Podcast
Questions and Answers
What is the primary functional purpose of the brachial plexus's plexiform arrangement?
What is the primary functional purpose of the brachial plexus's plexiform arrangement?
- To increase the speed of nerve signal transmission to the muscles of the upper limb.
- To protect the nerves from injury by distributing them across a wide area.
- To allow neurons from multiple spinal cord segments to be distributed to the periphery via a single nerve. (correct)
- To ensure each muscle in the upper limb receives innervation from a single spinal nerve root for precise control.
Which spinal nerve rami form the roots of the brachial plexus?
Which spinal nerve rami form the roots of the brachial plexus?
- Ventral rami of C5 to T1 (correct)
- Dorsal rami of C5 to T1
- Ventral rami of C4 to T2
- Dorsal rami of C4 to T2
In the formation of the brachial plexus, which roots unite to form the superior trunk?
In the formation of the brachial plexus, which roots unite to form the superior trunk?
- C7 and C8
- C5 and C6 (correct)
- C8 and T1
- C6 and C7
Which anatomical structure serves as the primary reference point for naming the cords of the brachial plexus?
Which anatomical structure serves as the primary reference point for naming the cords of the brachial plexus?
What is formed by the posterior divisions of all three trunks of the brachial plexus?
What is formed by the posterior divisions of all three trunks of the brachial plexus?
Which muscles do the dorsal rami innervate?
Which muscles do the dorsal rami innervate?
What is a dermatome?
What is a dermatome?
Which nerve roots combine to form the inferior trunk of the brachial plexus?
Which nerve roots combine to form the inferior trunk of the brachial plexus?
Where do the roots of the brachial plexus lie anatomically?
Where do the roots of the brachial plexus lie anatomically?
What type of muscles are primarily supplied by the posterior cord of the brachial plexus?
What type of muscles are primarily supplied by the posterior cord of the brachial plexus?
Which nerve does not directly originate from the medial cord of the brachial plexus?
Which nerve does not directly originate from the medial cord of the brachial plexus?
A patient presents with weakness in forearm flexion and supination, along with loss of cutaneous sensation along the lateral forearm. Which nerve is most likely affected?
A patient presents with weakness in forearm flexion and supination, along with loss of cutaneous sensation along the lateral forearm. Which nerve is most likely affected?
The phrenic nerve receives contributions from which spinal nerve roots?
The phrenic nerve receives contributions from which spinal nerve roots?
Which of the following nerves is derived from the posterior cord of the brachial plexus?
Which of the following nerves is derived from the posterior cord of the brachial plexus?
A surgeon is operating in the axilla and needs to identify the cords of the brachial plexus. What is the most reliable landmark for locating these structures?
A surgeon is operating in the axilla and needs to identify the cords of the brachial plexus. What is the most reliable landmark for locating these structures?
Which nerve roots contribute to the formation of the radial nerve?
Which nerve roots contribute to the formation of the radial nerve?
Following a motorcycle accident, a patient has difficulty with wrist extension and finger abduction. Which of the following nerves is most likely injured?
Following a motorcycle accident, a patient has difficulty with wrist extension and finger abduction. Which of the following nerves is most likely injured?
Compression of the brachial plexus as it passes through the posterior triangle most likely affects which structures?
Compression of the brachial plexus as it passes through the posterior triangle most likely affects which structures?
Where are the divisions of the brachial plexus located?
Where are the divisions of the brachial plexus located?
Which nerve is formed by contributions from both the lateral and medial cords of the brachial plexus?
Which nerve is formed by contributions from both the lateral and medial cords of the brachial plexus?
Flashcards
What forms a Plexus?
What forms a Plexus?
Formed by fusion, bifurcation, and rejoining of ventral rami in regions other than the thoracic spine (T2-T11).
What is a dermatome?
What is a dermatome?
Area of skin innervated by dorsal and ventral rami of a single spinal nerve.
Brachial Plexus Function
Brachial Plexus Function
Provides motor and sensory innervation to the upper limb and associated muscles.
