The stapes or stirrup is a bone in the middle ear of humans and other mammals which is involved in the conduction of sound vibrations to the inner ear. This stirrup-shaped bone is connected to the oval window by its annular ligament, which allows the footplate to transmit sound energy through the oval window into the inner ear. The stapes is the smallest and lightest bone in the human body, and is so-called because of its resemblance to a stirrup ().
Introduction
Stapes
Stapes | Introduction
Middle ear of humans In middle ear. Middle ear In the middle ear.
what are the 3 smallest bones in the human body
user
Strapes is one of them
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what is the size of this above bone?
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Roughly 3 x 2.5mm
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which part of the body is this located?
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The stapes is the third bone of the three ossicles in the middle ear. The stapes is a stirrup-shaped bone, and the smallest in the human body. It rests on the oval window, to which it is connected by an annular ligament. The stapes is described as having a base, resting on the oval window, as well as a head that articulates with the incus. These are connected by anterior and posterior limbs (). The stapes articulates with the incus through the incudostapedial joint. The stapes is the smallest bone in the human body, and measures roughly 3 x 2.5mm, greater along the head-base span.
Stapes | Structure
The stapes or stirrup is a bone in the middle ear of humans and other mammals which is involved in the conduction of sound vibrations to the inner ear. This stirrup-shaped bone is connected to the oval window by its annular ligament, which allows the footplate to transmit sound energy through the oval window into the inner ear. The stapes is the smallest and lightest bone in the human body, and is so-called because of its resemblance to a stirrup ().
Stapes | Introduction
The stapes is commonly described as having been discovered by the professor Giovanni Filippo Ingrassia in 1546 at the University of Naples, although this remains the nature of some controversy, as Ingrassia's description was published posthumously in his 1603 anatomical commentary '. Spanish anatomist Pedro Jimeno is first to have been credited with a published description, in ' (1549). The bone is so-named because of its resemblance to a stirrup (), an example of a late Latin word, probably created in mediaeval times from "to stand" (), as stirrups did not exist in the early Latin-speaking world.
Stapes | History
The stapes is one of three ossicles in mammals. In non-mammalian four-legged animals, the bone homologous to the stapes is usually called the columella; however, in reptiles, either term may be used. In fish, the homologous bone is called the "hyomandibular", and is part of the gill arch supporting either the spiracle or the jaw, depending on the species. The equivalent term in amphibians is the "".
Stapes | Animals
The largest bone in the body is the femur or thigh-bone, and the smallest is the stapes in the middle ear.
Bone | Introduction
The stapes develops from the second pharyngeal arch during the sixth to eighth week of embryological life. The central cavity of the stapes, the obturator foramen, is due to the presence embryologically of the stapedial artery, which usually regresses in humans during normal development.
Stapes | Development
Situated between the incus and the inner ear, the stapes transmits sound vibrations from the incus to the oval window, a membrane-covered opening to the inner ear. The stapes is also stabilized by the stapedius muscle, which is innervated by the facial nerve.
Stapes | Function
The stapedius emerges from a pinpoint foramen in the apex of the pyramidal eminence (a hollow, cone-shaped prominence in the posterior wall of the tympanic cavity), and inserts into the neck of the stapes.
Stapedius muscle | Structure
It is occupied by the base of the stapes, the circumference of which is fixed by the annular ligament to the margin of the foramen.
Oval window | Introduction
Surgery may be complicated by a persistent stapedial artery, fibrosis-related damage to the base of the bone, or obliterative otosclerosis, resulting in obliteration of the base.
Stapes | Clinical relevance
The morphology of the stapes suggests that the animal was capable of hearing high-frequency sound. "B. woodi" does not possess lateral line sulci or an ossified branchial system. The principal method of respiration was probably buccal (gulping air through mouth) rather than costal (expanding chest volume to take in air), indicated by the small straight ribs.
Balanerpeton | Introduction
For example, the lower branch of the squamosal bone is shortened to offset the tall dorsal process of quadratojugal which connects to it. On the other hand, the rear branch jugal bone lengthens to fill some of the space left by the shortening of the anterior process of the quadratojugal. In archosauriforms, the jugal even re-encloses the lower temporal fenestra. The stapes are long, thin, and solid, without a perforating hole (stapedial foramen) present in the more robust stapes of other reptiles.
