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Fallow Deer: Description, Habitat, & Facts
Continue ReadingFallow Deer
Fallow Deer is a herbivore mammals belong to the genus Dama and the order Artiodactyla. They are seen in herds on sparse forests and grasslands of Europe and the Middle East. They belong to the family Cervidae that comprise reindeer, elks, and deer, etc.
They have characteristic shovel-shaped large palmate antlers and usually have a brown coat color with white spots. A range of genetic variations can be observed in them and they have an extensive range.
So besides the common brown coloration, varieties including Melanistic, Menil, and Leucistic also do occur. These color variations are influenced by several genes and their interaction with the environment they live in.
Fallow Deer Description
Males in early summer will start developing their antlers. Only 2 spikes can be observed in young bucks, that grow to become palmate antlers in a period of about 4 years. The antlers are significant to males, the males that possess the largest antler can defend their breeding territory or lek.
During rut that is a particular season in the fall, males attract females by defending a territory and this can earn them a chance to mate. After this season males shed their antlers that may be collected by mount creators in places where it is not prohibited.
They have an intriguing evolutionary history influenced by human history. They have been poached for sport and food from 500,000 years before in Paleolithic times, through the Roman Empire, and even today.
They have been introduced in many countries like South America, Australia, North America, and Africa. It may compete with the local native species in the regions they may have been introduced to.
Interesting Insights from the Fallow Deer!
They comprise a part of human history and demonstrate some important biological processes or concepts.
“The Rut” – A Timing Strategy
A rut specifies the timing in herd animals that have a mating cycle during which breeding season occurs. In the case of fallow deer and other related deer species, this starts in fall, following which the females gestate over in winter and give birth in spring.
The young will have much to feed on during the spring season. For the starting few months they feed on the milk of their mother, then with developing rumination, they acquire the ability to digest complex fibers of the plant.
They will then start to ingest huge quantities of leafy greens to grow in size. Females get sexually mature faster than males at 16 months, while males only mature by age of 4. The estrous cycle of the female is what drives the rut as they only come into estrous once every year.
This also means males get only limited opportunities and thus it tries to impregnate as many females as possible to increase the reproduction rate. Fallow deer bucks employ different kinds of strategies for attracting males, based on the population size and the local environment.
Fallow Deer Distribution
The population of fallow deer is distributed throughout the world and shows variations in these distinct populations. The ancestral population might have been brown. They were poached for food by humans for many thousands of years.
The red may have later evolved and expanded in Greece. These deers were brought to Europe where they evolved into the purple population that denotes Roman expansion. The teal population might be the modern form of fallow dear that might have emerged around the 1900s.
It has since then spread due to imports to South America, New Zealand, North America, Australia, and South Africa. They were originally native to Europe and the Middle East, and from there have been introduced to 4 other continents.
They are farmed often on ranches in places like Argentina and Texas. Their hunts may be sold to rich gun-owners, though there has been a decline in their hunting. Introduces species like these need to be monitored so they don’t impact the ecosystem functioning and destroy native species.
Fallow Deer and Polygyny
These fallow deer also exhibit polygyny like other cervids. They form groups of females heeded by 1 male. Whereas in polyandry, a group of many males is regulated by a single female as in fishes.
Polygynous groups have different rules and behaviors depending on species density, local behavior, and environment. Fallow deer exhibit 2 types of polygyny practices are Lekking and harem. In harem groups, the males stay with the group as they wander.
They tend to keep the females herded and will guard against entry or access of other males. In lekking, males defend the home range where the female is known as a lek. Only he can copulate with the female in his territory.
The local environment plays a key role which helps the male fallow deer decide on the polygyny practice it wants to engage in. If the environment is resource-scarce then the male forms harems so he may protect the female while they are foraging for food.
If the environment has abundant resources then the males will establish their territories where females hang out more. Defending territories is an energy-intensive process that can cause the deer to lose up to 17% of their weight during the rut season.
Fallow Deer Citations
- Molecular identification of two Sarcocystis species in fallow deer (Dama dama) from Lithuania. Parasitol Int . 2020 Apr;75:102044.
- Shiga toxin-producing Escherichia coli isolates from red deer (Cervus elaphus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) in Poland. Food Microbiol . 2020 Apr;86:103352.
- Carcass and meat characteristics from farm-raised and wild fallow deer (Dama dama) and red deer (Cervus elaphus): A review. Meat Sci . 2018 Jul;141:9-27.
- Wild fallow deer (Dama dama) as definitive hosts of Fasciola hepatica (liver fluke) in alpine New South Wales. Aust Vet J . 2020 Nov;98(11):546-549.
