Question

Review ears, eyes, nose, mouth, throat system

Review how to assess the thyroid gland, hearing, eyes,

Review types of hearing loss

Review abnormalities of the mouth

Review 12 cranial nerves and how to assess each of them

Answer 1

REWIEW OF EAR

• The ear is the organ of hearing and, in mammals, balance. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localisation.
• The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm.

The ear may be affected by disease, including infection and traumatic damage. Diseases of the ear may lead to hearing loss, tinnitus and balance disorders such as vertigo, although many of these conditions may also be affected by damage to the brain or neural pathways leading from the ear.

The ear has been adorned by earrings and other jewelry in numerous cultures for thousands of years, and has been subjected to surgical and cosmetic alterations.

REWIEW OF EYES

• Eyes are organs of the visual system. They provide animals with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons. In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.
• The most simple eyes, pit eyes, are eye-spots which may be set into a pit to reduce the angles of light that enters and affects the eye-spot, to allow the organism to deduce the angle of incoming light. From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment and to the pretectal area to control the pupillary light reflex.

REWIEW OF NOSE

• The human nose is the most protruding part of the face. It bears the nostrils and is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones and the nasal cartilages, including the nasal septum which separates the nostrils and divides the nasal cavity into two. On average the nose of a male is larger than that of a female.
• The main function of the nose is breathing, and the nasal mucosa lining the nasal cavity and the paranasal sinuses carries out the necessary conditioning of inhaled air by warming and moistening it. Nasal conchae, shell-like bones in the walls of the cavities, play a major part in this process. Filtering of the air by nasal hair in the nostrils prevents large particles from entering the lungs. Sneezing is a reflex to expel unwanted particles from the nose that irritate the mucosal lining. Sneezing can transmit infections, because aerosols are created in which the droplets can harbour pathogens.

Another major function of the nose is olfaction, the sense of smell. The area of olfactory epithelium, in the upper nasal cavity, contains specialised olfactory cells responsible for this function.

The nose is also involved in the function of speech. Nasal vowels and nasal consonants are produced in the process of nasalisation. The hollow cavities of the paranasal sinuses act as sound chambers that modify and amplify speech and other vocal sounds.

There are many plastic surgery procedures on the nose, known as rhinoplasties available to correct various structural defects or to change the shape of the nose. Defects may be congenital, or result from nasal disorders or from trauma. These procedures are a type of reconstructive surgery. Elective procedures to change a nose shape are a type of cosmetic surgery.

REVIEW OF MOUTH

• the mouth is the first portion of the alimentary canal that receives food and produces saliva.[1] The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.
• In addition to its primary role as the beginning of the digestive system, in humans the mouth also plays a significant role in communication. While primary aspects of the voice are produced in the throat, the tongue, lips, and jaw are also needed to produce the range of sounds included in human language.

The mouth consists of two regions, the vestibule and the oral cavity proper. The mouth, normally moist, is lined with a mucous membrane, and contains the teeth. The lips mark the transition from mucous membrane to skin, which covers most of the body.

REWIEW OF THROAT SYSTEM

• the throat is the front part of the neck, positioned in front of the vertebra. It contains the pharynx and larynx. An important section of it is the epiglottis, separating the esophagus from the trachea (windpipe), preventing food and drinks being inhaled into the lungs. The throat contains various blood vessels, pharyngeal muscles, the nasopharyngeal tonsil, the tonsils, the palatine uvula, the trachea, the esophagus, and the vocal cords.Mammal throats consist of two bones, the hyoid bone and the clavicle. The "throat" is sometimes thought to be synonymous for the fauces.
• It works with the mouth, ears and nose, as well as a number of other parts of the body. Its pharynx is connected to the mouth, allowing speech to occur, and food and liquid to pass down the throat. It is joined to the nose by the nasopharynx at the top of the throat, and to the ear by its Eustachian tube.The throat's trachea carries inhaled air to the bronchi of the lungs. The esophagus carries food through the throat to the stomach.Adenoids and tonsils help prevent infection and are composed of lymph tissue. The larynx contains vocal cords, the epiglottis (preventing food/liquid inhalation), and an area known as the subglottic larynx, in children it is the narrowest section of the upper part of the throat

HOW TO ASSESS THYROID GLAND

• Put your finger on tip of your chin (mentalis).
• Slide finger down the midline and the first hard structure you hit is the top of the thyroid cartilage. (Surprisingly, one does not feel the hyoid bone in the midline, although sometimes its lateral end is misidentified as a hard lymph node).
• Run your finger down the prow or the free edge of the thyroid cartilage (Adam's apple).
• The next thing you hit is the cricoid cartilage (and see if you can get your fingernail in between the thyroid and cricoid cartilage–that is the cricothyroid membrane which is where trans-tracheal aspirations for pneumonia can be performed).
• Below the cricoid ring are the first two rings of the trachea, and the ISTHMUS of the thyroid overlies those two rings.
• Ask patient to flex neck slightly forward and relax.
• Go through the landmarks as above.
• Place first two digits of both hands just below cricoid cartilage so that left and right fingers meet on the patient’s midline. Place thumbs posterior to patient’s neck and flatten all fingers against the neck.
• Use finger pads, not tips, to palpate.
• Identify the isthmus.
• Gently draw fingers laterally 1-2cm.
• Gently palpate lateral lobes.
• NOW ask patient to swallow (give them a glass of water if possible).
• Assess for asymmetrical elevation of lobes (suggests nodularity).

