Tag Archives: anatomy

The Hypothalamus and Pituitary Gland, with Animation.

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The hypothalamus and the pituitary gland are at the center of endocrine function. The hypothalamus is part of the brain, while the pituitary, also called hypophysis (hy-POFF-ih-sis), is an endocrine gland. The hypothalamus links the nervous system to the endocrine system via the pituitary gland. The two structures are located at the base of the brain and are connected by a thin stalk.

The hypothalamus produces several hormones, known as neurohormones, which control the secretion of other hormones by the pituitary. Pituitary hormones, in turn, control the production of yet other hormones by other endocrine glands.

The pituitary has two distinct lobes:

The anterior pituitary, also called adenohypophysis (AD-eh-no-hy-POFF-ih-sis), communicates with the hypothalamus via a network of blood vessels known as the hypophyseal portal system. Several neurohormones produced by the hypothalamus are secreted into the portal system to reach the anterior pituitary, where they stimulate or inhibit production of pituitary hormones. Major hormones include:

Gonadotropin-releasing hormone, GnRH, a hypothalamic hormone, stimulates the anterior pituitary to producefollicle-stimulating hormone, FSH, and luteinizing hormone, FSH and LH, in turn, control the activities of the gonads – the ovaries and testes.
Corticotropin-releasing hormone, CRH,promotes the secretion of adrenocorticotropic hormone, ACTH, which in turn stimulates production of cortisol by the adrenal gland.
Thyrotropin-releasing hormone, TRH, promotes the release of thyroid-stimulating hormone, TSH, and prolactin. TSH, in turn, induces the thyroid gland to produce thyroid hormones. Prolactin stimulates the mammary glands to produce milk.
Prolactin-inhibiting hormone, PIH, inhibits production of prolactin.
Growth hormone–releasing hormone, GHRH, promotes production of growth hormone, or somatotropin, which has widespread effects on the growth of various tissues in the body.
Growth hormone–inhibiting hormone, GHIH, or somatostatin, inhibits production of growth hormone.

The posterior pituitary, also called neurohypophysis, communicates with the hypothalamus via a bundle of nerve fibers. These are essentially hypothalamic neurons with cell bodies located in the hypothalamus while their axons EXTENDED to posterior pituitary. These neurons produce hormones, transport them down the stalk, and store them at the nerve terminals within the posterior pituitary, where they wait for a nerve signal to trigger their release. Two hormones have been identified so far:

– Vasopressin, also known as antidiuretic hormone, ADH, acts on the kidneys to retain water.

– Oxytocin causes the uterus to contract during childbirth and stimulates contractions of the milk ducts in lactating women.

Piriformis syndrome

Piriformis syndrome (PS) is a neuromuscular condition where the piriformis muscle – one of the deep gluteal muscles – presses on and compresses the sciatic nerve causing pain, tingling and numbness in the buttock area, and down the path of sciatic nerve to the thigh and leg. Sciatic nerve runs under the piriformis muscle (Fig. 1) and may be irritated when the muscle is too tight or shortened due to spasms. Piriformis syndrome is to be differentiated from sciatica which shows similar symptoms but has different causes.

Fig. 1 : Piriformis syndrome. Posterior view of the pelvis showing location of piriformis muscle and sciatic nerve. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Diagnosis is difficult as it produces similar symptoms as sciatica and is commonly done by exclusion of sciatica caused by compression of sciatic nerve roots by a herniated disc.

Fig. 2 : Sciatica caused by compression of spinal nerve roots by a herniated disc. Lateral view of the lumbar spine. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Causes and Risk factors

– Anatomical abnormality of the nerve/muscle relation. Some people are more likely to get PS than others.

– Tightness or spasm of piriformis muscle due to overuse injury. This commonly happens in sport activities that put pressure on the piriformis muscle such as bicycling, running without proper stretching, or any activity that involves repeated movements of the leg performed in sitting position.

Treatment

– Conservative treatment includes stretching exercises, massage, avoidance of causative activities.

– Physical therapy that strengthens the gluteus maximus, gluteus medius, and biceps femoris is usually recommended to reduce strain on the piriformis muscle.

– Relief of symptoms may be achieved with anti-inflammatory drugs or muscle relaxants.

Temporomandibular joint (TMJ) disorders – disc displacement.

