Medical brain notes 11

  The fetal skull   The bones of the skull develop from membranes, ossification starts as early as the 5 th  week following conception. At term ossification is almost complete except for the thin lines of membranes separating the bones from each other known as the sutures. Ossification of the skull is not complete until early adulthood.   The part of the fetal skull 1. The vault:  Is from the line from the nape of the neckto the orbital ridge. The vault is made up of 5 bones and two enter into the lateral wall. These are:   2 Frontal bones   2 Parietal bones:   1 Occipital bone   2 Temporal bones and the wings of the sphenoid bones form the side wall of the skull.   2. The face:  This area extends from the orbital ridge tothe junction of the neck with the chin. It is composed of 14 fused bones.   3. The base:  These bones are also firmly united and helpto protect the brain.   4. The Sutures   These are membranous...

  Measurements of the fetal skull-   1. Diameter of the fetal skull   These are the diameter the birth canal must stretch to allow the head to pass during labour. The lagest being mento vertical 13.5cm.   1.             Sub-Occipito Bregmatic (9.5cm) 2.             Sub-Occipito Frontal (10cm) 3.             Occipito Frontal (11.5m) 4.             Mento Vertical (13.5cm) 5.             Sub Mento Vertical(11.5) 6.             Sub-mento Bregmatic (9.5cm) 7.             Biparieta (9.5cm) 8.             Bitemporal (8.2cm). 2. Circumferences...

  Importance of the fetal skull to the midwife   ·                It contains the delicate brain and about 95% of babies present by head.   ·                Sound knowledge of fetal diameter and measurement cause least problems during labour and delivery through diagnosis of abnormalities presentation and position, also disproportion between the fetal head and the pelvis can be easily recognized.   ·                Delivery can be conducted with minimal injuries to the mother and baby.   ·                It is large in comparison with the fetal body and true pelvis; some adaptation has to be made between the head and the pelvis.   ·         ...

  The scalp The scalp of the fetus consists of five layers.   ·                The skin   ·                A subcutaneous tissue: Contains blood vessels and hair follicles. Is the part where caput succedaneum is formed.   ·                A layer of Tendon – Galea   ·                A loose layer of alveolar tissue. Limits movement of the scalp over the skull.   ·                The pericranium – is the periosteum of the cranial bones which covers the outer surface, and is adherent to their edge.   Cephalhaematoma is limited to the layer over the bones where it lays because it is attached to the edge of the b...

  The intracranial membranes and sinuses The skull contains delicate membranous structure which is liable to damage during delivery especially if subjected to abnormal molding. Structures include:   1.             Folds of Dura matter and 2.             Venous sinuses associated with them.   The membrane is in two layers, an outer periosteal layer which is adherent to the skull bones and the inner meningeal layer which covers the outer surface of the brain. The membrane does not only cover the brain but send fibrous partition to divide the brain into compartments.   1.             The Falx Cerebri:  It is a sickle-shaped fold of membranewhich dip down between the two cerebral hemispheres. It runs beneath the frontal and sagittal sutures – (Fr om root of the nose to the internal occipital protuberance...

  Moulding   This is the term applied to the change in shape of the fetal head which takes place as it passes through the birth canal. It is brought about by pressure between the fetal skull and the maternal pelvis. It results in compression of the movable bones and elongation of those which are not compressed. Moulding brings about a considerable reduction in the size of the presenting diameters while the diameter at right angle to them elongates. This is possible because of the sutures and fontanelles on the vault which allows slight degree of movement and the bones to override each other. In normal vertex presentation, the biperiatal diameter, sub occipito bregmatic reduce while the mentovertical lengthens. During moulding the anterior parietal bone override the posterior one, the frontal and occipital bones go under the parietal bones. The advantage of moulding is that it is a protective mechanism and prevents compression of the fetal brain, once it is not excessive, too r...

  The Vulva   The term ‘vulva’ applies to the external female gen ital organs. It consists of the following structures:   The mons veneris (‘mount of venus’) or mons pubis. This is a pad of fat lying over the symphysis pubis. It is covered with pubic hair from the time of puberty.   The labia majora (‘greater lip’). Theses are two foldsof fat and areolar tissue covered with skin and pubic hair on the outer surface. They arise in the mons veneris and merge into the perineum behind   The labia minora (‘lesser lip’)  these are two thin foldsof skin lying between the labia majora. Anteriorly they divide to enclose the clitoris; posteriorly they fuse, forming the fourchette.   The clitoris  This is a small rudimentary organcorresponding to the male penis. It is extremely sensitive and highly vascular and plays a part in the orgasm of sexual intercourse.   The vestibule  This is the area enclosed by the labiaminora in which are situated the op...