When you are done with above, move to next phase, which is displacing the soft tissues on one side to the midline while assessing for size with the other hand. Repeat in opposite direction.

HEARING

Hearing, or auditory perception, is the ability to perceive sounds by detecting vibrations,changes in the pressure of the surrounding medium through time, through an organ such as the ear. The academic field concerned with hearing is auditory science.

Sound may be heard through solid, liquid, or gaseous matter.It is one of the traditional five senses; partial or total inability to hear is called hearing loss.

In humans and other vertebrates, hearing is performed primarily by the auditory system: mechanical waves, known as vibrations, are detected by the ear and transduced into nerve impulses that are perceived by the brain (primarily in the temporal lobe). Like touch, audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation

• 6 basic steps to how we hear:
• Sound transfers into the ear canal and causes the eardrum to move
• The eardrum will vibrate with vibrates with the different sounds
• These sound vibrations make their way through the ossicles to the cochlea
• Sound vibrations make the fluid in the cochlea travel like ocean waves
• Movement of fluid in turn makes the hair cells The auditory nerve picks up any neural signals created by the hair cells. Hair cells at one end of the cochlea transfer low pitch sound information and hair cells at the opposite end transfer high pitch sound information.
• The auditory nerve moves signals to the brain where they are then translated into recognizable and meaningful sounds. It is the brain that “hears”

TYPES OF HEARING LOSS

Hearing loss can be present at birth or occur later in life, can last a short time or a lifetime, can be partial or total, slight to profound in severity and can be present in one ear (unilateral) or both ears (bilateral).

• Conductive Hearing Loss

A conductive hearing loss exists when there is an abnormality in the middle or outer ear but the inner ear (cochlea) functions normally. This causes sound to be attenuated before it reaches the inner ear. This type of loss often can be treated with either medication or surgery. The most common conductive hearing loss seen in children is caused by otitis media (ear infections causing accumulation of fluid in the middle ear).

Other causes include;

Extreme wax buildup

Holes in the eardrum or rupture of the eardrum

Small or absent ear canals or pinnas

Abnormalities of the bones in the middle ear

Sensorineural Hearing Loss

In this type of loss, the problem lies in the inner ear (cochlea) or in the transmission of impulses along the auditory (hearing) nerve.

Within the cochlea, the site of damage is usually the sensory hair cells. As a result of the hearing loss, not only does the individual notice decreased sensitivity to sound, but there is often a decrease in the clarity of the sound as well. Sound may reach the inner ear, but because of damage to the cochlea or auditory nerve, it is not received clearly by the brain, even if it is made sufficiently loud through the use of hearing aids.

There is usually no medical or surgical treatment for this type of hearing loss.

Potential causes include:

Heredity

Anatomical abnormalities of the cochlea

Noise exposure

Certain drugs that are toxic to the ear

Head injuries

Prolonged high fevers

Meningitis

• Mixed Hearing Loss

A mixed hearing loss is a combination of both a conductive and a sensorineural hearing loss. Usually the conductive component can be treated with medication or surgery.

• Auditory Neuropathy Spectrum Disorder (ANSD)

ANSD is a hearing disorder in which the hearing organ located in the inner ear (cochlea) seems to receive sounds normally.  

However, signals leaving the cochlea may be disorganized or the hearing itself may not process sound normally.  

For more information see Auditory Neuropathy Spectrum Disorder.

• Central, Corticol or Audiotry Processing Hearing Loss

This type of hearing loss refers to the inability of the brain to interpret sound information even though peripheral hearing sensitivity is essentially normal. Varying degrees of auditory comprehension result.

• Unilateral Hearing Loss

In a unilateral hearing loss, there is a hearing loss in one ear and normal hearing in the other. Unlike children with bilateral hearing loss, children with unilateral hearing loss typically respond to normal conversation and environmental sounds and demonstrate normal or near normal speech and language development. Before Newborn Hearing Screens, the average age at which a child with a unilateral hearing loss was identified was older than that of a child with a bilateral hearing loss. Thus, many of these children were not identified until they were in school.

ABNORMALITIES OF MOUTH

• Cold sores - painful sores on the lips and around the mouth, caused by a virus
• Canker sores - painful sores in the mouth, caused by bacteria or viruses
• Thrush - a yeast infection that causes white patches in your mouth
• Leukoplakia - white patches of excess cell growth on the cheeks, gums or tongue, common in smokers
• Dry mouth - a lack of enough saliva, caused by some medicines and certain diseases
• Gum or tooth problems
• Bad breath
• Treatment for mouth disorders varies, depending on the problem. If a mouth problem is caused by some other disease, treating that disease can help. It is also important to keep your mouth clean and healthy by brushing, flossing, and not using tobacco.

