Anatomy of Brachial Plexus Quiz

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Questions and Answers

Which nerve arises from the posterior cord of the brachial plexus?

Axillary Nerve (correct)

Median Nerve

Musculocutaneous Nerve

Ulnar Nerve

Which of the following nerve roots contribute to the formation of the inferior trunk of the brachial plexus?

C8 and T1 (correct)

Which of the following branches of the brachial plexus is responsible for innervating the majority of the flexor muscles of the forearm?

Musculocutaneous Nerve

Ulnar Nerve

Radial Nerve

Median Nerve (correct)

Which cord of the brachial plexus is responsible for the formation of the ulnar and medial nerves?

Medial Cord (B) Signup and view all the answers

Which of the following statements regarding the branches of the brachial plexus is TRUE?

The median nerve originates from both the lateral and medial cords. (B) Signup and view all the answers

Which nerve is responsible for cutaneous innervation of the medial forearm?

Medial antebrachial cutaneous nerve (A) Signup and view all the answers

Which spinal nerve root(s) contribute to the axillary nerve?

C5, C6 (D) Signup and view all the answers

What is the clinical significance of dermatomes?

They help identify the origin of nerve injuries or deficits. (B) Signup and view all the answers

Which nerve provides sensory innervation to the area around the shoulder joint and the skin over the deltoid muscle?

Axillary nerve (B) Signup and view all the answers

What is the meaning of "segmented cutaneous innervation"?

Each spinal nerve root innervates a specific segment of the skin. (C) Signup and view all the answers

What is the name of the artery that continues as the brachial artery at the lateral border of teres major muscle?

Axillary artery (C) Signup and view all the answers

Which lymph nodes receive lymph from the posterior aspect of the thoracic wall and scapular region?

Subscapular nodes (C) Signup and view all the answers

Which of the following are branches of the axillary artery?

Superior thoracic artery, Thoracoacromial trunk, Lateral thoracic artery, Posterior circumflex humeral artery, Anterior circumflex humeral artery, Subscapular artery (A) Signup and view all the answers

Which of these is NOT a part of the 'Run To Drink Cold Beverages' mnemonic for the brachial plexus?

Suprascapular Nerve (B) Signup and view all the answers

Which of the following statements is TRUE about the lymph nodes in the axilla?

The apical nodes receive lymph from all other groups of axillary nodes as well as from lymphatics accompanying the cephalic vein. (B) Signup and view all the answers

What does the mnemonic 'Run To Drink Cold Beverages' refer to?

The brachial plexus (D) Signup and view all the answers

Which of the following structures DOES NOT drain into the axillary vein?

Subclavian vein (A) Signup and view all the answers

Which lymph nodes receive lymph from almost all of the upper limb, except those carried by the cephalic vein?

Humeral nodes (C) Signup and view all the answers

Which nerve allows for some flexion at the wrist and the abduction of the wrist?

Ulnar Nerve (D) Signup and view all the answers

What are the root contributions to the Median nerve?

C6-C8, T1 (B) Signup and view all the answers

What is the main function of the radial nerve?

Allows for extension of the shoulder, elbow, wrist, and digits (B) Signup and view all the answers

What is the primary role of the Musculocutaneous nerve?

Flexion at the elbow and some flexion at the shoulder (D) Signup and view all the answers

What is the primary role of the Axillary nerve?

Lateral rotation, abduction, flexion and extension at the shoulder (B) Signup and view all the answers

What cord is responsible for the innervation of the muscles in the posterior compartment of the arm and forearm?

Posterior Cord (C) Signup and view all the answers

Which of these nerves is involved in the pronation of the forearm?

Median Nerve (B) Signup and view all the answers

Which of these nerves is involved in the flexion of the elbow?

Musculocutaneous Nerve (C) Signup and view all the answers

Which nerve contributes most to the innervation of the muscles in the hand?

Ulnar Nerve (D) Signup and view all the answers

What is the primary action of the muscles within the anterior compartment of the arm?

Flexion and supination (B) Signup and view all the answers

Which of the following bursae is directly associated with the elbow joint?

Olecranon bursae (D) Signup and view all the answers

Which nerve innervates the biceps brachii muscle?

Musculocutaneous nerve (B) Signup and view all the answers

Which vessel is the primary blood supply to the arm?

Brachial artery (A) Signup and view all the answers

Which of the following structures is NOT a content of the cubital fossa?

Radial nerve (B) Signup and view all the answers

What is the primary function of the radial nerve in the arm?

Innervating most extensor muscles of the forearm (D) Signup and view all the answers

The medial epicondyle is the attachment site for which muscle group?

Flexor muscles of the forearm (D) Signup and view all the answers

Which of the following conditions would MOST likely affect the function of the ulnar nerve?

Compression injury near the elbow (C) Signup and view all the answers

Which muscle primarily aids in extending the forearm against resistance?

Lateral head of the triceps brachii (A) Signup and view all the answers

What is the primary artery supplying the triceps brachii?

Brachial artery (A) Signup and view all the answers

A patient presents with weakness in wrist extension and a loss of cutaneous sensation to the dorsal hand. This is likely a result of:

A midshaft fracture of the humerus (D) Signup and view all the answers

Which of the following is NOT a function of the anconeus muscle?