Temporomandibular joint (TMJ) anatomy and function

Below is a narrated animation about TMJ anatomy, disc displacement and natural adaptation. Click here to license this video and/or other related videos on Alila Medical Media website.

The temporomandibular joint (TMJ) is the joint between the lower jawbone – the mandible – and the temporal bone of the skull (Fig. 1). The TMJ is responsible for jaw movement and is the most used joint in the body.

The TMJ is essentially the articulation between the condyle of the mandible and the mandibular fossa – a socket in the temporal bone. The unique feature of the TMJ is the articular disc – a flexible and elastic cartilage that divides the joint into two parts: a upper joint and a lower joint.
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Fig. 1 : Anatomy of the TMJ with jaw closed and open. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

The disc serves as a cushion between the two bone surfaces. The disc lacks nerve endings and blood vessels in its center and therefore is insensitive to pain. Anteriorly it attaches to lateral pterygoid muscle – a muscle of mastication (chewing). Posteriorly it continues as retrodiscal tissue fully supplied with blood vessels and nerves. This is commonly the source of pain in disorders with anterior disc displacement (see below).

The jawbone (mandible) is the only bone that moves when the mouth opens. The first 20 mm (three quarters of an inch) opening involves only a rotational movement of the condyle within the socket. For the mouth to open wider, the condyle and the disc have to move out of the socket, forward and down the articular eminence, a convex bone surface located anteriorly to the socket (see Fig.1 and video below). This movement is called translation.

Click here to see an animation of normal TMJ function on Alila Medical Media website where the video is also available for licensing.

TMJ disorders

The most common disorder of the TMJ is disc displacement, and in most of the cases, the disc is dislocated anteriorly (Fig. 2, middle and lower panels). As the disc moves forwards, the retrodiscal tissue is pulled in between the two bones. This can be very painful as this tissue is fully vascular and innervated, unlike the disc. The movements made by chewing or even talking cause a chronic bruise to the tissue resulting in inflammation and pain.

Fig. 2 : Anterior disc displacement, “clicking” and “locking” symptoms, see text for details. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

The forward dislocated disc is an obstacle for the condyle movement when the mouth is opening. In order to fully open the jaw, the condyle has to jump over the back end of the disc and onto its center. This produces a clicking or popping sound. Upon closing, the condyle slides back out of the disc hence another “click” or “pop”. This condition is called disc displacement with reduction. In later stage of disc dislocation, the condyle stays behind the disc all the time, unable to get back onto the disc. The clicking sound disappeared but mouth opening is limited. This is usually the most symptomatic stage – the jaw is said to be “locked” as it is unable to open wide. At this stage the condition is called disc displacement without reduction.

Click here to see an animation of TMJ disc displacement on Alila Medical Media website where the video is also available for licensing.

Fortunately, in most of the cases, the condition resolves by itself after some time. This is thanks to a process called natural adaptation of the retrodiscal tissue, which after a while becomes scar tissue and can functionally replace the disc. In fact, it becomes so similar to the disc that it is called a pseudodisc.

Glaucoma

Below is a narrated animation about glaucoma development and types of glaucoma. Click here to license this video and/or other eye and vision related videos on Alila Medical Media website.

Glaucoma is a group of eye diseases in which the optic nerve is damaged leading to irreversible loss of vision. In most cases, this damage is due to an increased pressure within the eye – elevated intraocular pressure.

How glaucoma develops

The eye produces a fluid called aqueous humor which is secreted by the ciliary body into the posterior chamber, a space between the iris and the lens. It then flows through the pupil into the anterior chamber between the iris and the cornea. From here, it is drained through a sponge-like structure located at the base of the iris called the trabecular meshwork and leaves the eye. In a healthy eye, the rate of secretion balances the rate of drainage.

In people with glaucoma, this drainage canal is partially or completely blocked. Fluid builds up in the chambers and this increases pressure within the eye. The pressure drives the lens back and presses on the vitreous body which in turn compresses and damages the blood vessels and nerve fibers running at the back of the eye. These damaged fibers result in patches of vision loss and if left untreated may lead to total blindness.

For eye anatomy basics click here.

Click here to see an animation of glaucoma progression on Alila Medical Media website where the video is also available for licensing.

