Anatomy Flashcards
What makes up the diencephalon?
Thalamus and hypothalamus
What bony structure does the pituitary lie in?
The pituitary fossa in sella turcica of the sphenoid bone
What is the progression of the visual system?
Optic nerves > optic chiasm > optic tracts > thalamus > optic radiation > visual cortex of the occipital lobe
What is the clinical effect of a pituitary tumour on the visual pathway?
It disrupts the transmission of APs from the nasal retina bilaterally. This means the patient lists the ability to see structures in the temporal side of the visual field bilaterally > bitemporal hemianopia
What is responsible for each hemifield?
The temporal left retina and the nasal right retina are responsible for the right hemifield, whereas the nasal left retina and the temporal right retina are responsible for the left hemifield.
What is involved in a transcranial approach?
Sub frontal approach - under the frontal love
What is involved in a transsphenoidal approach?
Via nasal cavities and sphenoid sinus (involves the surgical fracture of the nasal septum, floor and roof of the sphenoid sinuses)
In which bone is the cribriform plate?
Ethmoid bone
In which bone is the conchae?
Ethmoid bone
**What are the 4 paranasal sinuses?
Frontal, maxillary, ethmoid and sphenoid
What lines the paranasal sinuses?
Mucous-secreting respiratory mucosa
What are the 3 possible functions of the sinuses?
1) Make mucous and drain it into the nasal cavities through ostia
2) Reduce the weight of the skull
3) Add resonance to the voice
What approach can be used to access the nasal cavities to provide better surgical access in more complicated cases?
Le Fort I down-fracture
What is the tentorium cerebelli?
A tough sheet of dura mater “tenting” over the cerebellum within the posterior cranial fossa but with a central gap to permit the brainstem to pass through)
What is the diaphragm sellae?
A tough sheet of dura mater forming a roof (diaphragm) over the pituitary fossa
What are the 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 sinuses surround the pituitary gland?
The cavernous and intercavernous sinuses
Where do the dual venous sinuses drain into the internal jugular veins?
The jugular foraminae in the floor of the posterior cranial fossa
Where do the lobes of the thyroid gland attach?
Lateral aspects of the thyroid and cricoid cartilages and to the trachea
What does the isthmus lie anterior to?
2nd and 3rd cartilages of the trachea
Where are the parathyroid glands found and how many are they?
The 4 parathyroid glands are found on the posterior surfaces of the thyroid gland’s lateral lobes
What is the pyramidal lobe?
A normal variant where there is a third thyroid lobe, most commonly on the left lateral lobe.
What is the embryological development of the thyroid gland?
As a midline epithelial proliferation at the junction between the anterior 2/3rds (oral/horizontal part) and the posterior 1/3rd (oropharyngeal/vertical part) of the tongue (foramen caecum in the adult). The gland then migrates inferiorly whilst remaining attached to the tongue via the thyroglossal duct. The gland reaches its final position in relation to the larynx/trachea in the 7th week of development
What can be found at any position in the migratory path of the thyroid gland?
Thyroglossal duct cysts or ectopic thyroid tissue
At what vertebral level is the thyroid gland, and within which fascia?
C7, deep to the platysma within the deep fascia of the neck
In what fascia compartment of the neck is the platysma found?
Superficial fascia
What is the nerve supply of the platysma?
The facial nerve (CN VII), as it is a muscle of facial expression
** What are the layers of the fascia compartments?
Superficial > Investing > Paravertebral (posteriorly) and Pretracheal (anteriorly) and carotid sheaths (anterolaterally)
What is contained in the paravertebral fascia?
the cervical vertebrae & the postural neck muscles
What is contained in the investing fascia?
Encloses all the other neck fascial compartments, including 2 pairs of muscles: trapezius and sternocleidomastoid
What is contained in the carotid sheaths?
The internal jugular veins the carotid arteries the vagus nerves the deep cervical lymph nodes
**What is contained in the pretracheal fascia?
- the strap muscles
- the thyroid gland
- the trachea
- the oesophagus
- the recurrent laryngeal nerves
Where is the retropharyngeal space and why is this clinically relevant?
Between the pretracheal & pre vertebral fascia, and can spread infection
What is the arterial supply to the thyroid gland?
superior (from the ext. carotid) and inferior thyroid artery (from the subclavian artery)
What is the venous drainage of the thyroid gland?
superior, middle and inferior thyroid veins (superior and middle from internal jugular, and inferior from brachiocephalic vein)
What nodes drain the thyroid gland?
Superior and inferior deep cervical nodes, pre tracheal node and paratracheal nodes
Where does the nodes of the neck drain to in the right side?
returned via the right lymphatic duct to the right venous angle
Where does the nodes of the neck drain to in the left side?
returned via the thoracic duct to the left venous angle
What somatic branches of the neck does the vagus nerve give rise to?
- Superior laryngeal nerve
* Right recurrent laryngeal nerve
What is the pathway of the vagus nerve up to the neck?
Connects with the medulla oblongata, passes through the jugular foramen before descending through the neck in the carotid sheath
What is the route of the right vagus from the neck through the chest?
- right lateral aspect of trachea
- posterior to the right lung root
- onto the oesophagus
What is the route of the left vagus from the neck through the chest?
- left side of the arch of aorta
- gives the left recurrent laryngeal nerve
- posterior to the left lung root
- onto the oesophagus
After the chest, what is the route of both vagus nerves?
- Both vagus nerves pass through the diaphragm with the oesophagus and divide into their terminal branches on the surface of the stomach
- Supply the abdominal organs with parasympathetic axons to the distal midgut
How can the external carotid a. be differentiated from the internal?
The external gives of branches, which the internal doesnt
**What is the difference between the routes of the right and left recurrent laryngeal nerves?
The left nerve loops under the aortic arch, and the right nerve looping under the right subclavian artery then traveling upwards
What are the 4 strap muscles?
Sternohyoid, sternothyroid, thyrohyoid and omohyoid (omo = shoulder)
**What is the surface anatomy of the neck?
The anterior and posterior triangles are separated by the SCM
Which muscle is found in both triangles?
Omohyoid
**What is a classical thyroidectomy incision?
A “collar” incision is made within a natural skin crease or in the direction of Langer’s lines. The incision should be just superior to the clavicles & jugular notch. The incision is made through skin & platysma
What does the right recurrent laryngeal nerve supply?
Somatic motor supply to most of the skeletal muscles that move the right vocal cord (the intrinsic muscles of the larynx)
What occurs with injury to the recurrent nerve, unilaterally and bilaterally?
Paralysis of the vocal cord. Unilateral injury causes “hoarseness” or weakness of the voice & a weak cough. Bilateral injury causes aphonia (inability to produce sound) & inability to close the rima glottidis to prevent aspiration or to produce a good cough
