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Questions tagged [human-anatomy]

This tag is for questions about the general anatomical features of human beings as opposed to the anatomy of non-human animals.

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Anatomical Angle Made by the Fingers of an Extended Palm

Does the angle made by the fingers (excluding the thumb) of an extended palm (as shown in the figure below) have a name (such as the Lovibond or Cobb angle, for instance) ? I have already checked ...
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139 views

What's a “constitutionally small penis”?

I'm reading some urology papers and came across one involving penis growth (Kim & Song, 2008); here's an intro passage that I'm confused about: A total of 58 patients with constitutionally ...
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691 views

Does variation in human gut length vary predictably with diet of ancestors?

Background: Numerous online searches, textbooks and other sources seem to pin the average length of the human gut from mouth to anus (oroanal) between about 5-10m in length. To pick a reputable ...
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512 views

Why are lips covered with specialized skin?

I found out some interesting facts while studying our lips: They are covered in glabrous skin, while most of the skin surface is hairy; The outermost layer (stratum corneum) of the skin is far ...
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43 views

Do cells in healing ligaments have deformation processes? If so, what are they?

I am trying to better understand how non-muscle tissue in the muscuoloskeletal system heals. Specifically, I am interested in ligaments heal once torn. I read the following text: If the muscle ...
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785 views

What's so special about Chassaignac tubercle?

1-How does massaging of carotid artery at chassaignac tubercle( anterior tubercle of transverse process of C6 vertebra ) can relieve the symptoms of Supraventricular Tachycardia? My attempt: I think ...
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674 views

How do duplicate brain regions (ex: left/right amygdaloid body) operate together?

I frequently hear talk about parts of the brain like "Amygdala" or "Hypothalamus", so I looked them up in an app called "essential anatomy". What I see is that there's mirror symmetry, and most of ...
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89 views

Is there any evolutionary significance of downward facing nostrils in human beings?

The nostrils in apes and monkeys are almost at the front, but in humans nostrils (external nares) face downwards. Also a lot of non-primate mammals like goats have nostrils at the front. Is it the ...
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335 views

Why do hair on head not get pilo-erected?

Whenever we have "goosebumps", there is a momentary piloerection, due to which hair on our elbows and legs get "erected" and "stand" almost perpendicular to the surface of our skin. But why do our "...
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80 views

Changes in spongy urethra during tumescence

How does the columnar cells of spongy urethra expand during tumescence(erection of penis)? If we assume that the urethra has the length, long enough to sustain tumescence without expansion of cells, ...
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1k views

Do any non-human species have packed abs?

The classic "six-pack abs" in humans is due to tendons stretched across the abdominal muscles and low body fat. Do any other animals have a similar arrangement of tendons that could result in visible "...
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100 views

How do we sneeze?

When a stimulus triggers the sneezing pathway, known as the trigenimal nerve network, how do the droplets from a sneeze get created within the nose? What affects the size of these droplets?
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1k views

Skin extra sensitive to heat after burn

I just got my finger burnt (first degree burn $\Rightarrow$ I didn't even bother to bear the wound). It didn't hurt much, even when I pressed the wound. However, when exposed to heat (hot water, but ...
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200 views

Human female chest model or data representation?

I am looking for professionally used representation of female chest (I know how it sounds ;). Generally - a model comprehensive enough to effectively represent human chest, with focus on breasts. ...
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65 views

How can we usually “trust a fart” not to be liquid or solid?

Jack Nicholson's character Edward Cole in the movie The Bucket List said ...and never trust a fart, and a search for Al Roker leakage White House will clear up any doubts what that's all about. How ...
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42 views

Describing the location of the thalamic adhesion in simple English

I'm trying to describe the location of the thalamic adhesion as part of a personal project. I can't reference pictures, and I need to be as precise as possible without using convenient anatomical ...
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0answers
24 views

Exhaustion of skeletal muscle and ligaments

I read somewhere that while doing lifting back should be straight(means normal curve), so that erectors muscle in back do the work but it gets tired easily. Hence we form curve on our back like when ...
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135 views

Alpha-gamma co-activation

I am having trouble visualizing/grasping the necessity of alpha-gamma co-activation. My understanding is the following: When an external load causes stretching of the sensory muscle spindles, the 1a ...
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0answers
51 views

What causes the blue color seen in baboons?

Based off of this question from Worldbuilding SE. In that question, I talked about how the scrotum and buttocks of various animals have a blue color because of thick deposits of collagen in those ...
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228 views

Why does the clavicle ossify intramembraneously?

The clavicle is the only long bone which ossifies as a membrane bone. I studied this process, but I can't find the reason why it features intramembraneous ossification?
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518 views

Are differing shapes of the acromion congenital or acquired?

In the human body, the acromion is located here: There exist different shapes of acromion, at least 3: The frequency varies according to the acromion type: Some clinicians consider that there exist ...
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82 views

How to contract sternocleidomastoid muscle by thought?

If I do not turn my head, how can I contract ( or tighten) the sternocleidomastoid muscle ( like we can intensely tighten muscle in limbs)?
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37 views

Does human skeletal muscle fascia grow new additional collagen in response to increases in skeletal muscle size?

For example, if a human skeletal muscle is growing repeatedly due to periodic weightlifting, does the fascia eventually respond to the increasing volume by growing more quantities of collagen or other ...
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524 views

Does the humeroradial joint move medially/laterally?

The humeroradial joint is a ball-and-socket joint that, if unrestricted, would allow for movement around all possible axes. However (as succinctly stated from Wikipedia): the annular ligament, by ...
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0answers
87 views

Atlas from human brain structures to 3D coordinates?

I would like to visualize specific human brain structures in the three dimensional space and compute specific geometric properties of these brain structures (size, centroid, etc). Therefore, I am ...
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0answers
4k views

Physiologically, how can stress/anxiety cause neuropathy?

