THE HEAD

  • Fractures:
  • Pterion – impt clinical landmark. Overlies anterior branches of the middle meningeal vessles which lie in the grooves on the internal aspect of the lateral wall. Blow to side may fracture the bones forming pterion, rupturing the ant branch of the middle meningeal artery.  epidural hematoma. Left untreated may cause death in hours.
  • Depressed fractures – caused by hard blows to the head  fragment of bone is dpressed inward to compress or injure the brain
  • Comminuted fracture – bone broken into several pieces
  • Linear fractures – most frequent type – occur at point of impact. Fracture lines rotate away from it in two or more directions.
  • Contrcoup (counterblow) – occurs on the opposite side of the cranium rather than point of impact.
  • Facial injury – causes marked swelling (as does infection) due to lack of distinct layer of deep and superficial fascia  loose  enable large amts of fluid and blood to accumulate after bruising of face
  • Trigeminal Neuralgia – root of CN V. Characterized by sudden attacks of excruciating jabs of facial pain. Paroxysm…. Maxillary most frequently involved. Trigger zones of skin. Cause unknown.
  • Lesions of CN V – can cause widespread anesthesia involving the corresponding ant halfof scalp, face, cornea and conjunctiva, muscles of mastication, mucous membrane of nose and paranasal sinus, mouth andant part of tongue
  • Bells Palsy – CN VII - edema and compression of nerve in facial canal. Loss of tone of orbiculoaris ocli, weakens/paralyzes buccinator. Tears and saliva run from drooping lid and mouth.
  • Carcinoma of lip – usually involes the lower lip. Cancer cells from the central part of the lip spread to the submental LN whereas cancer from lateral parts of the lip drain to the submandibular LN
  • Injury to facial nerve – May be injured in parotidectomy
  • Infection of parotid gland (mumps)  inflammation and swelling  parotid sheath limits swelling… pain worse during chewing.  can cause pain confused with toothache and in auricle, external acoustic meatus and TMJ because the auriculotemporal n (CN V3), from which the parotid gland receives sensory fibers also supplies sensory fibers to skin over the temporal fossa and auricle.
  • Scalp injury and infections
  • Arteries protected by DCT and anastomose freely. reasonable change a partially detached scalp can be replaced.
  • Loose connective tissue layer = dangerous area of scalp because pus or blood spreads easily through its potential spaces. Infections in this cavity can also spread into the cranial cavity via emissary veins that pass through the parietal foramina in the clavaria and infect intracranial structures.. cannot pass posteriorly into the neck because the occipital belly of the occipitofrontalis muscles attaches to the occipital bone and mastoid parts of the temporal bones.
  • Infection or fluid can enter the eyelids and roof of the nose b/c the frontal belly of the occipitofrontalis muscles inserts into the skin and DCT and doesn’t attach to the bone.
  • Scalp lacerations are the most common type of head injury. Arteries held open by DCT in second layer of scalp.  profuse bleeding. May bleed to death.
  • Thrombophebitis – facial veins make clinically important connections with the cavernous sinus through superior ophthalmic veins. b/c they’re valvless, blood may pass superiorly to the superior ophthalmic vein and enter the cavernous sinus. Facial thrombophlebitis may be initiated by squeezing pimples on the side of the nose and upper lip.
  • Metastasis of tumor cells – basicalar and occipital sinuses communicate via foramen magnum with the internal vertebral venous plexuses. Compression of thorax, abd, or pelvis may force venous blood from these regions into the vertebral venous system and subsequently into the dural venous sinuses. As a result pus in abscesses and tumor cells from the trunk may spread to the vertebra and brain via these venous interconnections.
  • Fractures of the cranial base –may tear the internal carotid artery within the cavernous sinus  arteriovenous fistula  arterial blood rushes into the cavernous sinus  enlarge sinus  blood forced into the veins (esp the ophthalmic v)  exophthalmos and chemosis  pulsatile exophthalmos. May also affect CN III, IV, V1, V2, and VI because on the lateral wall of the cavernous sinus.
  • Blow to the head can detach the dura from the calvaria without fracturing the bones because dura att to periosteal layer tighter than to the calvaria.
  • Basal fracture usually tears the dura and arachnoid, resulting in leakage of CSF (into the neck)
  • Dural origin of headaches:
  • Dura is sensitive to pain …pulling on arteries at base of the cranium or non veins near vertex where they pierce the dura causes pain. Many headaches of dural origin due to stimulation of sensory nerve endings in the dura. When CSF is removed, brain sags slightly, pulling on dura  pain and headaches.
