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lower_limb-head.doc

  1. 1. LOWER LIMB Fractures of the Hip (319) Fracture of the hip bone often results from a violent injury such as occurs in a major vehicular accident. Anteroposterior compression of the hip bones fractures the public rami. Lateral compression of the pelvis may fracture the acetabula, as when one lands on the feet (e.g. from a roof) when the limbs are extended. Femoral Fractures Fractures of the femoral neck are fairly common, especially in persons with osteoporosis (reduction in quantity of bone). These fractures often interrupt blood supply to the femoral head, resulting in bone degeneration. Fractures between the greater and lesser trochanters (intertrochanteric fractures) or through the trochanters (pertrochanteric fractures) are common in persons older than 60 years. The femoral shaft is large and strong; however, a violent direct injury, such as may be sustained in an automobile accident, may fracture it. Coxa Vara and Coxa Valga The angle of inclination that the long axis of the femoral neck makes with the shaft (A) varies with age, sex and development of the femur (e.g. consequent to a congenital defect in ossification of the femoral neck). It may also change with any pathological process that weakens the neck of the femur (e.g. rickets). When the angle of inclination is decreased, the condition is coa vara; When the angle is increased it is coax valga. Coxa vara causes a mild shortening of the lower limb and limits the passive abduction of the hip. Patellar Fractures (320) A direct blow to the patella may fracture it into two or more fragments. Transverse patellar fractures may result from a blow to the knee or from sudden contraction of the quadriceps muscle, for example when one slips and attempts to prevent a backward fall. The proximal fragment of the patella is pulled superiorly with the quadriceps tendon and the distal fragment remains with the patellar ligament. Tibial and Fibular Fractures (321) The tibia is the most common long bone to be fractures and is the most frequent site of a compound fracture― one in which the skin is perforated and blood vessels are torn. Fracture of the tibia through the nutrient canal predisposes to nonunion of the bone fragments, resulting from damage to the nutrient artery. The tibial shaft is subcutaneous and unprotected anteromedically throughout its course. It is narrowest (and weakest) at the junction of its middle and inferior thirds. Fractures of the fibula commonly occur just proximal to the lateral malleolus and are often associated with fracture-dislocations of the ankle joint. When the person slips, forcing the foot into an excessively inverted position, the ankle ligaments tear, forcibly tilting the talus again the head of the lateral malleolus and sharing it off. Bone grafts The fibula is a common source of bone for bone grafting. Even after a piece of the fibular shaft has been removed, walking, running and jumping can be normal. The periosteum and nutrient artery are generally removed with the piece of bone so that the graft will remain alive and grow when transplanted to another site. The transplanted piece of fibula, secured in its new site, eventually restores the blood supply of the bone to which it is now attached. Healing proceeds as it merely a fracture were at each of its ends Flatfeet Flatfeet in adolescents and adults results from “fallen arches”, usually the medial parts of the longitudinal arches. When a person is standing, the plantar ligaments and plantar aponeurosis stretch somewhat under the body weight. If these ligaments become abnormally stretched during long periods of standing, the plantar calcaneonavicular ligament can no longer support the head of the talus. Consequently, the talar head displaces inferomedially and becomes prominent. As a result, some flattening of the medial part of the longitudinal arch occurs, along with lateral deviation of the forefoot. In the common type of flatfoot, the foot resumes its arched form when weight is removed from it.