According to the Mayo Clinic, stress/anxiety can cause "pins and needles" (neuropathy) sensations all over the body. But how can this be? My understanding of the sensory pathway is that sensory ...
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0answers
143 views

Questions regarding Scapulohumeral Rhythm

I'm actually an artist, but I wanted to ask this because it will help a lot in my figure drawings. My artistic anatomy teacher taught me about the Scapulohumeral Rhythm. He said that in during the ...
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319 views

Size of classical liver lobule across species

A classical liver lobule is made up of a central vein and the portal triads. A typical human liver weighs around 3 lbs. , while a typical bovine liver weighs around 12 lbs. I was wondering if anyone ...
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23 views

Is the tendon width determined by genetic predisposition, and if so, is genetics the sole factor?

Tendons' widths vary widely across humans. E.g.: {1}: "the mean patellar tendon width was 26.10mm (SD = 3.31; range 18.33mm-33.33mm)" {2}: "Size of the patellar tendon width, measured at the same ...
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0answers
75 views

What are the (statistically) normal pH levels in the most-outer part of human sexual organs?

What are the (statistically) normal pH values of the outer skin/epidermis of human sex organs (groin/crotch) in the male and female? e.g male testes, female vulva, male glans, the enveloping epiderm, ...
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0answers
51 views

What is the average human body density?

Looking for values of the average human body density on the Internet, one often finds the values of 0.98 for male, 0.87 for female. Other values are 0.985 for male and female. However, I can find no ...
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0answers
141 views

Why doesn't peritoneal dialysate leak through the fallopian tubes?

It is my understanding that the female peritoneum does not form a closed (potential) space due to its puncture by the uterine tubes. If that is indeed the case, why is peritoneal dialysis in women not ...
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26 views

Would preserving your Eyes from Light keep them healhty?

I read about why eyesight diminishes with age. I am aware of the fact that there are different causes that can affect the quality of image received by our eyes and that being vague would not lead to a ...
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0answers
43 views

does being battered build muscle?

My crude understanding of how people normally go about building muscle is something like this following 2 step process: 1) a person can lift weights (for example), which tears muscle and stimulates ...
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0answers
26 views

Muscle layers of pharynx and gi tract

Why does pharynx have an internal longitudinal muscle layer and external circular muscle layer, while oesophagus and the rest of gastrointestinal tract have inner circular and outer longitudinal ...
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0answers
58 views

Tensile strength of collagen?

Really specific question, but what is the average tensile strength of human collagen, type I? I've tried looking for it online, and either my google-fu skills are weak, or I'm just unlucky. Also, is ...
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0answers
98 views

In endochondral bone formation, why does only hyaline cartilage get ossified to form bone?

There are three types of cartilage: hyaline, fibro cartilage and elastic. Fibro cartilage does not have perichondrium...so it does not take part in ossification because perichondrium needs to develop ...
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37 views

Why do humans lose subcutaneous fat from the extremities with age?

Why does fat tissue die and shrink on the hands, knees, and lower legs of most people as they age, even when they are overweight? In most people, their bone definition becomes much more visible around ...
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41 views

Why are there sporadic lightly pigmented hairs in facial hair?

My body and scalp hair are entirely black. Until recently, I thought this was the case with my facial hair also, until I noticed a small handful of hairs that were anywhere from light brown to copper-...
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0answers
3k views

What is the occipital bun, precisely (in Neanderthals and Homo Sapiens)?

I've read that the occipital bun is an anatomical feature of the Neanderthals, and only because modern humans (except sub-Saharan Africans) carry a few percent of Neanderthal DNA due to ...
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0answers
98 views

Where does the human brain drain to?

When a brain has a aneurysm and the patient survives untreated then where does that blood drain to or how is it absorbed? How is the pain perceived?
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0answers
58 views

Are there wounds which never completely heal?

I have a cut on a knuckle which occasionally opens (usually during winter), to disappear after some time (it is usually fine during the summer). This is going on for years now and yes, I will show ...
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0answers
603 views

Strongest bone in body

AS internet tells is it is thigh bone which is strongest, but why, it carry only upper part of body, does not heel or any foot bones should be strongest in body as they carry full body weight ?
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26 views

Muscle involved in carrying load on head

I have seen people carrying heavy load on their head especially in 3rd world countries, does carrying on head any benefit or harm, which muscle get strengthen in doing it?
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532 views

Is the shape of the skull important for brain size?

I do not know biology, but I notice that human skull have a particular form that is like a upward spike and other skulls which are only oval. upward spike: oval: I know that in the example images ...
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0answers
189 views

What are the absolute facial features which features sexual dimorphism in humans?

Apart from beard and moustache, is there any facial feature that would help to distinguish between men and women? It is said that men have square, rectangular or oblong face and women have oval,...
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0answers
553 views

Do all body organs grow in proportion during the period of physical development?

It is obvious that during childhood and puberty, the human body grows uniformly or proportionally so that a child's arm length, for example, is shorter than an adult's arm length but is proportional ...
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0answers
231 views

Does the vagus nerve supply the human thoracic diaphragm?

The vagus nerve (CN X) passes through the oesophageal hiatus of the diaphragm at the vertebral level T10. But does the vagus nerve actually offer any nerve supply to the diaphragm?
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167 views

Significance of lip end curve

What is significance of curve at point where lips meet, how it is determined and what effects it has on attraction and other factors? For some people it is a downward curve, for others it's an upward ...
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579 views

How nasal hairs filter particles of micron size?

This book says: The larger particles (> 10 μm diameter) are filtered by hair in the nostrils If we see the anatomy of nasal hairs and its density in the nostrils then it seems that its impossible ...