Question Write briefly about the upper triangular space.
Answer:

The upper triangular space is one of the subscapular intermuscular spaces present in the region of axilla.

Upper Triangular Space Boundaries

Superomedial:

Teres minor

Lateral:

Long head of the triceps brachii

Inferior:

Teres major

Structure passing through the space

triangular space anatomy

The circumflex scapular artery which interrupts the origin of the teres minor to reach the infraspinous fossa.

Upper Triangular Space Applied anatomy

The circumflex scapular artery anastomoses with the suprascapular and deep branch of the transverse cervical arteries to form an important arterial anastomosis around scapula.

Question 8. Write briefly about the lower triangular space.
Answer.

The lower triangular space is one of the subscapular intramuscular spaces.

Lower Triangular Space Boundaries

Medial:

Long head of the triceps brachii

Lateral:

Shaft of humerus

Superior:

Teres major

contents of triangular space

Structures passing through this space

• Radial nerve
• Profunda brachii vessels

Lower Triangular Space Applied anatomy

The fracture of middle-third of humerus may damage radial nerve leading to wrist drop.

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Question. Write briefly about the quadrangular space.
Answer:

The quadrangular space is one of the subscapular intermuscular spaces present in the region of the axilla.

Quadrangular Space Boundaries

Quadrangular Space Superior

• Subscapularis in front
• Teres minor behind
• Capsule of the shoulder joint (in between the subscapularis and the teres minor)

quadrangular space anatomy

Quadrangular Space Inferior:

Teres major

Medial:

Long head of the triceps brachii

Lateral:

Surgical neck of the humerus

Structures passing through the space

boundaries of quadrangular space

• Axillary nerve
• Posterior circumflex humeral vessels

Quadrangular Space Applied Anatomy

The fracture of the surgical neck of the humerus may damage the axillary nerve, leading to paralysis of the deltoid muscle.

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Question 1. Write a short note on the triangle of auscultation.
Answer.

Triangle of Auscultation Location

The back of the thorax is near the inferior angle of the scapula.

auscultation

Triangle of Auscultation Boundaries

Medial:

Lateral border of trapezius muscle.

Lateral:

Medial border of the scapula.

Auscultation

Inferior:

Upper border of latissimus dorsi muscle.

Floor:

Sixth and 7th intercostal spaces and rhomboideus major muscle.

Triangle of Auscultation Applied Anatomy

• Respiratory sounds from the apex of the lower lobe of the lung can be heard over this triangle.
• Sounds of swallowed liquids may be auscultated over this triangle.

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Question 1. Give the origin, insertion, nerve supply, and actions of the latissimus dorsi muscle.
Answer.

Latissimus Dorsi Muscle Origin

Latissimus dorsi muscle arises from:

“Understanding the latissimus dorsi muscle through FAQs: Composition, functions, and uses explained”

• Spinous processes and supraspinous ligaments from T7 to T12
• Posterior layer of thoracolumbar fascia (attached to spinous processes of lumbar and sacral spines)
• The last four ribs
• Inferior angle of the scapula
• The posterior one-third of the iliac crest

“Factors influencing success with latissimus dorsi studies: Q&A”

Latissimus Dorsi Muscle Insertion

It enters the floor of the bicipital groove of the humerus after spiralling around the teres major muscle.

Latissimus Dorsi Muscle Nerve Supply

“Importance of studying the latissimus dorsi muscle for medical students: Questions explained”

Thoracodorsal nerve (C6, C7 and C8)

Latissimus Dorsi Muscle Actions

• Extends, adducts, and medially rotates the arm.
• Cortical attachment helps in deep inspiration and forced expiration.

The post Latissimus Dorsi Muscle appeared first on BDS Notes.

Question 1. Give the origin, insertion, nerve supply, and actions of the levator scapulae, rhomboideus minor, and rhomboideus major muscles.
Answer:

“Importance of studying the levator scapulae for medical students: Questions explained”

Origin, Insertion, Nerve Supply, and Actions of Levator Scapulae, Rhomboideus Minor, and Rhomboideus Major Muscles

“Understanding the levator scapulae through FAQs: Composition, functions, and uses explained”

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Question 1. Give the origin, insertion, nerve supply and actions of the deltoid muscle.
Answer.

The deltoid is a three-in-one muscle. It is a strong triangular muscle covering the shoulder like a hood. It is responsible for the rounded contour of the shoulder.

Deltoid Muscle Origin

Anterior unipennate part:

From the anterior border and upper surface of the lateral one-third of the clavicle.

scapular region anatomy

Intermediate multipennate part:

From the lateral border of the acromion process of the scapula.

Deltoid muscle anatomy

Posterior unipennate part:

From the lower lip of the crest of the spine of the scapula.

Deltoid Muscle  Insertion

In the V-shaped deltoid tuberosity on the lateral aspect of the shaft of the humerus.

Deltoid Muscle  Nerve Supply

Axillary/circumflex nerve.