Fig. 1 : Development of glaucoma. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Open-Angle Glaucoma vs. Angle-Closure Glaucoma

These are the two main types of glaucoma. The “angle” here refers to the corner between the cornea and the iris where the trabecular meshwork is located.

Primary Open-Angle or Chronic Open-Angle Glaucoma is the most common form of glaucoma accounting for about 90% of cases. This is caused by partial blockage of the drainage canal. The angle is “open”, meaning the entrance to the drain is clear, but the flow of aqueous humor is somewhat slow. The pressure builds up gradually in the eye over a long period of time. There is no pain and visual loss appears gradually, starting from peripheral vision, and may go on unnoticed until the central vision is affected. Progression of glaucoma can be stopped with medical treatments, but part of vision that is already lost can not be restored. This is why it’s very important to detect signs of glaucoma early with regular eye exams.

Closed-angle or Acute angle-closure glaucoma (AACG) is less common. This type of glaucoma is caused by a sudden and complete blockage of aqueous humor drainage. The pressure within the eye rises rapidly and may lead to total vision loss quickly. This is a medical emergency and requires immediate attention. Symptoms to watch out for: sudden severe pain inside and around the eye, redness, blurry vision, seeing halos around a light, some people may also feel headache, nausea.

Certain anatomical features of the eye make it easier for AACG to happen. These include: narrow drainage angle, shallow anterior chamber, thin and droopy iris, lens sitting too much forward. These features are often inherited and so AACG incidents are likely to run in the family.

Fig. 2 : Open angle vs closed angle glaucoma. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Typically, this is what happens in AACG : the pupil is dilated (e.g. when looking in the dark) and the lens is stick to the back of the iris. This prevents the aqueous humor from flowing through the pupil into the anterior chamber (primary block). As the fluid accumulates in the posterior chamber it presses on the iris causing it to bulge outward and block the drainage angle (secondary block).

Other types of Glaucoma

Normal pressure glaucoma – Some people can get glaucoma (vision loss due to damaged optic nerve) without elevated intraocular pressure. This may be due to poor blood supply (e.g. damaged blood vessels in diseases such as diabetes) to the nerve fibers.

Secondary glaucoma – glaucoma develops as a result of trauma after eye injuries.

Congenital glaucoma – glaucoma that is present at birth.

Treatments

Progression of glaucoma can be halted or slowed down with medical treatments, but part of vision that is already lost can not be recovered. This is why it’s very important to detect signs of glaucoma early with regular eye exams.

– Eye drops that lower intraocular pressure and/or reduce fluid production.

– Laser treatments : Laser is used to burn part of the trabecular meshwork to improve fluid flow – laser trabeculoplasty. It can also be used to remove part of the ciliary body to reduce fluid secretion. For acute glaucoma, small holes can be made in the iris to relieve the primary block – laser iridotomy.

– Eye surgeries: a procedure called trabeculectomy is used to create a channel – an alternative route – for aqueous fluid drainage. For acute glaucoma a procedure called iridectomy may be performed to drill a hole in the iris. Canaloplasty is a newer, less invasive surgical procedure performed for treatment of open angle glaucoma. This procedure involves enlargement of the eye’s natural drainage canal.

In people with AACG, laser and surgical treatments may be performed for the other, still healthy eye as well to prevent future development of glaucoma.

Reverse Total Shoulder Replacement

The videos on this page can be downloaded upon purchase of a license on Alila medical Media website. Click here!

Reverse Total Shoulder Replacement or Delta Shoulder Replacement is a modification of total shoulder replacement procedure. The conventional procedure has a metal ball on the humerus (replacing the natural humeral head) and a plastic component on the glenoid. The reverse procedure has the reverse positions of the prostheses : the metal ball is now fixed on the glenoid socket and the plastic cup is fixed in place of the humeral head (Fig. 1). This configuration is indicated for people with rotator cuff arthropathy.

Fig. 1: Configuration of conventional versus reverse total shoulder replacement. Note the location of the metal head and plastic component in each case. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Why a conventional total shoulder will not work with rotator cuff arthropathy?

