Neuroscience

Reduced levels of alpha-feto protein are seen in mothers of fetuses with Down syndrome. Failure to close results in ancephaly causing polyhydraminos and increased alpha-feto protein Failure to close results in spina bifida alpha-feto protein Figure IV-1-1. Third Week Neurulation Table IV-1-1. Germ Layer Derivatives Table IV-1-1. Germ Layer Derivatives Lens of eye Anterior pituitary Parotid gland Tympanic cavity Auditory tube GI tract Neuroectoderm Neural tube Central nervous system Retina S>...

Medical

Skeletal Muscles Innervated by Cranial Nerves (continued) Table III-6-4. Skeletal Muscles Innervated by Cranial Nerves (continued) Copyright 2000 Gold Standard Multimedia, Inc. Alt rights reserved. Copyright 2000 Gold Standard Multimedia, Inc. Alt rights reserved. Figure III-6-18. Head and Neck Posteroanterior View of Skull Figure NI-6-19. Head and Neck Lateral Skull Figure 111-6-22. Head and Neck CT, Skull Figure 111-6-22. Head and Neck CT, Skull Medial Optic Lateral Rectus...

Answers and Explanations

Cancer Risk Factors Gragh 2017

The mesencephalon (midbrain) contains the substantia nigra, which is the location of the degenerating dopaminergic neurons in Parkinson disease. 2. Answer E. In Parkinson disease, loss of dopamine enhances the effects of the indirect basal ganglia pathway, which is also driven by cholinergic neurons intrinsic to the striatum. A muscarinic blocker will reduce the stimulatory effects of ACh on the indirect pathway. 3. Answer D. The patient suffers from hemiballismus, which affects the...

The Brain Stem

The brain stem is divisible into three continuous parts the midbrain, the pons, and the medulla. The midbrain is most rostral and begins just below the diencephalon. The pons is in the middle and is overlain by the cerebellum. The medulla is caudal to the pons and is continuous with the spinal cord. The brain stem is the home of the origins or sites of termination of fibers in 9 of the 12 cranial nerves (CN). Two cranial nerves, the oculomotor and trochlear (CN III and IV), arise from the...

Venous Drainage of the Brain and the Dural Venous Sinuses Dural venous sinuses

Sinus Veineux

The dural venous sinuses receive cerebral veins from the brain and drain the venous blood mainly into the internal jugular vein (Figures III-6-12 and III-6-13). The superior sagittal sinus is located in the midsagittal plane along the superior aspect of the falx cerebri. It drains into the confluence of the sinuses. Arachnoid granulations protrude through the walls of the superior sagittal sinus. The arachnoid granulations transmit CSJ from the subarachnoid space into the venous circulation....

Review Questions

Which structure supplied by a branch of the celiac artery is not derived from foregut endoderm 2. An infant presents with an omphalocele at birth. Which of the following applies to this condition (A) It is also seen in patients with aganglionic megacolon. (B) It results from a failure of resorption of the vitelline duct. (C) It results from herniation at the site of regression of the right umbilical vein. (D) It is caused by failure of recanalization of the midgut part of the duodenum. (E) It...

Control of Horizontal Gaze

Gaze Paralysis

Horizontal gaze is controlled by two interconnected gaze centers. One control center is in the frontal lobe, the frontal eye field (Brodmann area 8). This area acts as a center for contralateral horizontal gaze. In the pons is a second gaze center, known as the pontine gaze center or the PPRF, the paramedial pontine reticular formation. This is a center for ipsilateral horizontal gaze. When activated by neurons in the frontal eye field, the pontine gaze center neurons send axons to synapse with...

Dopamine and cholinergic effects

Lateral Ventricle Anterior Horn

In addition to the GABA neurons, two other sources of chemically significant neurons enhance the effects of the direct or indirect pathways. Dopaminergic neurons in the substantia nigra in the midbrain project to the striatum. The effect of dopamine excites or drives the direct pathway, increasing cortical excitation. Dopamine excites the direct pathway through D( receptors and inhibits the indirect pathway through D2 receptors. Cholinergic neurons found within the striatum have the opposite...

Temporal Lobe Primary auditory cortex

On its superior and lateral aspect, the temporal lobe contains the primary auditory cortex. Auditory cortex areas 41 and 42 is located on the two transverse gyri of Heschl, which cross the superior temporal lobe deep within the lateral sulcus. Much of the remaining superior temporal gyrus is occupied by area 22 auditory association cortex , which receives a considerable projection from both areas 41 and 42 and projects widely to both parietal and occipital cortices. Patients with unilateral...

Descending Hypothalamic Fibers

The descending hypothalamic fibers arise in the hypothalamus and course without crossing through the brain stem to terminate on preganglionic sympathetic neurons in the spinal cord. Lesions of this pathway produce an jpsilateral Horner syndrome. Horner syndrome consists of miosis pupillary constriction , ptosis drooping eyelid , and anhidrosis lack of sweating in the face ipsOateral to the side of the lesion. Descending hypothalamic fibers course with the spinothalamic fibers in the lateral...