12 CRANIAL NERVES AND ASSESSMENT

• Olfactory Nerve

Ask the patient if they have noticed any change in sense of smell:

Characteristic smelling objects (e.g. peppermint) can be used to further discriminate pathologies, asking patient to close eyes and examining each nostril in turn.

• Optic Nerve

The optic nerve should be examined by various modalities:

Visual Acuity (VA) – Assess VA with a Snellen chart. Keep glasses on to correct for any refractory errors

Stand the patient 6m away from the chart, covering each eye separately with their hand in turn

Find the line of print which the patient can comfortably read at*

*VA is expressed as the distance between the patient and the chart over the number next to the smallest line that was read (e.g. 6/24 is an individual standing 6m away from the chart and can only read letters that a normal individual can read from 24m)

Alternatively, VA can be simply assessed by asking the patient to read text from a book or magazine

Visual Fields

Ask the patient to cover their left eye with their left hand and then cover your right eye with your right hand. The patient must continue to look straight ahead

Move your hand to the patient’s upper temporal visual field quadrant

Gradually move your finger to the centre of their vision from the periphery and ask the patient to inform you as soon as they see your finger moving

Repeat for the lower temporal, upper nasal, and lower nasal fields, then repeat on the other eye

Any abnormality detected can be further assessed by perimetry or central field assessment

Fundoscopy – Dim the lights if possible. Ask the patient not to look directly at the light (allowing the eye to stay in a fixed position)

• Oculomotor, Trochlear, and Abducens Nerves

Assessment of cranial nerves III, IV, and VI:

Pupillary light reflex

Ask the patient to fixate on a distant target

Shine a pen torch into each eye in turn, bringing the beam in quickly from the lateral side

Observe both the direct (ipsilateral) and consensual (contralateral) response

Pupillary accommodation – The accommodation reflex involves both convergence of the eyes (requiring adduction of both eyes) and simultaneous constriction of the eyes

Ask the patient to look at an object held at distance

Bring the object to within 10cm of the patient, asking the patient to follow it with their eyes

Watch the pupils for equal convergence and constriction

Ask the patient to look straight ahead and check for signs of nystagmus or ptosis

Ocular movements

Ask the patient to keep their head still and follow an object

Move the object around in an H formation, assessing both horizontal and vertical gaze

Watch the pupils to assess the eye movements and any signs of nystagmus

Checking the conjugate gaze may also be warranted at this point

Ensure to ask the patient to let you know if they experience any double vision throughout.

• Trigeminal Nerve

Both sensory and motor branches of the trigeminal nerve should be tested:

Sensation requires both light touch and pin prick assessment

Demonstrate to the patient what to expect from the light touch and pin prick sensations

Ask the patient to close their eyes and gently touch the forehead, cheeks, and chin regions (assessing ophthalmic, maxillary, and mandibular branches respectively)

Ensure to ask the patient to let you know if they experience any changes in sensation either side or cannot feel the sensation

Motor function is checked by the muscles of mastication

Ask the patient to clench their teeth tight and palpate for the contraction in the temporalis muscle and masseter muscle

Ask the patient to open their mouth, move their jaw from side to side, then close their mouth

Testing of the corneal reflex should not be performed unless sensory impairment suspected, as it is uncomfortable to the patient.

• Facial Nerve

Testing the facial nerve involves the assessment of the muscles of facial expression:

Initially assess for symmetry in the face at rest

Ask the patient to perform the following movements

Raise their eyebrows

Close their eyes tightly

Blow out their cheeks

Smile

These movements should also be able to be completed against the examiner’s resistance

• Vestibulocochlear Nerve

Examination of cranial nerve VIII should cover both cochlear and vestibular function:

Hearing can be assessed by whispering a number into each ear separately, making a distracting noise with your fingers in the contralateral ear, and asking the patient to repeat

If any hearing loss suspected, perform Rinne’s and Weber’s test

Balance has no truly satisfactory test for assessment

Formal vestibular testing can be performed.

• Glossopharyngeal and Vagus Nerves

CN IX and CN X nerves can be assessed together:

Ask the patient to cough (assessing CN X)

Ask the patient to open the mouth wide and say ‘ah’, using a tongue depressor to visual the palate and posterior pharyngeal wall (assessing CN IX and X)

The soft palate should move upwards centrally

Testing of the gag reflex should not be performed unless bulbar impairment is suspected, as it is uncomfortable to the patient.

• Accessory Nerve

The accessory nerve is a purely motor branch to the trapezius and sternocleidomastoid muscles:

Sternocleidomastoid can be assessed by asking the patient to turn their head to each side, against the examiners resistance

Trapezius can be assessed by asking the patient to shrug their shoulders, against the examiners resistance.

• Hypoglossal Nerve

The hypoglossal nerve is a purely motor branch to the muscles of the tongue:

Ask the patient to open their mouth and inspect the tongue for any wasting or fasciculation

Ask the patient to protrude the tongue and move from side to side.