Rotator cuff arthropathy or cuff tear arthropathy (CTA) is shoulder arthritis in a setting of rotator cuff tears. Rotator cuff muscles hold the ball and the socket together and prevent the humeral head from moving out of the socket when the deltoid muscle raises the arm. In people with torn rotator cuff, the head of the humerus moves upwards out of the socket resulting in shoulder instability. Conventional total shoulder preserving the natural configuration of the shoulder joint will encounter the same problem (Fig. 2, left panel).

Fig. 2: Conventional versus reverse total shoulder replacement with torn rotator cuff. The upward force displaces the humeral head in conventional configuration but stabilizes the joint in reverse configuration. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Why a reverse total shoulder would work?

In reverse total shoulder procedure, the arthritic humeral head is replaced with a plastic cup and the metal ball is fixed onto the glenoid surface. With this configuration, the contraction of the deltoid will move the arm up and compress the socket to the ball at the same time (Fig. 2, right panel). The ball and the socket will fit more snugly together providing stability.

> See all Orthopedic topics

Shoulder arthritis

The videos on this page can be downloaded upon purchase of a license on Alila Medical Media website. Click here!

Shoulder arthritis refers to loss of cartilage on the surface of the ball (humeral head) and the socket (glenoid) of the shoulder glenohumeral joint. The two bones rub against each other and produce pain, stiffness and difficulty moving an arm.

Types and Causes of Shoulder arthritis

Osteoarthritis (OA) – also called degenerative joint disease (DJD), is the “wear and tear” condition of the joint commonly due to old age. OA is characterized by loss of cartilage, bone spurs (osteophytes) and no major inflammation (Fig. 1).

Fig. 1: Osteoarthritis of the main shoulder joint. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Rheumatoid arthritis (RA) – Inflammation of the synovium – the membrane that encloses the joint and contains lubricant fluid. Inflammation brings in the cells of the immune system whose inflammatory chemicals damage and destroy the joint. It’s not clear how RA starts but genetic predisposition together with infection of the joint are likely to be among the causes.

Rotator cuff arthropathy or cuff tear arthropathy (CTA) – Shoulder arthritis as a result and in a setting of rotator cuff tears. Rotator cuff muscles hold the ball and the socket together and prevent the humeral head from moving out of the socket when the person raises an arm. In people with torn rotator cuff, the head of the humerus moves upwards and rub onto the acromion. This causes damages to the covering cartilage and eventually arthritis. Combination of cuff tear and arthritis is a devastating condition that seriously compromises function of the shoulder.

Post-traumatic arthritis – arthritis that develops after physical injury to the joint.

Chondrolysis – sudden loss of cartilage that happens occasionally after a shoulder surgery, commonly seen in association with infusion of local anesthetics into the joint for pain management.

Treatments

Non-surgical treatments include shoulder exercises and anti-inflammatory medications.

Surgical treatments include a variety of procedures :

1. Total shoulder replacement surgery : the arthritic humeral head is replaced with a metal ball on a stem that fits inside the humerus, the socket is replaced with a plastic component made of high density polyethylene.

Fig. 2: Total shoulder replacement procedure. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

2. Ream and Run Arthroplasty – a modification of total shoulder procedure above. The metal ball replaces the humeral head but the socket is simply shaped, smoothed to fit the ball and left to heal. No plastic component used. With time, the body grows a cartilage layer on top of the socket. This procedure is recommended for younger and more active individuals.

3. Reverse total shoulder or Delta total shoulder replacement – This is indicated for people with rotator cuff arthropathy (see types of shoulder arthritis above). This procedure reverses the positions of the prostheses : the metal ball is now fixed on the socket and the plastic component is fixed in place of the humeral head. This topic is covered in the next article about reverse total shoulder replacement.
> See all Orthopedic topics

Femoral acetabular impingement (FAI)

What is femoral acetabular impingement (FAI)?

Femoral acetabular impingement (FAI) is a condition of hip joint where the bones are abnormally shaped, they pinch each other on the covering cartilages when the joint is in motion and cause damages.

The hip joint is a ball-and-socket joint (Fig. 1). The femoral head (the ball) fits into the acetabulum (the socket). The femoral head is covered with articular cartilage, the acetabulum has a ring of cartilage around its rim called the labrum. In FAI, there are abnormal bone growths (spurs) on the ball or the socket or both (Fig. 2). The ball can no longer move smoothly inside the socket. They rub onto each other and pinch on the covering cartilages causing damages.

