Maxilla : easy and brief discussion

Maxilla :

•      2^nd largest bone of face

•      2 maxillae forms whole of upper jaw

•      Each maxilla contributes in formation of

1.      Face

2.      Nose

3.      Mouth

4.      Orbit

5.      Infra-temporal fossa

6.      Pterygopalatine fossa

•      Each maxilla has

•      A body

•      4 processes

1.      Frontal

2.      Zygomatic

3.      Alveolar

4.      Palatine

•      Body of maxilla

•      Shape pyramidal

•      It has

•      Base directed at nasal surface

•      Apex directed laterally at zygomatic process

•      4 surfaces

1.      Superior / orbital

2.      Anterior / facial

3.      Posterior / infratemporal

4.      Medial /nasal

•      Encloses a cavity  maxillary sinus 

Epiploic foramen

Epiploic foramen:

•      The omental foramen /epiploic foramen/ foramen of Winslow:  is the passage of communication, or foramen, between the greater sac  and the lesser sac of peritoneal cavity 

 

Boundary :

 

•      Anteriorly : the free border of the lesser omentum, also known as the hepatoduodenal ligament.

       Hepatoduodenal ligament has two layers and following structures present within

       these layers antero posteriorly :

1.      the common bile duct,

2.      hepatic artery, and

3.      portal vein.

•      A useful mnemonic to remember these is DAVE:
Antero posteriorly
1. bile Duct,
2. hepatic Artery,
3. portal Vein,
4. Epiploic foramen.

•      Posteriorly : inferior vena cava

•      Superiorly : caudate process of caudate lobe of liver

•      Inferiorly : 1^st part of duodenum 

 Summary of boundary of epiploic foramen

•       

The peculiarities of optic nerve

The peculiarities of optic nerve

1.      It is not a peripheral nerve but a prolongation of white matter of the brain

2.      Peripheral neuropathies like Guillain–Barré syndrome do not affect the optic nerve.

3.      the epineurium, perineurium, and endoneurium found in peripheral nerves but not is optic nerve

4.      optic nerve are incapable of regeneration, and, hence, optic nerve damage produces irreversible blindness..

5.      It is  covered by three meninges of brain with subdural and subarchnoid spaces

6.      Myelination of the optic nerve is derived from the oligodendrocyte and not from the Schwann cells

7.      Plial sheath projects into the substances of the nerve as numerous septa.

8.      The subject of the blood supply of the optic nerve. The circulation of the posterior ciliary artery is the main source of blood supply to the optic nerve, except for the surface nerve fiber layer which is supplied by the retinal circulation.