Archosauromorpha | Skull
The stapedius is the smallest skeletal muscle in the human body. At just over one millimeter in length, its purpose is to stabilize the smallest bone in the body, the stapes.
Stapedius muscle | Introduction
Scapes up to 15 cm tall bearing 4-10 bell-shaped magenta flowers.
Allium narcissiflorum | Introduction
The bony palate is short, with its posterior end often located between the third molars. The alisphenoid strut, an extension of the alisphenoid bone of the skull that separates two foramina (openings) in the skull, is present in some individuals. The mastoid bone usually contains some openings. In the holotype, the head and body length is 130 mm, the tail length is 160 mm, the hindfoot length (without claws) is 31 mm, the ear length is 27 mm, and the skull length is 35.7 mm.
Nephelomys levipes | Introduction
These are the most unusual of the braincase bones, and were previously misidentified as stapes. While they are not stapes, it is difficult to be certain what they are. As mentioned, they are sutured to the tubera basioccipitalia, and so could not have moved freely, meaning that they were not bones for the transmission of sound in this manner. Medially, they are sutured to the posterodorsal margins of the tubera basioccipitalia by a strongly serrate and partially intergrown suture. The posterior surface of this forms a steeply inclined trough running from the suture to the distal extremity of the paraoccipital process.
Phantomosaurus | Opisthotic bones
The configuration of the stapes is intermediate between non-amniote tetrapods and amniotes. On the one hand, its connection to the otic notch is unusual, since true reptiles and other amniotes have lost an otic notch, forcing the tympanum and stapes to shift downwards towards the quadrate bone of the jaw joint. On the other hand, the thin, sensitive structure of "Seymouria"'s stapes is a specialization over most non-amniote tetrapods, which have a thick stapes useless for hearing yet useful for reinforcing the skull. The inner ear of "Seymouria baylorensis" retains a cochlear recess located behind (rather than below) the vestibule, and its anterior semicircular canal was likely encompassed by a cartilaginous (rather than bony) supraoccipital.
Seymouria | Skull
The hindwing of an average adult is generally 30 mm or larger.
Tonyosynthemis claviculata | Body
The area below the cell to the inner margin and to near the termen has rather long hairs.
Syllepte berambalis | Introduction
The stapes appears to be relatively constant in size in different ethnic groups. In 0.01-0.02% of people, the stapedial artery does not regress, and persists in the central foramen. In this case, a pulsatile sound may be heard in the affected ear, or there may be no symptoms at all. Rarely, the stapes may be completely absent.
Stapes | Variation
The scapes are short, measuring , and the pedicel (the second segment of the antenna) is The flagellomeres vary in length, ranging between . The clypeus is shallow and measures (when excluding the denticles). It is broad, and the distance between its lateral-most denticles is . It is also more concave-shaped than it is straight. The oral margin of the clypeus is lined with a row of 30 denticles, which are peg-shaped. They also have rounded apices. The row of clypeal margin denticles is composed of two short rows. Each row is composed of 15 denticles each. The mandibles are short and barely overlap medially.
Zigrasimecia | "Z. tonsora"
A dark red zone borders the suture, and a broader and browner band surrounds also the middle of the body whorl.
Nassarius stolatus | Description
The outer area is rufous and there is a submarginal dentate line with dark marks on it.
Streptoperas crenelata | Introduction
Scattered hairs cover the body. Just in front of the anus there is in Chaetosorna a double, and in Tristicochaeta a triple row of about fifteen stout cylindrical projections upon which the animals creep. The females are a little larger than the males; in Ch. claparedii the former attain a length of 1.5 mm., the latter of 1.12 mm. The mouth opens into an oesophagus which passes into an intestine; this opens by a ventral anus situated a little in front of the posterior end. The testis is single, and its duct opens with the anus, and is provided with a couple of spicules.