Fig. 1 : Anatomy of the hip joint. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Types of FAI

Pincer – Bone spurs on the acetabulum, commonly on the upper edge (Fig. 2 ). This situation is also described as over-coverage of the socket over the ball.

Cam – Bones spurs on the femoral head and neck making the neck less prominent and the head not completely round.

Combined – both cam and pincer are present, this is a very common situation.

Fig. 2 : Types of FAI. Bones spurs are colored in red. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

What damages can it make?

Impingement results in cartilage breakdown on the femoral head and labral tears on the rim of the acetabulum. FAI is also the cause of premature hip osteoarthritis in young adults.

Causes and risk factors

The bone spurs are the result of abnormal bone growth during childhood development. The reasons why this happens are unclear.

FAI is more common in young athletes, dancers who practice a larger range of motions of the hip, and in active individuals.

Symptoms

Some of the symptoms may include:

– Pain at the groin area or inner hip is more common although the pain may be felt at the side of the hip.

– Pain after sitting for a long period of time.

– Stabbing pain when sitting down or standing up.

Treatment

Treatments range from lifestyle changes, physical therapies to surgeries.

Lifestyle changes usually involve being less active. Physical therapy helps to increase hip strength but stretching should be avoided.

Arthroscopic surgeries are commonly performed to remove damaged tissues, repair the labrum and stimulate cartilage growth by microfractures. Removal of abnormal bony structures are also recommended to prevent future damages to the joint.

> See all Orthopedic topics

Benign Prostatic Hyperplasia (BPH)

Below is a narrated animation about BPH and treatments. Click here to license this video on Alila Medical Media website.

Benign prostatic hyperplasia (BPH), also called benign prostatic hypertrophy or enlarged prostate, is a condition in which the size of the prostate gland is increased. It is considered “benign” because it’s NOT a cancer, and it does not increase the risk of cancer. However, when becomes sufficiently large, the prostate tissue may compress the urethra and block the urine flow causing a number of urination problems and urinary tract infection. BPH is very common in aging men: about 50% of men have some degree of BPH by the age of 60.

Anatomy

The prostate is a walnut-size exocrine gland of the male reproductive system. It is located just below the urinary bladder where it wraps around the first part of the urethra – prostatic urethra (see Fig. 1 and 2).

Fig. 1: Male reproductive and urinary organs, mid-sagittal view. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Prostate gland produces a milky fluid that is expelled into the urethra to mix with spermatozoa during ejaculation. The fluid serves as a lubricant and nutrition for the sperms.

Click here to see an animation of male reproductive system on Alila Medical Media website where the video is also available for licensing.

Click here to see an animation of male urinary system on Alila Medical Media website where the video is also available for licensing.

In BPH, the enlarged prostate presses on the prostatic urethra making it narrower. This affects normal flow of urine (Fig. 2).

Fig. 2: Normal prostate (left) and enlarged prostate (right). Same sagittal view as in Fig. 1 with other organs removed to simplify. The urethra is squeezed narrow in BPH. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Click here to see an animation of prostate hypertrophy on Alila Medical Media website where the video is also available for licensing.

Causes

BPH is considered a normal part of male aging as a result of hormonal changes. The rate of cell proliferation induced by androgens (male hormones) somehow exceeds the rate of programmed cell death (apoptosis) in aging prostate tissue resulting in enlargement of the prostate.
Severity of BPH (development of symptomatic BPH), however, has been associated with lifestyle. The incidence of clinically significant BPH is notably higher in men who lead a modern lifestyle compared to those who live in rural traditional settings.
About half of men with histopathologic BPH demonstrate clinically significant symptoms.

Symptoms

Obstruction of urine flow makes urine voiding difficult and incomplete. This leads to common symptoms of BPH:
– frequent urination.
– urgency : need to void that can not be deferred.
– urinary hesitation: difficulty to initiate urine stream, weak and interrupted stream.
– straining to void: need to push to completely empty the bladder.
– residual urine: constant feeling of need to void.
– dribbling
Altogether the voiding dysfunction resulted from BPH is called lower urinary tract symptoms (LUTS) – a more recent term for prostatism.

