Showing posts with label anatomy. Show all posts
Showing posts with label anatomy. Show all posts
Thursday, February 26, 2015
Cerebral aqueduct Anatomy
Cerebral aqueduct- also known as the mesencephalic duct or the aqueduct of silvius. It contains cerebraospinal fluid(CSF-Cerebrospinal fluid {CSF}Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space in the brain {he space between the skull and the cerebral cortex—more specifically, between the arachnoid and pia layers of the meninges}It is basically a saline solution with microglia and acts as a "cushion" or buffer for the cortex.) is within the mesencephalon (or midbrain) and connects the third ventricle in the diencephalon) to the fourth ventricle, which is between the pons and cerebellum.
Anatomy of the Clavicle
Other names for Clavicle are:
Collar bone,Beauty bone
The shoulder is the most freely moveable joint in the body. The extreme range of its possible movements makes the shoulder joint susceptible to dislocation. One of the bones that meet at the shoulder is the clavicle, which is also known as the collarbone. The collarbone is long, curvy, and located at the root of the neck. One of the main functions of the collarbone is to hold the arms freely and supported, away from the trunk. Fractures of the collarbone are common. A fracture is easy to detect because the clavicle lies directly under the skin, making any deformity immediately visible. Symptoms of a fractured collarbone include tenderness, swelling, and an inability to move the arm because of pain. The victim may also have the desire to hold the arm against the chest to stabilize it. It is common practice to apply a sling to stabilize the fracture, allowing it to mend. Extreme fractures may require surgery to pin the collarbone back together.
Clavicle canbe divided into a cylindrical part called the shaft, and two ends – medial (sternal end) and lateral (acromial end).
Structure of the Clavicle
The clavicle consists of cancellous tissue, enveloped by a compact layer, which is much thicker in the intermediate part than at the extremities of the bone. 11
Functions of clavicle
- The Clavicle allows the scapula to move freely on the thoracic wall due to the way in which it acts as a rigid support for the scapula and the arm. This gives the arm a higher range of movement.
- The collar bone protects the neurovascular bundle that supplies the upper limb.
- The Clavicle acts as a shock absorber by transmitting physical impacts from the upper limb to the axial skeleton.
Lateral 1/3:
Trapezius muscle,
Deltoid Muscle,
Coracoclavicular ligament.
Medial 1/3:
Sternocleidomastoid muscle,
Pectoralis major muscle,
Subclavius muscle,
Costoclavicular ligament.
Ossification of the Clavicle
The clavicle is the first bone in the human body to ossify. The ossification process is of two types - intramembranous or dermal and endochondral. ; it is ossified from three centers—viz., two primary centers, a medial and a lateral, for the body, 53 which appear during the fifth or sixth week of fetal life; and a secondary center for the sternal end, which appears about the eighteenth or twentieth year, and unites with the rest of the bone about the twenty-fifth year.
Articulations of the Clavicle
The clavicle articulates with three bones: the sternum, the scapula, and the first rib. The sternal extremity forms an ovoid articular facet that sits in the clavicular notch of the manubrium. Just inferior to this facet is a smaller oval surface for articulation with the costal cartilage of the first rib. Laterally, an oval facet on the inferior aspect of the acromial extremity articulates with the acromion of the scapula.
Gender Variations of the Clavicle
Female clavicle is shorter, lighter, thinner, smoother, and less curved than in males . The lateral end of the clavicle is a little below the medial end in females whereas In males, the lateral end is either at the same level or slightly higher than the medial end.
Borders of the Clavicle
The anterior border is concave, thin, and rough, and gives attachment to the Deltoideus. The posterior border is convex, rough, thicker than the anterior, and gives attachment to the Trapezius.
Surfaces of the Clavicle
The medial two thirds of the shaft of the clavicle is rounded and has four surfaces.
- The anterior surface- It is convex forwards,gives origin to pectoralis major
- The posterior surface- It is thickened and smooth,gives origin to sternohyoid muscle
- The superior surface- This surface iss rough in its medial part.
- The inferior surface- It has a rough oval impression at the medial end. It harbors a longtitudinal groove called subclavian groove in its lateral half,gives attachment to subclavius muscle
- Lateral (Acromial) End:articulates with with the acromian process of the scapula to form the acromioclavicular joint
- Medial (Sternal) End:articulates with the clavicular notch of the manubrium sterni to form sternoclavicular joint
READ MORE ABOUT:
Anatomy of the Scapula
Anatomy of the Clavicle
Sternum anatomy
Shoulder Anatomy
Sterno-Clavicular Joint Anatomy
abdominal anatomy
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Wednesday, February 25, 2015
Pharynx Anatomy
Pharynx
The pharynx, a channel for both air and food, has three parts. Read about the nasopharynx, oropharynx and hypopharynx, the three divisions of the pharynx.
The pharynx is a passageway located within the neck and is part of both the respiratory and digestive systems since it serves as a conduit for both air and food. Anatomically, the pharynx is divided into three parts – the nasopharynx, oropharynx and hypopharynx – from above downwards.