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Peacock: Description, Habitat, & Facts
Continue ReadingPeacock
Peacock is an omnivorous polygamous bird belongs to the genus Pavo and Afropavo and order Galliformes. This ground-dwelling bird belongs to the same family as pheasants that is Phasianidae.
These semi-domestic birds exhibit characteristic fan-like colorful plumage. Out of the 3 species, 2 are native to Asia and one to Africa. They can be seen in parks and aviaries throughout the world.
Peacock Description
The term peacock is used for males and they are collectively called peafowl. It is the male members that exhibit distinctive feather fans near their rump. These colorful displays are made for the female.
The plumage is iridescent, the feathers exhibit shades of white, blue, bright green. When these feather fans are not displayed they follow the birds in a train manner. They may grow up to measure 140 to 160 cm in length and may weigh up to 6 kg.
A Congo Peacock
In the case of congo peafowl, no sexual dimorphism is observed in males and females. But green and Indian peafowl show sexual dimorphism.
Generally, females have plumage of brown and grey and are not as colorful as the males, and also do not have a trail train. They weigh around 2.8 to 4 kg and are smaller than males and measure up to 90-110 cm in length.
Peacock Distribution and Habitat
The 3 species of peafowl include Pavo cristatus, Pavo muticus, and Afropavo congensis. The Pavo cristatus or Indian peafowl is a common native bird of the Indian subcontinent.
The Pavo muticus or green peafowl is found in southeast Asia, while the Afropavo congensis or Congo peafowl is endemic to the Congo Basin of Africa.
They prefer forested regions as their habitat. They often utilize trees as a roosting area and shelter, where they spend their night safely. During the day, they move away from the roosting area in search of food.
Peacock Diet and Predators
They are omnivores birds and forage for seeds and flower petals or other plant materials. They also feed on small animals like amphibians, small reptiles, and insects. They spend their daytime foraging for food in leaf litter in open areas.
They scratch the dirt and debris to hunt for edible plant materials. They will retreat back to their roosting place in the forest during the hottest times of the day. The native places they occur are also home to their predators like tigers, mongooses, and dogs in Southeast Asia and India.
In the case of Africa, the Congo peacocks are preyed on by lions. Their eggs are also preyed upon and hence are vulnerable.
Peacock Nesting and Reproduction
Peafowl’s nests are found on the ground and they build these by scraping out small depressions and then lining them with soft vegetation and grass in the ground. These nests are well concealed among high grass and under bushes to avoid any predators.
The peafowl will often mate with many males over their lifetime and are polygamous. The males display their tail feathers and shake them in courtship for attracting females and often during this time they will also peck on the ground.
The average clutch size is 2-10 eggs. After copulation and a period of 4 weeks of incubation chicks emerge from the eggs. The chicks often display cryptic plumage of brown and yellow shades.
They stick by their mother’s side for 7 to 10 weeks. Peafowl sexually matures by 2-3 years and grow adult plumage. While the males attain sexual maturity by 4 years and they also grow out their feather fan.
Peacock Conservation
As these birds are common they are listed under least concern species on the IUCN Red List. While the rest of the species are popular and common in aviaries throughout the world, the green peafowl has since 2009 been listed as Endangered and the Congo peafowl has come under the vulnerable category.
The decrease of the forest area has caused some species to inhabit secondary growth forests as a potential conservation strategy.
Fun Facts about Peacock!
All About Plumage: The green peacock besides its iridescent plumage also has bronze and green feathers. This iridescent plumage gives them a metallic look. Eyespots can also be observed in their feathers that make them more colorful. In the case of green peafowls, both sexes possess colorful plumage.
Sexual Selection: The tail feather fan of males is an example of sexual selection that is a result of natural selection. The selection pressures favor the maintenance of certain traits that are favorable for the population and increase their survivability.
In the recent handicap theory that has been proposed the researchers postulate that these feather fans are a hindrance that fit males will overcome. Thus, it represents the fitness of the male.
A Change of Sex: Sexual inversions have been observed in peahens. They may exhibit bilateral gynandromorphism where the individual possesses sexual organs of both sexes and under genetic or environmental influences can undergo sexual inversion.
This process in peacocks may occur due to sex ratios or demographics. The exact mechanism behind this hasn’t been discovered yet.
Peacock Citations
- Characterisation of peacock (Pavo cristatus) mitochondrial 12S rRNA sequence and its use in differentiation from closely related poultry species.Br Poult Sci . 2007 Apr;48(2):162-6.
- Deceptive copulation calls attract female visitors to peacock leks. Am Nat . 2014 Apr;183(4):558-64.
