Senses

Learning & Test Objectives

I. Sensory receptors: Types, Character and distribution, Structure and Function

II. Eye:

1. Topography of the orbit.
2. External structures and Functions- Eye lids, Ocular muscles, Lacrimal apparatus, Innervation and blood supply.
3. Internal structures and functions- anterior and posterior segments, Histology of the cornea, iris and retina, Aqueous humor circulation, retinal vasculation.
4. Optic nerve- Structure and course.
5. Embryological development of the optic cup.

III. Ear:

1. External ear structures and functions- Auricle and ear canal.
2. Topography of the tympanic cavity.
3. Middle ear structures and functions- Tympanic membrane, Ossicle apparatus, auditory tube.
4. Inner ear- Vestibulocochlear components and functions, Histology of the cochlea and vestibule.
5. Embryological development of the ear.

IV. Gustation:

1. Taste buds- Types and distribution, Histological structure.
2. General and special sensory innervation of the tongue.

V. Olfaction:

1. Olfactory nerve- Course, Olfactory bulb structure.
2. Histology of the superior nasal mucosa.  

VI. Interoception:

1. Receptors- types and function.
2. Anatomical distribution.
3. Regulatory functions.

VII. Pathways:

1. Visual pathway.
2. Papillary Reflex Pathway.
3. Auditory Pathway.
4. Vestibular Pathway.
5. Gustatory Pathway.
6. Olfactory Pathway.
7. Somatosensory and viscerosensory pathways.
8. Pain pathways.

 

Description of the test

The test is held by the general rules of written tests (see Continuous Testing – Organisation).

The test ‘Senses’ is in written format and follows the general rules for written tests (See Continuous testing – organisation). The test differs the previous in its extent as it comprises together question in anatomy, histology and embryology of the sensory organs. The main focus of the test are the sensory organs (taste, smell, vision, touch, audition and balance) and their pathways.

For the sensory organs it is necessary to know their external and internal structure, microstructure (histology), syntopy, topography, divisions, locations, pathways (tracts), blood supply, main functions and development (embrylogy). Questions on the accessory visual structures, interoceptors, clinical and other correlations may also appear in the test. Questions on the skin, its adnexa and the endocrine system will not be included in the test. At the end of the test the student is required to draw and described a scheme from the list of required schemes.

Clinical correlations

Otitis media / mesotitis is the most common disease of the middle ear. It occurs most commonly in infants and toddlers. It presents with a painful ear, headache, and even or even with a perforated eardrum.

Enlargement of the adenoid may block the auditory tube, and in doing so lead to a disorder of ventilation of the middle ear. This can predispose to inflammation of the middle ear (otitis media).

The cornea is the most sensitive tissue of the human body. Tactile stimulation of the corneal excites the corneal reflex, which causes blinking caused by contraction of orbicularis oculi.

Papilloedema means swelling of the optic disc. It is caused by increased intracranial pressure (intracranial hypertension) and is possible to see during examination of the fundus by ophthalmoscopy (fundoscopy).

The retina is not firmly attached to the choroid and thus it is liable to detachment (amotio).

Glaucoma is characterised by chronic and progressive atrophy of the optic nerve. It is usually caused by increased intraocular pressure.

Cataract is a clouding (opacification) of the lens. The affected lens can be replaced by surgery. To replace the lens an incision is made in the capsule of the lens, the opaque content is aspirated and an artificial lens is inserted into the capsule.

Palsy of the facial nerve manifests as an impairment in function of orbicularis oculi, which leads to the inability to close the palpebral fissure (lagophthalmus). This can lead to desiccation of the conjunctiva (xerophthalmia), which can gravely endanger the acuity of vision by predisposing to inflammation and ulceration of the cornea.

Strabismus / cross eyes /squint / heterotropia is a symptom of extraocular muscle palsy.

Interesting notes

The middle ear cavity contains the tympanic cavity, the mastoid antrum, mastoid air cells and the auditory tube.

The auditory tube / Eustachian tube has two parts: a lateral bony part and a medial cartilaginous part. Its function is to equalise the air pressure between the pharynx and tympanic cavity. The auditory tube is more horizontal, shorter and wider in children.

The optic papilla (papilla nervi optici) is a clinical term for the optic disc.

 

Required schemes for drawing

• Sagittal section of the eyebulb
• Sagittal section of the eye lid
• Scheme of the fundus of the eye
• Otoscopic view of the ear drum
• Scheme of the middle ear cavity
• Cross-section of the cochlea - osseous and membranous labyrinth (including the spiral organ of Corti)