  • Thus, patients told to go in trendelenburg position after a lumbar puncture to minimize/prevent headaches
  • Head Injuries
  • Extradural or epidural hemorrhage between endosteal layer of dura and calvaria may follow a blow to the head.
  • Bleeding from meningeal arteries  extradural or epidural hematoma.  increase blood mass  compress brain
  • Dural border hematoma (subdural hematoma) – venous in origin… Results from the tearing of a cerebral vein a it enters the superior sagittal sinus... follow s a blow to the head that jerks the brain inside the cranium and injures it.
  • Subarachnoid hemorrhage – blood into the subarachnoid space from rupture of saccular aneurysm (dilation of an intracranial blood vessel). Asscod with head trauma involving cranial fractures and cerebral lacerations.
  • Cerebral injuries
  • Cerebral Concussion - abrupt brief loss of consciousness immediately after a blow to the head.
  • Cerebral contusion - results from trauma… pia is stripped from the injured area of the brain and may be torn  blood enters subarachnoidal space.
  • Cerebral laceration – tearing of neural tissue…. Assocd with depressed cranial fractures or gunshot wounds
  • Results in rupture of blood vessels and bleeding into the brain and subarachnoid space, resulting in increased intracranial pressure and cerebral compression.
  • Cerebral compression produced by:
  • Intracranial collection of blood
  • Obstruction of CSF circulation or absorption of CSF
  • Intracranial tumors or abscesses
  • Edema of brain, as swelling assoc’d with head injury
  • Cisternal puncture
  • Get CSF from port cerebellomedullary cistern. Subarachnoid space and ventricles may also be used to measure and monitor CSF pressure.
  • Hydrocephalus – overprodn of CSF, obstruction of flow owr interference withabsorption  xs CSF in ventricles and enlargement of the head
  • Leakage of CSF –
  • Fracture in floor of middle cranial fossa  leak from ear.
  • Floor of ant cranial fossa  cribiform plate  leak from ear
  • CSF otorrhea and rrhinorrhea  risk of meningitis
  • Vascular stroke – older people  anastomoses of cerebrum inadequate when internal carotid is occluded
  • Common causes: CVA
  • Hemorrhagic stroke – from rupture of an artery or an aneurysm
  • Transient Ischemic attacks (TIAs) – neurological symptoms resulting from ischemia (deificient blood supply) of the brain.
  • Fracture of orbit:
  • Anterior blow to the eye may fracture medial and inf walls of the orbit
  • Medial wall – ethmoid and sphenoid sinus
  • Inf wall – maxillary sinus
  • If sharp object passes the superior wall  pierce frontal lobe of brain
  • Exophthalmos – may be caused by tumor in orbit. Entrance into orbital cavity = superior orbital fissre.
  • Also may be caused by hyperthyroidism  increased volume of orbital contents
  • Injury to facial nerve supplying eyelids  paralysis of orbicularis oculi  cant close eyes fully  eyes dry out  dust and such irritate eyeball  xs lacrimation (though inefficient)
  • Inflammation of palpebral glands – if ducts of ciliary glands obstructed  sty.
  • Papilledema – from increased intracranial pressure  increases CSF pressure in the extension of the subarachnoid space around the optic n. continued pressure may result in blindness
  • Detachment of retina – pigment layer detach from neural.. usu results from seepage of fluid between the neural and pigmented layers of the retina after trauma to the eye.
  • Corneal laceration = scratch from foreign objects sa sand
  • Corneal abrasion – caused by sharp objects such as fingernails
  • Corneal ulcers – may result when the sensory innervation of the cornea is damaged and is then injured by foreign particles like sand.
  • Presbyopia – reduced focusing power of the lenses as the lenses become harder and more flattened
  • Cataracts = clouding of the lens from areas of opaqueness
  • Glaucoma – pressure build up in the chambers of the eye due to reduced drainage of the aqueous humor.
  • Oculomotor nerve palsy – affects most of the ocular muscles, levator palpebrae superioris and the sphincter pupillae.  ptosis, pupils fully dilated, pupil abducted and depressed
  • Abducent nerve lesion loss of lateral gave to the ispilaterla side.
  • Horners syndrome – interruption of cervical symp trunk  paralysis of superior tarsal muscles.  ptosis Constricted pupil, sinking, redness, dryness of eye. Increased temp of the face on the affected side.
