1.
Which back muscle originates from the fascia of the back?
Correct Answer
B. Latissimus dorsi
Explanation
The latissimus dorsi muscle originates from the fascia of the lower back, which is a sheet of connective tissue that covers and supports the muscles. This large, flat muscle primarily helps in the movement of the shoulder joint, specifically aiding in actions like pulling and lifting. It extends across the lower half of the thoracic region, covers the lumbar area, and fans into the iliac crest. The latissimus dorsi is crucial for motions that involve pulling something toward the body or performing activities that require you to reach downwards or backward.
2.
How many layers make up the thoracolumbar fascia?
Correct Answer
C. 3
Explanation
The thoracolumbar fascia, a crucial structure in the lower back, is composed of three distinct layers. These layers are known as the anterior, middle, and posterior layers. Each layer has its specific role and contributes to the overall function and stability of the back and trunk. The fascia serves several functions, including enclosing muscles, transmitting muscular forces, and providing structural support that contributes to the mechanical stability of the lower back. This complex layering allows the thoracolumbar fascia to support movements and maintain posture efficiently.
3.
Which of the following is NOT a flat bone?
Correct Answer
B. Clavicle
Explanation
The clavicle, commonly known as the collarbone, is not classified as a flat bone. Unlike the scapula, sternum, and ribs, which are flat bones, the clavicle is considered a long bone. Flat bones typically consist of two thin layers of compact bone surrounding a layer of cancellous (spongy) bone, and they primarily provide protection and broad surfaces for muscle attachment. The clavicle, however, serves as a structural support that holds the arm away from the trunk and provides attachment points for muscles; it is more rod-like and curved, which is characteristic of long bones.
4.
Which of the following does the scapula NOT have three of?
Correct Answer
D. Processes
Explanation
The scapula, or shoulder blade, does not have three processes. It has two primary processes: the acromion and the coracoid process. The acromion extends laterally over the shoulder joint and serves as an attachment point for muscles of the upper limb, while the coracoid process provides attachment points for several muscles of the arm and chest. The scapula does have three fossae (the subscapular, supraspinous, and infraspinous fossae) and three angles (lateral, superior, and inferior), making it an exception in terms of the number of processes.
5.
Which muscle was likely NOT injured by an accidental gunshot that tore through the nuchal ligament during a community hunting expedition?
Correct Answer
E. Serratus posterior superior
Explanation
The serratus posterior superior muscle is likely not to have been injured in an incident where the nuchal ligament was torn by a gunshot. The nuchal ligament and the muscles primarily affected by its proximity, such as the trapezius, rhomboid minor, rhomboid major, and splenius, are all located in the upper back and neck area, directly associated with the nuchal ligament. The serratus posterior superior, however, is located more inferiorly on the back, not directly connected to the nuchal ligament, and primarily involved in rib movement and aiding respiration. Its position makes it less likely to be injured in a trauma affecting the nuchal ligament directly.
6.
Which ligament is the nuchal ligament an extension of?
Correct Answer
A. Supraspinous ligament
Explanation
The nuchal ligament is an extension of the supraspinous ligament. This ligament is found along the spine, running between the spinous processes from the sacrum to the seventh cervical vertebra. At the base of the neck, the supraspinous ligament extends and becomes known as the nuchal ligament. This continuation is particularly significant in humans, where it serves as a muscle attachment site that helps to support the head and facilitates various movements of the neck. The nuchal ligament plays a crucial role in maintaining posture and allowing head movements, which is especially important given the head's weight and mobility.
7.
Are dorsal primary rami larger than ventral primary rami?
Correct Answer
B. False
Explanation
The statement that dorsal primary rami are larger than ventral primary rami is false. In the nervous system, ventral primary rami are typically larger than dorsal primary rami. This is because ventral rami carry both motor and sensory fibers and contribute to the formation of larger nerve plexuses which innervate the limbs and body wall. In contrast, dorsal rami are generally smaller as they primarily innervate the muscles and skin of the back, handling more localized and less extensive regions than the ventral rami. This size difference reflects the broader distribution and function of the nerves derived from the ventral rami compared to those from the dorsal rami.