Brachial Plexus Roots
Brachial Plexus Roots
Signup and view all the flashcards
Brachial Plexus Trunks
Brachial Plexus Trunks
Signup and view all the flashcards
Superior Trunk Formation
Superior Trunk Formation
Signup and view all the flashcards
Inferior Trunk Formation
Inferior Trunk Formation
Signup and view all the flashcards
Middle Trunk Formation
Middle Trunk Formation
Signup and view all the flashcards
Brachial Plexus Divisions
Brachial Plexus Divisions
Signup and view all the flashcards
Brachial Plexus Cords
Brachial Plexus Cords
Signup and view all the flashcards
Medial Cord
Medial Cord
Signup and view all the flashcards
Phrenic Nerve
Phrenic Nerve
Signup and view all the flashcards
Musculocutaneous Nerve
Musculocutaneous Nerve
Signup and view all the flashcards
Median Nerve
Median Nerve
Signup and view all the flashcards
Ulnar Nerve
Ulnar Nerve
Signup and view all the flashcards
Axillary Nerve
Axillary Nerve
Signup and view all the flashcards
Radial Nerve
Radial Nerve
Signup and view all the flashcards
Axillary Sheath
Axillary Sheath
Signup and view all the flashcards
Brachial Plexus Main Nerves
Brachial Plexus Main Nerves
Signup and view all the flashcards
Brachial Plexus Location
Brachial Plexus Location
Signup and view all the flashcards
Study Notes
- A typical spinal nerve bifurcates into dorsal and ventral ramus.
- The dorsal ramus at each vertebral level passes segmentally to the back.
- Ventral rami in thoracic levels T2-T11 remain segmental.
- In other regions, ventral rami may fuse, bifurcate, and rejoin, forming a plexus.
- Dorsal and ventral rami innervate a strip of skin called a dermatome.
Structural Formation of the Brachial Plexus
- The brachial plexus innervates the upper limb.
- It is vulnerable to injury during obstetric delivery, accidents, and gunshot wounds.
- The plexus exhibits roots, trunks, divisions, and cords, with branches (nerves) added.
- The plexus is formed from the ventral rami of C5 to T1.
- Neurons from several cord levels are distributed to the periphery in a single nerve.
- There are 5 roots (C5-T1) that lie within the prevertebral musculature and emerge into the posterior triangle between the anterior and middle scalene muscles.
- Roots unite to form trunks which are named by their anatomical relationship to one another.
- The upper two roots form the superior trunk.
- The lower two roots unite to form the inferior trunk.
- The root from C7 continues to become the middle trunk.
- Behind the clavicle, each trunk divides into an anterior and posterior division.
Cords of the Brachial Plexus
- They form in the axilla by the union of the anterior and posterior divisions of the trunks.
- Cords are named after their relationship to the axillary artery.
- The posterior divisions of all 3 trunks unite to form the posterior cord that supplies the extensor muscles of the posterior aspect of the upper limb.
- The upper two anterior divisions unite to form the lateral cord.
- The remaining anterior division (of the lower trunk) forms the medial cord.
- The two cords formed by the anterior divisions supply flexor muscles on the anterior aspect of the upper limb.
- C5 gives off the final contribution to the phrenic nerve (C3,4,5) stemming from the roots.
- Lateral cord branches include the musculocutaneous nerve (C5,6,7) and the lateral root of the median nerve (C6,7).
- Medial cord branches include the medial root of the median nerve (C8, T1) and the ulnar nerve (C8, T1).
- Posterior cord branches include the axillary nerve (C5,6) and the radial nerve (C5-8, T1).
Relationship of Nerves and Vessels in the Axilla
- The axillary artery and axillary vein lie within the axillary sheath in the axilla.
- The cords of the branchial plexus are wrapped are the axillary artery.
- The five main nerves that arise from the plexus are:
- Musculocutaneous nerve
- Median nerve
- Ulnar nerve
- Axillary nerve
- Radial nerve
Regional Summary
- Roots of the brachial plexus are located in the prevertebral muscular floor of the posterior triangle.
- Trunks pass through the posterior triangle.
- Divisions are located behind the clavicle.
- Cords are positioned around the axillary artery in the axilla.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
The brachial plexus innervates the upper limb and is formed by the ventral rami of C5 to T1. Roots unite to form trunks, named by their anatomic location. It exhibits roots, trunks, divisions, cords, and branches.
