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The keratin in the [[Skin - Anatomy & Physiology#Epidermis|epidermis]], when cornified and thickened, is referred to as '''horn'''. Horn is particulary resistant to mechanical and chemical damage. The [[Skin - Anatomy & Physiology#Dermis|dermis]] of horn gives the structures their 3-D structure and shape. Cattle, some sheep, goats and antelope posess horns and these are permanent organs. Breeds without horns are termed '''polled''' breeds. Deer posess '''antlers''', which are temporary organs that develop during the '''rutting season''' and are then shed.
The keratin in the [[Skin - Anatomy & Physiology#Epidermis|epidermis]], when cornified and thickened, is referred to as '''horn'''. Horn is particulary resistant to mechanical and chemical damage. The [[Skin - Anatomy & Physiology#Dermis|dermis]] of horn gives the structures their 3-D structure and shape. Cattle, some sheep, goats and antelope posess horns and these are permanent organs. Breeds without horns are termed '''polled''' breeds. Deer posess '''antlers''', which are temporary organs that develop during the '''rutting season''' and are then shed.
==Horns==
Horns have a central, conical bony core or '''cornual process''' that grows out from the [[Skull and Facial Muscles - Anatomy & Physiology#Frontal Bone|frontal bone]] of the skull. After 6 months of age, the bone becomes hollow and the space within it is continuous with the [[Paranasal Sinuses - Anatomy & Physiology|frontal sinuses]]. The surface of the bone is ridged and porous and is covered with papillated [[Skin - Anatomy & Physiology#dermis|dermis]] that is continuous with the periosteum and [[Skin - Anatomy & Physiology#epidermis|epidermis]] which keratinises and forms the protective covering of the horn. The substance of the horn is similar to that of the [[Hoof - Anatomy & Physiology|hoof]] and is a mixture of tubules and intertubular horn. The new horn produced at the base is soft and often transparent and resembles the [[Hoof - Anatomy & Physiology|periople]] of the hoof, giving the horn a glossy appearance.
Horns have a central, conical bony core or '''cornual process''' that grows out from the [[Skull and Facial Muscles - Anatomy & Physiology#Frontal Bone|frontal bone]] of the skull. After 6 months of age, the bone becomes hollow and the space within it is continuous with the [[Paranasal Sinuses - Anatomy & Physiology|frontal sinuses]]. The surface of the bone is ridged and porous and is covered with papillated [[Skin - Anatomy & Physiology#dermis|dermis]] that is continuous with the periosteum and [[Skin - Anatomy & Physiology#epidermis|epidermis]] which keratinises and forms the protective covering of the horn. The substance of the horn is similar to that of the [[Hoof - Anatomy & Physiology|hoof]] and is a mixture of tubules and intertubular horn. The new horn produced at the base is soft and often transparent and resembles the [[Hoof - Anatomy & Physiology|periople]] of the hoof, giving the horn a glossy appearance.
[[image: Horns.jpg|thumb|200px|right|Horns are commonly observed in Highland cattle, as pictured here]]
[[image: Horns.jpg|thumb|200px|right|Horns are commonly observed in Highland cattle, as pictured here]]
The primary function of horns is to convey social hierarchy. The larger the horns, the higher up the social group the animal is. They also have a thermoregulatory roll in cattle and goats. When the ambient temperature increases, the blood flow through the dermis of the horn also increases, thus facilitating heat loss through radiation from the horn surface.
The primary function of horns is to convey social hierarchy. The larger the horns, the higher up the social group the animal is. They also have a thermoregulatory roll in cattle and goats. When the ambient temperature increases, the blood flow through the dermis of the horn also increases, thus facilitating heat loss through radiation from the horn surface.
===Antlers===
===Horn Procedures===
Horns may be a source of problem for animals, including avulsions and fractures. The usual management practice involves debudding and dehorning procedures for horned animals or selection of polled animals as they are easier to handle and manage. They also require less space in housing and transport along with many other benefits.
==Antlers==
'''Antlers''' are the usually large and complex horn-like appendages of most deer species, mostly present in males only, however, for some species such as caribou, are present in both sexes. They consist of bony outgrowths from the [[Skull and Facial Muscles - Anatomy & Physiology|skull]] with no covering of keratin as is found in true horns. Each antler grows from an attachment point on the skull called a''' pedicle'''. While an antler is growing it is covered with highly vascular [[Skin - Anatomy & Physiology|skin]] called '''velvet''', which supplies oxygen and nutrients to the growing bone; once the antler has achieved its proper size, the velvet is lost and the antler's bone dies. This dead bone structure is the mature antler. Antlers shed after each mating season.
'''Antlers''' are the usually large and complex horn-like appendages of most deer species, mostly present in males only, however, for some species such as caribou, are present in both sexes. They consist of bony outgrowths from the [[Skull and Facial Muscles - Anatomy & Physiology|skull]] with no covering of keratin as is found in true horns. Each antler grows from an attachment point on the skull called a''' pedicle'''. While an antler is growing it is covered with highly vascular [[Skin - Anatomy & Physiology|skin]] called '''velvet''', which supplies oxygen and nutrients to the growing bone; once the antler has achieved its proper size, the velvet is lost and the antler's bone dies. This dead bone structure is the mature antler. Antlers shed after each mating season.
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==Links==
[http://www.guardian.co.uk/science/2008/mar/21/medicalresearch.animalbehaviour Moose's sharp hearing is attributed to antlers, James Randerson, The Guardian, Friday 21 March 2008]
[http://www.guardian.co.uk/science/2008/mar/21/medicalresearch.animalbehaviour Moose's sharp hearing is attributed to antlers, James Randerson, The Guardian, Friday 21 March 2008]
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[[Category:Integumentary System - Anatomy & Physiology]][[Category:Image Review]]
[[Category:Integumentary System - Anatomy & Physiology]][[Category:Image Review]]