The cerebellum is the largest part of the hindbrain, recognized as a distinct division of the brain from the time of Herophilus (335–280 BC) and Galen (AD 131–200). It is situated in the posterior cranial fossa, beneath the tentorium cerebelli,…
The brainstem is situated in the posterior cranial fossa, where it faces the clivus and dorsum sellae ventrally and the cisterna magna, fourth ventricle and cerebellum dorsally ( Fig. 28.1 ). It is approximately 6–7.5 cm in length and 3–4…
The spinal cord provides innervation for the trunk and limbs via spinal nerves and their peripheral ramifications. It receives primary afferent fibres from peripheral receptors located in widespread somatic and visceral structures, and sends motor axons to skeletal muscle. It…
The brain is a highly vascular organ, its profuse blood supply characterized by a densely branching arterial network ( ). It has a high metabolic rate that reflects the energy requirements of constant neural activity. It receives about 15% of…
The meninges consist of three concentric membranes that envelop the brain and spinal cord, supporting and protecting the delicate tissues they surround. The individual layers, from outside to inside, are the dura mater (pachymeninx), arachnoid mater and pia mater. The…
The human nervous system is the most complex product of evolution. The activity of its billions of neurones constitutes the physical basis of sensory experience, motor behaviour, consciousness and self-awareness. Research to elucidate the mechanisms that underlie these functions is…
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Prenatal Stages Development of a human from fertilization to delivery at ‘full term’ averages 266 postfertilization days, or 9.5 lunar months (28 day units). It has long been customary to compute the length of a pregnancy, whether in a normal…
Development of the Posterior Coelom Wall From stage 11 (29–30 days postfertilization; see Fig. 23.3 for comparison of postfertilzation days and the clinical scale of postmenstrual weeks) the dorsal region of the wall of the intraembryonic coelom is composed of…
Postpharyngeal Foregut The primitive gut is divided by head- and tail-folding into three main compartments. The foregut extends from the buccopharyngeal membrane to its continuation into the central midgut region via the cranial intestinal portal. The midgut extends between the…