The olfactory pathway
Smells stimulate peripheral processes of olfactory neurons. Olfactory bulb, where bipolar neurons synapse on mitral cells Central processe pass through cribriform plate Cell bodies of bipolar neurons in olfactory epithelium Olfactory bulb, where bipolar neurons synapse on mitral cells Central processe pass through cribriform plate Cell bodies of bipolar neurons in olfactory epithelium ,T olfactory areas of forebrain Olfactory neurons are bipolar with cell bodies in olfactory epithelium....
Spinal accessory
This is motor to the muscles bounding the posterior triangle of the neck sternocleidomastoid and trapezius. 16.2 Origin and course of spinal accessory Fig. 16.1 Rootlets from upper four or five segments of spinal cord continue series of rootlets of IX, X and cranial XI. Emerge between ventral and dorsal spinal nerve roots, just behind denticulate ligament. Ascends through foramen magnum to enter posterior cranial fossa. Briefly runs with cranial XI before emerging through jugular foramen middle...
Position of nuclei within the brain stem
In the developing neural tube, motor components are in the ventral portion basal lamina and sensory components in the dorsal portion alar lamina . These are separated by the sulcus lim-itans on the wall of the central canal. Within both basal and alar laminae, visceral elements develop near the sulcus, and somatic elements towards the dorsal and ventral margins. Thus, from ventral to dorsal the components are found in the following order somatic motor, visceral motor, visceral sensory and...
Brain stem course
Axons of upper motor neurons descend through the central portions of the cerebral peduncles crura of the midbrain ventral to the substantia nigra and proceed as far as necessary, decussating just before synapsing on lower motor neuron cell bodies in the Fibres pass through internal capsule Fibres pass through cerebral peduncles of midbrain Fibres pass through internal capsule Fibres pass through cerebral peduncles of midbrain Trigeminal motor nucleus in pons Facial motor nucleus in pons...
Parasympathetic components of cranial nerves
Parasympathetic fibres emerge from the brain in only four cranial nerves III, VII, IX and X, and are delivered to their destinations in branches of V. They innervate the ciliary and iris muscles of the eyeball, and the salivary, lacrimal, nasal and palatal glands. They are arranged with two peripheral neurons pre- and postganglionic. Cell bodies of preganglionic neurons are in brain stem parasympathetic nuclei, and their axons synapse on postganglionic neurons in peripheral parasympathetic...
THE OPHTHALMIC NERVE Va
The ophthalmic nerve transmits sensory fibres from the eyeball, the skin of the upper face and anterior scalp, the lining of the upper part of the nasal cavity and air cells, and the meninges of the anterior cranial fossa. Some of its branches also convey parasympathetic fibres see below . 8.2 Origin, course and branches Fig. 8.1 originates from trigeminal ganglion in middle cranial fossa passes anteriorly through lateral wall of cavernous sinus. divides into three branches frontal largest ,...
UMN lesion of the facial nerve
The facial motor nucleus is divided into two parts 1 that for upper facial muscles orbicularis oculi and frontalis 2 that for lower facial muscles. The lower motor neuron LMN cell bodies in 1 receive UMNs from both cerebral motor cortices, ipsilateral as well as the usual contralateral. LMNs in 2 do not they receive only the customary contralateral innervation. Thus, a unilateral UMN lesion of the fibres supplying 1 will not result in complete functional loss since UMN input is also present...
Secondary sensory neurons sensory nucleus to thalamus
The axons of these neurons ascend from the nucleus, which contains their cell bodies, to the contralateral thalamus in the diencephalon , decussating soon after leaving the nucleus. In the thalamus, they synapse with the cell bodies of tertiary sensory neurons. There are many other destinations of impulses from the nucleus, for example reticular nuclei and cerebellum, for the dissemination of information and its integration with other functions and systems. Tertiary sensory neurons thalamus,...
The basic plan of sensory systems
The basic sensory system consists of three neuronal groups primary sensory neurons from receptor to central nucleus, with its cell body in a peripheral sensory ganglion secondary sensory neurons from nucleus to diencephalon usually the thalamus tertiary sensory neurons from thalamus to cortex. There are no synapses outside the brain and spinal cord the first synapse is in the central nervous system CNS between primary and secondary sensory neurons.
The Vagus Nervex
The main functions of the vagus are phonation and swallowing. It also transmits cutaneous sensory fibres from the posterior part of the external auditory meatus and the tympanic membrane. It supplies the gut tube as far as the splenic flexure of the transverse colon roughly , and the heart, tracheobronchial tree and abdominal viscera. These fibres, though, are by no means essential to life, whatever others may tell you, since they can be cut, as in vagotomy. And do you suppose heart surgeons...
Cranial nerves arising from the hindbrain VXII
The trigeminal nerve V arises from the lateral aspect of the mid pons. The abducens VI , facial VII and vestibulocochlear VIII nerves arise from the pontomedullary junction VI is close to the midline, VII and VIII arise laterally in the cerebellopontine angle. Fig. 1.2 Attachments of cranial nerves. Lateral view study with brain stem specimen. Fig. 1.2 Attachments of cranial nerves. Lateral view study with brain stem specimen. The glossopharyngeal IX , vagus X and accessory XI nerves arise from...
Upper motor neuron lesion spasticity hyperreflexia contralateral
If upper motor neurons to a muscle are severed, the ability to control and initiate movement in the muscle may be lost. However, Table 3.1. Voluntary somatic and branchiomotor motor components of cranial nerves. Trigeminal motor Branchiomotor Pons for chewing first arch Levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, inferior oblique Temporalis, masseter, digastric anterior belly , mylohyoid, medial and lateral pterygoids, tensor palati, tensor tympani Facial...