The pharynx connects the nasal and oral cavities above with the trachea (or the wind pipe) and the esophagus (or the food pipe) below. Although the main function of the pharynx is to ensure that food and air are directed into their respective pathways, all three subdivisions comprise many structures with varied functions. Let’s take a look at each of them.
Nasopharynx– Uppermost Division of the Pharynx
The Nasopharynx is the upper part of the pharynx, as the prefix of the word suggests, it is the nasal part of the pharynx. The Nasophaynx runs from the base of the skull to the top of the soft palate and is connected via the Eustachian tubes to the middle ear. It is the constriction and expansion of these tubes that regulate pressure in the middle ear in response to atmospheric changes, and can cause problems when air pressure changes dramatically, such as when taking off in a plane. At the back of the nasopharynx the choanae is a space which connects the pharynx to the nasal cavities. The pharyngeal tonsils, more widely referred to as the adenoids, are situated at the back wall of the nasopharynx and are an example of lymphatic tissue that can swell if an infection is present, causing the familiar ‘nasal’ tone of voice associated with colds.
Structures in the nasopharynx include:
- openings of the Eustachian tubes – these are tubes connecting the ear cavities with the pharynx. Their purpose is to ventilate the middle ear and equalize middle ear pressure with atmospheric pressure for optimal hearing.
- fossa of rosenmuller – This is a small but deep cavern, often the starting point for cancer in these parts.
- adenoids – a collection of lymphoid tissue located in the roof of the nasopharynx. It is part of the immune system and helps protect the body from infective organisms. Adenoids are usually only present in children. They regress in size and gradually disappear as the child grows older.
- tubal tonsils – also lymphoid tissue, located around the Eustachian tube openings.
The Nasal Cavity
On the lateral walls of the nasopharynx are the pharyngeal ostia, the opening of the auditory tube. These are supported and tethered by the torus tubarius formed by the stiff end of the cartilage which lifts the mucus membrane. From this opening there are two folds: the salpingopharyngeal fold which contains the salpingopharyngeal muscle amongst its mucus membrane, and the salpingopalatine fold, which is smaller and contains the levator veli palatini muscle. Posterior to the ostium of the auditory tube is the fossa of Rosenmüller (the pharyngeal recess). This is where the pharyngeal tonsil is located, which is particularly prominent during childhood and consists of lymphoid tissue similar to the adenoids. Above the tonsil is a depression in the mucous membrane known as the pharyngeal bursa.
The Oropharynx and HypopharynxOropharynx
The oropharynx lies behind the oral cavity, and forms the portion of the pharynx below the nasopharynx, but above the laryngopharynx. This section extends from the uvula which is the end of the palate, to the level of the hyoid bone. The oropharynx opens into the mouth through the isthmus faucium. On the anterior wall of the oropharynx is the base of the tongue and the epiglottic vallecula. The epiglottis, a flap of cartilaginous tissue, covers the glottis when food is being swallowed; this small flap of connective tissue plays a major role in keeping the respiratory tract free from food being inhaled accidentally. On the sides of the oropharynx are two palatine arches, and between these is the palatine tonsil. The roof of the oropharynx is the soft palate and the uvula.
Structures in the oropharynx include:
soft palate – this structure actually marks the boundary between the nasopharynx and oropharynx. When food swallowed is pushed into the oropharynx by the tongue, the soft palate immediately stretches to touch the pharyngeal wall, completely sealing off the oropharynx from the nasopharynx, preventing food from regurgitating into the nose and instead directing it down towards the esophagus. tonsils – these are lymphoid structures located on either side of the entry to the oropharynx from the oral cavity. These are the structures removed when a person undergoes tonsillectomy. base of the tongue – one-third of the tongue is actually fixed and located in the oropharynx. pharyngeal band – small nodules of lymphoid tissue scattered along the posterior pharyngeal wall.
Structures in the oropharynx include:
Hypopharynx
The hypopharynx, which forms the lower third of the pharynx, is also known as the laryngopharynx as it connects the throat to the oesophagus. It is below this point that bifurcation occurs, forming the larynx and oesophagus, and separating the respiratory and digestive routes. The oesophagus is posterior to the larynx and is accommodated by the ability of the trachea to collapse slightly upon food being swallowed due to its C-shaped cartilaginous rings.
Cervical Spinal NervesThe hypopharynx’s uppermost point is at the hyoid bone, which lies at approximately the same level as the 4th-6th cervical vertebrae. The pharynx is innervated by a number of nerves with their roots in the cervical spine. Damage to these nerve pathways can result in problems with the correct functioning of all three sections with ramifications for proper control of the separation of the larynx and oesophagus. Faults in innervation, both motor and sensory, in this area may prevent the two pathways functioning properly.
