DETAILED ANATOMY NOTES - Editorial Comment

• Elephants show a number of adaptations for their large size. 
• Elephants have a large brain with a highly convoluted temporal lobe which may be important for storage of social information and information about good feeding areas, dangerous places etc. The olfactory lobe is also large.
• The respiratory system is notable for the lack of a pleural space between the lungs and the body wall; the lungs are attached to the chest wall and diaphragm by extensive connective tissue; this suggests that diaphragmatic rather than costal movements are important for respiration. The diaphragm extends as far cranially as the second or third rib.
• The vomeronasal organ is well developed and connects only to the oral cavity, not to the nasal cavity.
• The heart has a double apex and paired anterior vena cavae. The ductus arteriosus connects between the left pulmonary artery and the aortic arch, as in humans, rather than from the pulmonary trunk to the aortic arch as in other mammals.
• The digestive system is broadly similar to that of the horse, with a simple, relatively small stomach but a large colon and a very large caecum. There is no gall bladder.
• The kidneys are retroperitoneal and multi-lobed. The bladder has a capacity of six to 18 litres. In females, the urethra and the vagina both open into the long urogenital canal which opens at the vulva between the hind legs. In males, the urethra extends to the end of the penis. There is no os penis. There is no scrotum, the testes remaining intra-abdominal. There are three types of accessory glands: seminal vesicles, prostate and bulbourethral glands. The uterine horns are joined externally for much of their length but remain separate internally until close to the vagina. The placenta is zonary and non-deciduate. Placental scars remain permanently visible in the uterus. The clitoris is well developed and has a large, erectile corpus cavernosum.
• The skeleton is well adapted for the size of the animal. The cervical vertebrae are short. The massive limb bones have thick, dense cortices (walls) and are filled with reticulated cancellous bone, lacking marrow cavities. The appendicular skeleton forms solid columns, with the glenoid fossa in the scapula and the acetabulum in the pelvis facing downwards, long femur and humerus, both radius and ulna fully present in the forelimb and fibula as well as tibia in the hind limb.

Further information is available within this section on the structure of the brain, respiratory system, vomeronasal organ, cardiovascular system, gastro-intestinal system, liver, spleen, urogenital system (including details of the reproductive systems of adult males and females), skeleton, skin and endocrine glands. 

(References are available in detailed literature reports below)

[See also Book Ref. 212 - Elephants and their Diseases - Part II Chapters I - VIII FULL TEXT INCLUDED]

Detailed Anatomy Notes

In General:

Elephants show a number of adaptations related to their large size. 

Brain:

• Elephants have a large brain, weighing in females 3.6 to 4.3 kg (8.0 - 9.5 lb) and in males 4.2 to 5.4 kg (9.3 - 12.0 lb). (B285.w3)
• The temporal lobe is highly convoluted; this may be related to storage of information regarding identities and behaviour of other elephants as well as good feeding areas, droughts, dangerous places etc. (B285.w3)
• The brain is large, up to 6.5 litres in volume, and weighing up to 6.0 kg (for a large African bull). (B384.4.w4)
• The cerebral cortex is large, as is the neopallium (responsible for memory). (B384.4.w4)
• The brain is situated at back of the skull. It is quite large and grows considerably after birth, the calf's brain being only 35% of the size of the adult's brain. The cerebrum is highly convoluted, although not large enough to cover the cerebellum. The temporal lobe increases in size most during development. (B451.1.w1)
• The brain is oval and weighs about 15 - 17 lb. It has large olfactory lobes, while the olfactory nerve and nerve to the ocular musculature are relatively small; the sensory and motor nerves to the trunk (proboscis) are very large. (B212.w5)
• Elephants have a large brain, averaging 4,783 g in the adult (range 4,000 - 6,075 g, excluding three reported as 6,500, 7,455 and 9,000 g) and 50% of this in the newborn calf. The cerebellum is very large, averaging 18.6% of the total brain weight, and is visible dorsally. There are well developed cerebral frontal, parietal, temporal, limbic and insular lobes; the occipital lobe is relatively small. The olfactory bulb is large and the olfactory tract foreshortened in comparison to this. Despite the complex sulcal pattern, the sulci are shallow and there are relatively few "buried gyri". The cortical thickness is fairly uniform, minimum 2.3 mm, maximum 4.1 mm. The cranial nerves follow a similar pattern to that in man; the greatest difference is the nerves to the proboscis; the maxillary division of the trigeminal (V) sensory nerve and the facial (VII) motor nerve come together anterior to the eye , forming the great proboscideal nerve. The pituitary gland is large, pear shaped, with a narrow infundibular proximal part, hollowed inside by the recess of the third ventricle. In one Asian elephant it measured 32 mm long, 2.2mm at its widest and weighed 6.16 g. The pineal gland is indistinct, and weighed 0.08 g in one elephant; in another it could not be identified. The dura mater is 10 mm thick (compared with 3 mm in humans) with four folds: the falx cerebri between the cerebral hemispheres, tentorium cerebelli between the cerebellum and cerebrum, falx cerebelli between the lateral lobes of the cerebellum and the diaphragma sellae "covering the roof of the sella turnica with the pituitary body inside, leaving a small opening for the pituitary stalk". The arachnoid membrane, subarachnoid space and pia mater are unremarkable, similar to those of humans. Two pairs of arteries supply the brain: the internal carotid and the vertebral arteries; the joining of these arteries and their branches forms the arterial circle at the base of the brain. The superior sagittal sinus, inferior sagittal sinus and straight sinus, collecting blood from the cerebral veins and returning it to the internal jugular, are identifiable. (J397.70.w1)

Respiratory system:

• There is no pleural space; the lungs are attached to the chest wall by fibrous connective tissue. (B10.49.w21, B384.3.w3)
• The lungs are bilobed. (B384.3.w3)
• Elephants breath by diaphragmatic movement rather than movement of the ribcage. (B384.3.w3)
• The lungs are directly adherent to the chest wall, with no pleural cavity. (B451.1.w1)
• The internal nares are high on the forehead. (B451.1.w1)
• There is no pleural space, the lungs being attached to the chest wall and diaphragm. (B212.w7). 
• The lungs weigh about 46 pounds. (B212.w7)
• The cartilaginous rings of the trachea are incomplete. (B212.w7)
• The left lung has one lobe while the right lung has two or three lobes. (B450.15.w15)
• The lungs are connected to the thoracic wall by extensive fibrous tissue. This suggests that diaphragmatic rather than costal movements are important for respiration. The diaphragm extends as far cranially as the second or third rib. (B450.15.w15)
• The lungs are directly connected to the thoracic wall. Using ultrasonograpic examination, the connective tissue layer is about 2 cm thick, with a 2-3 mm thick fluid layer between the parietal and visceral layers. (P501.2001.w7)

Vomeronasal organ

• The vomeronasal organ (VNO) is found on either side of the anterior base of the nasal septum and is encased by an incomplete cartilaginous ring. It connects via a duct to the roof of the mouth; the openings to the ducts are visible on the roof of the mouth. The lumen is horseshoe-shaped with a concave sensory mucosa (including receptor neurons) which is thicker than the convex non-sensory mucosa; both are classified as pseudostratified columnar epithelium. The caudal end of the vomeronasal organ connects to a large vomeronasal nerve projecting towards the brain. (J394.267.w1)

Cardiovascular system:

• The heart of Elephas has a double apex. (B147)
• Superficial veins are observable only on the ear (both interior and exterior surfaces), the anterior surface of the proximal forelimb and the medial aspect of the distal part of the hindlimb. (B10.49.w21)
• In "all sheltered areas of the body, including superficial and deep temporal, pharyngeal, pectoral, anterior and internal femoral, popliteal, axillary and brachial regions" there are large venous plexuses and free anastomoses. (B10.49.w21)
• The heart is about 5% of the elephant's body weight. (B384.4.w4)
• There are paired anterior vena cavae. (B384.4.w4)
• The extremity of the heart is bilobed. (B384.4.w4)
• Peculiarities of the elephant's heart include a bifurcated apex, and two anterior cavae as well as a single posterior vena cava entering the right auricle. (B212.w8)
• The heart weighs about 24 pounds (based on three hearts). (B212.w8) 
• The heart is about 0.5% of total body weight. The ventricles are slightly separated at the apex. There are paired vena cavae. (B451.1.w1)
• The heart has a bifurcated apex and paired anterior vena cavae. (B450.14.w14)
• The ductus arteriosus connects between the left pulmonary artery and the aortic arch, as in humans, rather than from the pulmonary trunk to the aortic arch as in other mammals. (B450.14.w14)
• There is variable anatomy of the vessels at the origin of the brachiocephalic trunk from the aortic arch as indicated by different dissections: there may be two branches from the aorta, a left subclavian and the brachiocephalic, this then dividing to give the right subclavian and the two carotid arteries, or three branches from the aorta, consisting of right and left subclavian arteries and a common trunk dividing to give the two carotid arteries. (B450.14.w14)
• The posterior vena cava has a ventral wall much thicker than its dorsal wall; this may provide protection against collapse due to suddenly high intra-abdominal pressure (extra support is not required for the dorsal wall which is protected by the vertebral column). (B450.14.w14) 

Gastro-intestinal system:

• The tongue is short. (B384.3.w3)
• A narrow, sphincter-like slit connects the mouth to the throat. (B384.3.w3)
• There is a distensible pharyngeal pouch separated from the oesophagus by a sphincter, lying superior to the larynx; the elephant uses this to control the flow of food/fluid into the oesophagus. (B10.49.w21)
• The stomach is simple. The digestive system is generally similar to that of horses. (B10.49.w21)
• Necropsy measurements have shown that the small intestines are about 2.1 m long, the large intestine 12.8 m long and the caecum 0.6 to 1.5 m long. (B10.49.w21)
• Elephants lack a gall bladder, (B10.49.w21, B384.3.w3) but the bile duct is large and sacculated. (B10.49.w21)
• The mouth is relatively small and does not open very wide. It has well developed salivary glands. (B451.1.w1)
• The oesophagus is short and has plentiful mucus-secreting glands. (B451.1.w1)
• The simple stomach is cylindrical in shape and nearly vertical in orientation. It is mainly a storage organ, although there is a central glandular region. (B451.1.w1)
• The intestines may be up to 19 m long. A large, sacculated caecum is present at the junction between the small and large intestines. The walls of the caecum are highly vascularised and relatively thin. (B451.1.w1)
• Over the anus is a distinctive skin fold, the anal flap. (B451.1.w1)
• The mouth is relatively small and mainly filled by the tongue. The lower lip is small and pointed while the upper lip, together with the nostrils [nose], forms the trunk. (B212.w9)
• The oesophagus is relatively narrow in diameter. (B212.w9)
• The stomach is a simple sac, situated towards the left side of the abdomen, and with the spleen attached. The cardiac end is long and tapering, with the oesophagus entering about half way down along the stomach. There are a number of transverse folds of the stomach. (B212.w9)
• The small intestine measured in four elephants was 66, 70, 73 and 74 feet long. (B212.w9)
• The capacious large intestine includes the very large caecum, the long colon and the shorter rectum terminating at the anus. Total length measured in four elephants was 38, 40, 46 and 43 feet. (B212.w9)
• The intestines are attached to the spine by the strong mesentry through which the vessels run. (B212.w9)
• The pancreas is found near the base of the spleen. (B212.w9)
• Elephants have a simple stomach; the cardiac portion mucosa has expansible folds; there is a thick cardiac sphincter. The posterior third has smooth mucosa. The empty weight of a female Asian elephant was found to be 17.35 kg and its capacity was reported as 76.6 litres. (B450.13.w13)
• There may normally be sand and small pebbles within the gastro-intestinal tract. (B450.13.w13)
• The liver may be bilobed or trilobed; weights of 25.2 kg and 23 - 26 kg have been reported. (B450.13.w13)
• A small intestine length of 15.6 m and a large intestine length of 11.77 m were reported in one dissection. (B450.13.w13)

