Anatomy of the pituitary gland Flashcards
What are the major endocrine glands in the body?
Cranial cavity: hypothalamus and pituitary gland (hypophysis)
Neck: 4 parathyroid glands and thyroid gland
Abdomen: 2 adrenal glands and pancreas
Pelvis (female): ovaries in broad ligaments
Pelvis (male): testes in scrotum
What is the diencephalon?
The thalamus and hypothalamus
Where can the diencephalon be found?
Central core of the cerebrum with connections to the right and left cerebral hemispheres and the midbrain
How is the hypothalamus connected to the pituitary gland?
Via the infundibulum/pituitary stalk
What part of the pituitary gland is connected to the hypothalamus?
The posterior lobe
What are the different parts of the anterior (adenohypophysis) lobe?
Pars distalis
Pars tuberalis
Pars intermedia
What are the different parts of the posterior (neurohypophysis) lobe?
Pars nervosa
What does the anterior lobe originate from in utero?
Rathke’s pouch - glandular tissue
What does the posterior lobe originate from in utero?
Neuroendocrine tissue - neural tissue
What hormones will the adenohypophysis release?
GH (growth hormone) TSH (thyroid stimulating hormone) ACTH (adrenocorticotrophic hormone) FSH (follicle stimulating hormone) LH (luteinising hormone) PRL (prolactin)
What hormones will the neurohypophysis release?
ADH - anti-diuretic hormone
OT - oxytocin
Where are the hormones released from the neurohypophysis made?
Hypothalamus
Where can the pituitary gland be found?
In the pituitary fossa within the sella turcica in the sphenoid bone
What structures lies superior to the pituitary gland?
Optic chiasm
What structures surround the pituitary gland?
Optic chiasm Occulumotor nerve Trochlear nerve Opthalmis and maxillary divisions of trigeminal Abducent nerve Internal carotid artery
What forms the optic chiasm?
Right and left optic nerves
Where do the optic nerves synapse?
They pass posterior from the chiasm to synapse in the thalamus where they pass via optic radiation to the visual cortex in occipital lobe
What is the retina split up into?
Nasal retina
Temporal retina
What occurs if the pituitary gland increases in size due to a tumour?
It will disrupt the action potential from the nasal retina bilaterally (temporal vision) causing the patient to lose the ability to see structures in the temporal side of the visual field
What will loss of vision in the temporal visual field cause?
Bitemporal hemianopia
What is the transcranial approach?
Subfrontal - under the frontal lobe
What is the transsphenoidal approach?
Via nasal cavities and sphenoid sinus
What is a sinus?
An air filled space within bones surrounding the nasal cavities
What lines the sinuses?
Mucous-secreting respiratory mucosa
What is the function of sinuses?
Make mucous and drain it into nasal cavities via ostia
Add resonance to voice
What are the different sinuses?
Frontal sinus
Maxillary sinus
Ethmoidal air cells
Sphenoid sinus
Where are the ethmoid air cells found?
Located between the nasal cavity and the orbit
Where are the maxillary sinuses found?
1 within each maxilla and known clinically as the antrum
Where are the sphenoid sinuses found?
Within the body of the sphenoid bone
Where are the frontal sinuses found?
Connect in midline - very anatomically unique between people
What bones need to be fractures in the transsphenoidal approach?
Nasal septum and the floor (septum) and roof of the sphenoid sinus
What do le fort fractures show?
The lines of least resistance in the skull
What is the dura mater?
The dura mater is a membrane that envelops the arachnoid mater. It surrounds and supports the dural venous sinuses and carries blood from the brain toward the heart
What is the diaphragm sellae?
A tough sheet of dura mater forming a roof over the pituitary fossa
What is the tentorium cerebelli?
A tough sheet of dura mater that covers the cerebellum within the posterior cranial fossa but with a central gap to allow the passing of the brain stem
What are the dural venous sinuses?
Venous channels within the dura mater that drain most of the venous blood from the cranial cavity (inc. brain) into the internal jugular veins
What sinuses surround the pituitary gland?
Cavernous and intercavernous sinuses
What is the function of the optic chiasm and what will occur if it is injured?
Conducts APs bilaterally from the nasal retinae and if damaged will cause bitemporal hemianopia
What is the function of the oculomotor nerve and what will occur if it is injured?
Motor to muscles that move the eyeball
Parasympathetic to sphincter of iris
If damaged will cause problems with several eye movement and a dilated pupil
What is the function of the trochlear nerve and what will occur if it is injured?
Motor to the superior oblique muscle that moves the eye inferiorly and laterally and if damaged these movements will be limited
What is the function of the trigeminal nerve and what will occur if it is injured?
Sensory to most of face
Motor to muscles of mastication
If damaged will cause damage to sensation of face and difficulty chewing
What is the function of the abducens nerve and what will occur if it is injured?
Motor to one muscle in the globe that abducts the eye
What is the function of the internal carotid artery and what will occur if it is injured?
Supplies arterial blood to the brain and orbit (inc globe) and if damaged will cause catastrophic haemorrhage
What is the function of the dura mater and what will occur if it is injured?
Protects the structures of the cranial cavity and if damaged will cause a CSF leak
What is the function of the cavernous sinus and what will occur if it is injured?
Drains venous blood and therefore if damaged will cause a venous haemorrhage
