Endocrine Anatomy Flashcards
Diencephalon? What does it form?
Thalamus + hypothalamus
* Diencephalon forms central core of cerebrum + connects to midbrain + right and left cerebral hemispheres
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What is the brainstem made up of?
Midbrain, pons + medulla
What is hypothalamus connected to? How?
Pituitary gland - by infundibulum or “pituitary stalk”
Pituitary gland divided into?
Anterior and posterior pituitary
Embryology of pituitary gland?
* Posterior lobe formed from infundibulum (diverticulum of dencephaluc floor)
* Anterior lobe formed from Rathke’s pouch (diverticulum of stomodeal roof)
Anterior lobe of pituitary gland also known as?
What is it made up of?
Function?
Adenohypophysis
* Pars distalis, pars tuberalis, pars intermedia
* Responsible for synthesis and release of most pituitary hormones: GH, TSH, ACTH, FSH, LH, PRL
Posterior lobe also known as?
Made up of?
Function?
Neurohypophysis
* Pars nervosa
* Actually an extension of the brain!! - releases ADH and OT (synthesised in the HYPOTHALAMUS)
Pituitary gland located?
In pituitary fossa of sphenoid bone - pituitary fossa found within sella turcica (Turkish saddle)
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Optic chiasm formed from?
Explain pathway
Right and left optic nerves (CN II)
* nerves pass posteriorly from chiasm
* Synapse in thalamus where axons pass the optic radiation to visual cortext in the occipital lobe!
(pic: note how nasal retinae cross over but temporal do not)
Explain the effect of a pituitary tumour on the visual pathway
What is this condition called?
Surgical access to pituitary fossa? (2)
Transcranial approach = subfrontal (under frontal lobe)
Transsphenoidal approach = via nasal cavities and sphenoid sinus
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Paranasal sinuses?
Examples? (4)
What are they lined by?
Air-filled spaces surrounding nasal cavities
* Frontal bone = frontal sinuses
* Maxillae = maxillary sinuses
* Ethmoid bone = ethmoidal air cells
* Sphenoid bone = sphenoid sinuses
Lined by mucous-secreting respiratory mucosa
Function of paranasal sinuses? (3)
* Make mucus and drain it into nasal cavities through ostia (drainage hole)
* Reduce weight of the skull
* Add resonance to the voice
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What does transphenoidal transnasal approach require?
What about in more complicated cases?
Surgical fracture of nasal septum and the roof + septum of sphenoid sinuses
* Complicated = le Fort I down-fracture
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What internally lines the entire cranial cavity?
What about pituitary?
Dura matter
* Diaphragm sellae - tough sheet of dura matter forming a roof over pituitary fossa
Tentorium cerebelli?
Tough sheet of dura matter “tenting” over cerebellum within posterior cranial fossa (has central gap to allow brainstem to pass thru)
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What are dural venous sinuses?
Where exactly do they drain?
Venous channels witin dura matter that drain venous blood from the cranial cavity (including the brain) into the internal jugular veins
* drain into internal jugular veins at jugular foraminae in posterior cranial fossa
What is pituitary gland surrounded by?
Function of anterior intercavernous sinus?
What pass through the cavernos sinuses?
Pituitary gland surrounded by cavernous and intercavernous sinuses
* Anterior intercavernus sinus = connects right and left cavernous sinuses anterior to pituitary gland
* Internal carotid arteries pass thru cavernous sinuses
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Structures at risk in pituitary gland surgery?
Function?
What happens if damaged?
What is the narrow connecting band between right and left lobes of the thyroid gland?
Where is it located?
Isthmus
* Anterior to 2nd + 3rd tracheal rings
What are the lobes of the thyroid attached to?
What is enlarged thyroid gland called?
Why does thyroid move superiorly when swallowing?
Attached to thyroid and cricoid cartilages+ trachea
* Enlarged gland = goitre
* Moves superiorly then inferiorly when swallowing due to relationship with larynx + trachea
How many parathyroid glands are there?