  2. 2. HEAD Fractures of Calvaria The pterion is an important clinical landmark because it overlies the branches of the middle meningeal vessels, which lie in the grooves on the internal aspect of the lateral wall of the calvaria. A blow to the head may fracture the thin bones forming the pterion, rupturing the anterior branch of the middle meningeal artery. The resulting etradural collection of blood (usually an epidural hematoma) exerts pressure on the underlying cerebral cortex. Untreated middle meningeal artery homorrhage may cause death within a few hours. The convexity of the calvaria distributes and therefore minimizes the effects of the blow to it. However, hard blows to the head in thin areas of the cranium are likely to produce depression fractures, in which a fragement of bone is depressed inward to compress or injure the brain. In comminuted fractures, the bone is broken into several pieces. Linear fractures, the most frequent type, usually occur at the point of impact, but fracture lines often radiate away from it in two or more directions. If the area of the calvaria is thick at the site of impact, the bone usually bends inward without fracturing; however, a fracture may occur some distanct from the site of direct trauma where the calvaria is thinner. In a contrecoup (counterblow) fracture, the fracture occurs on the opposite side of the cranium rather than at the point of impact. (p.500-501) Facial injuries Because the face does not have a distinct layer of deep fascia and the subcutaneous tissue (superficial fascia) is loose between the attachments of muscle, injury or infection causes marked swelling. The looseness of the subcutaneous tissue also enables relatively large amount of tissue and blood to accumulate after bruising of the face (e.g. a black eye). Furthermore, facial lacerations tend to gape (part widely); consequently, the skin must be sutured carefully to prevent scarring. Trigeminal neuralgia Trigeminal neuralgia (tic douloureux) is a sensory disorder of the sensory root of CN V that is characterized by sudden attacks of excruciating, lightning-like stabs of facial pain. A paroxysm (sudden sharp pain) can last for 15 minutes or more. The maxillary nerve is most frequently involved, then the mandibular nerve, and least frequently, the ophthalmic nerve. The pain is often initiated by touching a sensitive trigger zone of the skin. The cause of trigeminal neuralgia is unknown; however some investigators believe that most affected persons have an anomalous blood vessel that compresses the sensory nerve root of CN V. When the aberrant artery is moved away from the root, the symptoms usually disappear. In some cases, the symptoms it is necessary to section the sensory root for relief from Trigeminal neuralgia. Lesions of the trigeminal nerve Lesions of the entire trigeminal nerve may cause widespread anesthesia involving the: • Corresponding anterior half of the scalp • Face, except for an area around the edge of mandible • Cornea and conjunctiva • Mucous membranes of the nose and paranasal sinuses, mouth, and anterior part of the tongue. Paralysis of the muscles of mastication also occurs. Bell Palsy The most common nontraumatic cause of facial palsy or paralysis is inflammation of the facial nerve near the stylomastoid foramen. This produces edema and compression fo the nerve in the facial canal (bell’s palsy). The loss of tonus of the orbicularis oculi causes the lower lid to evert (turn away from the surface of the eye) so that the cornea of the affected side is not adequately hydrated or lubricated with lacrimal fluid, making it vulnerable to laceration. People with Bell’s Palsy cannot whistle, blow a wind instrument of chew effectively. The palsy weakens of paralyzes the buccinator and orbicularis oris, the cheek and lip muscles that aid chewing by holding food between the occlusal surfaces of the teeth and out of the oral vesibule (gutter between the cheek and teeth). Food accumulates there during chewing and must often be continually removed with a finger. Displacement of the mouth is produced by contraction of the
  3. 3. upopposed contralateral facial muscles and by dropping of the corner of the mouth by the unopposed pull of gravity, resulting in food and saliva dribbling out of the side of the mouth. People frequently dab their eyes and mouth with a handkerchief to wipe the fluid (tears and saliva), which runs from the drooping lid and mouth. Nasopalatine nerve block The nasopalatine nerves can be anesthetized by injecting anesthetic into the mouth of the incisive fossa in the hard palate. The needle is inserted posterior to the incisive papilla, a slight elevation of the mucosa that covers the incisive fossa. The affected tissues are the palatal mucosa, the lingual gingivae, and the alveolar bone of the si anterior maxillary teeth and the hard palate. Greater palatine nerve block The greater palatine nerve can be anesthetized by injecting anesthetic into the greater palatine foramen. The nerve emerges between the 2nd and 3rd molar teeth. This nerve block anesthetized, on the side concerned, all the palatal mucosa and