Liver

• The liver has a large number of small ducts uniting into a large duct taking bile to the intestines at the duodenum; the pancreatic duct enters at the same place; there is no gall bladder. There is a larger right lobe and a smaller left lobe. The liver is found approximately between the diaphragm and the stomach, to the right of midline. The liver may weigh 50 to 58 pounds. (B212.w9)

Spleen

• The spleen weighs about 7 pounds. Long and flat, it is broadest in the centre and found to the left of the stomach. (B212.w9)

Urogenital system:

• Elephants have lobulated kidneys, with five to seven lobes per kidney. (B10.49.w21)
• The kidneys of an adult female Asian elephant were described as follows. The left kidney was more elongated than the right kidney, 31 cm long, 21 cm medio-lateral and weighed 2.95 kg; the right kidney was 34 cm long, 22 cm medio-lateral and weighed 3.25 kg. Externally six renal lobes were visible through the fibrous capsule: cranial, central and caudal lobes in the dorsal and ventral parts of the kidney. Internally, the central and caudal lobes of both the dorsal and ventral kidney were fused. The medulla was dark red while the cortex was grey-red. The cortex was separated by numerous medullary rays into many lobules. The renal sinus and ureters ran cranio-caudally and connected directly with the renal calix; there was no obviously identifiable renal pelvis collecting the branches from the renal calix. Histologically, proximal and distal convoluted tubules were seen, the later smaller than the former. In each glomerulus, many mesangial cells and some podocytes were visible. Many renal corpuscles consisted of Bowman's capsule and the glomerulus; the Bowman's capsules measured 150 -200 mm diameter, larger than in other mammals. (J392.31.w1) 
• In females, the urethra enters the long urogenital canal just posterior to where the vagina joins the urogenital canal. (B10.49.w21)
• The vagina and the urethra open into a long urogenital canal, which opens at the vulva between the hind legs. (B451.1.w1)
• The kidneys, found ventral to the lumbar vertebrae, one on either side of the spine, are lobulated, with five or six distinct lobes in each kidney. They weigh about 6.0 - 8.0 lb. (B212.w10)
• The ureters enter the bladder only about two or three inches from one another. (B212.w10)
• The bladder is relatively small (volume about 4 - 6 L) and pear shaped. There are three layers of smooth muscle. the bladder is well fixed by ligaments. The urethra is about 8 - 11 cm long and 3 - 4 cm diameter. The caudal parts of the ureters about 4 - 6 mm thick, are integrated into the bladder wall. (J54.19.w1)
• The urethra in males reaches from the bladder neck to the end of the penis while in females it is short, entering the urogenital canal. (B212.w10)

Reproductive Male:

• The testes are retained within the abdominal cavity, near the kidneys. (B147, B10.49.w21, J359.7.w3)
• The penis is generally similar in structure to that of horses; "additional tendon and muscle structures aid in voluntary "searching" motions during mating." (B10.49.w21)
• Elephants possess seminal vesicles, prostate and bulbourethral glands. (B10.49.w21) 
• The testes remain intra-abdominal, suspended in a fold of peritoneum and connective tissue from the lumbar region of the dorsal body wall. There is no obvious epididymis. Spermatozoa are stored in the Wolffian duct. This contains a mass of coiled tubules, about 1.0 m long and has a diameter initially of 1 mm, increasing to 5.0 mm centrally and more than 1.0 cm distally. It opens into the duct of the seminal vesicle, forming a common ejaculatory duct. (B451.1.w1)
• The penis does not contain a baculum. Erection involves dilation of blood vessels in erectile tissue, with muscular contraction then giving an S-shaped flexure for penetration of the female's vulva. The end of the penis, and the prepuce enclosing it, are unpigmented. The urethral opening on the tip is Y-shaped. Most of the time the penis is within a dermal sac on the perineal region. (B451.1.w1)
• The testes are found suspended in the abdomen, below the posterior ends of the kidneys. On section their substance is a light brownish colour. (B212.w11)
• The opening of the urethra at the tip of the penis is Y-shaped. (B212.w11)
• During musth, the testes increase in size. (J359.7.w3)
• The testes are internal, close to the kidneys, nearly round, and can reach 15-23 cm diameter; in the immature elephant it may be 2 cm (in a newborn) to about 9 cm diameter. Elephants have paired bulbourethral glands, caudal to the root of the penis and about 2 cm under the surface of the skin; these are "fist-sized"; by ultrasound they appear mainly solid, with an irregular-shaped central cavity. The root of the penis is about 20 cm diameter and heavily vascularised. The colliculus seminalis is an integral part of the dorsal wall of the urethra, about 1 cm caudal to the urinary bladder, about 1.5 cm long, 8 mm diameter, and contains the joint ducts of the ampullae and paired seminal vesicles as well as at least three individual ducts on each side from the lobes of the prostate. The prostate gland, about 2 cm in size (each side) is paired, each half consists of three lobes and it is found above the pelvic urethra and caudal to the ampullae, which are cone-shaped, with a maximum diameter of 5 cm. The ampullae are located above the urinary bladder, at the cranial part of the urethra, at the ends of the ductus deferens, collecting sperm directly from the testes (no well-developed epididymes). The seminal vesicles may contain up to 400 ml fluid each and the central cavity of each gland is surrounded by a wall 5-10 mm thick with an internal mucosal layer and an external muscular layer. The ductus deferentes complex, strongly coiled, was up to 2 cm in its widest diameter and about 1 m in length. (J54.19.w6)
• The intra-abdominal testes may weigh 2 kg each in a breeding bull. During musth, the volume of the testes may be four times the size outside musth. The prostate of Asian elephants has a maximum diameter of 2 cm and the three lobes on each side are fused to form a solid, globe-shaped structure. (J23.40.w1)

Reproductive Female:

• A urogenital canal, 40 to 100 cm long in an adult cow elephant, separates the vagina from the vulva. (B10.49.w21)
  • The long urogenital canal forms a common passage for the urinary and genital tracts of the female elephant. (B396.3.w3)
• The urogenital canal (vestibule) is very long (1.0 - 1.4 m) in elephants. This tube-like structure runs vertically upwards from between the hind legs toward the tail before curving forward horizontally to form a 20-40 cm sac above the bony pelvis; the urethra and vagina open into this sac. The glans clitoris, close to the external opening of the urogenital canal, measures about 7-12 cm. The vagina, about 30 by 15 by 10 cm, has many longitudinal folds. Semen is deposited here during mating, and during pregnancy it fills with thick mucus. In nulliparous females there is a hymen-like structure; this is not ruptured by mating. The vaginal os is about 0.4 by 0.2 cm and is flanked by two blind pouches which are relicts of the Wolffian ducts. By one year postpartum, the vaginal os measures about 1.0  by 1.0 cm and the blind pouches are no longer detectable. (J54.19.w1)
• The urogenital canal or vestibule of elephants is about 1.3 m long. In nulliparous females there is a hymenal membrane with an opening (os) of only 4 mm x 2mm, on either side of which is a blind pouch of a similar diameter and 60 +/- 28 mm long. (J23.40.w1)
• During the first half of pregnancy there are many corpora lutea, seven on average (range two to 26 on one ovary). (B384.5.w5)
• The placenta of elephants is zonary and leaves a thin horizontal scar which may be detectable in the uterus for 30 years. (B384.5.w5)
• The corpora lutea remain rather than regressing following pregnancy. They do not secrete progesterone. (B451.1.w1)
• The clitoris is well developed and has a large, erectile corpus cavernosum. (B451.1.w1)
• The well-developed vulva normally faces anteriorly but due to erection of the clitoris, during copulation it is turned ventrally and posteriorly. (B451.1.w1)
• The vulva is found not close to the anus but in a similar position to that of the penis in the male. Inside the vulval lips is found the large fleshy clitoris, about 12 - 16 inches long. (B212.w11)
• The ovaries are small and surrounded by a firm fibrous capsule. (B212.w11)
• Most of the uterus is divided into two horns. (B212.w11)
• The elephant's placenta is non-deciduate (no maternal tissue is found in the expelled placenta) and zonary (the villi are arranges in a strap-like manner around the membranes). (B212.w11)
• In the last days of pregnancy in elephants, large blood vessels are present within the mammary gland (visible using ultrasound); and in the last 24 hours before parturition, large fluid filled irregularly-shaped cavities are present within the mammary glands. (B455.w3)