  • Paralysis of extraocular muscles – may be due to the head injury or disease of the brainstem. Results in diplopia
  • Blockage of central retinal artery  blindness
  • Blockage of central retinal vein  because of the central vein of the retina enters cavernous sinus, thrombophlebitis of the sinus may result in passage of thrombi to the central reintal vine and produce clotting in the small retinal veins. Block of the vein results in slow loss of vision.
  • Mandibular nerve block – anesthetics the auriculotemporal, inf alveolar, lingual ,a and buccal branches of the mandibular n
  • Inf alveolar n block. – anesthetizes inf alveolar n (CN V3). Injected at the mandibular foramen
  • Dislocation of TMJ – head of mandible dislocates anteriorly... in front of the articular tubercle  mouth remains wide open. Side ways blow when mouth is open will dislocate the jaw.
  • Injury to the articular br of the auriculotemporal n supplying the TMJ assocd with traumatic dislocation and rupture of the articular capsule and lat lig  laxity and instability of TMJ
  • Nasopalatine nerve block – inject into the incisive fossa.
  • Greater palatine n block (V2)- inject into the greater palatine foramen.
  • Gag Reflex:
  • CN IX and X responsible for contraction of sides of pharynz. IX = afferent limb
  • Paralysis of genioglossus – tongue shift posteriorly  obstruct airway
  • Injury to CN XII – may be due to fractured mandible  paralysis and atrophy on one side of the tongue. Deviate to paralyzed side.
  • Sublingual absorption of drug. Under the tongue where thin mucosa allows drug to enter deep lingual veins in less than a minute.
  • Lingual carcinoma:
  • Post part of tongue  superior deep cervical LN on both sides
  • Apex and anterolat parts – don’t metastasize to inf deep cervical LN until late in the disease.
  • May spread to the submental and submandibular regions and along IJV into the neck.
  • Excision of submandibular gland - because of a stone in duct or tumor in gland. Avoid mandibular br of facial n. so incise at least 2.5 cm inf to angle of mandible
  • Nasal fracture – cribiform plate of ethmoid (from direct blow)  leakage of CSF (rhinorrhea)
  • Epistaxis = nose bleed – usually in the ant third of the nose (Kiesselbach’s area). Supplied by anastomosing br of five diff arterial sources.
  • CSF Rhinorrhea = may be due to resp tract infectionjs or also may be CSF from hread injury. From fracture of cribiform plate, tearing cranial meninges.
  • Rhinitis – infections from nasal cavities may spread to the …
  • Ant cranial fossa through cribiform plate
  • Nasopharynx and retropharyngeal soft tissues
  • Middle ear through pharyngotympanic tube
  • Paranasal sinus
  • Lacrimal app and conjunctiva
  • Infection of ethmoidal cells – if nasal drainage is blocked, infections of the ethmoidal cells of sinus may break through the fragile medial wall of the orbit. May cause blindness because some of these cells lie close to the optic canal.
  • Infection of maxillary sinuses – piece of root of molar may be driven superiorly through to the maxillary sinus. Can be drained by passing a cannula through the nostril and into the maxillary ostium of the sinus.
  • Otitis media – bulging red tympanic membrane - may cause partial or ompltee blockage of the pharyngotympanic tube.
  • If left untreated.. may cause scarring of the ossicles  impair hearing.
  • May cause perforation of the tympanic membrane.
  • May cause mastoiditis. Via the mastoid antrum
  • Paralysis of stapedius – (lesion of CN VII)  xs acuteness of hearing. Hyperacusis. Uninhibited mvmt of the stapes
  • Blockage of the pharyngotympanic tube – form route for infection to pass from the nasooharynx to the tympanic cavity. . when occluded  air in the tympanic cavity is absoerbed intot he mucosal bl vess  dec pressure in cavity, retract membrane … interfere with its free mvmt.
  • Motion sickness – result from fluctuating stimulation of the maculae
  • High tone deafness – degen. Changes due to persistent exposuree to excessively loud sounds
  • Otic barotraumas – injury caused to the ear by an imbalance in the pressure between ambient air and the air in the middle ear.

THE NECK

  • Spread of infection in the neck – investing layer of deep cerv fascia helps prevent spread of abscesses. Usually will not spread past the sup edge of the manubrium.
  • If in between the investing and pretracheal layers… can spread to the thoracic cavity ant to the pericardium.
  • Retropharyngeal abscess – cause difficulty in swallowing and speaking.
  • Injury of platysma –
  • Paralysis from laceration of (CN VII – cerv br) – cause skin to fall away from the neck in the slack folds.
