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Questions and Answers
What is the primary function of the Brachial Plexus?
What is the primary function of the Brachial Plexus?
- Regulating blood pressure
- Production of hormones
- Supplying motor and sensory innervation to the upper limb (correct)
- Supplying motor and sensory innervation to the lower limb
How many roots does the Brachial Plexus have?
How many roots does the Brachial Plexus have?
Five
Which nerves are branches of the Brachial Plexus? (Select all that apply)
Which nerves are branches of the Brachial Plexus? (Select all that apply)
- Ulnar nerve (correct)
- Musculocutaneous nerve (correct)
- Sciatic nerve
- Radial nerve (correct)
The axillary nerve arises from the anterior cord of the Brachial Plexus.
The axillary nerve arises from the anterior cord of the Brachial Plexus.
What muscles does the axillary nerve innervate?
What muscles does the axillary nerve innervate?
The five roots of the Brachial Plexus include spinal nerves C5, C6, C7, C8, and ______.
The five roots of the Brachial Plexus include spinal nerves C5, C6, C7, C8, and ______.
Injury to the musculocutaneous nerve is common.
Injury to the musculocutaneous nerve is common.
Match the following nerves with their respective origins:
Match the following nerves with their respective origins:
What are the main functions of the musculocutaneous nerve?
What are the main functions of the musculocutaneous nerve?
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Study Notes
Brachial Plexus
- A network of nerves that supplies motor and sensory innervation to the upper limb
- Begins at the spinal cord
- Extends through the cervicoaxillary canal, over the first rib, and into the axilla
- Divided structurally into roots, trunks, divisions, cords, and branches
Roots
- Five roots: C5, C6, C7, C8, and T1
Trunks
- Superior Trunk: C5, C6
- Middle Trunk: C7
- Inferior Trunk: C8, T1
Divisions
- Six divisions from the three trunks created as each trunk splits within the posterior triangle of the neck
- Each trunk splits into an anterior and posterior division
Cords
- Three cords named for location relative to the axillary artery
- Lateral cord: Anterior division of the superior and middle trunks
- Posterior cord: All posterior divisions
- Medial cord: Anterior division of the inferior trunk
Branches
- Five terminal branches
- Several preterminal or collateral branches
- Branches include the musculocutaneous, axillary, radial, median, & ulnar nerves
Musculocutaneous Nerve
- Origin: C5, C6, & C7
- Motor: Coracobrachialis, biceps brachii, & brachialis muscles
- Sensory: Lateral cutaneous nerve of the forearm, supplying sensation to the lateral forearm
Axillary Nerve
- Origin: C5, C6
- Courses through the quadrangular space
- Winds around the surgical neck of the humerus.
- Motor: Deltoid & teres minor muscles
- Sensory: Superior lateral cutaneous nerve of the arm, supplying sensation to the deltoid
Median Nerve
- Origin: Lateral and medial cords
- Motor: Supplies muscles in the forearm and hand
- Sensory: Supplies sensation to the palmar surface of the hand and the lateral three and a half fingers
Radial Nerve
- Origin: C5, C6, C7, C8, and T1
- Motor: Supplies the majority of the posterior compartment of the arm and forearm
- Sensory: Supplies sensation to the dorsal surface of the hand and the lateral three and a half fingers
Ulnar Nerve
- Origin: Medial cord
- Motor: Supplies the majority of the muscles in the hand
- Sensory: Supplies sensation to the medial one and a half fingers
Common Nerve Injuries
- Musculocutaneous Nerve: May be injured due to trauma or compression in the axilla
- Axillary Nerve: Often injured due to fractures of the surgical neck of the humerus or anterior shoulder dislocations
- Radial Nerve: commonly injured in the humerus fracture
- Median Nerve: susceptible to injury in the carpal tunnel
- Ulnar Nerve: susceptible to injury at the elbow
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