Deltoid Muscle  Actions

Deltoid origin and insertion

• Lateral (acromial) fibres cause abduction of the shoulder joint from 15° to 90°.
• Anterior (clavicular) fibres cause medial rotation and flexion of the shoulder joint.
• Posterior (spinous) fibres cause lateral rotation and extension of the shoulder joint (i.e. they draw the arm backwards and rotate the humerus laterally).

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Question 1. Give the origin, insertion, nerve supply and actions of biceps brachii.
Answer.

Biceps Brachii Origin

biceps muscle

Biceps brachii is composed of two heads:

• Long head arises from the supraglenoid tubercle of the scapula (origin is intracapsular but extrasynovial).
• The short head arises from the tip of the coracoid process of scapula along with coracobrachialis.

Biceps brachii Insertion

By a tendon into the tuberosity of the radius (posterior rough part).

Biceps brachii Nerve supply

Musculocutaneous nerve.

biceps exercises

Biceps brachii Actions

Biceps brachii anatomy

• Flexor of the elbow joint.
• The supinator of the forearm when the elbow is flexed.
• The long head keeps the head of the humerus in position during abduction of the shoulder joint.

Biceps origin and insertion

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Question 1. Write a short note on the arterial anastomosis around the elbow joint.
Answer.

The arterial anastomosis around the elbow joint is formed between the branches of the following arteries:

• Brachial artery
• Radial artery
• Ulnar artery

Arterial anastomosis of the elbow

Question 2. Write a short note on the cubital fossa.
Answer.

The cubital fossa is a triangular hollow in front of the elbow joint.

Cubital Fossa Boundaries

• The base is formed by an imaginary horizontal line joining the medial and lateral epicondyles of the humerus.
• The medial wall is formed by the pronator teres.
• The lateral wall is formed by brachioradialis.
• The roof is formed by skin, superficial fascia, deep fascia, and bicipital aponeurosis.
• The superficial fascia contains the median cubital vein, the lateral cutaneous nerve of the forearm, and the medial cutaneous nerve of the forearm.
• The floor is formed by the brachialis muscle in the upper and medial part, and the supinator muscle in the lower and lateral part.
• Apex is a point where the pronator teres disappears underneath the brachioradialis muscle.

arterial anastomosis of elbow

Cubital Fossa Contents

From medial to lateral side:

• Median nerve
• Brachial artery
• Biceps tendon
• Superficial branch of the radial nerve
  Mnemonic: MBBS.

elbow joint anastomosis

Cubital Fossa Applied Anatomy

• The brachial artery is auscultated in the cubital fossa for recording the blood pressure.
• The median cubital vein is used in the region of the cubital fossa for venipuncture, as it lies superficial to the bicipital aponeurosis and is the most fixed vein.

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Question 1. Enumerate the contents of the posterior compartment of the arm.
Answer.

The contents of the posterior compartment of the arm are:

• Triceps brachii muscle
• Radial nerve
• Profunda brachii artery

Posterior compartment of forearm

Question 2. Give the origin, insertion, nerve supply and actions of triceps brachii.
Answer.

Triceps Brachii Origin

Triceps brachii muscle arises by three heads – long, lateral and medial.

Triceps Brachii Long head:

From infraglenoid tubercle of scapula.

Triceps Brachii Lateral head:

From oblique ridge above the spiral groove (i.e. lateral lip of the spiral groove).

posterior compartment of forearm

Triceps Brachii Medial head:

Extensor muscles of forearm

From posterior surface of shaft of humerus below the level of spiral groove.

Triceps Brachii Insertion

Into the posterior part of the superior surface of olecranon process of ulna.

Triceps Brachii Nerve supply

Radial nerve (C7, C8).

Note. Each head is supplied by a separate branch. The branch supplying long head arises in axilla, the branch supplying lateral head arises in spiral groove and the branch supplying medial head arises both in axilla and spiral groove.

Triceps Brachii Action

Extensor of elbow.

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Question 1. Enumerate the various anatomical events that occur at the level of insertion of the coracobrachialis.
Answer.

“Understanding the coracobrachialis muscle through FAQs: Composition, functions, and uses explained”

The anatomical events occurring at the level of insertion of the coracobrachialis are:

• Circular shaft of humerus becomes triangular below this level.
• Deltoid and coracobrachialis are inserted at this level.
• Upper end of the origin of the brachialis extends up to this level.
• The brachial artery passes from the medial side of the arm to its anterior aspect.
• Basilic vein pierces the deep fascia at this level.
• Median nerve crosses in front of the brachial artery from the lateral to the medial side.

“Importance of studying the coracobrachialis muscle for medical students: Questions explained”

• Radial nerve pierces the lateral intermuscular septum to pass from the posterior compartment of the arm to the anterior compartment of arm.
• Ulnar nerve pierces medial intermuscular septum to go from the anterior compartment of the arm to the posterior compartment of arm.
• Medial cutaneous nerves of arm and forearm pierce the deep fascia at this level.
• Nutrient artery pierces the humerus at this level.

Therefore, the site of insertion of the coracobrachialis is an important anatomical landmark in the arm.

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