- Isolation and characterization of peacock Chlamydophila psittaci infection in China. Avian Dis . 2011 Mar;55(1):76-81.
- Biomechanics of the Peacock’s Display: How Feather Structure and Resonance Influence Multimodal Signaling. PLoS One . 2016 Apr 27;11(4):e0152759.
- How conspicuous are peacock eyespots and other colorful feathers in the eyes of mammalian predators? PLoS One . 2019 Apr 24;14(4):e0210924.
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Albacore Tuna: Description, Habitat, & Facts
Continue ReadingAlbacore Tuna
Albacore Tuna predator belongs to the genus Thunnus and order Scombriformes. This pelagic fish can be found primarily offshore on temperate and tropical waters of the Atlantic, Indian and Pacific oceans comprising 6 distinct stocks.
They can grow up to 7ft in length and comes under the family Scombridae. They are commonly found in sport and commercial fisheries and have a lifespan of 10-12 years.
Albacore Tuna Description
Albacore Tuna fish has a streamlined body and at the end of its cone-shaped head, there is a largemouth. They appear silver-white on the ventral side and appear dark blue on their dorsal side.
They have large eyes and long pectoral fins. They have an anal fin and 2 dorsal fins and several finlets on their hind section and tail that make a larger caudal fin.
Albacore Tuna Distribution and Habitat
These 6 distinct stocks are distributed across the Meditteranean Sea, Indian, Atlantic, and the Pacific Ocean that makes them cosmopolitan. They prefer surface waters in the range of 50-77oF and may dive up to a distance of 2,000 ft deep.
They like other tuna species are schooling. They may either school with the same species or with other fishes like skipjack tuna who have a similar size to them. They do not mix with separate stocks and may travel great distances.
Albacore Tuna Diet
This fast-swimming fish is an excellent predator due to its largemouth, keen eyesight, and speed. But opposed to other tuna species that feed exclusively on fishes, they also prey on pelagic crustaceans, cephalopods like cuttlefish, squids, and octopuses along with fishes.
Albacore Tuna Reproduction
This tuna species is oviparous and its development occurs externally. Spawning occurs generally between November and February, females release a large number of eggs approximately 2 million at a time into the waters.
The males also simultaneously release sperms into the water. This synchronized release of gametes increases the probability of fertilization. After fertilization of the egg, the embryo formed is now a part of the zooplankton community that moves with the whim of the ocean currents.
Fry will always remain proximal to the spawning area, after 12 months they move on. They attain sexual maturity at the age of 5 to 6 years and have a life span of 12 years.
Albacore Tuna Conservation Status
Adults in this tuna species are highly migratory and travel great distances in the ocean. So as a stock, they can be difficult to manage due to their migratory tendencies. It is a task to regulate and protect their stock and requires international cooperation in policymaking and enforcement.
These fishes may be overfished due to their demand as they often are in great demand at sport and commercial fisheries. This species comes under the Near Threatened category of IUCN Red of Threatened species.
Fun Facts about the Albacore Tuna!
They may not be the most commercially valuable of tuna species, but this predator travels long distances and form a part of the GDP of various Pacific Nations. They have various interesting facts.
The Traveling Tuna: The migratory pattern of each stock of this species may differ. For instance, the North Pacific Stock travels between the temperate waters of the Pacific Northwest, British Columbia, and Baja California. While the North Atlantic stock migrates to the Bay of Biscay.
Fisheries management maybe even more complicated for tuna as they have vast ranges that involve different jurisdictions and require cooperation for effective management. The ecology and population dynamics may differ in different stocks.
For instance, older fishes are caught more often in catches made from cooler waters in the Atlantic Ocean, while in the Pacific Ocean the older fishes are found more often in warmer waters.
This can be understood in the concept of global climate changes that affect the ocean temperature that in turn affects the range, distribution, and spawning timings of the tuna stock.
Ever-Ready: These warm-blooded fishes rarely rest as it keeps its large muscles oxygenated at all time. This requires them to be on the move so that water can pass over the gills and the bloodstream may be oxygenated continually.
Asymmetrical Gonads: They generally have asymmetrical gonads. In the case of males, the right teste is larger and in females, the right ovary is larger. They also exhibit asynchronous oocyte development, the development of female eggs does not occur at a fixed frequency. So, at a time eggs will be at different stages of development.
Albacore Tuna Citations
- Optimal immobilization of trypsin from the spleen of albacore tuna (Thunnus alalunga) and its characterization. Int J Biol Macromol . 2020 Jan 15;143:462-471.
