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Questions and Answers
A patient presents with weakness in shoulder abduction and lateral rotation following a fall. Which part of the brachial plexus is MOST likely affected?
A patient presents with weakness in shoulder abduction and lateral rotation following a fall. Which part of the brachial plexus is MOST likely affected?
- Posterior cord
- Lower trunk
- Upper trunk (correct)
- Medial cord
During a surgical procedure in the axilla, a surgeon accidentally severs a structure that leads to loss of sensation in the medial aspect of the forearm and an inability to flex the wrist. Which cord of the brachial plexus was MOST likely damaged?
During a surgical procedure in the axilla, a surgeon accidentally severs a structure that leads to loss of sensation in the medial aspect of the forearm and an inability to flex the wrist. Which cord of the brachial plexus was MOST likely damaged?
- Upper trunk
- Lateral cord
- Posterior cord
- Medial cord (correct)
A rock climber falls and sustains a brachial plexus injury. Physical examination reveals an inability to flex the elbow and supinate the forearm, along with loss of cutaneous sensation over the lateral forearm. Which nerve is MOST likely injured?
A rock climber falls and sustains a brachial plexus injury. Physical examination reveals an inability to flex the elbow and supinate the forearm, along with loss of cutaneous sensation over the lateral forearm. Which nerve is MOST likely injured?
- Ulnar nerve
- Axillary nerve
- Musculocutaneous nerve (correct)
- Radial nerve
Which combination of spinal nerve roots forms the lower trunk of the brachial plexus?
Which combination of spinal nerve roots forms the lower trunk of the brachial plexus?
A patient exhibits weakness in external rotation and abduction of the arm. Which nerve, originating directly from the roots of the brachial plexus, is MOST likely affected?
A patient exhibits weakness in external rotation and abduction of the arm. Which nerve, originating directly from the roots of the brachial plexus, is MOST likely affected?
A nursing infant is inadvertently stretched during delivery, resulting in an 'Erb's palsy'. Which combination of movements is MOST likely impaired due to this type of brachial plexus injury?
A nursing infant is inadvertently stretched during delivery, resulting in an 'Erb's palsy'. Which combination of movements is MOST likely impaired due to this type of brachial plexus injury?
Following a stab wound to the axilla, a patient has lost the ability to abduct the arm beyond the first 15 degrees. Which nerve is MOST likely damaged?
Following a stab wound to the axilla, a patient has lost the ability to abduct the arm beyond the first 15 degrees. Which nerve is MOST likely damaged?
The cords of the brachial plexus are named based on their position relative to which anatomical structure?
The cords of the brachial plexus are named based on their position relative to which anatomical structure?
A patient is unable to perform movements requiring scapular protraction, such as punching or reaching far forward. Which nerve is MOST likely damaged?
A patient is unable to perform movements requiring scapular protraction, such as punching or reaching far forward. Which nerve is MOST likely damaged?
Which of the following nerves arises from the posterior cord of the brachial plexus?
Which of the following nerves arises from the posterior cord of the brachial plexus?
A construction worker falls and injures their brachial plexus. They are later diagnosed with Klumpke paralysis. Which of the following deficits would MOST likely be observed?
A construction worker falls and injures their brachial plexus. They are later diagnosed with Klumpke paralysis. Which of the following deficits would MOST likely be observed?
The lateral cord of the brachial plexus is formed by the union of the anterior divisions of which trunks?
The lateral cord of the brachial plexus is formed by the union of the anterior divisions of which trunks?
Following a motorcycle accident, a patient exhibits winging of the scapula during arm abduction. Which nerve has MOST likely been damaged?
Following a motorcycle accident, a patient exhibits winging of the scapula during arm abduction. Which nerve has MOST likely been damaged?
Which spinal nerve root does NOT contribute to the formation of the brachial plexus?
Which spinal nerve root does NOT contribute to the formation of the brachial plexus?
A patient presents with difficulty in flexing the distal interphalangeal joints of the 4th and 5th digits of their hand. Which nerve is MOST likely affected?
A patient presents with difficulty in flexing the distal interphalangeal joints of the 4th and 5th digits of their hand. Which nerve is MOST likely affected?