Chaetosomatida | Introduction
A much more detailed description of the first two ossicles followed in Andreas Vesalius' "De humani corporis fabrica" in which he devoted a chapter to them. Vesalius was the first to compare the second element of the ossicles to an anvil although he offered the molar as an alternative comparison for its shape. The first published description of the stapes came in Pedro Jimeno's "Dialogus de re medica" (1549) although it had been previously described in public lectures by Giovanni Filippo Ingrassia at the University of Naples as early as 1546. The term "ossicle" derives from , a diminutive of "bone" (; genitive ).
Ossicles | History
The stapes, the bone transmitting sound waves from the eardrum to the middle ear, is elongated and not pierced by a foramen. Pterygoid teeth are typically lacking.
Ichthyosaur | Skull
The clypeus is setose, meaning that it bears bristles or setae, except on the middle part. The mandibles are small and only contain two teeth. The antennae are moderately long, the scapes are very short but the pedicel is even shorter. The mesosoma measures and is setose. Several setae are seen around the metanotum (the dorsal sclerite) and propodeum. The coxae, the proximal segment and functional base of the leg, are setose (bearing bristle or setae), inflated and large. The metapleural gland opening is small and noticeable, located away from the propodeum and above the metacoxa (the hind of the coxa).
Sphecomyrma | "S. mesaki"
The length of the body varies between 5 mm and 14 mm.
Verconia simplex | Description
Above is a small process or fulcrum — the point at which the two plates are articulated. Immediately behind this point there is the dorsal margin of the plates is reflected and expanded into an arched lobe for muscular attachment. The length of the jaw is 2.8 mm. The maximum width and maximum height of the jaw is 1.3 mm.
Fiona pinnata | Digestive system
This species is likely now extinct.
Theliderma stapes | Conservation
The bursa of fabricius is a circular pouch connected to the superior dorsal side of the cloaca . The bursa is composed of many folds, known as plica, which are lined by more than 10,000 follicles encompassed by connective tissue and surrounded by mesenchyme. Each follicle consists of a cortex that surrounds a medulla. The cortex houses the highly compacted B lymphocytes, whereas the medulla houses lymphocytes loosely. The medulla is separated from the lumen by the epithelium and this aids in the transport of epithelial cells into the lumen of the bursa. There are 150,000 B lymphocytes located around each follicle.
Bird anatomy | Anatomy
Otosclerosis is a congenital or spontaneous-onset disease characterized by abnormal bone remodeling in the inner ear. Often this causes the stapes to adhere to the oval window, which impedes its ability to conduct sound, and is a cause of conductive hearing loss. Clinical otosclerosis is found in about 1% of people, although it is more common in forms that do not cause noticeable hearing loss. Otosclerosis is more likely in young age groups, and females. Two common treatments are stapedectomy, the surgical removal of the stapes and replacement with an artificial prosthesis, and stapedotomy, the creation of a small hole in the base of the stapes followed by the insertion of an artificial prosthesis into that hole.
Stapes | Clinical relevance
As of 2008, it was located at an angular separation of from the primary.
16 Lacertae | Introduction
The squamous part of occipital bone, is situated above and behind the foramen magnum, and is curved from above downward and from side to side.
Squamous part of occipital bone | Introduction
The dorsal process of the stapes in "Theriognathus" is greatly reduced or entirely absent. The dentary is short, shaped like a banana, and continuously tapers anteriorly to a narrow edge. The dentarys’ lateral surface is smooth. The posterodorsal terminal end of the coronoid process is more rounded, and the dorsal extent terminates below the middle of the orbit in adults. The postdentary bones are reduced to form a free standing coronoid process. The reflected lamina is spade shaped and does not extend below the dentary The area between left and right dentaries remains relatively long and narrow just posterior to symphyseal region.
Theriognathus | Lower jaw
Nudibranchs vary in adult size from .
Nudibranch | Anatomical description
Males have a body about 13 mm long, females about 19 mm long.
Zorodictyna oswaldi | Introduction
The part of the skeleton that is ‘tucked under’ (the doublure) has no sutures crossing it to form a rostral plate.The thorax has 11 (rarely 10) segments, the side lobes (or pleurae) are furrowed, and the articulating facets distinct.
