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Horn (anatomy)
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Look up <i> horn</i> in Wiktionary, the free dictionary. <p>A horn is a permanent pointed projection on the head of various animals that consists of a covering of <a href="/facts/Keratin/tBh0bY47">keratin</a> and other <a href="/facts/Protein/Jxmagu3E">proteins</a> surrounding a core of live <a href="/facts/Bone/kwJaR6IQ">bone</a>. Horns are distinct from <a href="/facts/Antler/74sc5yEe">antlers</a>, which are not permanent. In mammals, true horns are found mainly among the <a href="/facts/Ruminant/tTcBMxk4">ruminant</a> <a href="/facts/Artiodactyl/LS4ra9ET">artiodactyls</a>,[<i>not verified in body</i>] in the families <a href="/facts/Antilocapridae/15xR1XIv">Antilocapridae</a> (<a href="/facts/Pronghorn/mQzoTUER">pronghorn</a>) and <a href="/facts/Bovidae/pUVW36Nh">Bovidae</a> (<a href="/facts/Cattle/44qV9B6S">cattle</a>, <a href="/facts/Goat/BrsPJmdX">goats</a>, <a href="/facts/Antelope/Qwt40F7N">antelope</a> etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone. </p><p>One pair of horns is usual; however, two or more pairs occur in a few wild species and in some <a href="/facts/Domestication/tWB5s52s">domesticated</a> breeds of sheep. <a href="/facts/Polycerate/enHvUXF2">Polycerate</a> (multi-horned) sheep breeds include the <a href="/facts/Hebridean_sheep/6x8K1s2s">Hebridean</a>, <a href="/facts/Icelandic_sheep/Iu2l4v1w">Icelandic</a>, <a href="/facts/Jacob_sheep/ddPYlo1H">Jacob</a>, <a href="/facts/Manx_Loaghtan/JKYbz0aX">Manx Loaghtan</a>, and the <a href="/facts/Navajo-Churro/4IurvpDp">Navajo-Churro</a>. </p><p>Horns usually have a curved or <a href="/facts/Spiral/4R331aba">spiral</a> shape, often with ridges or fluting. In many species, only males have horns. Horns start to grow soon after birth and continue to grow throughout the life of the animal (except in pronghorns, which shed the outer layer annually, but retain the bony core). Partial or deformed horns in livestock are called <a href="/facts/Scur/9dC0JNyz">scurs</a>. Similar growths on other parts of the body are not usually called horns, but <a href="/facts/Spur_(zoology)/SH7YTkKk">spurs</a>, <a href="/facts/Claw/GroswzjA">claws</a>, or <a href="/facts/Hoof/akrIlYRN">hooves</a>, depending on the part of the body on which they occur. </p>