Where are they located?
4
* posterior surfaces of thyroid gland
Pyramidal love of thyroid gland?
40% prevalance - originates from left lateral lobe and attaches superiorly to thyroid cartilage (may extend as far superiorly as hyoid bone)
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Platysma muscles located?
WHich muscle group do they belong to?
Nerve supply?
Superficial fascia of neck
* Belong to muscles of facial expression
* Nerve supply is cranial nerve VII (facial nerve)
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External jugular vein found within?
Drains into?
Anterior jugular vein found within?
Drains into?
External
* Superficial fascia
* Drains into subclavian vein
Anterior
* Superficial fascia
* Drain into external jugular vein
Sternocleidomastoid found in which fascia?
2 heads + attachments?
Sternocleidomastoid found in investing fascia
* Sternal head = attaches to manubrium of sternum
* Clavicular head = attaches to medial end of clavicle
both heads attach superiorly to mastoid process of temporal bone!!
Whch muscles does spinal accessory nerve supply?
Sternocleidomastoid + trapezius
Where are carotid sheaths located?
Where do they attach? (2)
What structures are found within carotid sheath? (4)
Located deep to investing fascia and anterolaterally in the neck (either side of thyroid gland)
* Attach superiorly to base of skull
* Blend inferiorly with mediastinal fascia
Each carotid sheath contains:
* Internal jugular vein
* Common then internal carotid arteries
* Vagus nerve
* Deep cervical lymph nodes
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Blood supply to thyroid gland?
Branch from?
Uncommon variant?
Superior + inferior thyroid artery
* Superior = internal carotid artery
* Inferior = subclavian artery
Uncommon variant = thyroid ima artery (branches from brachiocephalic trunk)
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Venous drainage of thyroid gland?
What do they drain into?
Superior thyroid vein, middle thyroid vein + inferior thyroid vein
* Drain into (thus branch from) internal jugular veins which drain into brachiocephalic veins, which drain into SVC
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Lymphatic drainage of thyroid gland?
Superior + inferior deep cervical lymph nodes
* Right = drains into right lymphatic duct to right venous angle
* Left = drains into thoracic duct to left venous angle
Tracheal lymph nodes?
Pretracheal + paratracheal nodes
Vagus nerve route from brain?
* Branch from medulla oblangata
* Exit skull via jugular foramen
* Descend thru carotid sheath
* Descend in chest - right nerve lateral to trachea, left nerve left side of aortic arch
* Both pass thru diagphragm with the oesophagus
* Divide into terminal branches on surface of the stomach to supply the abdominal organs
Recurrent laryngeal nerve pathways?
* Right = recurs under subclavian artery
* left = recurs under arch of aorta
Anatomical releations of thyroid? (4)
Located in pretracheal fascia
* Trachea
* Oesophagus (larynx)
* Strap muscles
* Recurrent laryngeal nerves
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Strap muscles? (4)
* Sternohyoid
* Thyrohyoid
* Sternothyroid
* Omohyoid (omo=shoulder)
Surgical approaches to thyroid gland? (4)
* Classical thyrodectomy
* Endoscopically assisted thyroidectomy
* Endoscopic trans-axillary approach
* Endoscopic trans-breast approach
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Where is incision made in classic thyroidectomy? (2)
Which tissues are cut through?
“Collar” incision = made within natural skin crease or in direction of Langer’s lines
* Just superior to clavicles + jugular notch
Skin + platysma
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Function of right recurrent laryngeal nerve?
provides somatic motor supply to most of the skeletal muscles that move the right vocal cord
(the intrinsic muscles of the larynx)
What can injury to recurrent nerves during thyroidectomy result in? (2)
* Unilateral = “hoarseness” or weakness of voice + weak cough
* Bilteral = aphonia (inability to produce sound), inability to close rima glottidis (difficult to prevent aspiration or produce good cough)
back of the eye (retina)
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