Back Of The Body And Scapular Region Notes

Back of the body

Question 1. Give a brief account of posterior axio-appendicular muscles.
Answer.

• These are the muscles that attach the scapula with the back of the trunk.
• These are arranged into two layers:
• • Superficial layer
    • Trapezius
    • Latissimus dorsi
  • Deep layer
    • Levator scapulae
    • Rhomboideus minor
    • Rhomboideus major

Question 2. Give the origin, insertion, nerve supply and actions of trapezius muscle.
Answer.

Origin

Trapezius muscle arises from:

• Medial one-third of the superior nuchal line of occipital bone.
• Ligamentum nuchae.
• Spinous processes and supraspinous ligaments from C7 to T12.

Insertion

It is inserted as follows:

• Superior fibres, into lateral one-third of the posterior border of clavicle.
• Middle fibres, into medial margin of the acromion and upper lip of the crest of spine of scapula.
• Lower fibres, into deltoid tubercle of the spine of scapula.

Nerve supply

• Spinal root of accessory nerve
• Ventral rami of C3 and C4 spinal nerves

Actions

• Shrugging of shoulder
• Retraction of scapula
• Rotation of scapula to help abduction of arm beyond 90°

Question 3. Give the origin, insertion, nerve supply and actions of latissimus dorsi muscle.
Answer.

Origin

Latissimus dorsi muscle arises from:

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

Insertion

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

Nerve supply

Thoracodorsal nerve (C6, C7 and C8)

Actions

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

Question 4. Write a short note on the triangle of auscultation.
Answer.

Location

Back of thorax near the inferior angle of scapula.

Boundaries

Medial:

Lateral border of trapezius muscle.

Lateral:

Medial border of scapula.

Inferior:

Upper border of latissimus dorsi muscle.

Floor:

Sixth and 7th intercostal spaces and rhomboideus major muscle.

Applied anatomy

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

Question 5. Give the origin, insertion, nerve supply and actions of levator scapulae, rhomboideus minor and rhomboideus major muscles.
Answer.

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

Scapular region

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 strong triangular muscle covering the shoulder like a hood. It is responsible for the rounded contour of the shoulder.

Origin

Anterior unipennate part:

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

Intermediate multipennate part:

From lateral border of acromion process of scapula.

Posterior unipennate part:

From lower lip of crest of spine of scapula.

Insertion

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

Nerve supply

Axillary/circumflex nerve.

Read And Learn More: Selective Anatomy Notes And Question And Answers

Actions

• Lateral (acromial) fibres cause abduction of 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).

Question 2. Enumerate the structures under cover of deltoid muscle.
Answer.

Following are the structures under cover of deltoid muscle:

• Axillary nerve
• Insertion of all the muscles of rotator cuff (supraspinatus, infraspinatus, teres minor and subscapularis)
• Circumflex humeral vessels
• Surgical neck of humerus

Question 3. Give the origin and insertion of supraspinatus, infraspinatus, teres minor, subscapularis and teres major muscles.
Answer.

Origin and Insertion of Supraspinatus, Infraspinatus, Teres Minor, Subscapularis and Teres Major Muscles

Question 4. Give nerve supply and actions of supraspinatus, infraspinatus, teres minor, subscapularis and teres major muscles.
Answer.

Question 5. Write a short note on musculotendinous cuff/rotator cuff of the shoulder joint.
Answer.

The musculotendinous cuff is a fibrous sheath around the shoulder joint. It is formed by the flattened tendons of four muscles, which blend with the capsule of shoulder joint as follows:

• Supraspinatus, superiorly
• Infraspinatus and teres minor, posteriorly
• Subscapularis, anteriorly

Question 6. Write briefly about the quadrangular space.
Answer.

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

Boundaries

Superior

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

Inferior:

Teres major

Medial:

Long head of the triceps brachii

Lateral:

Surgical neck of the humerus

Structures passing through the space

• Axillary nerve
• Posterior circumflex humeral vessels

Applied anatomy

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

Question 7. 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.

Boundaries

Superomedial:

Teres minor

Lateral:

Long head of the triceps brachii

Inferior:

Teres major

Structure passing through the space

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

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.

Boundaries

Medial:

Long head of the triceps brachii

Lateral:

Shaft of humerus

Superior:

Teres major

Structures passing through this space

• Radial nerve
• Profunda brachii vessels

Applied anatomy

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