Anatomy Flashcards
Name 7 endocrine glands/ gland pairs?
Pituitary Gland Parathyroid Glands Thyroid Gland Adrenal Glands Pancreas Ovaries Testes
What forms the diencephalon? What does it do?
Diencephalon = Thalamus (T) + Hypothalamus (H)
Diencephalon forms the central core of the cerebrum with connections to the right and left cerebral hemispheres & the midbrain
Describe the location of the pituitary gland?
Hangs off the hypothalamus which is in the centre of the brain superior to the mid brain
The pituitary gland is a midline structure in the pituitary fossa of the sphenoid bone. The pituitary fossa (space) lies within the sella turcica (Turkish saddle)
Describe how the pituitary gland is connected to the hypothalamus?
The infundibulum (funnel) connects the hypothalamus to the posterior lobe of pituitary gland. The anterior lobe does not connect but hugs around the posterior lobe.
The pituitary gland is anatomically & functionally divided into the ___________________
anterior pituitary and the posterior pituitary
Describe the embryological origins of the two lobes of the pituitary glands?
The posterior part of the pituitary has its embryological origins in nervous tissue. It is formed from a downgrowth of the diencephalon that forms the floor of the third ventricle. The anterior part is derived from an upgrowth from the oral ectoderm of the primitive oral cavity called Rathke’s pouch.
Neurohypophysis is another name for the __1__
Adenohypophysis is another name for ___2___
1) posterior pituitary gland
2) anterior pituitary gland
Describe the differences in tissue in the anterior and posterior pituitary glands?
The posterior pituitary gland is a continuation of the hypothalamus. Axons project down through infundibulum to posterior pituitary and the hormones are transported to the posterior pituitary within the axoplasm (cytoplasm of the axons) by axoplasmic transport. So it’s NEURAL tissue.
The anterior pituitary gland has no direct connection to the CNS so needs vascular tissue to secrete the hormones. So the tissue is GLANDULAR.
The posterior pituitary secretes two hormones made by the hypothalamus which are ___________
oxytocin and ADH/ vasopressin
The anterior pituitary secretes six hormones which are ___________
Growth hormone (GH) Prolactin (milk production) Thyroid stimulating hormone (TSH) Adrenocorticotrophic hormone (ACTH) Lutenising hormone (LH) Follicle stimulating hormone (FSH)
What are the two portal venous systems in the body?
Hypophyseal portal system
Hepatic portal system
Explain how the hypophyseal portal system works?
The hypothalamic neurones secrete releasing hormones or release-inhibiting hormones into a “portal system” of veins
the “hypophyseal portal system” drains venous blood:
1. from hypothalamus to anterior pituitary capillary beds
this blood contains the releasing or release-inhibitory hormones
2. from the anterior pituitary a second set of veins drains the venous blood to the hypophyseal veins and then eventually to the SVC
this blood contains the anterior pituitary hormones
hence the hypothalamic hormones control the release of the hormones manufactured by the anterior pituitary
What is the optic chiasm?
X-shaped structure formed by the crossing of the optic nerves in the brain. The optic nerve connects the brain to the eye.
Explain the visual pathway
Light travels in straight line so Temporal field goes to the nasal retina and cross to other side of brain. Nasal field goes to temporal retina and does not cross to other side of brain.
What is the name given for loss of temporal vision on both sides?
Bitemporal hemianopia
Explain how the visual pathway can be disrupted with a pituitary tumour?
If the tumour presses on the optic chiasm those which cross over (the temporal vision) will not work properly so will lose your temporal vision but nasal vision will be in tact, this is called bitemporal hemianopia.
Describe the paranasal sinuses
Air-filled spaces within the bones surrounding the nasal cavities Frontal bone (frontal sinuses) Maxillae (maxillary sinuses) Ethmoid bone (ethmoidal air cells) Sphenoid bone (sphenoid sinuses)
Lined by mucous-secreting respiratory mucosa
No real function?
Make mucous and drain it into the nasal cavities through ostia (singular = ostium – bony drainage hole)
Reduce the weight of the skull
Add resonance to the voice
What type of fracture may give better access in pituitary gland surgery?
Le Fort 1 of the mid face
What is dura matter? Where is it?
The tough outermost membrane enveloping the brain and spinal cord. The entire cranial cavity is lined internally with dura matter.
Describe the role of dural venous sinuses
Venous channels within the dura mater that drain most of the venous blood from the cranial cavity (including the brain) into the internal jugular veins (not histologically veins but function like veins)
What are the cavernous sinuses?
dural venous sinuses of the head
these are specific dural venous sinuses near the pituitary