THE MANDIBULAR NERVE Vc
The mandibular nerve is a mixed sensory and motor nerve. It transmits sensory fibres from the skin over the mandible, side of the cheek and temple, the oral cavity and contents, the external ear, the tympanic membrane and temporomandibular joint TMJ . It also supplies the meninges of the cranial vault. It is motor to the eight muscles derived from the first branchial arch mylohyoid, anterior belly of digastric tensor tympani, tensor palati As an aid to memory, note the four groups of two...
Intracranial course and branches Fig 111
From cerebellopontine angle, crosses posterior cranial fossa, enters internal acoustic meatus IAM with VIII . Nervus intermedius joins main root of facial nerve in IAM. Lingual nerve, submandibular ganglion Fig. 11.1 Facial nerve intracranial . Nervus intermedius Facial canal on medial wall of tympanic cavity Fig. 11.1 Facial nerve intracranial . from facial motor nucleus to muscles of facial expression, stapedius, etc. parasympathetic preganglionic fibres from superior salivatory nucleus Q...
Upper motor neurons cortex to nucleus
For cranial nerves, cell bodies of upper motor neurons are in the head and neck area of the motor cortex. Axons descend, decussating just before synapsing with cell bodies of lower motor neurons which make up the motor nucleus of that cranial nerve. The term upper motor neurons is also used clinically to include fibres from other brain centres e.g. parietal lobe, basal ganglia, cerebellum, reticular formation, midbrain, etc. that connect with the lower motor neurons in the cranial nerve...
Salivation and taste
Parasympathetic fibres in cranial nerves are secretomotor they are concerned with the stimulation of secretions from the submandibular, sublingual, parotid and minor palatal salivary glands. These impulses originate in the superior and inferior salivatory nuclei and pass to the glands through branches of the facial and glossopharyngeal nerves, and, peripherally, the trigeminal. They are considered in more detail in Part IV. Impulses from the sensory nuclei of the trigeminal nerve pass to the...
The second branchial arch otic vesicle and facial nerve
The facial nerve is the nerve of the second branchial arch which gives rise to part of the hyoid bone, the styloid process, the stylohyoid ligament, the stapes and the muscles listed in Section 11.3 the muscles of facial expression which migrate into superficial layers , stylohyoid, posterior belly of digastric, occipitofrontal and stapedius. Arterial components of the second arch degenerate. The facial nerve develops in association with the otic vesicle, and with the first branchial pouch...
THE MAXILLARY NERVE Vb
The maxillary nerve transmits sensory fibres from the skin of the face between the palpebral fissure and the mouth, from the nasal cavity and sinuses, and from the maxillary teeth. At its origin it contains only sensory fibres. Some of its branches transmit postganglionic parasympathetic fibres from the pterygopalatine ganglion which pass to the lacrimal, nasal and palatine glands see Section 17.3 , and others convey taste visceral sensory fibres from the palate to the nucleus of the solitary...
Sensory ganglia for somatosensory fibres
Most somatic sensory fibres are carried in the trigeminal nerve their cell bodies are in the trigeminal ganglion. The small number of somatosensory fibres in the vagus nerve X have cell bodies in the jugular superior vagal ganglion those in the facial nerve VII have cell bodies in the geniculate ganglion and those in the Fig. 4.1 Trigeminal somatic sensory system e.g. cutaneous sensation , see also Fig. 5.1. Fig. 4.1 Trigeminal somatic sensory system e.g. cutaneous sensation , see also Fig....
Brain stem motor nuclei Table 22 Fig 21
Axons of cranial nerve motor neurons originate from brain stem nuclei of three types corresponding to the embryological origin of the muscle groups 1 Somatic nuclei These are close to the midline, equivalent to spinal cord ventral horn cells. Somatic nuclei are oculomotor, trochlear, abducens and hypoglossal nuclei. 2 Branchiomotor nuclei These develop lateral to somatic nuclei, between them and parasympathetic nuclei. Branchiomotor nuclei are trigeminal motor, facial motor and the nucleus...
Ganglion and nucleus beware of confusion Fig 13
Ganglia and nuclei are easily confused. Both contain nerve cell bodies, and some cranial nerves are associated with both a ganglion and a nucleus with the same name. For example, the trigeminal nerve V is associated with the trigeminal ganglion and several trigeminal nuclei, and the vestibulocochlear nerve VIII is associated with vestibular and cochlear ganglia and vestibular and cochlear nuclei. Furthermore, the term ganglion is applied to two different structures associated with nerves....
Cranial nerves arising from the midbrain III IV
The oculomotor nerve III arises from the interpeduncular fossa on the ventral aspect of the midbrain. Table 1.2. Attachments and foramina of cranial nerves. Forebrain Telencephalon limbic system Diencephalon lateral geniculate body Upper midbrain, ventral, interpeduncular fossa Lower midbrain, dorsal, below inferior colliculi Pontomedullary junction Near midline Cerebellopontine angle Rootlets, lateral to inferior olive, extending down to cervical cord Rootlets between pyramid and olive Nerve...
Stanley Monkhouse
University of Nottingham Medical School at Derby Sometime Professor of Anatomy at the Royal College of Surgeons in Ireland Lecturer in Human Morphology at the University of Nottingham and Clinical Assistant in Ear Nose and Throat, Queen's Medical Centre, Nottingham Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, Sao Paulo Cambridge University Press The Edinburgh Building, Cambridge cb2 2ru, UK Published in the United States of America by Cambridge University Press, New York...