Treatment

Patients with mild symptoms and who are not bothered by their symptoms are usually advised to follow a “watch and see” approach with regular check-up and lifestyle changes such as low-fat diet, reduced consumption of alcohol and caffeine, reduced fluid intake before bedtime, avoidance of certain products and medications such as diuretics,…
1. Medication
There are two main classes of medication:
– alpha-blockers: these drugs relax smooth muscle in the prostate and by doing so relieve blockage of urine flow.
– 5-alpha reductase inhibitors: these inhibit local production of the hormone that is responsible for prostate enlargement.

2. Minimal invasive treatment
These non-surgical therapies use heat to cause cell death (necrosis) in prostate tissue. The heat is delivered in small amount and to a specific location to minimize unwanted damage. Different procedures differ mainly in the type of energy used.
– Transurethral microwave thermotherapy (TUMT): use of microwave energy delivered through a probe inside a catheter inserted into the urethra.
– Transurethral needle ablation (TUNA) : use of radio frequency energy delivered through a transurethral device with needles.
– Photoselective vaporization of the prostate (PVP): use of laser to vaporize prostate tissue.
3. Surgery
Transurethral resection of the prostate (TURP) is a surgical procedure for removal of prostate tissue through the urethra. This procedure has been around for a long time and is still considered gold standard for treatment of severe BPH. Nowadays, it is usually performed when medications and less invasive methods fail.

See all Urology topics

Paranasal sinuses and sinus conditions

The videos on this page can be downloaded upon purchase of a license on Alila Medical Media website. Click here!

Paranasal sinuses, or simply “sinuses” in common language, are air cavities in the bones of the skull. There are four pairs of sinuses (see Fig. 1, 2 and upper panel of Fig. 3):

– the maxillary sinuses are under the eyes, in the maxillary bones.
– the frontal sinuses are above the eyes, in the frontal bone.
– the ethmoid sinuses are between the nose and the eyes, in the ethmoid bone.
– the sphenoid sinuses are behind the nasal cavity, in the sphenoid bones.

Fig.1: The four pairs of sinuses. Red = frontal, green = ethmoid, blue = sphenoid, beige = maxillary. The right panel show normal sinuses on half of the head and inflamed sinuses on the other half. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

The sinuses are lined with respiratory epithelium producing mucus. The mucus drains into nasal cavity through small openings (Fig. 2 left panel, Fig. 3 upper panel). Impaired sinus drainage has been associated with inflammation of sinuses (sinusitis, see below).
Biological function of the sinuses remains unclear.

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Fig. 2: Front view of the sinuses (left panel) showing connections to the nasal cavity. Right panel shows mid-sagittal section of the head. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Sinusitis or rhinosinusitis is inflammation of the paranasal sinuses (Fig. 1, right panel). This can be due to:
– allergy (allergic rhinitis): allergens such as pollen, pet dander,.. trigger overreaction of the mucosa of the nose and sinuses resulting in excess mucus, nasal congestion, sneezing and itching.
– infection: usually as a complication of an earlier viral infection of the nasal mucosa, pharynx or tonsils such as during a common cold. Impaired sinus drainage due to inflammation of nasal mucosa during a cold often leads to infection of the sinus itself. Cold-like symptoms plus headache and facial pain/pressure are common complaints.
– other conditions that cause blockage of sinus drainage: structural abnormality such as deviated nasal septum (Fig. 3); formation of nasal polyps (Fig. 4). When a sinus is blocked, fluid builds up making it a favorable environment for bacteria, viruses or fungi to grow and cause infection.

Fig. 3: Front view of the sinuses (upper panel) showing connections to the nasal cavity, also shown the nasal septum (light blue color). Lower panel shows deviated septum blocking drainage of the right maxillary sinus (your left). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Fig. 4: Nasal polyps – overgrowths of nasal mucosa – block sinus drainage. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Treatment depends on the cause of sinusitis:
– For viral infection : symptom relief medications such as nasal spray for irrigation and decongestion; other conservative treatment for common cold such as rest and drinking plenty of fluid.
– For bacterial infection: antibiotics may be prescribed.
– For allergy: intranasal corticosteroids are commonly used.
– For recurrent (chronic) sinusitis due to structural abnormalities or nasal polyps, nasal surgery may be recommended.

See all Respiratory topics

Asthma (with Animation Video)

The videos on this page can be downloaded upon purchase of a license on Alila Medical Media website. Click here!

