PHYSIOLOGY

The hypothalamus has important connections with the limbic

system, a controlling influence on autonomic nervous system

activity and a role in neuroendocrine function.

Cerebellum

The cerebellum coordinates movement by maintenance of equi-

librium (the archicerebellum, the flocculonodular lobe and fas-

tigial nuclei), posture and muscle tone (the paleocerebellum, the

midline vermis, paravermis and the globose and emboliform

nuclei) at an unconscious level. The neocerebellum (the

remainder of each cerebellar hemisphere and the dentate nu-

cleus) is concerned with muscular coordination, including tra-

jectory, speed and force of movements. The cerebellar cortex

consists of highly convoluted folia, which cover the white matter.

Within the white matter are embedded the cerebellar nuclei,

which are the source of efferent fibres to the brainstem by way of

three pairs of cerebellar peduncles.

Brainstem

The third ventricle drains into an aqueduct in the midbrain,

which opens into the fourth ventricle dorsal to the pons and

ANAESTHESIA AND INTENSIVE CARE MEDICINE 15:4 200

upper medulla oblongata. From the fourth ventricle cerebrospi-

nal fluid emerges from three apertures into the subarachnoid

space. A negligible amount moves into the central canal of the

spinal cord. The brainstem houses the nuclei of cranial nerves III

to XII, all of which emerge anteriorly except the trochlear nerve

(cranial nerve IV) (Figure 5).

The tectum (roof) of the midbrain is formed by four colliculi e

the paired superior colliculi are associated with the visual system,

and the inferior colliculi with the auditory system. The interme-

diate region of the brainstem is known as the tegmentum, which

contains the reticular formation, the ascending sensory pathways

carrying general sensory information from the trunk and limbs

(especially the posterior column-medial lemniscal pathways), and

the descending motor corticospinal tracts e the latter two decus-

sate in the medulla oblongata. A

FURTHER READING

Crossman AR, Neary D. Neuroanatomy. 3rd edn. Edinburgh: Churchill

Livingstone, 2005.

Fitzgerald MJT, Gregory G, Mtui E. Clinical neuroanatomy and neurosci-

ence. 5th edn. Philadelphia: Saunders, 2007.

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