8.
Do dorsal primary rami supply the intrinsic back muscles?
Correct Answer
A. True
Explanation
The statement that dorsal primary rami supply the intrinsic back muscles is true. Dorsal primary rami, which are branches of the spinal nerves, innervate the intrinsic (deep) muscles of the back. These muscles include groups like the erector spinae and the transversospinales. The function of these muscles primarily revolves around the movement and stabilization of the spine. The dorsal rami not only supply these muscles but also provide sensory innervation to the skin overlying this region. This specific innervation pattern is crucial for both motor control and sensory feedback from the muscles and skin of the back.
9.
Which of the following is made up of both intrinsic and extrinsic muscles?
Correct Answer
B. Posterior Axio-appendicular muscles
Explanation
The posterior axio-appendicular muscles, which include groups like the trapezius and latissimus dorsi, are composed of both intrinsic and extrinsic muscles. Intrinsic muscles, such as those within the deep back, are primarily involved in movements and stabilization of the spine and trunk, directly attaching to the vertebrae. Extrinsic muscles, on the other hand, originate from the axial skeleton (vertebrae or ribs) and extend to the appendicular skeleton (limbs), aiding in larger movements and the connection between the trunk and the limbs. The posterior axio-appendicular group notably includes muscles that assist in controlling and moving the upper limb and supporting the shoulder, integrating both intrinsic deep postural control and extrinsic broader range motion functions.
10.
What is the innervation of the trapezius muscle?
Correct Answer
A. Spinal Accessory
Explanation
The trapezius muscle is innervated by the spinal accessory nerve (cranial nerve XI). This nerve is crucial for the function of the trapezius, which plays a key role in various movements of the shoulder and neck, including elevation, retraction, and rotation of the scapula. The spinal accessory nerve solely provides motor innervation to the trapezius, enabling these specific muscular actions that are vital for upper limb mobility and posture maintenance. This innervation is essential for the trapezius muscle's ability to perform its functions effectively, contributing to the overall dynamics of the upper back and neck.
11.
Which muscle is important for overhead abduction?
Correct Answer
B. Deltoid
Explanation
The deltoid muscle is crucial for overhead abduction, a movement that involves lifting the arm away from the body and overhead. This muscle is cap-like in shape and covers the shoulder joint. It consists of three segments: anterior, middle, and posterior. The middle segment, in particular, is key for the abduction of the arm once it is lifted beyond 15 degrees from the body. The deltoid muscle's ability to contract and lift the arm upward is essential for numerous daily activities and athletic motions, making it fundamental for shoulder mobility and function.
12.
Which muscle is associated with the superficial branch of the transverse cervical artery?
Correct Answer
A. Trapezius
Explanation
The trapezius muscle is associated with the superficial branch of the transverse cervical artery. This artery supplies blood to the superficial muscles of the neck and shoulder, including the trapezius. The trapezius muscle extends from the lower part of the skull and vertebral column across to the shoulder blade and clavicle. It plays a vital role in various shoulder and neck movements. The blood supply from the transverse cervical artery is crucial for the trapezius muscle's function and health, enabling it to perform tasks such as rotating, retracting, elevating, and depressing the scapula.
13.
Which muscle is considered the "swimming muscle"?
Correct Answer
D. Latissimus Dorsi
Explanation
The latissimus dorsi muscle is often referred to as the "swimming muscle" due to its crucial role in the movements required for swimming. This large, flat muscle spans the lower back and, through its connection to the shoulders, helps in the powerful pulling motions necessary for swimming strokes such as freestyle and butterfly. The latissimus dorsi is involved in the adduction, extension, and internal rotation of the shoulder joint, making it essential for generating the force needed to propel the body through water efficiently. This muscle's functionality enhances endurance and power in swimming, contributing significantly to a swimmer's ability to maintain speed and stamina in the water.
