Turner syndrome

Turner syndrome, a condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing.

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Turner syndrome may be diagnosed before birth (prenatally), during infancy or in early childhood 

Prenatal ultrasound of a baby with Turner syndrome may show:

• Large fluid collection on the back of the neck or other abnormal fluid collections (edema)
• Heart abnormalities
• Abnormal kidneys                                 Signs of Turner syndrome at birth or during infancy may include:
• • Wide or weblike neck
  • Low-set ears
  • Broad chest with widely spaced nipples
  • High, narrow roof of the mouth (palate)
  • Arms that turn outward at the elbows
  • Fingernails and toenails that are narrow and turned upward
  • Swelling of the hands and feet, especially at birth
  • Slightly smaller than average height at birth
  • Slowed growth
  • Cardiac defects
  • Low hairline at the back of the head
  • Receding or small lower jaw
  • Short fingers and toes।                        Causes
  • Monosomy
  • Mosaicsm
  • X chromosomal changes 

  • Complications

    Turner syndrome can affect the proper development of several body systems, but this varies greatly among individuals with the syndrome. Complications that can occur include:

    • Heart problems. Many infants with Turner syndrome are born with heart defects or even slight abnormalities in heart structure that increase their risk of serious complications. Heart defects often include problems with the aorta, the large blood vessel that branches off the heart and delivers oxygen-rich blood to the body.
    • High blood pressure. Turner syndrome can increase the risk of high blood pressure — a condition that increases the risk of developing diseases of the heart and blood vessels.
    • Hearing loss. Hearing loss is common with Turner syndrome. In some cases, this is due to the gradual loss of nerve function. An increased risk of frequent middle ear infections can also result in hearing loss.
    • Vision problems. An increased risk of weak muscle control of eye movements (strabismus), nearsightedness and other vision problems can occur with Turner syndrome.
    • Kidney problems. Turner syndrome may be associated with malformations of the kidneys. Although these abnormalities generally don't cause medical problems, they may increase the risk of urinary tract infections.
    • Autoimmune disorders. Turner syndrome can increase the risk of an underactive thyroid (hypothyroidism) due to the autoimmune disorder Hashimoto's thyroiditis. There is also an increased risk of diabetes. Sometimes Turner syndrome is associated with gluten intolerance (celiac disease) or inflammatory bowel disease.
    • Skeletal problems. Problems with the growth and development of bones increase the risk of abnormal curvature of the spine (scoliosis) and forward rounding of the upper back (kyphosis). Turner syndrome can also increase the risk of developing weak, brittle bones (osteoporosis).
    • Learning disabilities. Girls and women with Turner syndrome usually have normal intelligence. However, there is increased risk of learning disabilities, particularly with learning that involves spatial concepts, math, memory and attention.
    • Mental health issues. Girls and women with Turner syndrome may have challenges functioning in social situations, may experience anxiety and depression, and may have an increased risk of attention-deficit/hyperactivity disorder (ADHD).
    • Infertility. Most females with Turner syndrome are infertile. However, a very small number may become pregnant spontaneously, and some can become pregnant with fertility treatment.
    • Pregnancy complications. Because women with Turner syndrome are at increased risk of complications during pregnancy, such as high blood pressure and aortic dissection, they should be evaluated by a heart specialist (cardiologist) and a high-risk pregnancy doctor (maternal-fetal medicine specialist) before pregnancy.

Genetics of prostate cancer

The public health burden of prostate cancer is substantial. A total of 268,490 new cases of prostate cancer and 34,500 deaths from the disease are anticipated in the United States in 2022, making it the most frequent nondermatological cancer among U.S. male. 

Inharitant variants in particular genes, such as BRCA1, BRCA2, and HOXB13, account for some cases of hereditary prostate cancer. Men with variants in these genes have a high risk of developing prostate cancer and, in some cases, other cancers during their lifetimes. Prostate cancer may occur due to other cause. 

variants in the  BRCA1, BRCA2, and HOXB13, genes are inherited in an autosomal dominant pattern which means one copy of the altered gene in each cell is sufficient to increase a person's chance of developing cancer. In other cases, the inheritance of prostate cancer risk is unclear. It is important to note that people inherit an increased risk of cancer, not the disease itself. Not all people who inherit variants in these genes will develop cancer.