Phacopina | Description
It is divided into the following parts: Two sphenoidal conchae are situated at the anterior and inferior part of the body.
Sphenoid bone | Structure
Neck: Shoulder: Vertebral column: Knee
Accessory bone | Other locations
The species are 8–20 mm. in length. Ratio of body length to greatest body width 2.5–4.55. Body slightly flattened to moderately convex. Sides of body not evenly curved. Body not capable of conglobation (rolling into a ball). Upper surfaces of body clothed with distinct hairs, setae or scales. Vestiture of upper surfaces not including stiff, erect, dark bristles; not including scales or scale-like setae. Upper surfaces of body without deep foveae. Prothorax, metathorax and-or abdomen without extrusible glands. Underside of body without hydrofuge surface(s).
Cebrionini | General
freyi". The width and length of the head are the same at and the scapes measure The length of the mesosoma varies in the holotype and paratype, ranging from .
Sphecomyrma | "S. canadensis"
The shape of the body is elongate and narrow. Rhinophoral sheaths are elevated with an irregular edge. Cerata are relatively short and branched. Edge of the oral veil is with relatively long appendages. Rhinophores are long and branched. Background color is translucent gray with a distinctive reticulate network of opaque white across the dorsum. It is up to 11 mm long.
Tritonia bayeri | Description
The gyne is notably larger than the worker, at approximately long, and has a head that is wider than long when the mandibles are excluded. Also unlike the worker, the eyes are placed at the midpoint of the head, though they are small as the workers are. There are a number of denticles along the chewing margin on the large triangle shaped mandibles. While the scape extends beyond the back of the head, its total length is less than that of the head.
Paraneuretus | "P. dubovikoffi"
The ossicles are suspended in the head and loosely coupled to the skull. When the head moves, the ossicles move out of phase with the head, but still follow the same cyclic motion. This causes the stapes to move in and out of the oval window. When vibrations come from the mastoid, inertial bone-conduction is greatest below 800 Hz. Putting the bone vibrator on the forehead instead of the mastoid does not significantly create this affect.
Bone conduction auditory brainstem response | Inertial bone-conduction
The clypeus is distinctly divided into three sections, the large median area and two lateral sections. The lateral strips are narrow, running from the mandible bases up the sides of the median lobe. The median area is slightly rectangular, with the front edge flaring a little past the front edges of the lateral sections. along the back edge it is bordered by the two frontal ridges and the antennae sockets. The antennae have widened flat scapes that reach between towards the back of the head, but not past it. The upper end of the scape has an uneven top with a divot possibly for the base of flagellum when it was at rest.
Bradoponera | "B. meieri"
The length of the body is up to 5–6 cm. The dorsal part of the head and foot is dark brown in color. The ventral parts are creamy white in color. The eye tentacles are long, and the eye spots are large.
Quantula striata | Anatomy
The rostrum reaches to or slightly beyond the end of the antennular peduncle, failing to reach the tip of the scaphocerite. It is straight, with the tip directed slightly upward. The upper margin bears nine or ten teeth, four of which are placed behind the orbit, the others are concentrated in the basal two-thirds of the rostrum. A small epigastric tooth is present on the dorsal margin of the carapace. In its proximal half the rostrum is of almost uniform height, in the distal half it narrows to the acute tip. A slightly larger immovable hepatic spine is placed below and a considerable distance behind the antennal.
Periclimenes pholeter | Description
The head and segments of the antenna tend to be smaller in the holotype specimen while in the paratype they are slightly larger. The pubescence is short but scattered throughout the body, measuring . The colour of the specimens appears to be light-brown. The metapleural gland exhibits a notably wide and oval-shaped orifice, (openings into the body). The separation between the orifice and the posterior portion of the propodeum is twice the diameter than the orifice itself. The cuticle situated in the anterior portion (referring to what is in front) of the orifice is thinner in contrast to the cuticle surrounding the mesosoma, where it is notably transparent.
Sphecomyrma | "S. freyi"
In front of the clypeus, the bases of the long straight mandibles are placed close together. On the masticatory margin there are no denticles, with possibly three teeth present at the tip end of each mandible, though only two are visible. The thorax is slightly elongated, with a mesoscutum that is a little wider than long and attaching with no overhang of the sclerites to the propodeum. The petiole is rounded and narrow, without a spine on the upper surface.