14.
Which of the following is not involved in the triangle of auscultation?
Correct Answer
D. Internal Oblique muscle
Explanation
The triangle of auscultation is an area on the back where lung sounds can be heard more clearly. It is bounded by the trapezius muscle, the latissimus dorsi muscle, and the scapula border. The internal oblique muscle is not involved in this triangle, as it is located on the anterior abdominal wall and not on the back.
15.
What is the clinical importance of the lumbar triangle?
Correct Answer
B. Hernias
Explanation
The lumbar triangle is clinically important because it is a common site for hernias to occur. Hernias are a condition where an organ or tissue pushes through a weak spot in the surrounding muscle or connective tissue. In the case of the lumbar triangle, hernias can occur due to the weakness of the posterior abdominal wall. This can lead to symptoms such as pain, swelling, and a bulge in the lower back or flank area. Therefore, understanding the clinical importance of the lumbar triangle is crucial for diagnosing and treating hernias in this region.
16.
Which muscle is a border for 2 important triangles?
Correct Answer
B. Latissimus Dorsi
Explanation
The latissimus dorsi muscle is a border for two important triangles: the posterior triangle and the quadrangular space. The posterior triangle is formed by the trapezius muscle superiorly, the clavicle anteriorly, and the latissimus dorsi muscle posteriorly. The quadrangular space is formed by the teres major muscle superiorly, the long head of the triceps brachii muscle inferiorly, the surgical neck of the humerus laterally, and the teres minor muscle medially, with the latissimus dorsi muscle forming its posterior border.
17.
Which muscle is innervated by the thoracodorsal nerve?
Correct Answer
B. Latissimus Dorsi
Explanation
The latissimus dorsi muscle is innervated by the thoracodorsal nerve. The thoracodorsal nerve arises from the brachial plexus and supplies motor innervation to the latissimus dorsi muscle. This muscle is responsible for various movements of the shoulder joint, including adduction, extension, and medial rotation.
18.
Which muscle is considered a "push-up muscle"?
Correct Answer
B. Deltoids
Explanation
The deltoids are considered key muscles for performing push-ups. This muscle group, located on the shoulder, plays a crucial role in pushing the body up from the ground. During a push-up, the deltoids work in conjunction with the pectoral muscles and the triceps to stabilize the shoulder and provide the necessary force to lift the body. The deltoids, specifically the anterior fibers, help to press the arms downward and forward, which is essential for the upward phase of a push-up. This movement highlights the deltoids' importance not only in shoulder mechanics but also in exercises that involve upper body strength and stability.
19.
Which muscle is innervated by the dorsal scapular nerve?
Correct Answer
C. Levator Scapulae
Explanation
The correct answer is Levator Scapulae. The levator scapulae muscle is innervated by the dorsal scapular nerve. This nerve originates from the brachial plexus and provides motor innervation to the levator scapulae muscle, which is responsible for elevating the scapula. The other muscles listed, such as the trapezius, latissimus dorsi, and serratus posterior superior, are not innervated by the dorsal scapular nerve.
20.
Which artery supplies the serratus posterior muscles?
Correct Answer
D. Intercostal arteries
Explanation
The intercostal arteries supply the serratus posterior muscles. These arteries run along the spaces between the ribs and provide blood to the muscles and tissues in this region. The superficial and deep branches of the transverse cervical artery do not specifically supply the serratus posterior muscles. The thoracodorsal artery supplies the latissimus dorsi muscle, not the serratus posterior muscles.
21.
Which muscles play an important role in inspiration?