lingual gingival posterior to the maxillary canine teeth and the underlying bone of the palate. Gag Reflex One may touch the anterior part of the tongue without feeling discomfort; however, when the pharyngeal part is touched, one usually gags. CN IX and X are responsible for the muscular contraction on each side of the pharynx. CN IX provides the afferent limb of the gag reflex. Paralysis of the genioglossus When the genioglossus is paralyzed, the tongue mass has a tendency to shift posteriorly, obstructing the airway and presenting the risk of suffocation. Tonal relaxation of the genioglossus muscle occurs during general anesthesia; therefore, the tongue of an anesthetized patient must be prevented from relapsing by inserting an airway. Injury to the hypoglossal nerve Trauma, such as a fractured mandible, may injure the hypoglossal nerve, resulting in paralysis and eventual atrophy of one side of the tongue. The tongue deviates to the patalyzed side during protrusion because of the “anchoring” effect of the inactive side. Sublingual absorption of drugs For quick transmucousal absorption of a drug—for instance when nitroglycerin is used a vasodilator in angina pectoris (chest pain) — the pill is put under the tongue where the thin mucosa allows the absorbed drug to enter the deep lingual veins in less than a minute. Lingual carcinoma Malignant tumors in the posterior part of the tongue metastasize to the superior deep cervical lymph nodes on both sides. In contrast, tumors in the apex and anterolateral parts usually do not metastasize to the inferior deep cervical nodes until late in the disease. Because the deep nodes are closely related to the IJVs, carcinoma from the tongue may spread to the submental and submandibular regions and along the IJVs into the neck. Excision of the submandibular gland Excision of the submandibular gland because of a calculus (stone) in its duct or a tumor in the gland is not uncommon. Risk to the mandibular branch of the facial nerve may be avoided by making the skin incision at least 2.5 cm inferior to the angle of the mandible. Sialography The parotid and submandibular glands may be examined radiographically after the injection of a contrast medium into their ducts. This special type of radiograph (Sialography) demonstrates the salivary ducts and some secretory units. Because of the small size and number of sublingual ducts of the sublingual glands, one cannot usually inject contract medium into them. Nasal fractures
  4. 4. Deformity of the external nose is usually present with a fracture, particularly when a lateral force is applied by someone’s elbow for example. When the injury results from a direct blow (e.g. a hockey stick), the cribiform plate of the ethmoid bone may fracture, resulting is CSF rhinorrhea. (573) Epistaxis Epistasis (nose bleeding) is common because of the rich blood supply to the nasal mucosa. In most cases the cause is trauma and the bleeding is located on the anterior third of the nose (Kiesselbach’s area). Recall that this area is supplied by the anastomosing branches from five different arterial sources. Spurting of blood from the nose results from rupture of these arteries. Epistaxis is also associated with infections and hypertension. CSF rhinorrhea Although nasal discharges are commonly associated with upper respiratory tract infections, a nasal discharge after a head injury may be CSF. CSF rhinorrhea results from fracture of the cribiform plate, tearing of the cranial meninges, and leakage of CSF from the nose. (576) Rhinitis The nasal mucosa become swollen and inflamed (rhinitis) during upper respiratory infections and allergic reactions (e.g. hay fever). Swelling of this mucus membrane occurs readily because of its vascularity and abundant mucosal glands. Infections of the nasal cavities may spread to the • Anterior cranial fossa through the cribiform plate • Nasopharynx and retropharyngeal soft tissues • Middle ear through the pharyngotympanic (auditory) tube • Paranasal sinuses • Lacrimal apparatus and conjunctiva Infection of the ethmoidal cells If nasal drainage is blocked, infections of the ethmoidal air sinuses may break through the fragile medial wall of the orbit. Severe infections from this source may cause blindness because some posterior ehtmoidal air cells lie close to the optic canal, which gives passage to the optic nerve and ophthalmic artery. Spead of infection from these cells could also affect the dural sheath of the optic nerve, causing optic neuritis. Infection of the maxillary sinuses The maxillary sinuses are the most commonly infected, probably because their ostia are located on their superomedical walls, a poor location for natural drainage of the sinus. When the mucus membrane of the sinus is congested, the maxillary ostia are often obstructed. The proximity of the molar teeth to the floor of the maxillary sinus poses potentially serious problems. During removal of a maxillary molar tooth, a fracture of a root may occur. If proper retrieval methods are not used, a piece of the root may be driven superiorly into the maxillary sinus. A communication (fistula) may be created