- Reproductive Biology of Albacore Tuna (Thunnus alalunga) in the Western Indian Ocean. PLoS One . 2016 Dec 21;11(12):e0168605.
- Connectivity and population structure of albacore tuna across southeast Atlantic and southwest Indian Oceans inferred from multidisciplinary methodology. Sci Rep . 2020 Sep 24;10(1):15657.
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Leopard Gecko: Description, Habitat, & Facts
Continue ReadingLeopard Gecko
Leopard Gecko is ground-dwelling reptiles belong to the genus Eublepharis and come under the order Squamata. These geckos live a solitary life and have an average lifespan of 15 years.
They reside in dry rocky grasslands and weigh around 54 to 65 grams. This genus comprises 3-5 species that are commonly found in Asia and the Middle East. The leopard gecko has been adapted as a pet by many and maybe the first lizard species to be domesticated.
The species include E. macularius commonly known as leopard gecko, E. fuscus known as West Indian leopard gecko, and E. turcmenicus, known as East Indian leopard geckos.
Leopard Gecko Physical Description
The genus is named for the fully functional eyelids present in the species they comprise. These sturdy small lizards are referred to as leopard geckos due to the presence of spotted patterns in shades of brown and yellow.
They possess long tails that are the same length as their torso. They use their tails to evade predators and later regenerate them. The regenerated tail would be less symmetrical and may be shorter than the original tail.
The adult length measures up to 20.5-27.5 cm and they have tough bumpy skin around their neck, back, and head. They also shed their skin as they grow. The sexes have subtle differences and can be segregated only on close inspection of their undersides.
Leopard Gecko Range, Habitat, and Behavior
They are native to the Middle East and southwestern and eastern Asia where they dwell in rocky grasslands. During the day they often live in burrows on the ground to escape the heat and are commonly nocturnal.
They have strong eyesight that helps them to hunt insects at night. They ambush small insects like mealworms, crickets, and caterpillars. Their predators are reptiles like snakes and foxes and other mammals.
These predators also eat their eggs. They employ their sense of sight and hearing to avoid predation. They camouflage well with their surroundings and may utilize this to hide from their predators.
Burrowing helps them not only to stay cool but also to avoid their predators. There is not enough information on their interactions with other members but they do come together for mating.
In the wild, they abide in loose colonies but live a solitary life. Whereas in the case of captivity also they usually are kept alone.
Leopard Gecko Reproduction
Breeding occurs in the summer months in the wild. The females store sperms and produce 2 eggs at a time, and they may lay about 20 eggs in a period of one month. After 3 to 4 weeks of copulation, the first eggs are laid.
The incubation period of eggs may vary due to factors like humidity and temperature; they typically require about 30 to 90 days for the young to hatch. The young ones on hatching weight only 3 gram and has a length of 6.5 to 8.5 cm.
They are independent from the moment they hatch. The sex of the young is determined by temperature as in other reptiles. The temperature of their environment during incubation determines their sex.
At around 26-29°C that is in colder temperatures, more females will be produced. While in case of warmer temperatures more males are produced. This process of temperature determinant sex determination happens in the first 2 weeks after an egg is laid.
Fun Facts about Leopard Gecko!
These beautiful lizards are docile geckos. In recent times there is an increasing trend of adopting them as pets as they are not large or venomous. They exhibit various interesting characteristics.
They cannot climb well like other geckos this can be attributed to their size and shape. They also do not have adhesive lamellae that help other geckos to cling to smooth vertical walls or surfaces. The fact that leopard geckos enjoy hot, dry conditions is a misconception that may arise due to the ranges they occur in.
They are usually found in dry hot regions like Afghanistan. They are adapted to such conditions for their survival in these regions. They often inhabit the coolest regions of the range like rocky grasslands and may prefer them over desert plains.
But this becomes disadvantageous for the geckos during winter months when they come close to near freezing conditions. During such times they enter brumation after moving in their burrows.
Brumation is the state of semi-hibernation that utilizes a similar hibernation as seen in cold animals but differs in terms of their metabolism processes. Before going into brumation, the gecko will try to increase their fat reserve stores. During the winter months, they burrow deep and live there without food for months.
They the temperature increases then they may wake up sometimes, to drink some water. They unlike hibernating mammals are influenced by ambient temperature changes.
This species is a common pet species with approximately 3 million individuals bred in the United States itself. They also have more color morphs due to selective breeding than their wild species.
Leopard Gecko Citations
- Constitutive cardiomyocyte proliferation in the leopard gecko (Eublepharis macularius). J Morphol . 2018 Sep;279(9):1355-1367.
