Cerebellopontine Angle

Frontal n

Trigeminal ganglion

Cavernous sinus syndrome

Ophthalmic a. Optic chiasm

Ophthalmic a. Optic chiasm

Pituitary gland and stalk

- Optic chiasm

Pituitary gland and stalk

Frontal sinus Olfactory bulb Nasal cavity

Frontal n

Trigeminal ganglion

Ganglion Trigeminal Carotis

Sphenoid wing syndrome

(Foster-Kennedy syndrome)

Cavernous sinus

Internal carotid a.

Pituitary gland and stalk

Orbital apex syndrome

Sphenoid wing syndrome

(Foster-Kennedy syndrome)

Internal carotid a.

Pituitary gland and stalk

- Dorsum sellae, posterior clinoid process

Pituitary gland and stalk

Orbital apex syndrome

Dorsum sellae

Cavernous sinus

Trigeminal ganglion

Chiasm syndrome

(arrows show direction of compression)

Jugular foramen, petrosal sinus, IX, X, XI

Chiasm syndrome

(arrows show direction of compression)

Jugular foramen, petrosal sinus, IX, X, XI

Pituitary fossa in sella turcica

Inferior Alveolar Ganglion

Pituitary fossa in sella turcica

Internal acoustic meatus (VII, VIII, labyrinthine a.)

Sphenoid sinus

XII in hypoglossal canal

Mandibular branch

Foramen magnum Mandibular foramen,

(posterior margin) x—Tumor inferior alveolar n. Jugular foramen, foramen magnum

Cavernous sinus

Trigeminal ganglion

Dorsum sellae

Sphenoid sinus

XII in hypoglossal canal

Mandibular branch

Tumor VI

Cerebellopontine Angle

Cerebellopontine angle

Tumor VI

Cerebellopontine angle

Olfactory epithelium. The olfactory mucosa on either side of the nasal cavity occupies an area of approximately 2.5 cm2 on the roof of the superior nasal concha, extending to the nasal septum. The mucus covering the olfactory epithelium is necessary for olfactory function, because molecules interact with olfactory receptors only when they are dissolved in the mucus. Olfactory cells are bipolar sensory cells with a mean lifespan of about 4 weeks. Fine bundles of cilia project from one end of each olfactory cell into the mucus. Olfactory receptors located on the cilia are composed of specific receptor proteins that bind particular odorant molecules. Each olfactory cell produces only one type of receptor protein; the cells are thus chemotopic, i.e., each

¡3 responds to only one type of olfactory stimulus.

C Olfactory cells are uniformly distributed throughout the olfactory mucosa of the nasal

"g conchae.

'c Olfactory pathway. The unmyelinated axons of

2 all olfactory cells converge in bundles of up to 20 fila olfactoria on each side of the nose (these bundles are the true olfactory nerves), which pass through the cribriform plate to the olfactory bulb. Hundreds of olfactory cell axons converge on the dendrites of the mitral cells of the olfactory bulb, forming the olfactory glomeruli. Other types of neurons that modulate the olfactory input (e.g., granular cells) are found among the mitral cells. Neural impulses are relayed through the projection fibers of the olfactory tract to other areas of the brain including the prepiriform cortex, limbic system, thalamus (medial nucleus), hypothalamus, and brain stem reticular formation. This complex interconnected network is responsible for the important role of smell in eating behavior, affective behavior, sexual behavior, and reflexes such as salivation. The trigeminal nerve supplies the mucous membranes of the nasal, oral, and pharyngeal cavities. Trigeminal receptor cells are also stimulated by odorant molecules, but at a higher threshold than the olfactory receptor cells.

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