cricopharyngeus muscle receives sensory innervation primarily from the:
cricopharyngeus muscle, an integral part of the upper esophageal sphincter,
receives sensory innervation primarily from the glossopharyngeal nerve (CN IX).
It receives motor innervation primarily from the vagus (CN X) and to a lesser
extent from CN IX. It acts as a barrier to regurgitation in the conscious patient.
Arterial blood supply to the larynx arises from the
uperior and inferior thyroid arteries
The superior thyroid artery, a branch of the external
carotid, gives rise to the superior laryngeal artery. This artery supplies the
supraglottic region of the larynx. The inferior laryngeal artery, a branch
of the inferior thyroid artery, supplies the infraglottic region of the larynx.
The ansa cervicalis innervates the
The ansa cervicalis, a component of the cervical plexus, provides motor innervation
to the sternohyoid and the inferior belly of the omohyoid muscles.
Chassaignac's tubercle may be palpated at
the cricoid cartilage at C6
Chassaignac's tubercle is an anatomic landmark for the placement of interscalene
and cervical plexus blocks. It is the transverse process of the verterbal body at C6 and may be palpated lateral to the cricoid cartilage.
Cerebrospinal fluid flows from the third to the
fourth ventricle via the:
cerebral aqueduct of Sylvius
CSF is secreted by the choroid plexus in lateral ventricles 1 and 2, flows through the
foramen of Munro to the 3rd ventricle, through aqueduct of Sylvius (A.K.A. cerebral aqueduct) to 4th ventricle
and through the foramina of Magendie and Luschka (A.K.A. lateral and medial apertures of 4th ventricle) to
the subarachnoid space.
Organs designated as preportal organs include the
stomach, small intestines, pancreas and spleen
The preportal organs are the stomach, spleen, pancreas, small intestine, and colon.
Motor innervation of the superior oblique muscle of the
eye is supplied by the
Although the majority of extraocular muscles receive motor innervation
from the oculomotor nerve (CN III), the trochlear nerve (CN IV) provides motor innervation to
the superior oblique muscle of the eye. The abducens (CN VI) provides motor innervation to the
lateral rectus muscle of the eye.
Of the following, the therapeutic intervention that causes the
least ventilatory compromise in the prone patient is the:
use of a Jackson table
The degree to which pulmonary mechanics are altered are suggested
to be frame-dependent and not dependent on body habitus. Use of the Jackson table resulted
in the smallest change in pulmonary compliance and peak airway pressures when compared with
use of the Wilson frame and chest rolls.
Components that comprise the thin filament of the contractile
actin, troponin, tropomyosin
The sinus which is in close proximity to the optic
chiasma and the hypophysis is the:
The sphenoid sinuses are paired and may extend into
the basal part of the occipital bone. The roof of the sinus has close connections
with the optic canal and the chiasmatic groove (upward) as well as to the hypophysis
toward the back. Pituitary tumor surgery may be achieved via a trans-nasal approach
through the sphenoid sinus. Overall, the paranasal sinuses play an important role
as the site of infectious processes.
The parietal cells of the stomach are responsible for the secretion of:
:hydrochloric acid Parietal cells in the stomach secrete hydrochloric acid in response to the sight and smell of food; pepsinogen is also secreted by the chief cells at this time. Gastrin is secreted by the G cells in response to gastric distention. Other gastric secretions include serotonin, histamine and mucus. Secretin and pancreatic bicarbonate are released in response to duodenal acidity.
functions of the spleen
Functions of the spleen include: hematopoiesis in the fetus,
blood filtering by splenic sinusoids, removal of foreign antigens by macrophages,
IgM production, and removal of aged RBCs and abnormal blood cells. The spleen has
a minor role as a reservoir of platelets but has no specific reservoir function
the portal triad consists of the:
hepatic artery, portal vein, bile duct
In the cardiac myocyte, the area which delineates the
border between two separate sarcomeres is known as the
The "Z" band, named from the German zuckung (twitch) line,
bisects each "I" band of the sarcomere. The "I" band represents the region of the
sarcomere which contains thin filaments only while the "A" band is characterized
by an area of overlap of thick and thin fibers. The "M" band is present centrally
within the "A" band and is composed of thick filaments which form a hexagonal
matrix of myosin binding with protein C.
The pneumotaxic center:
The pneumotaxic respiratory center is in the rostral pons.
Its primary function is to limit the depth of inspiration When maximally activated,
the pneumotaxic center increases ventilatory frequency; however, it performs no
pacemaking function and has no intrinsic rhythmicity.
