APPLIED ANATOMY | Part IV Flashcards
All of the following sacral anatomic landmarks are used to identify the proper location for caudal block EXCEPT:
A. Posterior superior iliac spines (PSISs)
B. Sacral ala
C. Sacral cornu
D. Sacral hiatus
B. Sacral ala
Caudal anesthesia involves the injection of local anesthetics into the caudal epidural
space, the lowest portion of the epidural system accessed through the sacral hiatus.
The sacral hiatus is a defect in the lower part of the posterior wall of the sacrum
formed by the failure of the laminae of S5 and/or S4 to meet and fuse in the midline and is bound by the sacral cornu (palpable on either side of the midline about 1 cm
apart).
The sacral hiatus can be located by drawing/visualizing an equilateral
triangle between the bilateral PSIS and sacral hiatus. Once the sacral hiatus is
identified, a short beveled needle is directed at about 45° to skin and inserted till a
pop is felt, as the sacrococcygeal ligament is pierced.
The needle is then carefully
directed in a cephalad direction at an angle approaching the long axis of the spinal
canal.
When performing a single-shot caudal block, you must first pierce through which ligament?
A. Sacrococcygeal
B. Sacrotuberous
C. Sacrospinous
D. Sacroiliac
A. Sacrococcygeal
Caudal anesthesia involves the injection of local anesthetics into the caudal
epidural space, the lowest portion of the epidural system accessed through the
sacral hiatus. The sacral hiatus is a defect in the lower part of the posterior wall of
the sacrum formed by the failure of the laminae of S5 and/or S4 to meet and fuse in
the midline and is bound by the sacral cornu (palpable on either side of the midline about 1 cm apart).
The sacral hiatus can be located by drawing/visualizing an equilateral triangle between the bilateral PSIS and sacral hiatus. Once the sacral hiatus is identified, a short beveled needle is directed at about 45° to skin and inserted till a pop is felt, as the sacrococcygeal ligament is pierced. The needle is then carefully directed in a cephalad direction at an angle approaching the long axis of the spinal canal.
Piercing this membrane during caudal block produces the “pop” sensation:
A. Sacrococcygeal
B. Sacrotuberous
C. Sacrospinous
D. Sacroiliac
A. Sacrococcygeal
Which of the following pathways carries fibers that control fine touch, vibration, proprioception, and pressure?
A. Dorsal column
B. Spinothalamic
C. Corticospinal
D. Reticulospinal
A. Dorsal column
The dorsal column tract represents an ascending spinal pathway that contains nerve bundles that communicate through a three-neuron system.
First-order neurons have sensory receptor endings and cell bodies in the dorsal root ganglion of the spinal nerve. They synapse with second-order neurons in the dorsal horn, which cross the spinal cord to the opposite side as they ascend to higher levels.
Third-order neurons
are located in the thalamus, which then project to sensory areas in the sensory
cortex. The dorsal column pathway carries fibers that control fine touch, vibration,
proprioception, and pressure.
The spinothalamic tract, an anterolateral system, carries fibers involved in pain
and temperature sensation. It is also an ascending spinal tract that contains nerve bundles that communicate through a three-neuron system.
The corticospinal tract is a
descending pathway that innervates skeletal muscles and muscle stretch receptors.
The reticulospinal tract is a descending pathway that influences voluntary movement and reflexes and is involved in the hypothalamic control of autonomic activity.
- Which of the following pathways carries fibers that are involved in pain and
temperature sensation?
A. Dorsal column
B. Spinothalamic
C. Corticospinal
D. Reticulospinal
B. Spinothalamic
The spinothalamic tract in an ascending spinal pathway carries fibers involved in
pain and temperature sensation. Axons from the periphery travel to the spinal cord
and ascend or descend one to two segments before synapsing at the dorsal root ganglion. Second-order fibers then cross over to the anterolateral portion of the contralateral spinal cord and travel to synapse with third-order neurons in the
thalamus.
From there, third-order neurons carry signals to the cortex.
The dorsal columnar tract represents an ascending spinal tract that carries fibers
that control fine touch, vibration, proprioception, and pressure. The corticospinal tract is a descending pathway, which innervates skeletal muscles and muscle stretch receptors.
The reticulospinal tract is a descending pathway that influences voluntary
movement and reflexes and is involved in the hypothalamic control of autonomic
activity.
What is the potential space between the arachnoid and pia mater?
A. Epidural
B. Subarachnoid
C. Subdural
D. Arachnoid
B. Subarachnoid
The subarachnoid cavity is the interval between the arachnoid and pia mater and
contains the subarachnoid fluid. The arachnoid space refers to the middle meninges.
The spinal dura mater is separated from the arachnoid by a potential cavity, the
subdural cavity. The two membranes are, in fact, in contact with each other, except
where they are separated by a minute quantity of fluid, which serves to moisten the surfaces.