Linkage analyses led to the successful identification of HOXB13 at 17q21-22 as a prostate cancer susceptibility gene

Gastroschisis

 

Gastroschisis

It is a birth defects characterized by a protrusion of abdominal contents through the body wall directly into the amniotic cavity

Situation: lateral umbilicus usually on the right

Cause: due to abnormal closure of the body wall around the connecting stalk , more common in young women , cocaine user

Covering of protruded structure : not covered by  peritoneum or amnion

Features :

1.  bowel may be damaged by exposure to amniotic fluid

2. 1/10000 births

3.   large region of intestine may damage  due to  of  lose  of blood supply due to rotation of gut (volvulus)

General somatic afferent : lecture notes

 General somatic afferent 

General somatic afferent

General somatic afferent fibers convey impulses for exteroreceptors of the skin (cutaneous sensation of pain, temperature, touch, vibration, or pressure) & from proprioreceptors localized in the muscles, joints, ligaments, or in the periosteum of bones via spinal nerves and some cranial nerves.

Nerves contain general somatic afferent fibres

1. All the spinal nerves, except occasionally the first cervical, and conduct impulses of pain, touch and temperature from the surface of the body through the dorsal roots to the spinal cord and impulses of muscle sense, tendon sense and joint sense from the deeper structures

2. Trigeminal nerve:

Ophthalmic nerve:   general somatic afferents fibre of this nerve supply  to the upper face, skull, and eye:

·         Face: Upper eyelid and associated conjunctiva. Eyebrow, forehead, scalp all the way to the lambdoid suture.

·          

·         Skull: Roof of orbit, frontal, ethmoid, and possibly sphenoid sinuses.

·         Eye: The eye itself (all the intraocular structures such as cornea) and the lacrimal gland and sac.

 

·         Maxillary nerve : general somatic afferents fibres of this nerve supply to the mid-face and skull:

·         Face: Lower eyelid and associated conjunctiva. Cheek, upper lip.

·         Skull: Orbital floor, maxillary sinus, upper teeth, nasal cavity, and palate, cheekbone.

 

 Mandibular nerve : The sensory fibres associated with the mandibular branch of CN V provide innervation to:

·         The facial skin in the lower third of the face, including the chin and lower lip

·         Inferior row of teeth and gingiva

·         The anterior two thirds of the tongue

3. Facial  nerve : The facial nerve carries axons of type GSA, general somatic afferent, to skin of the posterior ear. 

4. Glossopharyngeal nerve: the glossopharyngeal nerve transmits general sensory information from inside of the tympanic membrane, skin of the external ear, upper portion of the pharynx and general sensation from the posterior one-third of the tongue.

5. Vagus nerve GSA axons carry pain, temperature, and touch sensations from the posterior cranial fossa, posterior ear, external auditory meatus, pharynx, and posterior, and the external surface of the tympanic membrane

General somatic afferent (sensory) nuclei

General somatic afferent (sensory) nuclei related with spinal nerve

• Marginal zone (MZ, posterior marginalis) – located at the tip of the dorsal horn, and is important for relaying pain and temperature sensation to the brain.
• Substantia gelatinosa (SG) – located at the top of the dorsal horn, the SG is important for relaying pain, temperature and light touch sensation to the brain.
• Nucleus proprius (NP) – located in the ‘neck’ of the dorsal horn, the NP relays mechanical and temperature sensation to the brain.

General somatic afferent (sensory) nuclei related with trigeminal, facial, glossopharyngeal & vagus nerve

 

·         The main or principal sensory nucleus of the trigeminal nerve: This nucleus lies in the upper part of the pons, in the lateral part of the reticular formation. It lies lateral to the motor nucleus of the trigeminal. The superior sensory nucleus is mainly concerned in mediation of proprioceptive impulses, touch and pressure.

·         The spinal nucleus of the trigeminal nerve: The spinal nucleus is another sensory cranial nerve nucleus which extends from the main nucleus (superior sensory nucleus) in the pons down into the medulla, &  into the upper two segments of the spinal cord. The lower end of the spinal nucleus is continuous with the substantia gelatinosa of the spinal cord. The spinal nucleus receives general somatic sensations carried by the facial, glossopharyngeal and vagus nerves. Functions of the spinal nucleus includes mediation of pain and thermal sensibility. The spinal nucleus is divisible (cranio-caudally) into three sub-nuclei, the oralis, interpolaris, and caudalis.

