Topographical anatomy of the dog / by O. Charnock Bradley.

  • Orlando Charnock Bradley
Date:
1927
Catalogue details

Licence: In copyright

Credit: Topographical anatomy of the dog / by O. Charnock Bradley. Source: Wellcome Collection.

    260/288 (page 244)
    The roof or dorsal boundary of the ventricle is formed by the two medullary vela and the thin pial continuation of the posterior velum. Seen in sagittal section, the roof is somewhat tent-like, being continued into a recess, the fastigimn^ between the vermis attachments of the two vela. The roof, moreover, is rendered irregulcir on a level with the lateral recesses by an invagination produced by the choroid plexus (plexus chorioideus ventriculi quarti). That part of the plexus which is related to the recesses can readily be seen in the intact brain as a vascular tuft occupying an angular depression formed by the cerebellum and medulla oblongata. The membranous roof is defective at the extremity of the lateral recess, where a small irregular opening, the lateral aperture (aper- tura lateralis ventriculi quarti), places the cavity of the ventricle in communication with the subarachnoid space. The floor of the ventricle is formed by the medulla oblongata and the pons. Divided into two lateral halves by a median longitudinal groove, the floor is further subdivided into areas. A longitudinal limiting groove (sulcus limitans) forms the lateral boundary of an elongated and narrow medial area. The limiting groove is quite shallow, but deepens a little at two places known as the anterior and posterior fovecc. A prominent medial eminence (eminentia medialis) occurs about the middle of the length of the strip demarcated by the median and limiting grooves. A triangular area, the hypoglossal t7dgone (trigonum nervi hypoglossi) intervenes between the posterior fovea and the median groove, while lateral to it is the grey ala cinerea. An elevated acoustic area (area acustica) forms a conspicuous object lateral to the limiting sulcus and opposite the recess of the ventricle. Dissection.—The remains of the muscles attached to the vertebral column, the ribs, the pelvis, and the occipital bone must now be removed in order that the ligaments connected with these parts of the skeleton may be examined. The Joints of the Vertebral Column {^Articulationes columnce vertehralis^.—The bodies of adjacent vertebrae are connected by disc-shaped intervertebral jlbro-cartilages (fibrocartilagines inter- vertebrales). Each cartilage is composed of a peripheral fibrous portion (annulus fibrosus) and a much softer central part (nucleus pulposus). Assisting in the firm union of the vertebrae are two longitudinal bands. The venti'al longitudinal ligament (lig. longi- tudinale ventrale) is attached along the ventral aspect of the vertebral bodies from the sacrum to about the fifth thoracic vertebra, where it materially diminishes in volume. The dorsal longitudinal liga^nent (lig. longitudinale dorsale) is more sharply defined. Running along the floor of the vertebral canal from the sacrum to the dens of the epistropheus, it has the form of