  • Injury of SCM – CN XI. Tilt of head. And stiff neck from fibrosis and shortening of the SCM
  • Subclavian vein puncture – RSv = point of entry to the venous syst for central line placement.
  • Danger to pleura and subclavian a
  • EJV prominent in increased pressure such as in heart failure… usually not prominent.
  • Spinal root XI injury – drooping of shoulders, unilateral paralysis of the traps
  • Phrenic n lesion  paralysis of diaphragm.
  • Regional anesthesia @ cerv plx or supraclavicular brachial plx
  • Ligation of ext carotid a – decrease bl flow through artery and branches. Blood will flow retrogradely into the artery from the ext carotid artery on the other side through communications between its branches.
  • When ext carotid or subclavian arteries are ligated – desc br of occipital a = main collateral circln.
  • Carotid triangle – impt surgical approach to carotid syst of a, the IJV, CN X and XII, and cerv symp trunk.
  • Carotid pulse – groove between trachea and infrahyoid m. palpated just deep to the ant border of the SCM at the level of thee sup border of the thyroid crtlg.
  • Internal jugular pulse – pulsation of IJV caused by contraction of the RV of the heart may be palpated sup to the medial end fo the clavicle.
  • IJV puncture – needle and catheter may be inserted in to the IJV for diagnostic or therapeutic purposes. … aim at apex of triangle between sternal and clavicular heads of the SCM.
  • Cervicothoracic ganglion (stellate) – block transmission of stimuli through cerv and superior thoracic ganglia.
  • Lesion of symp trunk  horners syndrome: pupil constricted, ptosis, eye sinks in, vasodilation and absence of sweating on the face and neck.
  • Radial neck dissections = remove all tissue with LN and try to prevent cancerous cells from escaping and circulating causing metastsis spread of the cancer.
  • Pyramidal lobe of thyroid – in 50%
  • Parathyoroid glands safe in subtotal thyroidectomy (leave the post portion of the thyroid). If inadvertently removed  tetany – convulsive muscles spasm from fall in bl calcium levels.
  • Accessory thyroid gland – may form.. usually found on the thyrohyoid muscles. From thyroglossal duct.
  • Injury to laryngeal nerves  paralysis of vocal folds  hoarse voice.
  • Dyspnea may result because inable to abduct vocal folds to permit increased respiration.
  • Hoarseness = most common symptom of serious disorder of larynx
  • More CC (no not the chief complaint) on Larynx (pg 629)
  • Aspiration of foreign bodies – may enter vestibule accidentally where it gets trapped sup to the vestibular folds. Muscles go into spasm… tense folds. Rima glottidis closes and no air enters the trachea. HEIMLICH! (don’t sue me please)
  • When doing a tracheotomy and tracheostomy, remember:
  • Inferior thyroid veins – arise from the thyroid plx of veins and descend on the anterolateral surface of the trachea
  • A small thyroid artery may be present and ascend to the isthmus of the thyroid gland
  • Left brachiocephalic v, jugular venous arch, and pleurae may be encountered.
  • Thymus covers the inf part of the trachea in infants and children.
  • Trachea is small mobile and soft in infants, making it easy to cut through its post wall and damage the esophagus.
  • Tonsillitis and tonsillectomy- bleeding usu from the large ext palatine vein. CN IX accompanies tonsiallar artery on the lateral wall of the pharynx. . int carotid artery is vulnerable – lies directly lateral to the tonsil.
  • Adenoiditis – inflammation of the pharyngeal tonsils (adenoids). Can obstruct passage of air from the nasal cavieties through the choanae into the nasopharynx.
  • Foreign bodies of laryngopharynx – foreign bodies entering pharynx may be lodged in the piriform recess. May pierce mucous membrane and injure sup laryngeal n and its int laryngeal br.
  • Zones of neck trauma –
  • Zone 1 – root of neck from clavicle and manubrium to the cricoid crtlg.
  • Structures: cerv pleura, apices of lung, thyroid and parathyroid, trachea, esophagus, common carotid a, jugular v,
  • Zone 2 – cricoid crtlg to angle of mandible
  • Structures – apices of thyroid gland, thyroid and cricoid crtlg, larynx, laryngopharynx, carotid a, jugular v, esophagus,
  • Zone 3 – superior to angles of mandible
  • Structures – salivary gland, facial n, oral and nasal cavities, oropharynx and nasopharynx
  • Injury to Zones 1 and 3 – obstruct airway and have greatest risk for morbidity and mortality
  • Injuries in Zone 2 – most common

CRANIAL NERVES