Podcast
Questions and Answers
Which spinal nerves contribute to the formation of the phrenic nerve?
Which spinal nerves contribute to the formation of the phrenic nerve?
- C3-C5 (correct)
- C5-T1
- C1-C5
- C1-C3
What is the function of the lesser occipital nerve?
What is the function of the lesser occipital nerve?
- Innervates peripherally the medial aspect of the upper third of the ear (correct)
- Innervates the posterior neck muscles
- Transmits sensory information from the skin of the neck
- Supplies the medial aspect of the upper third of the ear
Which of the following pairs of plexuses receive contributions from the same spinal nerve roots?
Which of the following pairs of plexuses receive contributions from the same spinal nerve roots?
- Cervical and lumbar
- Lumbar and sacral
- Cervical and brachial (correct)
- Brachial and sacral
What is the role of the ansa cervicalis within the cervical plexus?
What is the role of the ansa cervicalis within the cervical plexus?
Which nerve located in the cervical plexus innervates the skin around the shoulder?
Which nerve located in the cervical plexus innervates the skin around the shoulder?
Which characteristic of the diaphragm's innervation is significant when considering spinal cord injuries?
Which characteristic of the diaphragm's innervation is significant when considering spinal cord injuries?
Where do the fibers of the greater auricular nerve originate from?
Where do the fibers of the greater auricular nerve originate from?
The cervical plexus provides sensory innervation to which of the following areas?
The cervical plexus provides sensory innervation to which of the following areas?
Which plexus is responsible for the innervation of the diaphragm?
Which plexus is responsible for the innervation of the diaphragm?
What is the primary condition associated with cancers of the upper part of the lung?
What is the primary condition associated with cancers of the upper part of the lung?
Which type of lung cancer is most commonly associated with Pancoast tumors?
Which type of lung cancer is most commonly associated with Pancoast tumors?
In cases of myocardial infarction, pain may radiate to which part of the body?
In cases of myocardial infarction, pain may radiate to which part of the body?
What anatomical structures are likely irritated in Pancoast syndrome?
What anatomical structures are likely irritated in Pancoast syndrome?
The brachial plexus can be affected by irritation from which type of tumor?
The brachial plexus can be affected by irritation from which type of tumor?
Intercostobrachial neuralgia may result from which of the following?
Intercostobrachial neuralgia may result from which of the following?
Which nerve system can provide pain referral to the upper arm during upper thoracic issues?
Which nerve system can provide pain referral to the upper arm during upper thoracic issues?
Pancoast tumors were more commonly diagnosed in the past due to what factor?
Pancoast tumors were more commonly diagnosed in the past due to what factor?
Which symptom can indicate a problem with heart pathologies, particularly myocardial infarctions?
Which symptom can indicate a problem with heart pathologies, particularly myocardial infarctions?
Which term refers to the exchange of nerve fibers between branches of the brachial plexus and intercostal nerves?
Which term refers to the exchange of nerve fibers between branches of the brachial plexus and intercostal nerves?
What forms the medial cord of the brachial plexus?
What forms the medial cord of the brachial plexus?
Which of the following nerves is NOT a direct branch from the medial cord?
Which of the following nerves is NOT a direct branch from the medial cord?
Which structure is formed by the merging of all posterior divisions?
Which structure is formed by the merging of all posterior divisions?
Which ventral rami contribute to the formation of the superior trunk?
Which ventral rami contribute to the formation of the superior trunk?
What is the primary function of the brachial plexus?
What is the primary function of the brachial plexus?
Which of the following is a nerve that originates from the posterior cord?
Which of the following is a nerve that originates from the posterior cord?
Which statement is true regarding the lateral cord?
Which statement is true regarding the lateral cord?
The branches of the brachial plexus traverse which anatomical structure?
The branches of the brachial plexus traverse which anatomical structure?
What type of nerves arise from the trunks of the brachial plexus?