- The nocturnal leopard gecko (Eublepharis macularius) uses UVb radiation for vitamin D 3 synthesis. Comp Biochem Physiol B Biochem Mol Biol . 2020 Dec;250:110506.
- The tongue of Leopard Gecko (Eublepharis macularius): LM, SEM and confocal laser study. Anat Histol Embryol . 2020 Jan;49(1):51-59.
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Non-Coding DNA: Definition, Function, and Structure
Continue ReadingNon-Coding DNA: Definition, Function, and Structure
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Sea Otter: Description, Habitat, & Facts
Continue ReadingSea Otter Definition
Sea Otter is a endangered otters belong to the genus Enhydra and come under the order Carnivora. These marine predators may weigh up to 14-45 kg. They are found in offshore and coastal marine habitats along the west coast of North America.
They are also the smallest marine mammals that due to hunting have become endangered and exist in only a small fraction of their original historic range.
What is Sea Otter?
Sea Otter are medium-sized mammals that are members of the family Mustelidae. Sea otters are the largest of this weasel family and are the only members who do not partake in burrowing.
They have brown fur with shades of lighter tan and yellow on the adult heads. They possess small black eyes, small ear flaps, and long whiskers. One of its adaptations includes its nostrils that they can close during long dives and broad long webbed hind feet that make them efficient swimmers.
Their clawed short front paws equipped with pads help in gripping the slippery prey targets. They also have sharp pointed front teeth as other mammals that aid in tearing and slicing their food apart and their round flat molars help them grind and crush the food. These adaptations help these mammals to survive in marine habitats.
Sea Otter Distribution
They are ubiquitous along with the range from Alaska to Mexico. Their historic range extended even across North Pacific to Japan and Russia. They were endangered due to the increased demand for their fur in the 1740s, which nearly drove them to extinction.
They prefer the coastal waters, though some may be found offshore as well in this range. They dwell in sheltered regions that provide them protection from extreme ocean winds. They spend their whole life in water that makes them distinct from other weasel family members.
Sea Otter Diet and Predators
These carnivorous predators prey on sea urchins and are usually diurnal according to their foraging pattern. They normally forage in the early morning, late afternoon, and even around midnight. They rest during the middle of the day and night.
They forage on the seafloor by diving up to 100 ft depth. They also feed on crustaceans like crabs, mollusks, and sometimes even fish. They feed primarily on sea urchins in abundance till they stain their teeth purple.
Their predators include sea lions and orcas. Eagles may also prey on young otters. Pups are also vulnerable to predators like coyotes and bears. Though white sharks overlap some parts of their ranges there is no evidence that they prey on them.
Sea Otter Reproduction
They exhibit polygyny where the males have multiple partners. They breed throughout the year and the phenomenon of delayed implantation is also seen in them. This delay permits them to give birth in favorable conditions and can also be influenced by the presence of alternate males.
The females give birth to one pup at a time following a gestation period of 6 months. These pups till the age of 2 months, stick around their mothers and will often ride on their backs. The pups start to dive and catch their own food around 2 months.
Females will nurse them for another 3 more months. They attain sexual maturity at 3 to years and males often mature 1-2 years later or slower than females.
Sea Otter Conservation
They had a large range in historical times and were up to 300,000 in number. They were poached extensively in the colonial era generally for their pelt during 1741 to 1911 due to which their numbers dropped to over 1000 and their range was also significantly reduced. As a result of the protective conservation measures, their numbers inclined again to approximately two-thirds of their original range.
Fun Facts about Sea Otter!
They have charismatic personalities and appearance due to which they are gaining popularity. Their importance that was once limited to a pelt has since then emerged as an important keystone species.
i. Thick Fur
They have dense fur where up to 150,000 hair follicles are present per square centimeter that makes them the densest in all animal kingdoms. This may be one of the reasons why their fur was so valued in the colonial period.
The fur comprises waterproof long guard hairs that are spotted over their shorter underfur that keep the waterway from their skin. They only need their fur for keeping warm and no fat layer like other marine mammals are required.
ii. Regulators
They as a keystone and predator species check the population of organisms they feed on. In their absence, the sea urchins may overtake the kelp. This leads to wasting away from sea kelp forests that are significant as they provide habitat for various species and are also the nursery for commercially fished species. The presence of sea otters helps in avoidance of such situations and thus maintain the kelp forest.
iii. Tool Time
They are intelligent organisms that make powerful foragers. They can employ tools like rocks to dislodge their feed like mollusks from the substrate.
Sea Otter Citations
- Aquatic Adaptation and Depleted Diversity: A Deep Dive into the Genomes of the Sea Otter and Giant Otter. Mol Biol Evol . 2019 Dec 1;36(12):2631-2655.