Asthma is a chronic respiratory condition where the airway is inflamed and narrowed causing breathlessness, wheezing, chest tightness and coughing. Symptoms come as recurrent episodes called asthmatic attacks more commonly during the night and early morning. Asthma is usually diagnosed in childhood and lasts for life.

Anatomy of asthma

Our lungs consist of millions of air tubes or airways (bronchi and smaller bronchioles) bringing air in and out of the body. Each tube ends with a cluster of air sacs (alveolus, plural alveoli) where the gas exchange process takes place. The airways have a layer of smooth muscle in their wall which enables them to constrict or dilate. In response to the body’s higher demand of air, such as during exercise, the airways dilate to increase air flow. In response to presence of pollutants in the air, they constrict to prevent the lungs from being polluted. In people suffering from asthma these airways are inflamed, narrowed and become more sensitive to certain substances. Asthmatic attack (or exacerbation) happens when the airways react to these substances. During the attack smooth muscle contracts squeezing the airways making them even narrower, mucus secretion increases further obstructs the airways.

Causes of asthma

Causes of asthma are complex and not fully understood but likely involve a combination of genetic and environmental factors. Family history is a known risk factor for asthma. There are at least over twenty genes associated with asthma of which many are involved in the immune system. Most people who have asthma also have allergies. Many environmental factors such as air pollution, chemicals, smoking, allergens have been associated with development of asthma or triggering of asthmatic attacks.

Triggers of asthmatic attack

Triggers are factors that initiate the attack, these can be very different from person to person. Common triggers include :
– allergens (pollen, animal fur, pet dander, sulfites in preserved food..)
– irritants (cigarette smoke, industrial chemicals, dust, household chemicals,..)
– some medication (aspirin, beta blockers,..).
– physical activity, exercise.

Treatments

There is no cure for asthma. The most effective way to manage symptoms is to identify the triggers of asthmatic attack and avoid them.
There are two main classes of medication:
– bronchodilators – substances that dilate bronchi and bronchioles – are used as short-term relief of symptoms.
– inflammation moderators such as corticosteroids are used as long-term treatment.
Asthma inhalers are used to deliver medication to the lungs.

Associated conditions

A number of conditions tend to occur more frequently in people with asthma:
– Allergies : eczema and hay fever. These individuals are considered hyperallergic (high tendency to develop allergic reactions). The combination of these conditions is called atopy or atopic symdrome.
– Gastroesophageal reflux disease (GERD): a condition in which stomach acid backs up and damages the mucosal lining of the esophagus. GERD may worsen asthma symptoms and medications for asthma often worsen GERD symptoms. Treating GERD usually improves asthma and must be included in asthma treatment plan.
– Obstructive sleep apnea (OSA): asthmatic patients tend to develop OSA. The mechanism is not fully understood but it’s likely due to nasal obstruction. Click on the link to read more about OSA.
– Sinusitis: inflammation of paranasal sinuses. Sinusitis commonly worsens asthma symptoms and makes treatment less effective.

See all Respiratory topics

See all Immunology topics

Medical Information Illustrated

Medical and health topics fully illustrated with pictures and videos for easy understanding.

Tag Archives: anatomy

Piriformis syndrome

Causes and Risk factors

Treatment

Temporomandibular joint (TMJ) disorders – disc displacement.

Temporomandibular joint (TMJ) anatomy and function

TMJ disorders

Glaucoma

How glaucoma develops

Open-Angle Glaucoma vs. Angle-Closure Glaucoma

Other types of Glaucoma

Treatments

Reverse Total Shoulder Replacement

Why a conventional total shoulder will not work with rotator cuff arthropathy?

Why a reverse total shoulder would work?

Shoulder arthritis

Types and Causes of Shoulder arthritis

Treatments

Femoral acetabular impingement (FAI)

What is femoral acetabular impingement (FAI)?

Types of FAI

What damages can it make?

Causes and risk factors

Symptoms

Treatment

Benign Prostatic Hyperplasia (BPH)

Anatomy

Causes

Symptoms

Treatment

Paranasal sinuses and sinus conditions

Asthma (with Animation Video)

Anatomy of asthma

Causes of asthma

Triggers of asthmatic attack

Treatments

Associated conditions