Flexing the forearm (A) Signup and view all the answers

What is the origin of the long head of the triceps brachii?

Infraglenoid tubercle of the scapula (D) Signup and view all the answers

Which of the following nerves directly innervates the triceps brachii?

Radial nerve (A) Signup and view all the answers

A fracture of the distal end of the humerus can affect which of the following structures?

Median nerve and brachial artery (B) Signup and view all the answers

Which of the following muscles helps resist humerus dislocation?

Long head of the triceps brachii (A) Signup and view all the answers

Study Notes

Brachial Plexus and Axilla

The brachial plexus is a network of nerves that innervate the upper limb.
It is formed by the anterior rami of spinal nerves C5-T1.
The plexus has roots, trunks, divisions, cords, and branches.
The axillary region contains the axillary artery, brachial plexus, and lymphatics.
The axillary artery is a continuation of the subclavian artery and its branches include branches that supply the shoulder, scapula and arm.

Axilla Borders

Apex: Cervico-axillary canal, passageway between neck and axilla.
Base: Thoracic wall and medial aspect of humerus.
Posterior wall: Scapula and subscapularis, teres major, and latissimus dorsi.
Anterior wall: Pectoralis major and minor.
Lateral wall: Intertubercular sulcus on the humerus.
Medial wall: Thoracic wall (1st–4th ribs).

Axilla Contents

Axillary vessels: Axillary artery and vein, lymphatic vessels.
Brachial plexus: Network of nerves supplying the upper limb.
Lymphatics: Lymphatic vessels that drain various regions of the body.

Axillary Lymph Nodes

There are five principal groups: pectoral, subscapular, humeral, central, and apical.
These groups are arranged in a pattern that mirrors the shape of the axilla.
The apical nodes receive lymph from other axillary nodes and cephalic vein lymphatics.
The central nodes receive lymph from the humeral, subscapular, and pectoral nodes.
The humeral nodes receive lymph from most of the upper limb.
The subscapular nodes receive lymph from the posterior thoracic wall and scapular region.
The pectoral nodes receive lymph mainly from the anterior thoracic wall, including most of the breast.

Nerves of Brachial Plexus

Musculocutaneous nerve: Innervates anterior compartment arm muscles, lateral forearm.
Median nerve: Innervates forearm & hand muscles, and some hand cutaneous area.
Ulnar nerve: Innervates forearm & hand muscles, and some hand cutaneous area.
Axillary nerve: Innervates shoulder muscles, part of shoulder skin.
Radial nerve: Innervates posterior compartment arm and forearm muscles and part of the dorsum of the hand.

Brachial Plexus Roots, Trunks, Divisions and Cords

The roots comprise the anterior rami of c5, c6, c7, c8, and t1.
These roots merge to form superior, middle, and inferior trunks.
These three trunks branch to form anterior and posterior divisions
From the divisions the cords are formed, which are the lateral, medial, and posterior cords.
The cords give rise to named peripheral nerves.

Humeral Fractures

Proximal: Surgical neck damage may affect nerves and muscles of the shoulder.
Midshaft: Radial nerve damage affects wrist extension and cutaneous sensitivity to part of the hand.
Distal: Supracondylar injuries may impact median nerve function (handgrip, and sensation changes) or ulnar nerve (loss of wrist flexion, handgrip).

Elbow Joint

It's a hinge joint (flexion/extension only).
The joint capsule has an outer fibrous layer and an inner synovial membrane.
The olecranon bursae cushion the elbow.

Arm overview

The arm moves at the elbow and glenohumeral joint.
The anterior compartment muscles control flexion, supination.
The posterior compartment muscles control extension.

Arterial Supply

The axillary artery delivers blood to the shoulder, arm.
Branches (e.g., brachial artery) supply the upper limb.
There are collateral and recurrent arteries for blood flow to all tissues.

Venous & Lymph Drainage

Blood from the upper limb drains into the veins, and then to axillary and eventually the superior vena cava.
Lymph fluid from the upper limb is drained to the axillary lymph nodes and ultimately returns to the venous blood stream.

Cubital Fossa

A triangular region in the forearm; contains important structures for blood draws/assessments.
Contains: Biceps tendon, median nerve, brachial artery, and median cubital vein.

Clinical Correlates

Describes how various injury/disorders affect anatomy of the arm.
Example of Erb's Palsy (upper trunk injury) or Klumpke's Palsy (lower trunk injury).
Demonstrates some clinical applications of the brachial plexus (e.g blood draws, injury, blood pressure).

Dermatomes

Shows cutaneous distribution for each spinal nerve.
Clinically important for diagnosis of nerve damage.

Muscles in the Anterior and Posterior Compartments of the Arm

Anterior: Contains muscles for flexion, supination (muscles like biceps brachii, coracobrachialis, brachialis).
Posterior: Contains muscles for extension of the arm, elbow, and forearm (muscles like triceps brachii, anconeus). Their origins, insertions and actions are important to know.

Nerve root contributions

The various nerves of the brachial plexus are supplied by multiple spinal cord segments. These segments are represented in the table of muscle innervated and their main actions to be performed.

Quiz Time

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Description

Test your knowledge on the anatomy and functions of the brachial plexus with this quiz. Answer questions related to nerve origins, branches, and their clinical significance in the upper limb. Perfect for students studying human anatomy or preparing for medical exams.