10 Questions
Which of the following nerves is responsible for innervating the rhomboids and levator scapulae muscles?
Dorsal Scapular Nerve
What is the origin of the inferior trunk of the brachial plexus?
Union of the C8 and T1 roots
Which of the following nerves is a branch from the lateral cord?
Lateral Pectoral Nerve
What is the function of the brachial plexus?
Motor, sensory, and autonomic innervation of the upper limb
Which of the following muscles is not innervated by a branch from the roots of the brachial plexus?
Pectoralis major
What is the pathway of the roots of the brachial plexus?
Through the gap between the anterior and middle scalene muscles
What is the formation of the posterior cord of the brachial plexus?
Union of the posterior divisions of the superior, middle, and inferior trunks
Which of the following nerves is not a branch from the superior trunk?
Lateral Pectoral Nerve
What is the function of the long thoracic nerve?
Innervation of the serratus anterior muscle
Which of the following statements is true about the formation of the brachial plexus?
The roots of the brachial plexus unite to form three trunks
Study Notes
Brachial Plexus
- A major nerve network that begins in the neck and extends into the axilla, supplying the upper limb with motor, sensory, and autonomic innervation.
Formation
- Formed by the union of the anterior rami of the last four cervical and the first thoracic spinal nerves that constitute the roots.
- Roots usually pass through the gap between the anterior and middle scalene muscles with the subclavian artery.
- In the inferior part of the neck, the roots unite to form three trunks: superior, middle, and inferior trunks.
- Superior trunk formed by the union of C5 and C6 roots.
- Middle trunk is a continuation of the C7 root.
- Inferior trunk formed by the union of C8 and T1 roots.
Divisions and Cords
- Each trunk divides into anterior and posterior divisions as the plexus passes through the cervicoaxillary canal posterior to the clavicle.
- Anterior divisions of the superior and middle trunks unite to form the lateral cord.
- Anterior division of the inferior trunk continues as the medial cord.
- Posterior divisions of all three trunks unite to form the posterior cord.
Branches of Brachial Plexus
- Branches from the roots:
- Dorsal Scapular Nerve (C5): innervates rhomboids and levator scapulae.
- Long Thoracic Nerve (C5,6,7): innervates serratus anterior.
- Branches from the trunks (Superior only):
- Suprascapular Nerve (C5,6): innervates supra and infraspinatus.
- Nerve to Subclavius (C5,6).
- Branches from Lateral Cord:
- Lateral Pectoral Nerve (C5,6,7): innervates pectoralis major.
- Musculocutaneous Nerve (C5,6,7): innervates biceps brachii and coracobrachialis.
- Lateral root of Median Nerve (C5,6,7).
- Branches from Medial Cord:
- Medial Pectoral Nerve.
Learn about the formation and function of the brachial plexus, a complex network of nerves that supplies the upper limb.
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