- Wild sea otter mussel pounding leaves archaeological traces. Sci Rep . 2019 Mar 14;9(1):4417.
- Prolonged recovery of sea otters from the Exxon Valdez oil spill? A re-examination of the evidence. Mar Pollut Bull . 2013 Jun 15;71(1-2):7-19.
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Levator Scapulae: Definition, Anatomy, & Examples
Continue ReadingLevator Scapulae Definition
Levator Scapulae comprises a strap-like muscle also called lev scap that is found on the back of the neck on either side. A posterior view makes them difficult to observe as they are hidden by the trapezius muscles which are also present in the back.
These 2 muscles originate from the back of the neck and from either side they descend towards the upper back and shoulders. They primarily function to rotate shoulders and to elevate them. Any dysfunction or shoulder, neck, or back pain may be lead to tightness in these muscles.
What is Levator Scapulae?
Levator Scapulae muscles have their origin from posterior bony projections or tubercles of the cerebral vertebrates: C1, C2, C3, C4. This muscle is inserted towards the superior broad part of the medial border of the scapula or shoulder blade from the superior angle to the inner triangular cavity.
These are supplied by dorsal scapular nerves and the nerves of the cervical plexus (C3-C5). The former emerges from the root of C5 of the branchial plexus and innervates 3 muscles: rhomboid major, the levator scapulae, and the rhomboid minor.
Anatomic Variation in Levator Scapulae
The attachments in this muscle are variable in different individuals. Research has revealed the presence of other potential accessory attachment sites where it can also be inserted like the muscles of serratus posterior superior, muscles in the upper back, and the upper ribs and their associated muscles.
These variations in attachments may be the cause of inflammation and pain as they also impact the function of these muscles.
Levator Scapulae Function
The name of this muscle is derived from its function that is the movement of the scapula and the shoulders. The contraction of these muscles helps in elevating or raising the shoulders that can be usually seen when we shrug our shoulders. It also regulates the downward rotation of the shoulder wherein the scapula move downwards.
This movement can follow the elevation of the arms and brings the arms to arrest position as in simple exercises. So, to summarize the basic movement of arms is brought about by 2 rotations, the downward and the upward rotation.
Elevating arms require upward rotation while bringing them down requires downward rotation. If the shoulders are pushed towards each other from the posterior side, then they come together and results in a posture where the chest sticks outside.
This movement is referred to as adduction and is also a function of the levator scapulae. For these functions or movements, these muscles also require the aid of accessory muscles like the trapezius, pectoralis minor, and the major and minor rhomboids.
Levator Scapulae Associated Pain
Overworking of these muscles can result in inflammation and pain that is also a common issue that the majority of people face when they complain of skeletal muscle pain. Slumping over or frequent elevation of shoulders can result in tightness and inflammation.
This might be common in people who work in desk jobs often involving computer work. To avoid this the chairs and desk should be ergonomically designed. This is also vulnerable for people who have a head forward posture or in individuals who usually carry a heavy weight on one side of their shoulders and in people who engage in repetitive arm movement requiring sports or activities like shot putters, tennis players, and swimmers.
The resultant pain may be felt in the areas surrounding this muscle like the shoulders, neck, shoulder blades, and upper back or directly in the muscle itself.
This tightness or inflammation can cause dysfunctions in the movement of the shoulders and even in cervical structures and can even cause cervicogenic headaches. The cause of these pain issues can be tracked to the manipulated insertion points of this muscle.
The pain and chronic inflammation experienced in this muscle are known as levator scapulae syndrome, a historic term of this medical condition.
Levator Scapulae and Myofascial Pain Syndrome
This kind of pain is associated with the trigger or pressure points of the muscles. The overuse of any muscle or other associated muscles can result in the development of hypersensitive regions that are tight.
For example, strenuous exercises or training practices in sports activities may cause repetitive contractions of muscles. One of the common sites of these pressure points is the levator scapulae muscle.
The worsening of these pressure points leads to the development of myofascial pain syndrome. The pathology of this disorder is unclear and is suggested as a subtype of fibromyalgia.
Levator Scapulae Treatment
The symptoms can be treated and reduced by physiotherapy and massage that decreases the tightness, pain, and inflammation to an extent. Further, the overuse of muscles should be avoided by doing stretching exercises that help in the relaxation of muscles and prevent them from becoming taunt.
If the pain is not relieved by these steps then the patient may be advised to take local steroid injections into the pressure points.
Levator Scapulae Citations
- Anatomic variations of levator scapulae in a normal cohort: an MRI study. Surg Radiol Anat . 2017 Mar;39(3):337-343.