between the oral cavity and the maxillary sinus. The maxillary sinus often can be cannulated and drained by passing a canula through the nostril and into the maxillary ostium of the sinus. Otoscopy Examination of the tympanic membrane begins by aligning the cartilaginous and bony parts of the meatus. In adults, the helix (margin) of the auricle is graped and pulled posterosuperiorly (up, out and back). These movements straighten the meatus, facilitating use of the otoscope. The external acoustic meatus is relatively short (lacks a bony part) in infants; therefore, extra care must be taken to prevent damage fo the tympanic membrane. Otitis media A bulging red tympanic membrane may indicated pus or fluid in the middle ear, a sign of otitis media. Infection of the middle ear is often secondary to upper respiratory infections. Inflammation and swelling of the mucous membrane lining the tympanic cavity may cause partial or complete blockage of pharyngotympanic tube. The tympanic membran becomes red and bulges and the person may complain off “ear popping”. If untreated, otitis media may produce impaired hearing as a result of scarring of the auditory ossicles, limiting the ability of these bones to respond to sound. Perforation of the tympanic membrane
  5. 5. Perforation of the tympanic membrane may result from otitis media. Perforation may also result from foreign bodies in the external acoustic meatus, trauma, or excessive pressure. Because the superior half of the tympanic membrane is much more vascular than the interior half, incisions (e.g. to release pus) are made posteroinferiorly through the membrane. This incision also avoids injury to the chorda tympani nerve and auditory ossicles. Severe bleeding through a ruptured tympanic membrane and the external acoustic meatus may occur after a sever blow to the head. Fractures of the floor of the middle cranial fossa may tear the meninges and result in loss of CSF through a ruptured tympanic membrane. Mastoiditis Infection of the mastoid antrum and mastoid cells (Mastoiditis) result from middle ear infections (otitis media) that cause inflammation of the mastoid process. Infections may spread superiorly into the middle cranial fossa through the petrosquamous fissure in children or may cause osteomyelitis (bone infection) of the tegmen tympani. During operations for mastoiditis, surgeons are conscious of the course of the facial nerve so that it will not be injured. One point of access to the tympanic cavity is through the mastoid antrum. In children, only a thin plate of bone must be removed from the lateral wall of the mastoid antrum to expose the tympanic cavity. In adults, bone must be penetrated for 15 mm or more. At present, most mastoidectomies are endaural (i.e. performed through the posterior wall of the external acoustic meatus) (p583) Paralysis of the stapedius The tympanic muscles have a protective action in that they dampen large vibrations of the tympanic membrane resulting from loud noises. Paralysis of the stapedius muscle (e.g. resulting from a lesion of the facial nerve) is associated with excessive acuteness of hearing—hyperacusis of hyperacusia. This condition results from uninhibited movements of the stapes. Blockage of the pharyngotympanic tube The pharyngotympanic tube forms a route for infections to pass from the nasopharynx to the tympanic cavity. This tube is blocked easily by swelling of its mucous membrane, even as a result of mild infections, because the walls of the cartilaginous parts are normally already in apposition. When the pharyngotympanic tube is occluded, residual air in the tympanic cavity is usually absorbed into the musousal blood vessels, resulting in lower pressure in the tympanic cavity, retraction of the tympanic membrane and interference with its free movement. Finally, hearing is affected. The more sudden, usually temporary, pressure changes resulting from air flight can usually be equalized by swallowing or yawning; these movements open the pharyngotympanic tube. Motion sickness The maculae of the membranous labyrinth are primarily static organs, which have small dense particles— otolyths—embedded among hair cells. Under the influence of gravity, the otoliths cause bending of the hair cells, which stimulate the vestibular nerver and provide awareness of the position of the head in space; the hairs also respond to quick tilting movements and to linear acceleration and deceleration. Motion sickness results mainly from fluctuating stimulation of the maculae. High tone deafness Persistent exposure to excessively loud sounds causes degenerative changes in the spiral organ, resulting in high tone deafness. This type of hearing loss commonly occurs in workers who are exposed to loud noises and do not wear protective earmuffs. It has also been determined that individuals associated with chronic exposure to high volume stereo music via earphones exhibit high tone deafness. Otic barotraumas Injury caused to the ear by an imbalance in pressure between ambient air and the air in the middle ear is called otolithic barotraumas. This type of injury occurs in fliers and divers.