The epidural space describes the space between the wall of the vertebral
canal and the dura and contains a venous plexus and loose areolar tissue.
What is the potential space between the dura and arachnoid mater?
A. Epidural
B. Subarachnoid
C. Subdural
D. Arachnoid
C. Subdural
The spinal dura mater is separated from the arachnoid by a potential cavity, the
subdural cavity. The two membranes are, in fact, in contact with each other, except
where they are separated by a minute quantity of fluid, which serves to moisten the surfaces.
Activation of which opioid receptor types can provide relief from opioid-induced
itching?
A. Mu
B. Delta
C. Sigma
D. Kappa
- Activation of spinal KAPPA receptors is
responsible for the antipruritic effect.
Four major opioid receptor types have been identified: mu (μ), kappa (κ), delta (δ),
and sigma (σ). All opioid receptors couple to G proteins; binding of an agonist to an
opioid receptor causes primarily inhibitory effects that decrease neuronal
excitability.
In the spinal cord, opioids inhibit the release of nociceptive and inflammatory mediators P from dorsal horn sensory neurons attenuating transmission
of painful stimuli (periphery to cortex). In the brainstem, opioids act on descending
inhibitory pathways to attenuate the transmission of painful stimuli.
During neuraxial blockade, the level of sympathetic blockade is generally how
far away from the sensory level?
A. 1-2 dermatomes above
B. 4-6 dermatomes above
C. 1-2 dermatomes below
D. 4-6 dermatomes below
E. 0 dermatome change
The sympathetic level is generally 1-2 dermatome levels higher than the sensory
level. This phenomenon is referred to as differential blockade and is seen in both
neuraxial and peripheral nerve blocks.
In general, sympathetic nerve fibers are
blocked by the lowest concentration of the local anesthetic, followed by sensory
fibers, and then by motor fibers. It is thought that this observation is due in part to nerve fiber diameter and degree of myelination, with smaller diameter and
unmyelinated fibers being more sensitive to the effects of the local anesthetic.
However, this is unlikely to be the sole explanation for the observation of
differential blockade, which is likely a multifactorial phenomenon. Sympathetic
blockade is usually 1-2 dermatomes above the sensory blockade, which is generally
1-3 levels beyond the motor blockade.
During neuraxial blockade, the level of sensory blockade, in general, is how
many dermatomes away from the level of motor blockade?
A. 0
B. 2
C. 4
D. 6
E. 8
B. 2
Cutaneous infiltration of a local anesthetic to block the intercostobrachial
nerve provides anesthesia to which dermatome(s)?
A. C7
B. C8
C. T1
D. T2
T2
The intercostobrachial nerve is a lateral cutaneous branch of the second intercostal
nerve that supplies sensation to the skin of the proximal arm, T2 dermatome.
It is unreliably blocked (often spared) during an axillary brachial plexus approach; to
ensure complete blockade, additional infiltration of local anesthesia can be added
superficially. This superficial block is often performed when tourniquet use is
planned.
Morgan & Mikhail’s Anesthesia
A 37 year old ASA 1 is scheduled for a surgical procedure involving the bladder. At what spinal level does pain conduction of the dome of bladder is:
A. T11 – L2
B. S2 – S4
C. L1 – L2
D. T10
A. T11 – L2
Which of the following findings best indicates complete resolution of spinal anesthesia?
(A) Ability to ambulate
(B) Ability to urinate
(C) Perianal pinprick sensation
(D) Pain at the surgical site
(E) Proprioception of the big toe
(B) Ability to urinate
An analgesic effect similar to the epidural administration of 2.5 mg of morphine could be achieved by which dose of intrathecal morphine?
A. 0.05 mg
B. 0.1 mg
C. 1 mg
D. 2 mg
B. 0.1 mg
The “snap” felt just before entering the epidural space represents passage
through which ligament?
A. Posterior longitudinal ligament
B. Ligamentum flavum
C. Supraspinous ligament
D. Interspinous ligament
B. Ligamentum flavum
which of the following is the correct order of anatomical structures encountered when using paramedian approach for lumbar spinal anesthesia
A) ligamentum flavum, dura, arachnoid matter
B) interspinous ligament, ligamentum flavum, dura, arachnoid matter
C) posterior longitudinal ligament, ligamentum flavum, dura, arachnoid matter
D) anterior longitudinal ligament, ligamentum flavum, dura, arachnoid matter
E) ligamentum flavum, dura, pia matter, arachnoid matter
A) ligamentum flavum, dura, arachnoid matter
Tingling of the 5th finger during spinal anesthesia is associated with anesthesia at
which of the dermatomes?
A) C4
B) C6
C) C8
D) T2
E) T4
C) C8
