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< > APPEARANCE/ MORPHOLOGY: HEAD AND NECK with literature reports for the Asian Elephant - Elephas maximus: Use sub-contents list below, or simply scroll down the page to view findings.

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HEAD AND NECK - Editorial Comment

Editorial Comment (Editorial Overview Text Replicated on Overall Species page - Asian Elephant - Elephas maximus

Adult: Elephants have a huge head on a short neck. The ears of the Asian elephant are large and fan-like although smaller than the ears of Loxodonta. The elephant's trunk is derived from the upper lip and nose, extremely elongated and very muscular. On the tip of the trunk are located the nostrils, also a dorsal finger-like projection. It bears sensory hairs and is important in touch and olfaction. The trunk is extremely important for many of the elephant's daily activities. The mouth is relatively small. The elephant's skull is massive, containing many large sinuses which reduce its weight. The brain is situated ventrally towards the back of the skull. The forehead of the Asian elephant is bulbous, due to large sinuses in this region.
Newborn: The newborn elephant has a relatively short trunk. The skull is much smaller, relative to the body, than in the adult, since the huge pneumatisation (expansion of air cavities) of the bones has not yet developed.

DENTITION:
Adult:
Elephants have the dental formula i 1/0, c 0/0, pm 3/3 m 3/3 (one upper incisor - the tusk, no canines, three premolars and three molars, i.e. six cheek teeth). The cheek teeth vary in size, with the first being smallest and the sixth being largest. each bears a number of ridges or laminae. The cheek teeth erupt from the caudal aspect of the jaw and progress forward, coming into wear sequentially, with one, or parts of two, molars in wear at any one time. The worn out tooth has its roots resorbed as it reaches the front of the mouth and the remains of the crown are spat out or swallowed. The tusks are modified upper incisors. Initially they are capped with enamel but this is soon worn away. The main part of the tusk is composed of ivory, a form of dentine with a unique structure. The tusk grows throughout the elephant's life, from odontoblasts lining the sensitive pulp cavity, which contains blood vessels, nerves and connective tissue. Tusks of males grow more in both length and thickness than do those of females. Female Asian elephants, and some males, do not have full tusks but merely small "tushes"; some males do not have even tushes, and some have a single tusk.
Newborn: At birth, the first and second molars are present. Parts of the first three cheek teeth may be in wear at the same time in the calf. The milk tusks cut the gum when the calf is about five to seven months of age while the permanent tusks may be visible by about two or three years of age. 

EYES:
Adult:
The eyes, about the same size as in humans, have a round pupil in a hazel or brown iris. The eyelashes on the upper and lower lids are long. There is no functional lachrymal gland (tear gland) to produce tears nor any tear ducts to take fluid away from the eye. The eyes are moisturised from the secretions of the Harderian gland, which opens on the internal side of the third eyelid (nictitating membrane) and moisture either evaporates or drains down the side of the face.
Newborn:
Elephant calves are precocial, therefore the eyes are open and functional in the newborn calf. 

(References are available in detailed literature reports below)

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General Head Structure

Adult SUMMARY: Elephants have a huge head on a short neck. The ears of the Asian elephant are large and fan-like although smaller than the ears of Loxodonta. The elephant's trunk is derived from the upper lip and nose, extremely elongated and very muscular. On the tip of the trunk are located the nostrils, also a dorsal finger-like projection. It bears sensory hairs and is important in touch and olfaction. The trunk is extremely important for many of the elephant's daily activities. The mouth is relatively small. The elephant's skull is massive, containing many large sinuses which reduce its weight. The brain is situated ventrally towards the back of the skull. The forehead of the Asian elephant is bulbous, due to large sinuses in this region.