Skeleton:

• The skeleton makes up 12-15% of the total body mass of the elephant. (B147)
• There are 282 bones in the skeleton, including 61 vertebra. (J359.7.w3)
• Elephants have short necks, with a massive double spine on the axis. In Asian elephants the neck is held at about a 45 degree angle upwards. (B451.1.w1)
• Elephants have robust vertebrae and stout neural spines; these are high particularly in the thoracic region. (B451.1.w1)
• Elephants have 20 ribs, arising from vertebrae most of the distance down the spinal column; the rib cage is large and barrel-shaped. (B451.1.w1)
• The limb bones form rigid columns, with the shoulder and pelvis nearly vertical and the glenoid cavity and acetabulum facing ventrally. The humerus and femur are long, approximately equal in length to the lower limb bones. The radius and ulna are crossed in permanent pronation. (B451.1.w1)
• The limb bones are well developed and filled with spongy bone; they lack a marrow cavity. (B147)
• The forefeet are semi-digitigrade; the hindfeet are semi-plantigrade. (B285.w3)
• Vertebrae: 
  • There are seven cervical vertebrae, 20 dorsal (thoracic), three lumbar, three or four sacral and 21 caudal vertebrae. There appears to be some individual variation. In some individuals there are only 19 vertebrae bearing ribs. (B212.w5)
    • The neck is short. The atlas is signet ring shaped. The axis has a conical tooth-like process and a massive, posteriorly bifurcated spine. The third to fourth cervical vertebrae are short with short spinous processes while the seventh has a large spinous process and, on its posterior ends, a cavity for articulation of the first rib. (B212.w5)
    • There are nineteen or twenty thoracic (dorsal) vertebrae, with long, posteriorly inclined spinous processes. They have articulations for the heads of the ribs.
    • There are three lumbar vertebrae, with transverse processes which are longish and flattened. (B212.w5)
    • The short, arched sacrum is formed by the fusion of three or four bones (separate in the young animal). Approximately triangular, with the base anterior and the apex posterior, it forms the dorsal side of the pelvis. The last lumbar vertebra may be fused to the sacrum in elderly elephants. (B212.w5)
    • There are thirty one caudal vertebrae; some may have been lost due to accidents in some individuals. While some of the anterior caudal vertebrae show the basic vertebral shape, the more posterior bones are simple cylinders with both the anterior and posterior surfaces convex. (B212.w5)
  • Based on data from three adult Asian elephants, the vertebral column includes seven cervical, 19-20 thoracic, three to four lumbar, four sacral and 24-30 caudal vertebrae. There is a ventral convexity in the spinal column at the cervico-thoracic junction and a ventral concavity at the lumbo-sacral junction. The neural spines, directed upwards and backwards, increase in height to T5, then gradually diminish further caudally. The bodies of the vertebrae are basically circular. The thoracic and lumbar vertebrae, tightly packed together, form a strong arch to support the elephant's heavy body. (P502.1.w14)
    • The cervical vertebrae are relatively short, the axis is longest, with a transversely elongated body while the bodies of the other cervical vertebrae are roughly circular. The seventh cervical vertebra has a longer body than do C3-6, and has a large costal facet for the first rib. On C3-C5 is a rough ridge marking the ventral spine. The vertebral foramen is vertically elongated in the atlas and axis, then triangular from C3 caudally, becoming narrower further caudally. The neural spine, small in C3, increased to C7. The cranial articular processes are directed dorsally and medially, the caudal articular processes  are directed ventrally and laterally. (P502.1.w14)