Correct Answer
D. Serratus Posterior muscles
Explanation
The serratus posterior superior muscle plays a significant role in the process of inspiration. This muscle is located at the upper back, and it helps elevate the ribs during the deep inhalation process, thereby expanding the chest cavity and allowing more air to enter the lungs. It is one of the secondary muscles involved in respiration, assisting the primary muscles like the diaphragm and the intercostal muscles. By raising the ribs, the serratus posterior superior increases the volume of the thoracic cavity, which is essential for drawing air into the lungs effectively during forceful breathing.
22.
Which group does Splenius capitis belong to?
Correct Answer
A. Spinotransversalis
Explanation
Splenius capitis is a muscle that belongs to the Spinotransversalis group. This group of muscles is located in the back and includes muscles that run from the spinous processes of the vertebrae to the transverse processes of the vertebrae. Splenius capitis specifically arises from the lower half of the ligamentum nuchae, spinous processes of the vertebrae from C7 to T4, and inserts onto the mastoid process and lateral third of the superior nuchal line. Therefore, option A, Spinotransversalis, is the correct group to which Splenius capitis belongs. Thank you for bringing this to my attention.
23.
Which group does Iliocostalis belong to?
Correct Answer
B. Sacrospinalis
Explanation
Iliocostalis is a muscle that belongs to the Sacrospinalis group, also known as the erector spinae muscles. The erector spinae muscles are located in the back and play a significant role in extending and straightening the spine. The group includes three muscles: iliocostalis, longissimus, and spinalis. Iliocostalis specifically runs from the iliac crest and sacrum to the ribs and vertebrae.
24.
Which group does Longissimus belong to?
Correct Answer
B. Sacrospinalis
Explanation
Longissimus is a muscle that belongs to the Sacrospinalis group, also known as the erector spinae muscles. The erector spinae muscles are located in the back and play a significant role in extending and straightening the spine. The group includes three muscles: iliocostalis, longissimus, and spinalis. Longissimus specifically runs from the pelvis to the vertebrae and ribs.
25.
Which group does Spinalis belong to?
Correct Answer
B. Sacrospinalis
Explanation
Spinalis is a muscle that belongs to the Sacrospinalis group, also known as the erector spinae muscles. The erector spinae muscles are located in the back and play a significant role in extending and straightening the spine. The group includes three muscles: iliocostalis, longissimus, and spinalis. Spinalis specifically runs from the pelvis to the vertebrae and ribs.
26.
Which group do the Semispinalis muscles belong to?
Correct Answer
C. Transversospinalis
Explanation
The Semispinalis muscles belong to the Transversospinalis group. This group of muscles is located in the back and runs obliquely from the transverse processes of the vertebrae to the spinous processes of the vertebrae above. The Semispinalis muscles specifically help with extension, lateral flexion, and rotation of the spine.
27.
Which group does the Rotatores belong to?
Correct Answer
C. Transversospinalis
Explanation
The Rotatores muscles belong to the Transversospinalis group. This group of muscles is located in the back and runs obliquely from the transverse processes of the vertebrae to the spinous processes of the vertebrae above. The Rotatores muscles specifically assist in rotation and stabilization of the spine.
28.
Which group does Multifidus belong to?
Correct Answer
C. Transversospinalis
Explanation
Multifidus belongs to the group Transversospinalis. This group consists of a set of deep muscles located in the back that run along the spine. Multifidus specifically plays a role in stabilizing and supporting the spine, helping to maintain proper posture and movement.
29.
Where does multifidus attach?
Correct Answer
D. Mammilary process
Explanation
The multifidus muscle attaches to the mammillary process. The mammillary process is a small bony projection on the posterior aspect of each of the lumbar vertebrae. The multifidus muscle is a deep muscle of the back that helps stabilize and extend the spine. By attaching to the mammillary process, the multifidus muscle contributes to the overall stability and movement of the lumbar spine.
30.
Which group does interspinalis belong to?
