Summary of Pure Sensory cranial nerve

Summary of Pure Sensory cranial nerve  

olfactory nerve, optic nerve and vestibulocochlear nerve (1, 2, 8)

Function of sensory nerve in short:

1. Olfactory nerve : carry smell
2. Optic nerve : responsible for vision
3. Vestibulocochlear nerve : vestibular part responsible for balance and cochlear nerve responsible for vision

No.	Sensory nerve	Component	Name of the opening through which nerve enter  into the cranium	Arises from
I	Olfactory nerve	SVA	Cribriform plate of ethmoid	Axon of olfactory nerve arises from the Olfactory  cells which are situated in the nasal mucosa
II	Optic nerve	SSA	Optic canal	Optic nerve fibres are arises from  the ganglionic cells of the retina
VIII	Vestibulocochlear  nerve	SSA	Internal acoustic meatus	Nerves are arises from inner ear (hair cells)

 

Base of the skull : all important viva questions

Viva question of Base of the skull:

1. Define skull:  cranium with mandible is known as skull

Parts of the skull : base of the skull and cranial vault

Ossification : base of the skull : intracartilaginous ossif) & cranial vault : intramembranous ossification

Anatomical points:

1. infraorbital margin and and upper border of external auditory meatus lies in same horizontal line , this line is known as  Frankfort  line

2. orbital cavity directed anteriorly

3. foramen magnum lies horizontally and directed  inferiorly

q. show different view of skull :

norma verticalis : viewed from above

norma frontalis  from front

norma basalis from below

norma occipitalis from behind

norma lateralis from sides

Identification and definition of: bregma, lambda , asterion, pterior  

** pterior: it is the meeting point of 4 bones frontal , squamous part of temporal bone, parietal bone and greater wings of sphenoid clinical important : deep to this point branches of middle meningeal vessels are present . this vessel torn in accident , barr hole operation done here

Cranial fossa : three in number anterior, middle and posterior

Learn Boundary and content of each cranial fossa :

 *** foramen through which cranial nerves are passage 

 

Identify the sulcus which lodges cranial dural sinus

Cranial dural sinus

Cranial dura has two layer : endoesteum layer and meningeal layer

The sinuses of the dura mater are venous channels which drain the blood from the brain;

They are situated between the two layers of the dura mater

They are devoid of valves, and and lined by endothelium but no smooth muscle cells layer.

Different types of dural venous sinus:

1. Pair: cavernous sinus, transverse sinus, sigmoid sinus etc.
2. unpair: superior sagittal sinus, inferior sagittal sinus, straight sinus etc.

Superior sagittal sinus > right transverse sinus > right sigmoid sinus > right internal jugular vein

 Inferior sagittal sinus > straight sinus > left transverse sinus > left  sigmoid sinus > left internal jugular vein

 The cavernous sinuses are placed one on either side of the body of the sphenoid bone, extending from the superior orbital fissure to the apex of the petrous portion of the temporal bone.

 Medial wall (central part) is related to –

1. the internal carotid artery,
2. abducent nerve.

Lateral wall : is related to

1. the oculomotor
2. trochlear nerves,
3. the ophthalmic nerves
4. maxillary divisions of the trigeminal nerve  

The cavernous sinus : tributaries :

1. the superior ophthalmic vein
2. superior and inferior  petrosal sinus
3. pterygoid venous plexus veins
4. The two sinuses also communicate with each other by means of the anterior and posterior intercavernous sinuses.

Sulcus (a bony impression)	Structure lodge on sulcus	Bone
Sagittal sulcus	Superior sagittal sinus	Frontal bone, parietal bone, occipital bone
Transverse sulcus	Transverse sinus	occipital bone
Sigmoid sulcus	Sigmoid sinus	Mastoid part of temporal bones

 

q. Identify the Suture :  coranal , sagittal, lamdoid suture

q:  Suture,  what type of joint: fibrous variety

Location of anterior and  posterior frontanelle and their time of closer

Anterior frontanelle : located in between coronal and sagittal suture close : 8–24 months after birth

Pos frontanelle : located in between coronal and lambdoid suture. close : 6–8 weeks after birth

 

 

Summary of development of skeletal system

Summary of development of skeletal system 

The skeletal system develops from paraxial, somatic layer of lateral plate mesoderm and neural crest

 Neural crest: develops facial skeleton, and most of the vault of cranium and prechordal part of  base of the skull (area of base of the skull just rostral to the rostral half of the sella turcica)

Paraxial mesoderm: parietal bone, occipital bone, petrous part of temporal bone, vertebrae, ribs

Somatic layer of lateral plate mesoderm: develops all  bones of upper and lower limb

 

Lecture note: gastroschisis

Gastroschisis

Gastroschisis Ventral body wall defect resulting from a lack of closure of the lateral body wall folds in the abdominal region resulting in protrusion of intestines and sometimes other organs through the defect.

It occurs lateral to the umbilicus usually on the right

Cause : abnormal closure of body wall around the connecting stalk

Content:  intestines, other organs including the stomach and liver  protruded, which  are not covered by peritoneum or amnion

Out come : the bowel may be damaged by  exposure to amniotic fluid

Diagnosis : like omphalocele it can be diagnosed later part of pregnancy by ultrasound

Incidence : 1/10000 birth but is increasing in frequency especially among young women <20 years old.

It is not associate with chromosomal abnormality or other birth defect like omphalocele so the survival rate is excellent

Death usually occurs due to volvulus formation (rotation of bowel ) resulting in compromised blood supply may kill large regions of the  intestine and lead to fetal death .