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Questions and Answers
What is the primary action of the brachialis muscle?
What is the primary action of the brachialis muscle?
From which part of the humerus does the medial head of the triceps arise?
From which part of the humerus does the medial head of the triceps arise?
Which nerve supplies the posterior compartment of the arm?
Which nerve supplies the posterior compartment of the arm?
What is the insertion point of the triceps muscle?
What is the insertion point of the triceps muscle?
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What type of muscle is the coracobrachialis considered to be?
What type of muscle is the coracobrachialis considered to be?
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Which bursa is particularly vulnerable to inflammation as a result of repeated friction?
Which bursa is particularly vulnerable to inflammation as a result of repeated friction?
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Which artery is a continuation of the axillary artery?
Which artery is a continuation of the axillary artery?
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What is the primary role of the long head of the triceps in addition to extending the elbow?
What is the primary role of the long head of the triceps in addition to extending the elbow?
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Which structure does the musculocutaneous nerve pass through?
Which structure does the musculocutaneous nerve pass through?
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Which muscle arises from the infraglenoid tubercle of the scapula?
Which muscle arises from the infraglenoid tubercle of the scapula?
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What structure separates the anterior and posterior compartments of the arm?
What structure separates the anterior and posterior compartments of the arm?
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Which muscle is located in the anterior compartment of the arm?
Which muscle is located in the anterior compartment of the arm?
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What nerve innervates the muscles of the anterior compartment of the arm?
What nerve innervates the muscles of the anterior compartment of the arm?
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Where does the long head of the biceps brachii originate?
Where does the long head of the biceps brachii originate?
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What is the primary action of the biceps brachii?
What is the primary action of the biceps brachii?
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Where does the tendon of the biceps brachii insert?
Where does the tendon of the biceps brachii insert?
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What is the role of the bicipital aponeurosis?
What is the role of the bicipital aponeurosis?
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In terms of flexion, what additional action does the long head of the biceps brachii assist with?
In terms of flexion, what additional action does the long head of the biceps brachii assist with?
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Which of the following muscles is NOT part of the anterior compartment of the arm?
Which of the following muscles is NOT part of the anterior compartment of the arm?
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What is the function of the radial tuberosity in relation to the biceps brachii?
What is the function of the radial tuberosity in relation to the biceps brachii?
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Study Notes
Introduction to the Arm
- The arm is enclosed by a sheath of deep fascia.
- Two fascial intermuscular septa extend to the medial and lateral supracondylar ridges of the humerus.
- The medial and lateral intermuscular septa divide the arm into anterior and posterior fascial compartments.
Anterior Compartment
- Contains three muscles: biceps brachii, coracobrachialis, and brachialis.
- The nerve of the compartment is the musculocutaneous nerve.
- The artery is the brachial artery.
Biceps Brachii
- This muscle has two heads of origin.
- The long head is lateral and the short head is medial.
- The long head arises from the supraglenoid tubercle of the scapula within the capsule of the shoulder joint.
- The long head emerges at the top of the intertubercular sulcus, surrounded by a tube-like extension of the synovial membrane.
- The long head lies in the sulcus then joins the short head.
- The medial head arises from the tip of the coracoid process of the scapula in common with the coracobrachialis muscle.
- The muscle lies in front of the brachialis with the musculocutaneous nerve before it.
- The tendon is inserted into the radial tuberosity.
- A bursa is present between the tendon and the radial tuberosity.
- A bicipital aponeurosis is an extension from the tendon of biceps brachii, a thin sheet of connective tissue.
- It passes medially to blend with the deep fascia of the forearm.
- The muscle is a powerful flexor and supinator of the forearm.
- Its long head helps in flexion at the shoulder.
- The supinator action is due to insertion onto the posterior aspect of the radial tuberosity.
- When the biceps contracts, the forearm is flexed and the radius unwinds as its tuberosity is rotated anteriorly: i.e. the forearm supinates.
Brachialis
- Arises from the front of the distal part of the humerus and the intermuscular septa.
- Is inserted into the coronoid process and tuberosity of the ulna.
- Passing in front of the elbow joint, it is a powerful flexor of the elbow.
Coracobrachialis
- Is a small muscle, arising from the tip of the coracoid process in common with the short head of biceps brachii.
- Is inserted into the middle third of the medial surface of the humerus.
- It is a weak flexor and adductor of the shoulder.
- The musculocutaneous nerve passes through the muscle, giving its branch of supply before doing so.
Posterior Compartment
- Contains one muscle with three heads: triceps brachii.
- The nerve of the compartment is the radial nerve.
- The artery of the compartment is the profunda brachii and ulnar collateral branches of the brachial artery.
Triceps Brachii
- As its name indicates, this muscle has three heads of origin: long, lateral, and medial.
- The long head arises from the infraglenoid tubercle of the scapula.
- The lateral head arises from the posterior surface of the humerus superior to the radial groove.
- The medial head arises from the posterior surface of the humerus inferior to the radial groove.
- The tendon of the muscle is inserted in the olecranon process of the ulna.
- The muscle is an extensor of the elbow.
- Its long head arising from the infraglenoid tubercle aids in extending the shoulder joint.
- It's an essential factor in maintaining the stability of the abducted shoulder.
Bursae Related to Triceps Tendon
- There is a subcutaneous bursa located in subcutaneous tissue.
- There is a subtendinous olecranon bursa located between the tendon and the olecranon.
- The subcutaneous bursa is liable to inflammation from repeated friction, known as "student's elbow."
Brachial Artery
- Is the continuation of the axillary artery.
- At the cubital fossa in front of the elbow joint, it ends opposite the neck of the radius by dividing into radial and ulnar arteries.
Median Nerve
- Is formed by the union of the medial and lateral roots lateral to the axillary artery.
- Crosses anterior to the brachial artery in the middle of the arm.
- At the elbow, the median nerve lies medial to the brachial artery.
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Description
This quiz covers the anatomy of the arm, focusing on the compartments and the muscles within them, specifically the biceps brachii. It explores details about the fascial structures, nerves, and arteries that are associated with the arm. Test your knowledge on the intricate design and functionality of arm muscles.