Correct Answer
D. Kinesiology monitor
Explanation
The Interspinalis muscles are thin, intersegmental muscles located between adjacent spinous processes of the vertebrae. They play a role in proprioception and kinesiology, providing feedback about the movement and position of the spine.
31.
Which group does intertransversarii belong to?
Correct Answer
D. Kinesiology monitors
Explanation
The intertransversarii muscles belong to the Kinesiology monitors group. These muscles are thin and located between the transverse processes of adjacent vertebrae. They play a role in proprioception and kinesiology, providing feedback about the movement and position of the spine.
32.
Which group does levator costae belong to?
Correct Answer
D. Kinesiology monitors
Explanation
The levator costae muscles actually belong to the Kinesiology monitors group. These muscles are thin and located between the transverse processes of the vertebrae, providing feedback about the movement and position of the spine.
33.
A stab wound in the back during a gang war left a first year undergraduate with inability to raise his arms above his shoulder, what nerve(s) have been damaged?
Correct Answer
C. Spinal accessory and long thoracic
Explanation
The spinal accessory nerve and the long thoracic nerve have been damaged. The spinal accessory nerve controls the movement of the trapezius muscle, which is responsible for raising the arms above the shoulder. The long thoracic nerve innervates the serratus anterior muscle, which also assists in raising the arms. Therefore, damage to both of these nerves would result in the inability to raise the arms above the shoulder.
34.
A pilot who lost the function of his parachute was lucky to come on with only a fall on his back with crush injury of some muscles of the back and dorsal primary rami: Which of those injured muscles are innervated by these nerves
Correct Answer
E. All of the above
Explanation
All of the muscles mentioned (Splenius, Iliocostalis, Semispinalis, Levator costae) are innervated by the dorsal primary rami of the spinal nerves. The dorsal primary rami are responsible for supplying the deep muscles of the back, including these muscles. Therefore, it is likely that all of these muscles would be affected by the crush injury, as they are innervated by the same nerves.
35.
Which nerve supplies the sub occipital region?
Correct Answer
B. Sub-occipital nerve
Explanation
The sub-occipital region is supplied by the sub-occipital nerve. This nerve is responsible for innervating the muscles located at the base of the skull, including the rectus capitis posterior major, rectus capitis posterior minor, and obliquus capitis superior muscles. It plays a role in controlling head movements and providing sensory information from this region. The other options mentioned, such as the ventral primary rami, spinal accessory, and dorsal scapular nerve, are not specifically associated with the sub-occipital region.
36.
Which is NOT involved in the suboccipital triangle?
Correct Answer
B. Rectus Capitus Posterior Minor
Explanation
The suboccipital triangle is a small region located at the base of the skull, formed by the rectus capitus posterior major, obliquus capitus superior, and obliquus capitus inferior muscles. These muscles play a role in the movement and stabilization of the head and neck. The rectus capitus posterior minor, however, is not involved in the suboccipital triangle. It is a small muscle located deep to the rectus capitus posterior major and has a different function, namely assisting in the rotation and extension of the head.
37.
Which muscle does NOT attach to the atlas?
Correct Answer
D. Rotatores
Explanation
The atlas (C1) is the first cervical vertebra of the spine and is involved in the nodding and rotation movements of the head. The muscles Rectus Capitis Posterior Major, Rectus Capitis Posterior Minor, and Obliquus Capitis Inferior all attach to the atlas and are involved in head and neck movements. Rotatores, on the other hand, are a group of small muscles located along the vertebral column, but they do not attach to the atlas; they primarily stabilize and rotate the vertebrae in the thoracic region.
38.
Jefferson Fracture would affect which muscle?
Correct Answer
A. Obliquus capitis Inferior
Explanation
The Rotatores muscles, which are part of the deeper layer of intrinsic back muscles, do not attach to the atlas (C1 vertebra). These small muscles primarily span from one vertebra to another over one or two segments throughout the thoracic spine, contributing to spinal rotation and stability. In contrast, the muscles listed such as Rectus Capitis Posterior Major, Rectus Capitis Posterior Minor, and Obliquus Capitis Inferior are specifically part of the suboccipital group that connects directly with the atlas and axis to facilitate head movements. Thus, Rotatores, being more associated with thoracic movements and stabilization, do not connect to the atlas.