When performing a glossopharyngeal nerve block, the branches
of the nerve are most easily accessed via
The glossopharyngeal nerve provides sensory innervation
to the following areas: posterior third of the tongue, the vallecula,the anterior
surface of the epiglottis, the walls of the pharynx, and the tonsils. When
performing a glossopharyngeal nerve block, the nerves are most easily accessed
as they traverse the palatoglossal folds, the soft ridges that extend from the
posterior aspect of the soft palate to the base of the tongue bilaterally.
Primary branches of the trigeminal nerve (CN V) include the
During the division of the tracheobroncheal
tree, loss of cartilage occurs at approximately the:
Subdivisions, A.K.A. airway generations, are utilized to classify branching of the tracheobronchial tree. The trachea comprises 0 generation and the airways further divide until the alveolar sacs and alveoli are reached terminally at the 23rd generation. The airways begin to lose cartilage just distal to the small intrasegmental bronchi. This occurs at approximately the 16th airway generation.
Sensory innervation of the larynx below the level of the vocal cords is provided by the:
recurrent laryngeal nerve
The larynx receives innervation from two major nerves.
The superior laryngeal nerve branches into two nerves: the internal branch which
provides sensory innervation to the larynx above the vocal cords and the external
branch which provides motor innervation to the cricothyroid muscle. The recurrent
laryngeal nerve provides sensory innervation to the larynx below the vocal cords
and motor innervation to all of the muscles of the larynx with the exception of
the cricothyroid muscle.
dead space equation
Dead space can be estimated using the Bohr
VD/VT = (PACO2
Causes of increased peak inspiratory pressure
and unchanged plateau pressure include
I:E ratio, increased
airway resistance, bronchospasm, kinked endotracheal tube, secretions and
foreign body aspiration.
β-2 stimulation results in
Sympathetic activity mediates
bronchodilation and decreased secretions via the β-2 receptors. α-1 receptors stimulation
also decrease secretions, but may cause bronchospasm.
Arterial oxygen tension can be approximated
by the formula:
Arterial oxygen tension can be approximated
by the formula:
PaO2 = 102 - (Age/3)
Most airway resistance comes from
medium-sized bronchi (before the 7th generation)
Normal total airway resistance is
about 0.5 - 2 cm H2O/L/s, with the largest
contribution coming from medium-sized bronchi (before the
Stimulation of vagal afferents and
efferents of the bronchi is associated with
Vagal afferents in the bronchi are sensitive to histamine and multiple noxious stimuli. Vagal activation results in bronchoconstriction, which is mediated by an increase in cGMP.
Laminar flow in the airways is found
in bronchioles < 1 mm in diameter
Laminar flow normally occurs only
distal to small bronchioles (< 1 mm). Flow in larger airways is probably turbulent.
β2-adrenergic agonists produce bronchodilation
increasing intracellular cAMP
Activation of β2-adrenergic receptors on bronchiolar smooth muscle activated adenylate cyclase, which results in the formation of intracellular cAMP.
Capnographic evidence of bronchospasm includes:
increased slope of phase III
In the normal capnogram, phase III is nearly
flat with a slope approaching zero. With obstruction, the slope of
phase III increases.
The dichotomous division of the tracheobronchial tree is estimated to involve
Dichotomous division, starting with the trachea
and ending in alveolar sacs, is estimated to involve 23 divisions. Gas
exchange can occur only across the flat epithelium, which begins to
appear on pulmonary bronchioles (generations 17 - 19).
and also decreases secretions via β2 receptors. α1-adrenergic
receptor stimulation decreases secretions, but may cause bronchospasm.
Dead space ends and gas exchange begins at the
Gas exchange can occur only across the flat
epithelium, which begins to appear on the respiratory bronchiole
(generations 17 - 19).
Sympathetic innervation of the lung
Sympathetic innervation to the lung
originates at T1 - T4. Sensory and parasympathetic innervation
of the lung is provided by the vagus nerves.
In the adult, carbon dioxide stores are
Methylxanthines produce bronchodilation
Traditionally, methylxanthines are
thought to produce bronchodilation by inhibiting phosphodiesterase, but their effects appear to be much more complex. Additional pulmonary effects include increased catecholamine release, histamine blockade and diaphragmatic stimulation.
The inhibition of ventilation, preventing
over-inflation of the lung, is controlled by the:
Two pontine areas influence the dorsal
(inspiratory) medullary center. A lower pontine (apneustic)
center is excitatory, whereas an upper pontine (pneumotaxic)
center is inhibitory.
Prior to pneumonectomy, preoperative laboratory criteria necessitating split lung function testing includes
Split lung function testing is indicated if pneumonectomy is
contemplated in a patient not meeting any of the following criteria: