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
Function of and consequences of damage to the oculomotor nerve in pituitary gland surgery
It supplies motor to muscles that move the eyeball (globe)
parasympathetic to the sphincter muscle of the iris
Damage to it problems with several eye movements and pupil dilation.
Function of and consequences of damage to the trochlear nerve in pituitary gland surgery
Motor to one muscle that moves the globe
Damage will cause problems with specific eye movements
Function of and consequences of damage to the trigeminal nerve in pituitary gland surgery
Sensory to most of the face
motor to the muscles of mastication
Damage will cause sensory symptoms on the face and difficulty chewing
Function of and consequences of damage to the abducent nerve in pituitary gland surgery
motor to one muscle that moves the globe
Damage will cause problems with specific eye movements
What is the thyroid gland closely related too? (in position)
The trachea and the larynx.
Structure of the thyroid gland
Two lateral lobes (right and left) connected by an isthmus.
Where does the thyroid gland attach?
To the lateral aspects of the thyroid and cricoid cartilage and the trachae.
Where on the trachae does the isthmus lie?
2nd or 3rd trachael cartilages.
Where would you expect to find the parathyroid glands?
Posterior surface of the lateral lobes. 2 on each side- one superior, one inferior.
Significance of a pyramidal lobe
Only 25-50% of the population have it. In embryological development the thyroid gland starts as epithelial proliferation on the tongue and moves down to the larynx. A pyramidal lobe will occur along this line of migration. It is usually from the left lateral lobe of the thyroid gland and attaches superiorly to the hyoid bone.
In embryological development, when will the gland reach its final position?
week 7
Muscle of facial expression
Left and right platysmal muscle (extends down towards the clavicle. If you make a sad face- this muscle contracts)
Describe the arrangement of deep fascia in the neck
Deep fascia is arranged in tubes. They span from the base of the skull to the thorax
Most superficial layer of deep fascia
Investing fascia
Investing fascia encloses
All other deep fascia in the neck.
2 pairs of muscles- trapezius and sternocleidomastoid.
2nd most deep deep fascia of the neck
Prevertebral fascia
Prevertebral fascia location and what it encloses
It is located posteriorly.
It encloses the cervical vertebrae and the postural muscles.
3rd most deep deep fascia of the neck
Pretrachael fascia
Position of pretrachael fascia and what it encloses
Position anteriorly in the neck Encloses the strap muscles The thyroid gland The trachea The oesophagus The recurrent laryngeal nerves.
Where is the retropharyngeal space?
Space between the pretrachael and prevertebral fascia.
Points of attachment of the sternomasticloid muscle
Superiorly to the mastoid process of the temporal bone.
Inferiorly- sternal head attaches to the manubrium of the sternum
Clavicular head attaches to the medial end of the clavicle.
Points of attachment of the trapezius muscle
superiorly to the occiputal bone
Inferiorly-
To the spine of the scapula and lateral end of the clavicle.
Which nerve supplies the sternomasticloid and trapezius muscle?
Spinal accessory nerve.
Where does the anterior jugular vein run in relation to the muscles in the neck?
Runs in the superficial fascia more anterior and medial to the sternomasticloid muscle.
Where does the external jugular vein run in relation to the muscles in the neck?
Runs in the superficial fascia superficial to the sternomasticloid muscle
Where does the anterior jugular vein drain too?
External jugular vein
Where does the external jugular vein drain too?
The subclavian vein.
Where do the carotid sheaths lie?
Deep to the investing fascia. Located anterior-laterally in the neck either side of the thyroid gland
Attachments of the carotid sheaths
Superiorly to the base of the skull, blend inferiorly with the mediastinal fascia.
What is enclosed within the carotid sheath?
The internal jugular vein
The common and internal carotid arteries
The vagus nerve
Deep cervical lymph nodes
What exits the carotid sheath within the neck
The external jugular vein.
Describe the blood supply to the inferior thyroid and parathyroid gland
The right inferior thyroid artery.
Where does the right inferior thyroid artery stem from?
Branch from the subclavian arteries.
What supplies the superior thyroid gland
superior thyroid artery.
Where does the superior thyroid artery branch from?
External carotid artery
Venous drainage of the thyroid artery
Superior, middle and inferior thyroid veins.
Where do the superior and middle thyroid veins drain back too?
Internal jugular vein
Where does the inferior thyroid vein drain too?
Brachiocephallic vein.
Lymph drainage of the thyroid and parathyroid glands
Superior aspect of each will drain to either L or R superior deep cervical nodes.
Inferior aspect of each will drain to either L or R inferior deep cervical nodes.
On the right these drain too the right venous angle. On the left they drain to the left venous angle via the thoracic duct.
Nervous supply to the thyroid gland
Essentially comes from the vagus nerve- descends through the neck via the carotid sheath and branches at the larynx in the neck to form the superior laryngeal nerve and the right recurrent laryngeal nerve. It then descends through the chest branching into R and L.
Left vagus nerve gives off the left recurrent laryngeal nerve by the arch of the aorta.
Which structure does the right recurrent laryngeal nerve loop around
Subclavian vein
Which structure does the left recurrent laryngeal nerve loop around?
The arch of the aorta.
4 strap muscles
Sternohyoid
Sternothyroid
Omohyoid
Thyrohyoid
Attachment of the sternohyoid
Superiorly- hyoid bone
Inferiorly- sternum
Attachment of sternothyroid
Superiorly- thyroid cartilage
Inferiorly- sternum
Attachments of omohyoid
Hyoid bone superiorly
Extends towards shoulder. Passes through fascial sling to change direction.
Attachments of thyrohyoid
Superiorly- hyoid bone
Inferiorly- thyroid cartilage.
What sort of incision is made to access the thyroid gland?
Collar incision.