39.
In a motor accident where a young man's axis was crushed, which muscle of the suboccipital region was spared?
Correct Answer
D. Semispinalis Cervicis
Explanation
The Semispinalis Cervicis muscle, which is part of the deeper layer of the intrinsic back muscles and not classified among the suboccipital muscles, would likely be spared in an injury primarily involving the axis (C2 vertebra). The suboccipital muscles specifically include the Rectus Capitis Posterior Major, Rectus Capitis Posterior Minor, and the Obliquus Capitis Superior and Inferior. These muscles are intimately associated with the occipital bone and the upper cervical vertebrae (C1 and C2) and directly facilitate head movements at the atlanto-occipital and atlanto-axial joints. Since the semispinalis cervicis extends more inferiorly beyond these levels, it is not primarily localized in the suboccipital region, thus likely spared in an injury focused at the axis.
40.
Where should a spinal tap be performed?
Correct Answer
C. L3/L4
Explanation
A spinal tap, also known as a lumbar puncture, is a medical procedure in which a needle is inserted into the lower back to collect cerebrospinal fluid (CSF) for diagnostic purposes. The procedure is typically performed between the L3 and L4 vertebrae, as this location provides the best access to the CSF without the risk of damaging the spinal cord. The L3/L4 level also allows for easier identification of the spinal landmarks, ensuring accurate placement of the needle. Therefore, L3/L4 is the appropriate location for performing a spinal tap.
41.
In a caudal epidural anesthesia the needle is inserted into which one of the following spaces of the vertebral structure?
Correct Answer
A. Epidural
Explanation
In a caudal epidural anesthesia, the needle is inserted into the epidural space of the vertebral structure. The epidural space is located outside the dura mater and contains fat, blood vessels, and connective tissue. By injecting medication into the epidural space, anesthesia can be achieved in the lower part of the body, such as the pelvic region and lower limbs. This technique is commonly used during childbirth or for surgical procedures in the lower abdomen or legs.
42.
Which layer is NOT pierced in epidural anesthesia?
Correct Answer
D. All of the above
Explanation
In epidural anesthesia, none of the layers listed — pia mater, arachnoid mater, or dura mater — are pierced. Epidural anesthesia involves the injection of an anesthetic just outside the dural mater, in the epidural space, which lies outside these three meningeal layers that encase the spinal cord. The purpose of epidural anesthesia is to block pain in a particular region of the body, typically during childbirth or surgeries. By injecting the anesthetic into the epidural space, healthcare providers can effectively numb the area without directly affecting the spinal cord or its surrounding meninges, ensuring targeted pain relief while maintaining safety.
43.
What are common causes of low back pain?
Correct Answer
F. All of the above
Explanation
Low back pain can result from various factors, each represented by the options listed. Spondylolysis refers to a defect or stress fracture in the pars interarticularis of the vertebral arch, commonly affecting athletes in sports requiring repetitive back extension. Spasms in the erector spinae muscles can occur due to overuse or improper use, leading to significant discomfort. Poor weight lifting technique often leads to strain and injury by imposing undue stress on the lower back. Disc prolapse involves the bulging or rupture of an intervertebral disc, which can press on nerves. Osteoarthritis, the wear and tear of the joints, also commonly affects the spinal joints, contributing to back pain. Each of these conditions can independently or collectively be a source of low back pain, making them all correct answers to the question about common causes.
44.
A congenital anomaly made it impossible for a young boy to adduct his scapula, which nerve pair is involved?
