4.SCAPULAR REGION
DELTOID MUSCLE (SE)
Origin
Anterior Fibers - Anterior border of lateral 1/3rd of clavicle
Acromial Fibers/middle fibers - Lateral border of acromion ( multipennate) Posterior Fibers- Lower lip of crest of spine of scapula
Insertion
Deltoid tuberosity of humerus
Nerve supply
Axillary nerve ( C5, C6)
Acromial fibres- powerful abductors of arm (15- 90 degree)
Anterior fibres – flexor and medial rotators of arm
Posterior fivers- extensor and lateral rotators of arm
Applied anatomy
Deltoid is the preferred place to give intramuscular injections in the arm. Injection should be given in the middle of the muscle to prevent injury to Axillary nerve
DELTOID – NERVE SUPPLY AND ACTION (SA)
Nerve supply of deltoid- axillary nerve (C5,C6)
Action
Anterior fibers - flexor and medial rotator of arm
Middle fibers- strong abductor of shoulder (15- 90 degree)
Posterior fibers – extensor and lateral rotator of arm.
CLINICAL IMPORTANCE OF DELTOID MUSCLE (SA) Deltoid muscle is the powerful abductor of shoulder joint
It is the preferred muscle to give intramuscular injections in the upper limb. Injection must be given to the middle of the muscle to avoid injury to Axillary nerve.
AXILLARY NERVE- MUSCLES SUPPLIED & CLINICAL IMPORTANCE (SA) Axillary nerve supplies
Deltoid muscle and Teres Minor muscle.
Clinical importance
Axillary nerve may be damaged in,
Dislocation of shoulder joint and fracture of surgical neck of humerus
Effects of injury
Paralysis of deltoid muscle
Inability to abduct shoulder ( 15- 90 degree)
Loss of rounded contour of shoulder
Loss of sensation over lower half of Deltoid muscle.
AXILLARY NERVE (LE)
Axillary Nerve is a branch of posterior cord of Brachial plexus. Root Value: C5,C6
Course and Distribution
In the Axilla –
Axillary nerve is located posterior to third part of Axillary artery. It leaves Axilla by passing through the quadrangular space.
It is accompanied with posterior circumflex humeral vessels. Here it is related to medial aspect of surgical neck of humerus. It gives a branch to shoulder joint.
Then divides into 2 divisions - anterior and posterior
Distribution ( Branches):
Trunk- articular twig to shoulder joint
Anterior division
Supplies deltoid muscle and skin over lower part of deltoid.
Posterior division- Supplies Teres minor and
gives upper lateral cutaneous nerve of arm
Applied anatomy
Axillary nerve may be injured by
,Dislocation of shoulder joint Fracture of surgical neck of humerus
Effects of injury to Axillary nerve-
Rounded contour of shoulder is lost
DESCRIBE THE ROOT VALUE, FORMATION, COURSE, RELATIONS AND BRANCHES OF AXILLARY NERVE. GIVE ITS APPLIED ANATOMY. WHAT ARE EFFECTS OF INJURY AT SURGICAL NECK OF HUMERUS (LE).
Root value:
Its root value is ventral rami of 5th and 6th cervical segments of spinal cord ( C5, C6 )
Formation:
The axillary nerve arises from the posterior cord of the brachial plexus near the lower border of subscapularis.
Course:
Runs backwards on subscapularis the enter the quadrangular space and terminates into anterior and posterior branches
Relations:
In the lower part of axilla:
The nerve runs downwards behind the third part of axillary artery Lies on the subscapularis muscle and related
Medially - median nerve Laterally - coracobrachialis
The nerve leaves the axilla by winding round the lower border of subscapularis and enters quandrangular space.
In the quandrangular space:
Here it is accompanied by posterior circumflex humeral vessels.
Relations
Superiorly:
Subscapularis
Lowest part of capsule of the shoulder joint
Surgical neck of humerus
Inferiorly:
Teres major
Medially:
Long head of triceps brachii
In the quandrangular space,the nerve divides into anterior and posterior branches in relation to the deltoid muscle.
Branches:
Anterior branch:
Accompanied by posterior circumflex humeral vessels.
Winds around surgical neck of humerus
Supplies the deltoid and skin over its anteroinferior part
Posterior branch:
Supplies teres minor and posterior part of the deltoid and continues as upper lateral cutaneous nerve of the arm.
The nerve to teres minor bears a pseudoganglion
Applied anatomy:
Intramuscular injections are often given into the deltoid. They should be given in the middle of the muscle to avoid injury to the axillary nerve.
The axillary nerve may be damaged by dislocation of the shoulder or by the fracture of surgical neck of humerus.
Effects of injury at surgical neck of humerus:
Rounded contour of shoulder is lost, greater tubercle of humerus becomes prominent.
Deltoid is paralysed with loss of power of abduction upto 90˚ at the shoulder.
There is sensory loss over the lower half of deltoid in a badge like area called regimental badge.
