | 2 |
Radius | 2 |
Carpals | 14 |
Metacarpals | 10 |
First phalanx | 10 |
Second phalanx | 8 |
Third phalanx Sessamoid bones | 10 15 |
Total: | 75 |