  6. 6. Perforation of the tympanic membrane may result from otitis media. Perforation may also result from foreign bodies in the external acoustic meatus, trauma, or excessive pressure. Because the superior half of the tympanic membrane is much more vascular than the interior half, incisions (e.g. to release pus) are made posteroinferiorly through the membrane. This incision also avoids injury to the chorda tympani nerve and auditory ossicles. Severe bleeding through a ruptured tympanic membrane and the external acoustic meatus may occur after a sever blow to the head. Fractures of the floor of the middle cranial fossa may tear the meninges and result in loss of CSF through a ruptured tympanic membrane. Mastoiditis Infection of the mastoid antrum and mastoid cells (Mastoiditis) result from middle ear infections (otitis media) that cause inflammation of the mastoid process. Infections may spread superiorly into the middle cranial fossa through the petrosquamous fissure in children or may cause osteomyelitis (bone infection) of the tegmen tympani. During operations for mastoiditis, surgeons are conscious of the course of the facial nerve so that it will not be injured. One point of access to the tympanic cavity is through the mastoid antrum. In children, only a thin plate of bone must be removed from the lateral wall of the mastoid antrum to expose the tympanic cavity. In adults, bone must be penetrated for 15 mm or more. At present, most mastoidectomies are endaural (i.e. performed through the posterior wall of the external acoustic meatus) (p583) Paralysis of the stapedius The tympanic muscles have a protective action in that they dampen large vibrations of the tympanic membrane resulting from loud noises. Paralysis of the stapedius muscle (e.g. resulting from a lesion of the facial nerve) is associated with excessive acuteness of hearing—hyperacusis of hyperacusia. This condition results from uninhibited movements of the stapes. Blockage of the pharyngotympanic tube The pharyngotympanic tube forms a route for infections to pass from the nasopharynx to the tympanic cavity. This tube is blocked easily by swelling of its mucous membrane, even as a result of mild infections, because the walls of the cartilaginous parts are normally already in apposition. When the pharyngotympanic tube is occluded, residual air in the tympanic cavity is usually absorbed into the musousal blood vessels, resulting in lower pressure in the tympanic cavity, retraction of the tympanic membrane and interference with its free movement. Finally, hearing is affected. The more sudden, usually temporary, pressure changes resulting from air flight can usually be equalized by swallowing or yawning; these movements open the pharyngotympanic tube. Motion sickness The maculae of the membranous labyrinth are primarily static organs, which have small dense particles— otolyths—embedded among hair cells. Under the influence of gravity, the otoliths cause bending of the hair cells, which stimulate the vestibular nerver and provide awareness of the position of the head in space; the hairs also respond to quick tilting movements and to linear acceleration and deceleration. Motion sickness results mainly from fluctuating stimulation of the maculae. High tone deafness Persistent exposure to excessively loud sounds causes degenerative changes in the spiral organ, resulting in high tone deafness. This type of hearing loss commonly occurs in workers who are exposed to loud noises and do not wear protective earmuffs. It has also been determined that individuals associated with chronic exposure to high volume stereo music via earphones exhibit high tone deafness. Otic barotraumas Injury caused to the ear by an imbalance in pressure between ambient air and the air in the middle ear is called otolithic barotraumas. This type of injury occurs in fliers and divers.

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