Motor innervation occurs through the glossopharyngeal nerve (IX), the vagus nerve (X), the allied spinal accessory nerve (XI), and the recurrent laryngeal nerve. Sensory innervation in the oropharynx section occurs as a result of the glossopharyngeal nerve (IX), with the vagus nerve (X) providing for the nasopharynx and the hypopharynx/laryngopharynx. As the sensory fibers from the glossopharyngeal nerve (IX) and the vagus nerve (X) enter the brainstem they are bundled together and terminate in the trigeminal nucleus. The trigeminal nerve (CN5) is responsible for creating a complete sensory map of the face and mouth with pain, touch, temperature and position signals all processed through this nerve. Accordingly, trigeminal neuralgia as a result of disc herniation, disc bulging, spondylolisthesis and spinal kyphosis or slippage, amongst other conditions, can be responsible for serious problems with the innervation of the face, jaw, and pharynx. Facial pain, jaw pain, neck pain, problems with chewing and swallowing, a sensation of a lump in the throat, and muscular spasms in the face, jaw, and neck can all result from compression of the cervical spinal nerves.
Functions of the Pharynx
The main function of the pharynx is to act as a channel for food and air, directing each to its respective destination. Peristaltic or propulsive waves in the pharynx during deglutition or swallowing help drive food into the esophagus. It is very important that food be prevented from entering the trachea as anything other than air entering this passage into the lungs can result in dangerous aspiration or choking.
The lymphoid structures in the pharynx play a role in immunity. Together with the adenoids, tubal tonsils and the pharyngeal band, the tonsils form what is called the Waldeyer’s ring, a ring of protection around the nose and mouth, common portals of entry for infection. The pharynx also provides resonance to voice.
The pharynx, divided into three parts namely the nasopharynx, oropharynx and hypopharynx, acts as a passage for both air and food and plays an important role in respiration, deglutition and immunity.
Conditions affecting the Pharynx
The location of the thyroid, and parathyroid glands in the neck also impacts the action of the pharynx and larynx, with any swelling in the area due to conditions such as Hashimoto’s Thyroiditis or hypothyroidism, capable of causing constriction of circulation and nerve pathways. In addition, conditions such as cervical arthritis, disc herniation, spinal stenosis, spondylolisthesis, and fibromyalgia may cause inflammation, neuralgia, radiculopathy, and difficulties with swallowing, controlling the airway, and even changes in the voice. Muscle spasms and cramps, found in conditions such as temporomandibular joint syndrome and fibromyalgia, are also possible mechanisms for dysfunction in this area.
The Tonsils
The Tonsils
The pharynx contains specialised lymphatic tissue that is designed to prevent pathogens’ entry into either the digestive, or the respiratory system. This ‘ring’ of lymphatic tissue consists of three groups: the nasopharyngeal tonsils (adenoids), the palatine tonsils (tonsils), and the lingual tonsils on the posterior surface of the tongue. The presence of recurrent infections can lead to inflammation and pain in these structures with many tonsillectomies performed in an attempt to prevent further tonsillitis. Whether this removal of lymphatic tissue has adverse consequences for systemic immunity is open for debate, with orthodox and naturopathic physicians often holding significantly differing opinions. Infection of the tonsils can cause glands to swell in other areas of the neck and may involve a stiff neck andneck pain along with fever and other bodily aches and pains.
Ethmoid BONE ANATOMY
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SKIN Anatomy Layers
The epidermis
The epidermis is the outer layer of your skin and includes the part of your skin you see every day – the surface. However, the epidermis is comprised of more than just the skins surface. It consists of a number of levels, each with their own distinct role.
Cells in the deepest level of your epidermis are extremely active and divide constantly to make more and more new cells.
Once generated, these new cells are pushed upward through the other levels of the epidermis and toward the surface of your skin. Along the way, they die and eventually become filled with keratin, a very strong protein. These dead, keratin-filled cells make up the outer parts of the epidermis and provide your body with the tough, protective overcoat it needs to survive.
The dead cells on the outer parts of your skin are constantly shed and replaced by new ones. As a result, every 20-30 days, your body has an entirely new surface of skin.
The dermis
The dermis is the inner layer of your skin. It is a thick layer of connective tissue and is itself divided into two levels. The upper level of the dermis, known as the papillary region, is made of loose connective tissue, while the lower level, called the reticular layer, is comprised of tissue that is more tightly packed.
Your dermis consists of strong collagen and elastic fibres pierced by blood vessels. These blood vessels help regulate the temperature of your body by increasing blood flow to the skin when you are hot and need to release some heat, or by restricting blood flow to the skin when you are cold and need to keep warm.
The dermis includes a network of nerves and receptors that help you sense touch, pressure and pain, and it is also full of hair follicles and sweat and oil glands, which are designed to keep your skin soft and healthy.
As well as performing all of the roles described above, the dermis acts as a cushion against injury. When you cut yourself, the dermis heals by forming new tissue, which is rich in new blood vessels and cells. It is this tissue which helps pull the edges of a cut on your skin back together over the course of 1 to 3 weeks.
Hypodermis
It is the innermost layer of the skin and consists of fibroblasts, adipose tissue and macrophages. It plays an important role as thermo regulator and energy reservoir.
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