General:

  • The head is huge and the neck is short. (B147)
  • With increasing age the forehead becomes broader, therefore the temporal region appears sunken. (B384.5.w5)
  • With increasing age in the bull, the head lengthens as a proportion of the body, in order to accommodate the increase in weight and length of the tusks, and the face changes shape, becoming hourglass-shaped: wide across the forehead and eye area, then narrow, and widening again at the tusk gums. (B384.5.w5)

Ears:

  • The ears are large and fan shaped, although smaller than in Loxodonta. (B147)
  • When it is hot, the veins stand out from the ear's medial surface. (B285.w3)
  • The ears are important in signaling and in temperature regulation. (B451.1.w1)
  • The ear flap is made up of a cartilaginous sheet covered with closely attached relatively thin skin. (B451.1.w1)
  • The top edge of the ear typically turns over forwards in mature Asian elephants. (B451.1.w1)

Trunk:

  • The trunk of elephants has developed from the upper lip and nose, becoming greatly elongated and muscularised. (B285.w3)
  • The trunk, an elongated nose, is very muscular and flexible; the nostrils are located at the tip, together with a fingerlike projection. (B147)
  • The trunk is muscular and has great flexibility, power and contractility. On the tip is a finger-like process, which enables the elephant to pick up small objects. The skin over the trunk is soft and pliable; on the posterior side it forms a series of transverse ridges. (B212.w5)
  • The heavily-muscled trunk has a good blood supply and a good supply of both sensory and motor nerves. (B10.49.w21)
  • The trunk contains six pairs of major muscles. The longitudinal muscles are mostly superficial; they are found in four segments: (B384.3.w3)
    • Dorsally are the levators, originating at the frontal bone; they extend the whole length of the trunk to the finger-like appendage on the trunk tip;
    • Ventrally are the depressors, which are used to curl the trunk up. These do not reach the extremity of the trunk. 
    • Laterally are the longitudinal bands, to bend the trunk from side to side.

    (B384.3.w3)

  • Transverse muscles, deep to the longitudinal muscles, are probably used for more complex movements. (B384.3.w3)
  • The trunk is, anatomically, the nose and upper lip. Paired nostrils run through the whole length. The skin covering the dorsal surface is annulated, with deep furrows, and is sparsely covered with sensory hairs. The trunk is completely muscular. (B451.1.w1)
  • Proximally in the trunk the superficial muscle layer bundles run longitudinally in the dorsal region and obliquely in the ventral region, in the middle muscle layer some bundles run ventro-distally, others longitudinally and in the deep layer there is a complicated architecture with some bundles orientated medio-laterally and others proximo-distally. In the distal trunk, in the dorsal part the bundles run deep-superficial while the ventral part has bundles orientated longitudinally; near the nasal septum the bundles run laterally. The muscle is innervated by numerous branches from the facial and infraorbital nerves. (J27.63.w)
  • The dorsal trunk tip "finger" has a unique sensory innervation with three distinctive types of sensory terminals. There is a high density of free nerve endings in the superficial dermis, numerous corpuscle receptors including small Pacinian corpuscles and convoluted branched small corpuscles, and abundant vellus vibrissae (short vibrissae that do not protrude from the skin surface), while in the skin surrounding the trunk tip finger there are abundant regular vibrissae. This dense sensory innervation  is related to the tactile ability of the trunk finger, which is used for grasping small objects and for presenting samples to the ductal openings of the vomeronasal organ in the mouth. (J394.246.w1)

Skull:

  • The bones of the skull are greatly thickened. A system of air cells and cavities, interconnecting, reduces the total mass. (B147)
  • There are many air-filled sinus cavities in the huge skull. (B10.49.w21)
  • The premaxillary bones form the tusk sheaths. (B147)
  • A third of the length of the tusks is held within the alveolar processes of the skull; these grow as the tusks grow. (B10.49.w21)
  • The nasal bones are greatly shortened. (B147)
  • The cranium is domed. (B10.49.w21)
  • The skull makes up 12 - 25% of the elephant's body weight. (B285.w3)
  • The braincase is found behind the eyes and in line with the auditory canal. (B384.3.w3)
  • The main part of the skull is composed of sponge-like cancellous bone, with many thin-walled cavities between the two surfaces of each bone, which can be 30 cm apart, so that for their size the bones are relatively light. (B384.3.w3)
  • In elderly elephants, bone is absorbed wherever it is not required (wherever there is no stress on the bone). (B384.3.w3)
  • The bones of the skull are pneumatised. The forehead of the Asian elephant is bulbous, due to large sinuses in this region. (B451.1.w1)
  • The Asian elephant has a longer, narrower face than the African elephant, the skull appears more compressed from front to back and the jaw is very deep - nearly as deep as it is long. (B451.1.w1)
  • The skull is very large (e.g. average of five males, 114.5 lb), with the cranial portion much larger than the facial portion, with the upper cranium forming an expanded dome and the remainder of the bones having their inner and outer surfaces separated by air sinuses; these grow with age and provide a high degree of strength for relatively little bony material. The large size provides large surfaces for muscle attachments, while the sinuses reduce the overall weight for size. (B212.w5)
    • The nasal bones are short, triangular and pneumatic, forming the lump immediately dorsal to the trunk. The nasal cavities communicate with the skull sinuses and all are lined by mucous membrane. The internal bony nostrils re formed by the nasal and premaxillary bones, the nasal chambers are short and vertical, the turbinates are rudimentary.
    • The lachrymal bone is "small, protruberant and imperforate." (B212.w5)
    • The brain cavity is situated far back and low down in the skull. (B212.w5)
    • The mandible is short, with the vertical section nearly as long as the horizontal section; the junction between the lower jaws is short and pointed. The dental canal, housing the large cheek teeth, is wide. (B212.w5)
  • The bones of the roof and sidewalls of the braincase of the adult elephant are pneumatised, with extensive air cells, all interconnected and with perforations for blood vessels; dorsally, the total bone thickness including the air cells can reach 250 mm. (J397.70.w1)
Neonate / Young SUMMARY: The newborn elephant has a relatively short trunk. The skull is much smaller, relative to the body, than in the adult, since the huge pneumatisation (expansion of air cavities) of the bones has not yet developed.
  • Trunk:
    • In the newborn calf the trunk is short, only about 10-15 inches long. (B212.w11)
    • The trunk appears to be poorly controlled initially. (B384.5.w5)
  • Skull:
    • The air sinuses or cavities in the skull bones are much smaller in the young elephant than in the adult. (B212.w5)
    • The newborn elephant's skull is not pneumatised and the cranial bones are approximately 5-10 mm thick. (J397.70.w1)

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Dentition

Adult SUMMARY: Elephants have the dental formula i 1/0, c 0/0, pm 3/3 m 3/3 (one upper incisor - the tusk, no canines, three premolars and three molars, i.e. six cheek teeth). The cheek teeth vary in size, with the first being smallest and the sixth being largest. each bears a number of ridges or laminae. The cheek teeth erupt from the caudal aspect of the jaw and progress forward, coming into wear sequentially, with one, or parts of two, molars in wear at any one time. The worn out tooth has its roots resorbed as it reaches the front of the mouth and the remains of the crown are spat out or swallowed. The tusks are modified upper incisors. Initially they are capped with enamel but this is soon worn away. The main part of the tusk is composed of ivory, a form of dentine with a unique structure. The tusk grows throughout the elephant's life, from odontoblasts lining the sensitive pulp cavity, which contains blood vessels, nerves and connective tissue. Tusks of males grow more in both length and thickness than do those of females. Female Asian elephants, and some males, do not have full tusks but merely small "tushes"; some males do not have even tushes, and some have a single tusk.
  • Dental formula of elephants: i 1/0, c 0/0, pm 3/3, m 3/3, (B10.49.w, B147, B285.w3, W580.Sept2005.w1) giving a total of 26 teeth. (B147)

Cheek teeth:

  • The cheek teeth of elephants are large and high crowned. Each tooth is made of transverse planes of dentine covered with enamel and filled with cement, which also covers the enamel ridges when the tooth is unworn. (B147)
    • Each tooth is made of complex ridges of dentine covered with enamel, with cement between the ridges. (B10.49.w21)
  • The first cheek tooth is smallest, with the fewest number of ridges; each succeeding molar is larger with more ridges. There are six sets of grinding teeth in total. (B147, B10.49.w21)
  • Usually only one set of teeth is in wear at any one time. (B147)
  • Each molar, as it is worn away, is pushed forward and replaced by the next molar coming in obliquely from behind. The worn molar is usually pushed out in pieces. (B147)
    • The crown is worn and the blood supply is compromised by the succeeding tooth; the crown fractures transversely, the roots are resorbed and fractured sections of the old tooth crown are spat out or swallowed. (B10.49.w21)
  • The sixth cheek tooth is in wear for two fifths of the elephant's life. It is up to 21 cm long and more than 7cm wide, weighing nearly 4.0 kg. (B384.3.w3)
  • The six cheek teeth erupt in linear progression; each tooth appears caudally in the jaw and moves rostrally, becoming progressively worn down at the front and eventually dropping out. (B451.1.w1)
  • At any one time, one, or parts of two molars are in wear. In calves, parts of the first three cheek teeth may be in wear at the same time. (B451.1.w1)
  • Each molar has a series of laminae, ridges. When the tooth erupts the surface is rounded; the dentine of the ridges is covered with enamel. This wears down to leave exposed dentine with enamel surrounding, forming an efficient surface for rasping. (B451.1.w1)
  • Wear of the lower molars is faster and more regular than that of the upper molars. (B451.1.w1)
  • The jaws move up and down; they crush only those portions of food items which fall directly between the teeth. (B384.3.w3)
  • During chewing, the jaws move forwards and backward but there is little lateral movement. (B451.1.w1)
  • Molars have open roots filled with tooth pulp; the number of roots corresponds to the number of laminae. (B451.1.w1)
  • There is usually a gap between the roots of lamina 4 and lamina 5. (B451.1.w1)
  • Initially the roots are perpendicular to the tooth surface; later, as the tooth progresses forwards, the roots become inclined backwards. (B451.1.w1)
  • As the tooth moves forwards the anterior roots are resorbed, leaving an unsupported shelf of tooth, which is eroded from the front, breaks off and falls from the mouth or is swallowed. (B451.1.w1)
  • The cheek teeth are formed from subdivisions of dentine, in transverse ridges, coated with enamel and in a bed of cementum. The teeth are replaced in series, each by the tooth next tooth pushing forwards from behind. (B212.w5)
  • The jaws move backwards and forwards (with little sideways movement), so the teeth grate against one another like rasps. (B384.3.w3)
  • The molars of elephants are anelodont (teeth having a limited period of longitudinal growth) and sequentially erupting, each molar replacing the previous molar from a caudal direction in the mouth. At any one time, in any quadrant of the mouth, one molar is in wear, or one is partially-worn while another is partially-erupted. (P505.9.w1)

Tusks:

  • The tusk is the upper incisor, modified, which grows throughout the life of the elephant. It is generally found only in males, not females of this species. Enamel is present only on the tip and is soon worn away. (B147)
  • The tusk, a modified incisor, is composed of dentine. Initially it is capped with enamel but this is soon worn away, leaving the dentine surrounding the pulp canal. (B10.49.w21)
  • The tusks of elephants are modified upper incisors. The ivory is made of a unique mixture of dentine and calcium salts, with a regular diamond pattern on cross section, which is not present in tusks of other mammals. (B285.w3)
  • Female Asian elephants may be tusked but these tusks are rarely visible as they do not protrude beyond the tusk sulcus. (B10.49.w21)
  • Some Asian elephant bulls have small tusks of an odd shape; these are known as tushes. (B10.49.w21)
  • The tusks are the upper second incisors. (B384.3.w3)
  • There are no lower incisors, the upper first incisors and the canines are also absent. (B384.3.w3)
  • The female Asian elephant, rather than tusks, has short tushes, pointing downwards. These rarely reach more than 10 cm beyond the gum, and are generally broken off quite early. (B384.13.w13)
  • Asian elephant bulls in work may produce up to 7.5 cm length / 0.5 kg of ivory per year. (B384.13.w13)
  • The tusks are upper incisors. (B451.1.w1)
  • Tusks grow throughout life, therefore older elephants bear larger, heavier tusks. (B451.1.w1)
    •  
    • There is individual variation in tusk growth rate.(B451.7.w7)
    • Tusks may be worn down as fast as they grow. (B451.7.w7)
  • There are genetic differences in tusk growth between elephants. (B451.1.w1)
  • The growth of tusks follows a sinusoidal curve. (B451.1.w1)
  • Tusks are made of dentine; initially there is an enamel cap, soon worn away. (B451.1.w1)
  • Approximately one quarter of the tusk is inside the tusk socket and is covered with cement. (B451.1.w1)
  • The tusk base is hollow. It contains the tusk pulp, consisting of blood vessels and nerves surrounded by mesenchymal connective tissue. (B451.1.w1)
  • Odontoblast cells deposit dentine over the surface of the pulp, so that the tusk grows from its base. (B451.1.w1)
  • In Asian elephants, tusks of females are hardly visible. Some males have visible tusks, but not all. In India, tuskless males are called makhnas. (B451.1.w1)
    • The percentage of tuskless males varies regionally, e.g. about 50% in the north-east of India, and normal in Sri Lanka. (B451.1.w1)
    • Hunting for ivory may have played a role in selecting for tusklessness. (B451.1.w1)
  • The tusks are modified incisors. Females and some males do not have full tusks but merely small "tushes"; some males do not have even tushes, and some have a single tusk. (B212.w5)
    • The pulp cavity extends some distance into the tusk. (B212.w5)
    • Both tusks and tushes are embedded in deep bony sockets. (B212.w5)
    • There are a number of Burmese names given to describe tusks with different curvatures and divergence. (B212.w5)
    • Males may have a single tusk from birth, or lose on tusk due to fighting or other injury. (B212.w5)
    • In Sri Lanka [Ceylon], very few males, perhaps one in a hundred, have tusks; the rest have tushes, about 10 - 12 inches long and 1.0 - 2.0 inches in diameter. (B212.w5)
Neonate / Young Summary: At birth, the first and second molars are present. Parts of the first three cheek teeth may be in wear at the same time in the calf. The milk tusks cut the gum when the calf is about five to seven months of age while the permanent tusks may be visible by about two or three years of age. 
  • The first and second molars are present at birth in elephants. (B10.49.w21)
  • In calves, parts of the first three cheek teeth may be in wear at the same time. (B451.1.w1)
  • Milk tusks are present before the permanent tusks of elephants. (B10.49.w21)
  • The milk tusks are less than 5 cm long, with a solid, tapering root and a small, enamel-tipped cap. They cut the gum when the calf is about five to seven months old. (B384.13.w13)
  • By about two to three years of age the permanent tusks are visible. (B451.1.w1)

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Eyes

Adult SUMMARY: The eyes, about the same size as in humans, have a round pupil in a hazel or brown iris. The eyelashes on the upper and lower lids are long. There is no functional lachrymal gland (tear gland) to produce tears nor any tear ducts to take fluid away from the eye. The eyes are moisturised from the secretions of the Harderian gland, which opens on the internal side of the third eyelid (nictitating membrane) and moisture either evaporates or drains down the side of the face.
  • The pupil is round, the iris is usually hazel. (B384.4.w4)
  • The eyeball is small for the size of the animal, being similar in size to that of humans. (B384.4.w4)
  • The eyes have a paurangiotic retina; the retina appears pale with a few large blood vessels surrounding a pale optic disk. (B10.49.w21)
  • There is no lachrymal apparatus. (B10.49.w21)
  • Moisture and lubrication for the eyes is supplied by the Harderian gland, on the internal surface of the nictitating membrane. (B10.49.w21)
  • The eyes are brown and the pupil is round. (B212.w12)
  • The elephant has eyelashes. There is a third eyelid. (B212.w12)
  • There is no true lachrymal gland, however the Harderian gland, situate on the inner side of the orbit, produces a secretion filling the same role. There is no lachrymal apparatus and tears fall from the eyes onto the face. (B212.w12)
  • Data from three eyes included a mean axial length of 38.75 mm with the lens having an axial diameter of 10 mm. There were five distinct layers to the cornea. The posterior sclera was noted to be markedly thickened. There was a thin, meridionally-oriented smooth ciliary muscle apparatus. Within the posterior trabeculae of the uveal meshwork, muscle fibres were observed. There was a fibrous tapetum. There was no identifiable puncta and nasolacrimal duct.(P1.1993.w5)
Neonate / Young SUMMARY: Elephant calves are precocial, therefore the eyes are open and functional in the newborn calf. 
  • Elephant calves are precocial, therefore the eyes are open and functional in the newborn calf. (B147)

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Authors & Referees

Authors Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referees Susan K. Mikota DVM (V.w72)

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