Odontomachus paleomyagra | Description
The Stieda body is an organelle located at the polar region of the sporocyst of some coccidia visible with electron microscopy. It appears as a knob like structure and is a plug occluding a hole in the sporocyst. The breakdown of this body allows excystation of the sporozoites.
Stieda body | Introduction
An alisphenoid strut separates two foramina (openings) at the base of the skull, the buccinator-masticatory foramen and the foramen ovale accessorium. The pattern of grooves and foramina on the head indicates that the circulation of the arteries in the head of "T. ucucha" follows the primitive pattern. The tegmen tympani, the roof of the tympanic cavity, overlaps the suspensory process of the squamosal bone. At the back of the mandible (lower jaw), there is a capsular process to receive the root of the lower incisor, which is absent in "T. hylophilus".
Thomasomys ucucha | Description
The holotype measures in total length, whereas the other specimen is partly broken and measures . The body is wide. The body has 208–226 primary folds that are incomplete both above and below, except in the posterior part of the body. The eyes are present under bone. The tentacles are almost immediately below the nostrils. The head is whitish to light brown. The body is brown and vaguely variegated, except for the foremost one fourth that is violet brown. The venter is dull cream.
Oscaecilia hypereumeces | Description
Below it terminates in an acute or squarish narrow tooth. The parietal wall and the umbilicus are rugose, the latter bounded by a plicate-denticulate rib.
Clanculus maugeri | Description
This table lists the epithelia of different organs of the human body
Table of epithelia of human organs | Introduction
Typically, a member of this order was wider than it was long. In juveniles, there was a tiny hole at the animal's umbo for a stalk to emerge from. Tiny bumps cover the interior of the valves.
Strophomenida | Introduction
Commencing from behind [Fig. 2], that portion of the circumference of the great wing that extends from the body to the spine is irregular. In front of the spine the circumference presents a concave, serrated edge, bevelled at the expense of the inner table below, and of the outer table above, for articulation with the squamous part of the temporal bone. At the tip of the great wing is a triangular portion, bevelled at the expense of the internal surface, for articulation with the sphenoidal angle of the parietal bone; this region is named the pterion.
Greater wing of sphenoid bone | Margin
The scape is annular and much wider than it is long. It is the shortest segment. The pedicel is longer than scape, bearing conical sensorium on the distal surface near the outer rim, and a pair of pre-apical setae on the outer rim. The pedicel is slightly longer than the terminal segment. There are two longish setae projecting up from the pedicel. The antennae can be seen dorsally from the head capsule, but not dorsally from the entire body. The flagellum is dome-shaped with apical seta and several sensilla. The small, black, three stemmata (simple eyes) sit just behind the antennae at either end of the head capsule, wide apart from each other at approximately 10 times the width of the eye apart.
Bucolus fourneti | Head
A sacral length of around 6.5 is deduced. Dames observed 20 caudal vertebrae; Wellnhofer posits 21. Dames also noted the similarity in the long, rod-like structures of the tail to those in the flying pterosaur "Rhamphorhynchus", considering them to be ossified tendons. Thin, pointed cervical ribs begin at the third vertebra. The longest are about 50 mm and total eleven in number. Gastralia, or belly ribs, are arranged in 10 parallel rows and their position is suggested as evidence of post-mortem shrinking of the body. The scapulae are separated by about 17 mm and are flattened, narrow, and positioned much in their natural position.
Specimens of Archaeopteryx | Trunk
Beyond the cell, there is a straight transverse dark brown line running from beyond the middle of the costa to the middle of the inner margin, where it nearly touches the line crossing the middle of the cell. This is defined inwardly by a broad, pale grey shade. This line is followed by another straight transverse line running from the costa three fourths of the distance from the base to the inner margin two-thirds of the distance from the base, defined inwardly by a pale grey line, which is interrupted on the nervules by ochraceous dots, marking the origin of a regular series of markings which lie on the side toward the base with their points towards the base, which are dark brown shaded with pale grey toward the margin.