    • There are 19 or 20 thoracic vertebrae, each consisting of a body and a neural arch. The bodies are smaller than those of the cervical vertebrae and vary from round cranially to heart-shaped further caudally. The transverse processes are short, thick and are tuberous at the free ends. The triangular vertebral foramen becomes narrow posteriorly. There are large neural spines, directed obliquely backwards, increasing in height from T1 to T5 then gradually decreasing in height, overlapping one another up to  T14, but with clear interspinous spaces from t15 to the last thoracic vertebra. (P502.1.w14)
    • There are three or four lumbar vertebrae, with thicker bodies than the other vertebrae, well developed mammilary processes and no accessory processes. They bear long, flat transverse processes and short, broad neural spines, directed obliquely backwards. The neural foramen is a transverse oblong. (P502.1.w14)
    • The sacral vertebrae are fused to form a triangular mass with four sacral spines directed upwards and backwards, and a flat pelvic surface marked by three distinct transverse lines (the demarcations of the bodies of the individual sacral vertebrae). The oblong sacral canal decreased in size posteriorly. (P502.1.w14)
    • There were 24 to 30 caudal vertebrae, becoming smaller caudally, with arches only in the first eight vertebrae. The 17th to last vertebrae were cylindrical, constricted in the middle. (P502.1.w14)
• Sternum: In young animals the sternum is cartilaginous and composed of several segments; in the older animal these are consolidated. On the lateral surfaces are indentations for the attachments of the ribs. (B212.w5)
• Ribs: There are 19 or 20 pairs of ribs, long, arched bones, dorsally attached to the lateral sides of the thoracic vertebrae, and ventrally to the sternum. The ribs increase in length from first to tenth, then decrease. The "true" or sternal ribs attach directly to the sternum, while the "false" or asternal ribs do not and the floating ribs have no ventral attachment. (B212.w5)
• Pelvis: This is positioned nearly vertically with respect to the spinal column, with the acetabulae pointing nearly downwards. (B212.w5)
• Scapula: The large scapula is divided vertically by a ridge into two halves, with a process from the ridge centrally pointing posteriorly. The [glenoid] cavity for articulation with the humerus points ventrally. (B212.w5)
• Humerus: This large bone provides extensive areas for muscle attachments. (B212.w5)
• Forearm bones: Both the radius and the ulna are present as distinct bones, obliquely and permanently crossed with one another. Both the proximal and distal ends of the ulna are larger than those of the radius. (B212.w5)
• Carpus: This consists of eights small, hard and irregularly shaped bones. (B212.w5)
• Digits: There are five digits; the phalanges are short and stout, the terminal phalanges are small and irregular in shape. (B212.w5)
• Femur: The femur is long and approximately cylindrical. (B212.w5)
• Patella: The patella is "slightly convex lengthways and concave transversely at its articular surface." (B212.w5)
• Tibia and fibula: The tibia is much larger than the fibula, with the shaft of the bone expanded into a triangular shape; the lower end is expanded slightly. The fibula is complete and distinct, connected to the tibia just below the stifle joint while the distal end is involved in the formation of the hock joint. (B212.w5)
• Foot: This includes the seven bones of the tarsus or hock, the metatarsals and the phalanges. (B212.w5)

Mucous membranes:

• The mucous membranes of the upper respiratory tract, alimentary tract and urogenital tract is delicately pink in the healthy elephant. (B212.w6)

Muscles:

• The muscles contain large amounts of tendinous fibrous tissue. (B212.w6)