Brachial Plexus Flashcards
What is the brachial plexus?
The brachial plexus is a network of nerves that supplies motor and sensory innervation to the upper limb.
Which spinal nerve roots contribute to the brachial plexus?
The brachial plexus arises from the ventral rami of spinal nerves C5, C6, C7, C8, and T1.
How is the brachial plexus anatomically divided?
The brachial plexus is divided into roots, trunks, divisions, cords, and terminal branches.
What are the names of the five roots of the brachial plexus?
The five roots of the brachial plexus are C5, C6, C7, C8, and T1.
Which nerves arise directly from the roots of the brachial plexus?
The dorsal scapular nerve (C5) and long thoracic nerve (C5-C7) arise directly from the roots.
What is the function of the dorsal scapular nerve, and which root does it arise from?
The dorsal scapular nerve (C5) innervates the rhomboid major, rhomboid minor, and levator scapulae muscles.
What is the function of the long thoracic nerve, and which roots does it arise from?
The long thoracic nerve (C5-C7) innervates the serratus anterior muscle and prevents scapular winging.
How many trunks are in the brachial plexus, and what are their names?
The brachial plexus has three trunks: superior, middle, and inferior.
Which roots contribute to the superior trunk of the brachial plexus?
The superior trunk is formed by the union of C5 and C6 roots.
Which roots contribute to the middle trunk of the brachial plexus?
The middle trunk is a continuation of the C7 root.
Which roots contribute to the inferior trunk of the brachial plexus?
The inferior trunk is formed by the union of C8 and T1 roots.
What are the two major branches from the superior trunk of the brachial plexus?
The superior trunk gives rise to the suprascapular and nerve to subclavius.
What is the function of the suprascapular nerve, and which trunk does it arise from?
The suprascapular nerve (C5-C6) innervates the supraspinatus and infraspinatus muscles.
What are the divisions of the brachial plexus?
Each trunk divides into an anterior and posterior division.
What is the purpose of the anterior and posterior divisions of the brachial plexus?
The anterior divisions supply flexor muscles, and the posterior divisions supply extensor muscles.
How many cords are in the brachial plexus, and what are their names?
The brachial plexus has three cords: lateral, medial, and posterior.
How are the cords of the brachial plexus named?
The cords are named based on their position relative to the axillary artery.
Which divisions contribute to the lateral cord?
The anterior divisions of the superior and middle trunks form the lateral cord.
Which divisions contribute to the medial cord?
The anterior division of the inferior trunk forms the medial cord.
Which divisions contribute to the posterior cord?
The posterior divisions of all three trunks form the posterior cord.
What are the branches of the lateral cord?
The lateral cord gives rise to the musculocutaneous nerve and lateral root of the median nerve.
What are the branches of the medial cord?
The medial cord gives rise to the ulnar nerve, medial root of the median nerve, and medial cutaneous nerves.
What are the branches of the posterior cord?
The posterior cord gives rise to the axillary and radial nerves.
What is the function of the lateral pectoral nerve, and which cord does it arise from?
The lateral pectoral nerve (C5-C7) innervates the pectoralis major.
What is the function of the medial pectoral nerve, and which cord does it arise from?
The medial pectoral nerve (C8-T1) innervates the pectoralis major and minor.
What are the five major terminal branches of the brachial plexus?
The five major terminal branches are the musculocutaneous, median, ulnar, axillary, and radial nerves.
Which cord gives rise to the musculocutaneous nerve?
The lateral cord gives rise to the musculocutaneous nerve.
What is the function of the musculocutaneous nerve?
The musculocutaneous nerve innervates the anterior arm muscles and provides sensory innervation to the lateral forearm.
Which cords contribute to the median nerve?
The lateral and medial cords contribute to the median nerve.
What is the function of the median nerve?
The median nerve innervates most forearm flexors and thenar muscles.
Which cord gives rise to the ulnar nerve?
The medial cord gives rise to the ulnar nerve.
What is the function of the ulnar nerve?
The ulnar nerve innervates intrinsic hand muscles and flexor carpi ulnaris.
Which cord gives rise to the axillary nerve?
The posterior cord gives rise to the axillary nerve.
What is the function of the axillary nerve?
The axillary nerve innervates the deltoid and teres minor.
Which cord gives rise to the radial nerve?
The posterior cord gives rise to the radial nerve.
What is the function of the radial nerve?
The radial nerve innervates the extensor muscles of the upper limb.
What is Erb-Duchenne palsy, and which part of the brachial plexus is affected?
Erb-Duchenne palsy results from injury to the upper brachial plexus (C5-C6).
What are the common causes of Erb-Duchenne palsy?
Common causes of Erb-Duchenne palsy include shoulder dystocia and trauma.
What is Klumpke’s palsy, and which part of the brachial plexus is affected?
Klumpke’s palsy results from injury to the lower brachial plexus (C8-T1).
What are the common causes of Klumpke’s palsy?
Common causes of Klumpke’s palsy include birth trauma and excessive arm traction.
What is “winged scapula,” and which nerve is affected?
“Winged scapula” occurs due to long thoracic nerve injury, affecting the serratus anterior muscle.
What are the symptoms of a musculocutaneous nerve injury?
Musculocutaneous nerve injury causes weakness in elbow flexion and sensory loss in the lateral forearm.
What are the symptoms of a median nerve injury?
Median nerve injury leads to “ape hand” and loss of thumb opposition.
What are the symptoms of an ulnar nerve injury?
Ulnar nerve injury leads to “claw hand” and loss of intrinsic hand function.
What are the symptoms of an axillary nerve injury?
Axillary nerve injury leads to deltoid atrophy and shoulder weakness.
What are the symptoms of a radial nerve injury?
Radial nerve injury leads to “wrist drop” and loss of extension.
How does the brachial plexus contribute to the autonomic nervous system?
The brachial plexus contributes sympathetic fibers to the upper limb.
What is the significance of the interscalene triangle in brachial plexus anatomy?
The interscalene triangle is a potential site for nerve compression.
What is the clinical importance of the infraclavicular region in brachial plexus block?
The infraclavicular region is important for brachial plexus blocks in anesthesia.
What are the anatomical variations of the brachial plexus that may have clinical significance?
Anatomical variations include prefixed (C4-C8) and postfixed (C6-T2) plexuses.