Striginiana nobilis | Introduction
General outline of the body is rounded the front third, parallel sided the middle third, and progressively tapering backwards in the back third, ending at an angle of approximately 45° with the midline. Headshield (or cephalon is approximately ⅝× as long as wide. The (in this case only slightly) vaulted central axis in the head or glabella tapers gently forward and does not reach the anterior margin. The outer backside of the cephalon (or genal angle) has short genal spines. The thorax has 17 or 18 articulating segments, maintaining width or widening slightly backward to 8th segment, then tapering posteriorly.
Buenellus | Description
The stapedius dampens the vibrations of the stapes by pulling on the neck of that bone. As one of the muscles involved in the acoustic reflex it prevents excess movement of the stapes, helping to control the amplitude of sound waves from the general external environment to the inner ear.
Stapedius muscle | Function
Body length 13,5-17 mm. Eyes of the male hairy, and those of the female without any yellow postocular collar. Tibiae and venter mainly black, the latter with pale bands. Abdomen dorsally with three pairs of small, yellow spots and the apex yellow or orange.
Stratiomys singularior | Description
Such structures include a shelf at the rear of the surangular and a thick articular bone which has a tall retroarticular process with an inner prong pierced by a "chorda tympani" foramen.
Prestosuchus | Skull
The pterion is located in the temporal fossa, approximately 2.6 cm behind and 1.3 cm above the posterolateral margin of the frontozygomatic suture. It is the junction between four bones: These bones are typically joined by five cranial sutures:
Pterion | Structure
Below the skull, the fossil shows a remarkable degree of articulation. The cervical vertebrae, for example, are all but one preserved in their natural pose. Analysis of these vertebrae led Dames to estimate a neck length of 60.5 mm. Later researchers postulated an additional vertebra and a slightly different measurement. This discrepancy is based on differing interpretations of the first two cervical vertebrae. Britt et al. (1998) observed lateral openings in these neck vertebrae and interpreted them as pneumatic foramina, suggesting a modern air sac system. The first eleven or twelve dorsal vertebrae bear ribs and these have a length between 5.5 and 7 mm with large neural spines.
Specimens of Archaeopteryx | Trunk
The tympanum is hidden, and the body is more or less laterally compressed, and covered with unequal scales. No dorsal crest is present; and a nuchal crest can be present or absent. No gular sac or gular fold is present. A large rostral appendage occurs, at least in the males. No femoral or preanal pores are found.
Ceratophora | Description
This creates two very typical, isolated slits. The exoskeleton of "Mesonacis" is about 2⅓× as long as wide, measured between the genal angles. The outer ⅓ of the back (or posterior margin) of the headshield (or cephalon) angles forwards from the tip of the pleural spine to the genal angle. The central area of the cephalon (or glabella) and the frontal margin touch or the distance is as long as the margin at most (in jargon: the preglabellar field is short or absent). The thorax has approximately 25 segments, the pleura about 1½× as wide as the axis, excluding the genal spines.
Mesonacis | Description
The stapes bone transmits movement to the oval window. As the stapes footplate moves into the oval window, the round window membrane moves out, and this allows movement of the fluid within the cochlea, leading to movement of the cochlear inner hair cells and thus hearing. If the round window were to be absent or rigidly fixed (as can happen in some congenital abnormalities), the stapes footplate would be pushing incompressible fluid against the unyielding walls of the cochlea. It would therefore not move to any useful degree leading to a hearing loss of about 60dB. This is, unsurprisingly, the same as for conditions where the stapes itself is fixed, such as otosclerosis.
Round window | Function
The strobili containing the reproductive structures may be quite long, reaching up to 9 centimeters.
Selaginella wallacei | Introduction
V-shaped) spinelet.
Delturinae | Introduction
In "Anoualerpeton priscus", the suprapalatal fossa lies in the medial edge of the external nasal opening. In "Anoualerpeton unicus", however, it lies further mediad, outside the border of the external nasal opening.