What type of nerves arise from the trunks of the brachial plexus?
Which nerve emerges from the medial cord besides the ulnar nerve?
Which nerve emerges from the medial cord besides the ulnar nerve?
Which spinal nerve segments form intercostal nerves?
Which spinal nerve segments form intercostal nerves?
What is the main function of plexuses formed by spinal nerve branches?
What is the main function of plexuses formed by spinal nerve branches?
Which area of the body is NOT innervated by the ventral branches of spinal nerves?
Which area of the body is NOT innervated by the ventral branches of spinal nerves?
What is true about the intercostal nerves and the ribs?
What is true about the intercostal nerves and the ribs?
What branches from the intercostal nerve innervate the skin overlying the rib?
What branches from the intercostal nerve innervate the skin overlying the rib?
In which regions are the spinal nerve plexuses specifically located?
In which regions are the spinal nerve plexuses specifically located?
What happens when spinal nerves mix in a plexus?
What happens when spinal nerves mix in a plexus?
What role does the dorsal ramus play in spinal nerve function?
What role does the dorsal ramus play in spinal nerve function?
What is the primary consequence of a single spinal segment damage?
What is the primary consequence of a single spinal segment damage?
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Study Notes
Nerve Plexuses Overview
- Ventral branches of spinal nerves form plexuses, except for T2-T12.
- Plexuses are found in cervical, brachial, and lumbosacral regions.
- Each muscle typically innervated by multiple spinal nerves to prevent complete paralysis from segment damage.
Innervation of Specific Regions
- Back: Innervated by dorsal branches of spinal nerves.
- Thorax: Ventral branches from T1-T12 form intercostal nerves, located between ribs, supplying rib muscles, anterolateral chest, and abdominal wall.
Cervical Plexus
- Formed by spinal nerves C1-C5, with fibers mixing shortly after origin.
- Contains ansa cervicalis, which is adjacent to the hypoglossal nerve (XII).
- Provides sensory and motor innervation to neck, shoulder, and diaphragm (phrenic nerve).
Peripheral Branches of the Cervical Plexus
- Lesser Occipital Nerve: From C2, innervates skin of the upper ear.
- Greater Auricular Nerve: Behind sternocleidomastoid (SCM), innervates parotid and mastoid area skin.
- Transverse Cutaneous Nerve: Sensory innervation from the anterolateral neck’s skin.
- Supraclavicular Nerves: Supply skin around the shoulder area.
Brachial Plexus
- Originates from spinal nerves C5-T1; some contributions from C4.
- Comprised of three trunks:
- Upper trunk (C5-C6)
- Middle trunk (C7)
- Lower trunk (C8-T1)
- Trunks split into anterior and posterior divisions leading to three cords:
- Posterior cord: merges all posterior divisions.
- Lateral cord: anterior divisions of upper and middle trunks.
- Medial cord: anterior division of lower trunk.
Terminal Nerves of the Brachial Plexus
- Lateral Cord: Musculocutaneous and lateral root of the median nerve.
- Medial Cord: Ulnar nerve and roots of the median nerve.
- Posterior Cord: Axillary and radial nerves.
Lumbosacral Plexus
- Formed by spinal nerves L1-S4.
- Lumbar plexus (L1-L4) and sacral plexus (L4-S4) provide innervation to lower limbs.
Clinical Relevance
- Brachial plexus proximity to major arteries emphasizes surgical significance.
- Pancoast syndrome can occur due to lung tumors affecting plexus structures.
- Intercostobrachial nerves can relate to surgeries or trauma, leading to associated pain.
Additional Notes
- Cervical plexus contributes fibers to the brachial plexus.
- Diaphragm innervation mainly from phrenic nerve (C3-C5), lesions above C3 can affect respiration.
- Burnt-out luminal -- branches of intercostal nerves may lead to referred thoracic pain during heart pathology, especially left-side injuries.
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