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Anatomy of the head and neck
Published in Helen Whitwell, Christopher Milroy, Daniel du Plessis, Forensic Neuropathology, 2021
The pons is the upward continuation of the brainstem from the medulla and is divisible into anterior and posterior parts. The anterior part contains the pontocerebellar fibres, which arise from the pontine nuclei. These pass through the middle cerebellar peduncle to the contralateral side of the cerebellum. In the rostral part of the pons, the lateral wall of the fourth ventricle is composed of paired superior cerebellar peduncles, with a thin superior medullary velum connecting them and forming its roof. These peduncles converge towards the midline as they pass into the midbrain and contain cerebellar afferent and efferent fibres.
Clinical Neuroanatomy
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
The IVth cranial nerve is unique in several ways. It arises in the dorsal aspect of the brainstem at the level of the inferior colliculus. It then decussates within the superior medullary velum so that the right nucleus supplies the left superior oblique muscle and vice versa (see Figures 111.4 and 111.5(b)). It also has the longest intracranial course and is very slender, properties that possibly protect it from damage by extrinsic pressure around the brainstem and in the subarachnoid space. It enters the wall of the cavernous sinus beneath the IIIrd nerve, but crosses it to reach a higher position as it enters the superior orbital fissure to supply the superior oblique muscle. The nerve is rarely damaged in isolation in cavernous sinus lesions, the IIIrd and VIth nerves being much more vulnerable. A vascular lesion of the nerve due to diabetes is the most common cause. Of particular importance to the otolaryngologist is the small fibrocartilaginous loop attached to the trochlear fossa in the upper medial orbit through which the muscle tendon loops. Accidental or surgical trauma in this region may easily damage the tendon interfering with the action of the superior oblique muscle, mimicking a IVth nerve palsy.16
General Synonyms
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
For the more (most) rostral of two or more similar structures in the spinal cord or brain stem. “Cranial” may be used chiefly by some authors who received their primary training in Great Britain. 1a. cranial colliculus (M&M, p. 39)1b. superior colliculus (B&K, p. 88)2a. cranial cerebellar peduncle (M&M, p. 46)2b. superior cerebellar peduncle (B&K, p. 157)3a. cranial medullary velum (M&M, p. 46)3b. superior medullary velum (B&K, p.86)
Early Prenatal Diagnosis of Blakes’ Pouch Cyst by 2D/3D Ultrasound with Cristal and Realistic Vue Application
Published in Fetal and Pediatric Pathology, 2018
Gabriele Tonni, Gianpaolo Grisolia, Paolo Zampriolo, Edward Araujo Júnior, Rodrigo Ruano
Blake's pouch cyst (BPC) is due to an abnormal or delayed development of the area membranacea posterior of the brain. BPC cyst represents a posterior ballooning of the superior medullary velum into the cisterna magna (3) through the Magendie foramina and appear as an open fourth ventricle with intact but rotated cerebellum. However, caution must be exerted concerning an early diagnosis of posterior fossa cyst before the development of the cerebellar vermis may be completed (4–6), a finding known as open fourth ventricle. Open fourth ventricle may represents a morphologic variant in 10% of normal fetuses at 15–18 weeks (7). Determination of the brainstem-vermis (BV) and brainstem-tentorium angles may be useful to discriminate between normal variant and posterior fossa malformation during second trimester, as the BV angle is usually > 45° (7,8).
Microsurgical techniques for achieving gross total resection of ependymomas of the fourth ventricle
Published in Acta Chirurgica Belgica, 2020
Let us conceive of the fourth ventricular anatomy conceptually in order to facilitate a surgical understanding and appreciation of the relationships of its most critical structures and landmarks [48–52]. We accordingly describe the microsurgical anatomy and internal features of this most beautiful of Nature’s majestic designs [48,52]. The rostral roof the fourth ventricle is formed medially by the superior medullary velum and laterally by the bilaterally paired superior cerebellar peduncles. The caudal roof of the fourth ventricle is comprised rostrally by the midline nodule and laterally flanking inferior medullary velum draping mediolaterally, from which the tela choroidea drapes anteroinferiorly to attach to the dorsal surface of the myelencephalon. The telovelar margins insert into the taenia medullaris of the dorsal medulla. Two layers of delicate neural tissue comprise the tela choroidea. The ventricular surface of the tela choroidea houses the choroid plexus, constituted by cuboidal epithelium richly perfused by fenestrated capillary endothelium [48,52]. The median segment of the choroid plexus splays superolaterally towards the lateral recesses and foramina of Luschka bilaterally. Notable flocculus-adjacent tufts of choroid plexus in the deepest reaches of the cerebellopontine angle present a natural and useful surgical landmark to the astute neurosurgeon and may give rise to benign and malignant papillomatous choroid plexus neoplasms. Choroidal branches are provided by the posterior inferior cerebellar artery emanating from the vertebral artery and the anterior inferior cerebellar artery. The cerebrospinal fluid egresses from the fourth ventricle into the cisterna magna through the foramen of Magendie in the lower tela choroidea and into the lateral cerebellomedullary cisterns of Rhoton and cerebellopontine through the lateral recesses and foramina of Luschka [48,52].