Anoualerpeton | Morphology
The arms are around half the length of the legs and over half the length of the presacral vertebral column. The hands are long, and tridactyl, with a reduced third finger in "Caudipteryx" and "Ajancingenia". There are between 5 and 8 sacral vertebrae. The pubis is vertical or subvertical, with a concave anterior edge. The tibia is 15%-25% longer than the femur. The tail is short, with the number of vertebrae reduced to 24 or so, and proximally very thick, with broad transverse processes. The ischium retains the primitive character of a prominent, triangular obturator process and lack the proximodorsal process that is found in birds.
Oviraptorosauria | Description
Close to the wrist, the ulna has a styloid process.
Ulna | Structure
The scapula forms the back of the shoulder girdle. In humans, it is a flat bone, roughly triangular in shape, placed on a posterolateral aspect of the thoracic cage.
Scapula | Introduction
The supraoccipital bone, the part of the braincase directly above the foramen magnum (the skull's opening for the spinal cord), is large and visible from above, but does not contact the parietals. The paroccipital processes of the opisthotic (inner ear bones on the side of the foramen magnum) are wide enough to reach the squamosals, quadrates, and lateral extensions of the parietals on the sides of the head. The basioccipital bone directly below the foramen magnum has a slight keel along its lower edge. The occipital condyle, an extension of the basioccipital which connects to the vertebrae, is positioned further forward on the skull than the joint between the cranium and the lower jaw.
Jesairosaurus | Skull roof and braincase
The largest of the "Cyrtopone" species, "C. striata" has a body length of about and has the biggest difference between head and mesosoma, the head being 2.5 times shorter. The winged gyne is a dorsal impression showing distinct sculpturing on the head and scutum made of longitudinal ridges. The eyes are small, placed near the center of the head, and the gena below them are nearly one and a half times longer than the eye diameter. The scape is longer than in the other species with one third of its length extending past the back margin of the head. The metatibiae shows two spurs, a simple and a pectinate one.
Cyrtopone | "C. striata"
A slightly curved fascia is found from three-fourths of the costa to the tornus, somewhat narrowed on the tornus and there is a preterminal series of small partially confluent more infuscated spots, alternating with a terminal series of brown dots. The hindwings are dark grey.
Chlamydastis steloglypta | Introduction
The body of the sphenoid bone, more or less cubical in shape, is hollowed out in its interior to form two large cavities, the sphenoidal sinuses, which are separated from each other by a septum.
Body of sphenoid bone | Introduction
Occasionally the joints between the ossicles become rigid. One condition, otosclerosis, results in the fusing of the stapes to the oval window. This reduces hearing and may be treated surgically.
Ossicles | Clinical relevance
Species in this section have sessile leaves that are often minute, bract-like, and rarely form rosettes. Scapes are very short or mostly absent.
Stylidium sect. Tenella | Introduction
Caudal to what will eventually become the stapes, Reichert's cartilage also forms the styloid process of the temporal bone. The cartilage between the hyoid bone and styloid process will not remain as development continues, but its perichondrium will eventually form the stylohyoid ligament.
Pharyngeal arch | Reichert's cartilage
See Morphology of Diptera for terms. The thorax, seen from behind, with conspicuous whitish dusting at least in front of the suture. The middle tibia, anteriorly along almost whole length, with dense fine pubescence which is shorter than width of tibia. The discal vein of wing with a slight though distinct curve forward just before apex. Hind tibia with only 2-3 rather short anteroventral bristles. Middle femur, at base beneath, with numerous setulose hairs, many of which are more than twice as long as depth of femur. 6·5-7·75 mm.
Hydrotaea dentipes | Description
There are also a medial, postmedial and two crenulate submarginal lines.
Drapetodes croceago | Introduction
Ulapes is a municipality and village in La Rioja Province in northwestern Argentina.
Ulapes | Introduction
The length of the body varies between 6 mm and 18 mm.
Verconia haliclona | Description
Excluding the last flagellomere, all the segments after the scape are as wide or wider than long, while the tip flagellomere is enlarged to equal the lengths of flagellomeres ten to three.
Bradoponera | "B. meieri"
"G. alexandermendesi" may attain a snout-to-vent length (SVL) of . It has a very elongate spine on the supraciliary flap above the eye.