·         The mesencephalic nucleus of the trigeminal nerve: This is also called the mesencephalic nucleus of the trigeminal nerve. It extends cranially from the upper end of the main sensory nucleus in the pons into the midbrain. In the midbrain, the mesencephalic nucleus lies in the central grey matter lateral to the aqueduct. Functionally, this nucleus appears to be similar to sensory ganglia of the cranial nerves, and to the spinal ganglia, rather than to afferent nuclei. The processes (dendrites) of the neurons of this nucleus are believed to carry proprioceptive impulses from muscles of mastication, and possibly also from muscles of the eyeballs, face, tongue and teeth. The mesencephalic nucleus is the centre for jaw jerk.

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General somatic efferent: summarized lecture notes

 

General somatic efferent

General somatic efferent fibers carry motor impulses to somatic skeletal muscles.

GSE neurons innervate striated muscle of embryonic somite & limb buds origin

Nerves contain GSE functional components:

·         All Spinal nerves,

·         4 pure Motor Cranial nerves

1.      III (oculomotor ),

2.      IV(trochlear nerve ),

3.      VI (abducent nerve ), and

4.      XII (hypoglossal) carry these fibers.

General Somatic Efferent Nuclei

Spinal nerves :  The ventral horns of the spinal cord (lamina IX of Rexed ) contains somatic efferent neurons (motor neurons) arranged into clusters called motor nuclei. There are two groups of nuclei, medial and lateral .

Medial motor nuclei (column) extend the entire length of the spinal cord and contain motor neurons to the axial musculature

The larger lateral motor nuclei (columns)  of cervical and lumbosacral enlargements contain neurons to the musculature of upper and lower extremities. The alpha motor neurons of lateral nuclei are larger than the medial motor nuclei .

Cranial nerves :

1.      Oculomotor nucleus

2.      Trochlear nucleus

3.      Abducent nucleus

4.      Hypoglossal nucleus

Muscles supply by General somatic efferent

Spinal nerves:

Medial motor nuclei (unlabeled) innervate axial musculature and are present at all levels of spinal cord. Lateral motor nuclei (labeled below) innervate limb musculature and are found in cervical and lumbosacral enlargement segments.

In spinal nerve this functional components passes through the ventral roots, carrying motor impulses to skeletal muscle through a neuromuscular junction. As shown below, lateral motor nuclei are somatotopically organized. Proximal muscles are ventral; distal muscles are dorsal. Cranial muscles are lateral; caudal muscles are medial.

Cranial nerves

1.      Oculomotor nucleus: extra ocular muscles except superior oblique and lateral rectus

2.      Trochlear nucleus: superior oblique

3.      Abducent nucleus: lateral rectus muscle

4.      Hypoglossal nucleus: muscles of tongue

 

 

 

 

 

Cranial nerve nuclei : summarized lecture notes

Cranial nerve nuclei

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The cranial nerve nuclei are aggregate of cells (collection of cell bodies). Attached to these cell bodies are fibers called cranial nerves (bundles of axons). These nuclei are either sensory or motor but never both. However, cranial nerves can be sensory, motor or mixed nerves (when they have both sensory and motor functions).

The cranial nerve nuclei are a series of bilateral grey matter motor and sensory nuclei located in the midbrain, pons and medulla that are the collections of afferent and efferent cell bodies for many of the cranial nerves.

Some nuclei are small and contribute to a single cranial nerve, such as some of th motor nuclei.

 Other nuclei, however, are long and span several regions of the brainstem contributing to several cranial nerves.

 Several motor and sensory nuclei form longitudinal columns in the brainstem, leading to some authors describing them as single discontinuous longitudinal nuclear columns rather than the more numerous individual separate nuclei.

Three long discontinuous efferent columns have been described: somatic, brachiomotor and parasympathetic.

Extensive interconnections exist between many of these nuclei, as well as with other brainstem nuclei and white matter tracts such as the medial lemniscus and medial longitudinal fasciculus.