Correct Answer
C. Thoracodorsal nerve
Explanation
The thoracodorsal nerve is involved in the congenital anomaly that prevents the young boy from adducting his scapula. The thoracodorsal nerve innervates the latissimus dorsi muscle, which is responsible for adducting the scapula. Therefore, if there is an issue with the thoracodorsal nerve, it would result in the inability to adduct the scapula.
45.
Which back muscles are likely to be involved in multiple fractures of the upper cervical transverse processes?
Correct Answer
B. Rectus capitis posterior muscles
Explanation
Multiple fractures involving the upper cervical transverse processes are likely to involve the rectus capitis posterior muscles. These muscles, including the rectus capitis posterior minor and major, are located directly at the back of the neck, attached closely to the cervical vertebrae. They play a crucial role in extending and rotating the head at the neck. Due to their proximity and attachment to the cervical transverse processes, any fractures in this area can directly impact these muscles, affecting their function and potentially leading to significant pain, reduced mobility, and the need for targeted treatment and rehabilitation.
46.
Which site is common for dislocation in the vertebral column?
Correct Answer
B. C5/6
Explanation
The C5/6 level in the cervical spine is a common site for dislocation. This area of the spinal column is particularly vulnerable due to its location and the high degree of mobility it allows for neck movement. Dislocations at C5/6 often occur due to traumatic injuries, such as those from motor vehicle accidents, falls, or sports-related impacts. The nature of these injuries can lead to significant damage to the spinal cord because this region of the spine is densely packed with nerves that control body functions below the neck. Prompt and careful management is crucial to prevent permanent neurological damage.
47.
Are spinal taps safe for infants?
Correct Answer
A. True
Explanation
The statement that spinal taps are not safe for infants is false. Spinal taps, also known as lumbar punctures, are indeed safe for infants when performed by a skilled practitioner. This procedure involves inserting a needle into the lower part of the spinal canal to collect cerebrospinal fluid (CSF) for diagnostic purposes, such as checking for infections like meningitis. In infants, especially newborns, this procedure can be critical for diagnosing serious conditions. The technique and precautions taken ensure it is safely performed, considering the anatomical and physiological considerations unique to infants.
48.
In administering caudal epidural anesthesia, which anatomical space is utilized?
Correct Answer
D. Sacral Hiatus
Explanation
When delivering caudal epidural anesthesia, the sacral hiatus is the key anatomical space utilized. The sacral hiatus is an opening at the lower end of the sacral canal in the dorsal surface of the sacrum. It provides an accessible entry point for injecting anesthetics into the epidural space at the caudal end of the spinal column. This approach is often used for procedures involving the lower body, such as surgeries of the perineum or for pain relief in childbirth. The sacral hiatus's accessibility makes it a strategic point for effectively delivering anesthesia to the lower spinal nerves.
49.
Where does the spinal cord end?
Correct Answer
D. L1
Explanation
The spinal cord typically ends at the level of the first lumbar vertebra (L1), though this can slightly vary among individuals. At this point, the spinal cord tapers off into a region known as the conus medullaris. Below this level, the nerve roots that branch off the lower end of the spinal cord continue downward through the vertebral canal to form the cauda equina, resembling a horse's tail. The termination of the spinal cord at L1 is crucial for surgical and clinical considerations, as procedures involving the spine below this level are less likely to damage the spinal cord itself.
50.
Which muscle balances the forces that stabilize the vertebral column?
Correct Answer
D. Transversus abdominis
Explanation
The transversus abdominis muscle plays a critical role in stabilizing the vertebral column. This muscle forms the deepest layer of the abdominal muscles and wraps around the torso, functioning much like a corset. By contracting, it compresses the abdominal cavity, increases intra-abdominal pressure, and stabilizes the core, which in turn supports the vertebral column. This stabilization is crucial for maintaining proper posture and preventing lower back injuries. It also helps in evenly distributing forces through the pelvic and lower back regions, assisting in efficient movement and protecting the spine during physical activities that involve lifting, bending, or twisting.