Gonatodes alexandermendesi | Description
The Nerve to the Stapedius (tympanic branch) arises opposite the pyramidal eminence. It passes through a small canal in this eminence to reach the stapedius muscle.
Nerve to the stapedius | Introduction
The size may reach to—Length, 73 mm. ; of the body-whorl, 36 mm. :breadth, 3 mm. The ribs in the longer form may be much narrower, and may be obsolete before reaching the body whorl.
Mitromorpha axicostata | Description
The cage is circular and is approximately 4.5 meters in diameter and 5 meters in height. Two pieces of bone, that have been emptied of marrow, are stuck in the side of it. Several tapestries are hung on it.
Spider (Bourgeois) | The cage
The ocellus is small, the eye being two times larger than the former. It possesses three major head pores of similar size with a narrow connection between them. The animal's thorax is three times longer than its abdomen. The postabdomen narrows distally, the length of which is equal to about 2.5 heights. It counts with setae natatoriae about 2.1–2.3 the length of the preanal portion of its postabdomen. Its antennule is long and narrow, nearly reaching the tip of the rostrum; the antennular seta is thin, of about half the length of the antennule. It exhibits nine terminal aesthetascs, the two longest being about 2/3 the length of the antennule itself.
Celsinotum candango | Description
In males, there is a long pencil of whitish-ochreous hairs lying along the costa from the base.
Frisilia strepsiptila | Introduction
The length of the holotype individual was in 2019 estimated at long. Such a body size is rather limited for a troodontid. The specimen may represent an adult or subadult individual, due to the lack of cranial and body proportions associated with juvenile individuals. Nevertheless, either assignation would not be much different; for instance, the estimated would become . The describing authors established some derived or apomorphic traits relative to the Paraves. The jugal bone is pneumatised. The rear branch of the lacrimal bone is short, with less than 15% of the length of the descending branch, measured from the inner corner downwards.
Hesperornithoides | Description
The tympanic bullae are small and less than in length. The width of the basioccipital is less than . The width of the infraorbital canals is very narrow being less than . The width across the nasals is very narrow and their length is less than . They have medium-sized auditory bullae with a length of less than . The shield bullae have a shallow depth of less than . The skull also has a narrow basioccipital and is very broad across the carotid foramina. The mouth consists of a mandible whose height is less than with a mandible ramus depth of less than .
Omilteme cottontail | Anatomy
The palate itself is flat and ends a little behind the third molars. The posterolateral palatal pits, located near the third molars, are well developed. The mesopterygoid fossa, the opening behind the end of the palate, is rounded at the frond and broad. An extension of the alisphenoid bone known as the alisphenoid strut is usually present, separating two foramina (openings), the foramen ovale accessorium and the masticatory-buccinator foramen. The roof of the tympanic cavity, the tegmen tympani, is small. The upper incisors are opisthodont, with the chewing edge located behind the vertical plane of the incisors. As is usual for the genus, the molars are brachyodont, low-crowned, and bunodont, with the cusps higher than the connecting crests, and accessory crests such as mesolophs are present.
Oecomys sydandersoni | Description
The femur is held by the Muséum national d'histoire naturelle in Paris (No.7978); the location of the scapular fragment is unknown.
Protopelicanus | Introduction
The vestibule is somewhat oval in shape, but flattened transversely; it measures about 5 mm from front to back, the same from top to bottom, and about 3 mm across. In its lateral or tympanic wall is the oval window (fenestra vestibuli), closed, in the fresh state, by the base of the stapes and annular ligament. On its medial wall, at the forepart, is a small circular depression, the recessus sphæricus, which is perforated, at its anterior and inferior part, by several minute holes (macula cribrosa media) for the passage of filaments of the acoustic nerve to the saccule; and behind this depression is an oblique ridge, the crista vestibuli, the anterior end of which is named the pyramid of the vestibule.
Vestibule of the ear | Structure
Even though osteoderms are well-known, it is not certain where they were positioned on the body.
Struthiosaurinae | Introduction
The sori are circular to elliptic in shape; the sporangia lack hairs.
Ctenopterella | Description