1. oculomotor nucleus: somatic motor nucleus for the oculomotor nerve
2. Edinger-Westphal nucleus: general visceral motor (parasympathetic) nucleus for the oculomotor nerve,
3. trochlear nucleus: somatic motor nucleus for the trochlear nerve
4. motor nucleus of CN V: somatic motor nucleus for the trigeminal nerve
5. ​mesencephalic nucleus of CN V: somatic sensory nucleus for the trigeminal nerve
6. main sensory nucleus of CN V: somatic sensory nucleus for the trigeminal, facial, glossopharyngeal and vagus nerves
7. spinal nucleus of CN V: somatic sensory nucleus for the trigeminal nerve
8. abducent nucleus: somatic motor nucleus for the abducens nerve
9. facial nucleus: special visceral motor (branchial) nucleus for the facial nerve
10. superior salivatory nucleus: general visceral motor (parasympathetic) nucleus for the facial nerve
11. cochlear nuclei: group of two special sensory nuclei for the cochlear branch of the vestibulocochlear nerve
12. vestibular nuclei: group of four special sensory  nuclei for the superior and inferior vestibular branches of the vestibulocochlear nerve
13. inferior salivatory nucleus: general visceral motor (parasympathetic) nucleus for the glossopharyngeal nerve

14.    solitary tract nucleus: special visceral sensory nucleus for the facial, glossopharyngeal and vagus nerves

15.    ambiguus nucleus: special visceral motor (branchial) nucleus for the glossopharyngeal and vagus nerves

16.    dorsal motor nucleus: general visceral motor (parasympathetic) nucleus for the vagus nerve

17.    hypoglossal nucleus: somatic motor nucleus for the hypoglossal nerve

18.     the gracile and cuneate nuclei

the cranial nerve nuclei with motor functions can be grouped according to the following functional components to which their fibers belong:

·         General Somatic Efferents (GSE)

·         Special Visceral Efferents (SVE)

·         General Visceral Efferents (GVE)

Similarly, the cranial nerve sensory nuclei are grouped according to the information they receive, which constitutes the functional components to which their attached nerves belong. These functional components are:

·         General Somatic Afferents (GSA)

·         Special Somatic Afferents (SSA)

·         General Visceral Afferents (GVA)

·         Special Visceral Afferents (SVA)

In the brainstem, there are about 18 cranial nerve nuclei comprising of 10 motor cranial nerve nuclei and 8 sensory cranial nerve nuclei. 

 

General somatic efferent nuclei	Oculomotor, trochlear, abducens, hypoglossal
Special visceral efferent nuclei	Motor nucleus of trigeminal nerve, nucleus of facial nerve, nucleus ambiguus
General visceral efferent nuclei	Accessory oculomotor nucleus (Edinger-Westphal nucleus), salivatory nuclei, dorsal vagal nucleus
General and special visceral afferent nuclei	Nucleus of the solitary tract, commissural nucleus of the vagus, gustatory nucleus
General somatic afferent nuclei	Principal sensory nucleus of the trigeminal nerve, spinal nucleus of the trigeminal nerve, mesencephalic nucleus of the trigeminal nerve
Special somatic afferent nuclei	Cochlear and vestibular nuclei

 

Alar plate : the part of mantle layer of neural tube

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Alar plate

 Definition :

The alar plates (or alar lamina) is a neural structure in the embryonic nervous system. Sensory area in the dorsal region of the spinal cord and brain

Development:

they develops from dorsal aspect of mantle layer of neural tube

Location :  

the dorsal region of the spinal cord and brain

Functional components deal by alar plate :

 general somatic afferent (collect touch, pain, pressure, vibration temperature  sensation from body wall ) and general visceral afferent(collect  pain, pressure  sensation from viscera )  .

Structures derived from alar plate :

1. dorsal gray matter of the spinal cord,

2. the sensory nuclei of cranial nerves V, VII, VIII, IX, and X.

3. The inferior olivary nucleus, mesencephalic nucleus of V, and main sensory nucleus of V are also developed from this plate.

4.  the rhombic lip of the alar plate develops the cerebellum, which is considered to be a big exception since alar plate gives rise to sensory derivatives only.