Flashcards
Brachial Plexus
Brachial Plexus
A network of nerves that supplies the upper limb (except trapezius).
Brachial Plexus Formation
Brachial Plexus Formation
Formed by the anterior (ventral) rami of C5, C6, C7, C8, and T1 spinal nerves.
Brachial Plexus Roots
Brachial Plexus Roots
Ventral rami of C5, C6, C7, C8, and T1.
Upper Trunk
Upper Trunk
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Middle Trunk
Middle Trunk
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Lower Trunk
Lower Trunk
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Divisions of Brachial Plexus
Divisions of Brachial Plexus
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Lateral Cord
Lateral Cord
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Medial Cord
Medial Cord
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Posterior Cord
Posterior Cord
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Branches from Roots
Branches from Roots
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Branches from Upper Trunk
Branches from Upper Trunk
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Branches from Lateral Cord
Branches from Lateral Cord
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Branches from Medial Cord
Branches from Medial Cord
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Branches from Posterior Cord
Branches from Posterior Cord
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Study Notes
- The brachial plexus supplies nerves to the entire upper limb, excluding the trapezius muscle
Formation
- The brachial plexus forms from the union of the anterior (ventral) rami of the C5, C6, C7, C8, and T1 spinal nerves
Stages
- Roots
- Trunks
- Division
- Cords
- Branches
Site
- Roots and Trunks: Located in the neck (supraclavicular region)
- Divisions: Found behind the clavicle in the cervico-axillary canal
Roots
- Ventral rami of C5, C6, C7, C8, and T1
Trunks
- Upper trunk: Formed by the union of C5 and C6
- Middle trunk: Derived from C7
- Lower trunk: Union of C8 and T1
Divisions
- Each trunk divides into an anterior and posterior division
Cords
- Lateral cord: Formed by the union of the anterior divisions of the upper and middle trunks
- Medial cord: Continuation of the anterior division of the lower trunk
- Posterior cord: Formed by the union of the posterior divisions of the upper, middle, and lower trunks
- Cords are named relative to the second part of the axillary artery
Branches from Roots
- Nerve to rhomboids (dorsal scapular nerve): Originates from C5
- Long thoracic nerve: Originates from C5, C6, and C7
Branches from Trunks (Upper Trunk)
- Nerve to subclavius: Arises from C5 and C6
- Suprascapular nerve: Arises from C5 and C6
Branches from the Lateral Cord
- Lateral pectoral nerve: Originates from C5, C6, and C7
- Lateral root to the median nerve: Originates from C5, C6, and C7
- Musculocutaneous nerve: Originates from C5, C6, and C7
Branches from the Medial Cord
- Medial pectoral nerve: Originates from C8 and T1
- Medial root to the median nerve: Originates from C8 and T1
- Medial cutaneous nerve of the arm: Originates from C8 and T1
- Medial cutaneous nerve of the forearm: Originates from C8 and T1
- Ulnar nerve: Originates from C8 and T1
Branches from the Posterior Cord
- Upper subscapular nerve
- Lower subscapular nerve
- Thoracodorsal nerve
- Radial nerve: Originates from C5, C6, C7, C8, and T1
- Axillary nerve: Originates from C5 and C6
Spinal Nerves
- Each spinal nerve forms from the union of a ventral root and a dorsal root
- Spinal nerves divide into a ventral ramus and a dorsal ramus
- Only ventral rami unite to form plexuses
Lesions of the Upper Trunk (C5,6) - Erb's Palsy
- Causes: Head traction during birth, falls on the shoulder, or direct blows to the shoulder
- Affected nerves: Suprascapular, axillary, and musculocutaneous nerves
- Deformity: Policeman's tip (waiter's tip) posture, involving adduction and medial rotation of the arm, extension of the elbow, and pronation of the forearm
Lesions of the Lower Trunk (C8, T1) - Klumpke Paralysis
- Causes: Stretch of the upper limb during climbing or difficult breech delivery or Cervical rib
- Muscle atrophy: All the intrinsic muscles of the hand
- Deformity: Flail (claw) hand
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