Anatomy Flashcards
Name the main endocrine glands in the body and which cavity they sit in
Cranial- hypothalamus and pituitary glands
Neck- thyroid and parathyroid
Abdomen- 2 adrenal glands, pancreas
pelvis- ovaries (2) or testes
Divisions in the brain
Cerebum (superior part of the brain) divided into right and left hemispheres.
The little brain- cerebellum
Brain stem- consisting of midbrain, pons and medulla oblongata
What makes up the diencephalon?
The thalamus, hypothalamus and the pituitary gland.
Significance of the diencephalon
It connects the left and right hemispheres of the cerebrum and the midbrain.
Where does the pituitary gland sit in relation to the other structures of the brain?
The pituitary gland sits anterior to the thalamus and hypothalamus. Sits below the hemispheres but above the brainstem.
Connection between hypothalamus and pituitary
They are connected anatomically and functionally.
Connected via the infundibulum.
Divisions of the pituitary gland
Anterior and posterior
Where does the pituitary gland sit? (detailed)
It sits in the pituitary fossa which is in the sella turcica. (this is on the sphenoid bone)
Projections of the Sella turcica
Clinoid processes- mark the anterior and posterior borders of the
Two types of fields that the eye can see
Nasal side of the visual field (medial) and temporal side of the visual field (lateral)
When someone is seeing something in the nasal field, which retina will it be transferred too?
The temporal retina.
Describe seeing something in the nasal field in terms of how the signal is transmitted
Something is seen in the nasal field. This is picked up by the temporal retina. This travels down the optic nerve which extends backwards (in the optic canal) from the retina.
It then travels down the right optic chiasm and then to the right optic radiation to the visual cortex.
Describe seeing something in the temporal field in terms of how the signal is transmitted
Something is seen in the temporal side of the visual field. This is picked up by the nasal retina. This travels down the optic nerve which extends backwards (in the optic canal) from the retina. It then crosses over at the optic chiasm to the other side (left).
It then travels down the right optic chiasm and then to the right optic radiation to the visual cortex.
Significance of enlargement of the pituitary gland
Enlargement of the pituitary (could be due to tumour) can press on the optic chiasm. This will mean that anything transmitted via the nasal retina (e.g. anything seen in the temporal visual field) will not be transmitted to the visual cortex therefore won’t be seen.
Term for blindness due to compression on the optic chiasm
Bitemporal hemianopia.
Surgical access to the pituitary gland
Transcranial approach- under the frontal lobe
Transsphenoidal approach- via nasal cavities and sphenoid sinus
What is the nasal septum made up of?
Ethmoid bone superiorly and volar bone inferiorly
Lateral border of the nasal cavity
Has conchae- superior and middle conchae are part of the ethmoid bone
Inferior conchae is a bone in its own right.
Floor of the nasal cavity
Hard palette of the mouth.
What are parasinal sinuses?
They are air filled spaces within the bones surrounding the nasal cavities.
Lining of the parasinal sinuses
Respiratory mucosa therefore secrete mucous. They have holes to allow drainage (ostia)
Largest sinus
Maxillary sinus
Transphenoidal approach to the pituitary gland
Go in through the nasal cavity. Requires fracture of the nasal septum and the roof and floor of the sphenoid sinus.
What can the surgeon do to offer themselves more room in a transphenoidal approach?
They can do a LeFort type 1 fracture of the maxilla so that they can move the floor of the nasal cavity down. Along the alveolar process.
Dura mater
A meningieal layer that surrounds the brain- tough and fibrous tissue.
Tentorium cerebelli
A tough sheet of dura mater tenting over the cerebellum within the posterior cranial fossa.
Has a gap to permit the brainstem to pass through
Diaphragm sellae
Another tent formed by the dura mater that goes over the pituitary gland. Has an opening for the infundibulum.
Dural venous sinuses
Venous channels within the dura mater that drain most of the venous blood in the cranial cavity.
Where do the dural venous sinuses drain?
Into the internal jugular vein.
Dural venous sinus surrounding the pituitary gland
Cavernous sinuses. Left and right join together at the anterior aspect to form the intercavernous sinus.
Where does the internal jugular vein exit?
Internal jugular foramen.
Structures at risk in pituitary gland surgery
Optic chiasm- causes bitemporal hemianopia Oculomotor nerve Trochlear Trigeminal nerve Abducent nerve Cavernous sinus- venous haemorrhage Internal carotid artery- catroscophic heamorrhage Dura mater- cerebrospinal fluid leak