- Morphometric properties of the levator scapulae, rhomboid major, and rhomboid minor in human fetuses. Surg Radiol Anat . 2018 Apr;40(4):449-455.
- Low-grade myofibroblastic sarcoma of the levator scapulae muscle: a case report and literature review. BMC Musculoskelet Disord . 2020 Dec 10;21(1):836.
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Zygomatic Arch: Definition, Process, & Examples
Continue ReadingZygomatic Arch Definition
Zygomatic Arch also known as cheekbone, it refers to the parts from both temporal bone and zygomatic process that forms an arch. The zygomatic process is the extension of the temporal bone that attaches through a process to the zygomatic bone. This results in the formation of a tunnel by the 2 extensions through which tendon and muscles can pass.
What is Zygomatic Arch?
This feature is observed in all synapsids that have a hole in the temporal bone known as temporal fenestra. This hole was apparent and clearly distinct in ancestral mammal-like reptiles, while in modern mammals it molds with the eye orbit.
In humans and other primates, the eye sockets do not connect directly with the zygomatic arch. This arch helps in providing attachment points to several types of tissue of the skull. The hole permits the passage of the temporalis muscle and other associated tendons to pass under this arch and attach to the mandible bone of the skull.
The tendons of the temporalis muscle are linked to a small extension of the mandible known as the coronoid process that is tucked under the zygomatic bone. The masseter muscle which comprises a large muscle responsible for the movement of the jaw is attached directly to the large part of the mandible and the zygomatic arch.
This muscle is primarily involved in all jaw movements and the temporalis muscle aids in providing the extra tension required to mash, chew or grind food. The zygomatic arch and the linked structures help in providing attachment points for these muscles due to their large surface area.
"Zygomatic Arch also known as cheekbone"
Whenever we are chewing our food, we can feel the action of both these muscles. If fingers are laced between the eye and the ear and then during chewing the hard bone can be noticed.
The masseter muscle flexes on the bottom area while the temporal muscle flexes and produces a bulge above the zygomatic arch, during chewing of food. Chewing is a complex process that requires both these muscles.
This occurs only in mammals, whereas in other animals like lizards or birds, their size of the mouth is limited that also restricts the type and size of the food they can ingest. Sharks and other certain organisms have sharp teeth that they employ to cut the prey into huge chunks but even these are not chewed but rather swallowed.
In mammals, the presence of a zygomatic arch helps them to grind and chew their food. This not only enhances the rate of digestion but also expands their diet.
Zygomatic Arch Citations
- Using the zygomatic arch as a reference line for clinical applications and anthropological studies. Surg Radiol Anat . 2019 May;41(5):501-505.
- Zygomatic Arch Parosteal Osteosarcoma in Dogs and a Cat. Vet Pathol . 2019 Mar;56(2):274-276.
- Osteochondroma of the Zygomatic Arch: A Case Report and Review of the Literature. J Oral Maxillofac Surg . 2018 Sep;76(9):1912-1916.
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Miosis: Definition, Causes, & Examples
Continue ReadingMiosis Definition
Miosis implies constriction of the pupil and is also called myosis. This medical term pertains to the action of small eye muscles that helps in closing or constriction of pupils. This can be a response to the altering light intensity of the environment that requires reducing the amount of light entering the eyes.
Various recreational and medicinal drugs can also cause miosis. It can serve as a diagnostic symptom for impaired driving and can be a reason for the arrest. The term can be confused with terms for cell division like meiosis and mitosis.
Miosis Causes
Miosis results due to the local actions of contraction and relaxation of 2 muscles present in the iris of the eyes. Iris seen under the protective cornea represents the colored part of the eyes. The size of the pupil is regulated by the iris sphincter and iris dilator muscles that cause miosis are the relaxation and contraction of two muscles in the iris of the eye.
Pupils regulate the amount of light entering the eyes that will pass through the lens and will be focused on the retina. The retina contains specialized cells that help to detect light signals that are then sent as signals to optic nerve and then finally to the brain.
The photosensitive ganglions are the specialized cells in the eyes that sense the intensity of light received by the eyes. They signal the brain and the ANS through the optic nerve.
The ANS then based on the input received will continually automatically adjust the pupil size. If the light intensity entering the eyes and hitting the retina is high then miosis will happen, resulting in constriction of pupils.
During this process, the iris sphincter muscle will contract, and simultaneously the iris dilator muscles relax. This will cause constriction of pupils and to reduce the amount of light entering the eyes.
If pupils are constricting too much then again the ganglion will deduce then signal the brain leading to dilation of muscles and is called mydriasis.
Miosis Features
There can be various factors affecting and causing miosis. There is a complex pathway involved in this pathway that engages different regions of the brain and many neurons and chemicals. This pathway can be influenced or impaired by drugs like antipsychotic medications, nicotine, eye drops, and opioids.
Some of these chemicals may result in anisocoria, a condition where mydriasis occurs in one eye and miosis in the other. The alterations in light intensity caused by various recreational drugs can contribute to altered perception.
Diseases or nerve tissue degeneration may also cause miosis. Miosis can be observed in other animals besides humans, though the mechanism to regulate the quantity of light entering the eyes may differ.
Only 2 groups of animals have developed complex eyes, the cephalopods, and the vertebrates. The structure of eyes may differ as they rose from convergent evolution due to similar selection pressures.
Miosis Citations
- Posttraumatic headache with ptosis, miosis and chronic forehead hyperhidrosis. Headache . 1990 Jan;30(2):64-8.
- Ptosis and Miosis Associated with Fibrosing Mediastinitis. Am J Case Rep . 2021 Jan 12;22:e927556.
- Opioid-induced Miosis Is Unaltered by Obstructive Sleep Apnea: Comment. Anesthesiology . 2020 Feb;132(2):399-400.
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Lysogenic Cycle: Definition, Steps, & Examples
Continue ReadingLysogenic Cycle Definition
Lysogenic Cycle demonstrates a method utilized by viruses to replicate its genome using the host cell molecular machinery.
What is Lysogenic Cycle?
A virus can generally undergo 2 types of replication, the lytic cycle or the lysogenic cycle. In the case of the lysogenic cycle, replication is the main aim as the DNA is replicated but gene products are not expressed.
Whereas in the lytic cycle, the DNA replicates several times and proteins are translated utilizing the host’s machinery. The lysogenic can be usually observed in bacteria or prokaryotes and is also seen in eukaryotes.
A bacteriophage injects its genetic material into its host that is bacteria. The DNA may incorporate into the genetic material of the bacteria and whenever the bacterial cell would divide then the viral DNA would also be replicated using the same molecular machinery of the cell.
It does not alter the molecular processes rather it utilizes them. The quantity of viral DNA produced is less and the machinery is not hijacked as in the lytic cycle. Even though the viral DNA lays latent for some, it can employ the host cell to replicate its DNA through the lysogenic cycle without requiring any effort.
In favorable conditions, the viral DNA may be induced and then it moves to the lytic cycle. Then the viral DNA is transcribed and translated to produce protein coats that are needed to carry the genetic material of the virus.
When the bacteria becomes full of these virions, then they may lyse releasing these intracellular viruses that are ready to infect another host. The lysogenic cycle may continue if conditions are not suitable for the lytic cycle.
This dormant bacterial cell replicates the viral DNA and continues doing so till the lytic cycle is activated. This bacteria that is undergoing a lysogenic cycle may look healthy to an observer.
Lysogenic Cycle Steps
Step 1: The bacteriophage virus injects its DNA into the bacteria that would serve as its host into the cytoplasm, or intermembrane space between the cell wall. This viral DNA integrates into the host genome and is now known as prophage.
Step 2: The viral DNA replicates when the bacterial cell divides and does not have any additional proteins.
Step 3: The viral DNA may continue in the lysogenic cycle, or if conditions are favorable it may switch to the lytic cycle. In the lysogenic cycle, many copies of viral DNA occur in the bacterial cell as the viral DNA is replicated along with the bacterial DNA.
Step 4: When the viral DNA switches to lytic cycle, they employ the host’s machinery to produce the viral proteins required in their assembly and then the virus are packaged.
Step 5: These newly formed temperate viruses are released by the lysis of the cell and they are ready to infect other hosts. After infecting they can start the lysogenic cycle again. If the host condition is not great then they opt for the lytic cycle.
Lysogenic Cycle Citations
- Differential expression of cro, the lysogenic cycle repressor determinant of bacteriophage A2, in Lactobacillus casei and Escherichia coli. Virus Res . 2014 Apr;183:63-6.
- The lysogenic cycle of the filamentous phage Cflt from Xanthomonas campestris pv. citri. Virology . 1987 Feb;156(2):305-12.
- Lysogenic versus lytic cycle of phage multiplication. Cold Spring Harb Symp Quant Biol . 1953;18:65-70.
- Modulation of Lactobacillus casei bacteriophage A2 lytic/lysogenic cycles by binding of Gp25 to the early lytic mRNA. Mol Microbiol . 2016 Jan;99(2):328-37.
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