DELTOID MUSCLE – LOCATION, ATTACHMENTS NERVE SUPPLY AND ACTIONS (LE)
Location:
It is a scapulohumeral muscle
Attachments:
Origin:
The anterior clavivular part
Lateral third of clavicle – upper surface and anterior border The middle acromial part:
Acromion – lateral margin and upper surface The posterior spinous part:
Spine of scapula – lower lip of the crest of the spine
Insertion:
“V “ shaped deltoid tuberosity
Nerve supply:
Axillary nerve (C5, C6)
Actions:
Clavicular fibres – flexors and medial rotators
Spinous fibres | - extensors and lateral rotators |
Acromial fibres | - strong abductor of the arm 15˚ to 90˚ |
ROTATOR CUFF OF SHOULDER (SE)
Rotator cuff/musculotendinous cuff of the shoulder is the fibrous sheath formed by the tendons of
Supraspinatus
Infraspinatus Teres minor Subscapularis
They arise from scapula gets inserted into humerus and blend with the capsule of the shoulder joint.
Tendon of supraspinatus fuse superiorly
Tendon of infraspinatus and teres minor fuse posteriorly Tendon of subscapularis fuse anteriorly
Functions:
Stabilizes shoulder joint
Grasp the relatively large head of humerus and hold it against the smaller, shallow glenoid cavity.
QUADRANGULAR AND TRIANGULAR SPACES (SE).
Quadrangular space:
Boundaries:
Superior:
Subscapularis anteriorly
Teres minor posteriorly
Capsule of the shoulder joint
Inferior:
Teres major
Medial:
long head of triceps brachii Lateral:
surgical neck of humerus
Contents: Axillary nerve
Posterior circumflex humeral vessels
Upper triangular space:
Boundaries:
Medial:
teres minor
Lateral :
long head of triceps
Inferior: teres major
Contents:
Circumflex scapular artery
Lower triangular space:
Boundaries:
Medial:
long head of triceps
Lateral:
shaft of humerus
Superior:
teres major
Contents:
Radial nerve
Profunda brachii vessels
AXILLARY NERVE (CIRCUMFLEX NERVE) (SE)
Root value:
Its root value is ventral rami of 5th and 6th cervical segments of spinal cord
( C5, C6 )
Formation:
The axillary nerve arises from the posterior cord of the brachial plexus near the lower border of subscapularis.
Course:
Runs backwards on subscapularis, then enters the quadrangular space and terminates into anterior and posterior branches
Branches:
Anterior branch:
Accompanied by posterior circumflex humeral vessels.
Winds around surgical neck of humerus
Supplies the deltoid and skin over its anteroinferior part
Posterior branch:
Supplies teres minor and posterior part of the deltoid and continues as upper lateral cutaneous nerve of the arm.
The nerve to teres minor bears a pseudoganglion
ANASTOMOSIS AROUND SCAPULA(SE) |
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Arterial anastomoses | - subclavian artery | & | axillary artery |
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Sites: | 1st part of subclavian | 2nd part of axillary | 3rd part axillary | ||
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Body of | ∙ | Supra scapular |
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scapula |
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| Circumflex scapular |
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| ∙ | Deep branch of |
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| transverse cervical |
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Acromion |
| Acromion branch | Thoraco acromion | Posterior circumflex | |
process |
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| humoral artery. |
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NERVE SUPPLY AND ACTION OF DELTOID(SA)
Nerve supply:
Axillary nerve (C5, C6)
Actions:
Anterior/Clavicular fibres – flexors and medial rotators
Posterior/Spinous fibres | - extensors and lateral rotators |
Middle/Acromial fibres | - strong abductor of the arm 15˚ to 90˚ |
MUSCLES ATTACHED TO GREATER TUBERCLE OF HUMERUS WITH NERVE SUPPLY(SA)
Upper impression - supraspinatus
Middle impression - infraspinatus
Lower impression - teres minor
ROTATOR CUFF ( MUSCLES FORMING IT)(SA)
Rotator cuff/musculotendinous cuff of the shoulder is the fibrous sheath formed by the tendons of
Supraspinatus
Infraspinatus
Teres minor
Subscapularis.
QUADRANGULAR SPACE – BOUNDARIES AND CONTENTS(SA) Boundaries:
Superior: Subscapularis anteriorly
Teres minor posteriorly
Capsule of the shoulder joint
Teres major
long head of triceps brachii surgical neck of humerus
Axillary nerve
Posterior circumflex humeral vessels
CONTENTS OF INFERIOR TRIANGULAR SPACE OF ARM(SA) Radial nerve
Profunda brachii vessels
AXILLARY NERVE – MUSCLES SUPPLIED AND CLINICAL IMPORTANCE.(SA) Muscles supplied:
Anterior branch: deltoid
Posterior branch: deltoid and teres minor
Clinical importance:
(1)Intramuscular injections are often given into the deltoid. They should be given in the middle of the muscle to avoid injury to the axillary nerve.
(2)The axillary nerve may be damaged by dislocation of the shoulder or by the fracture of surgical neck of humerus.
CLINICAL IMPORTANCE OF DELTOID MUSCLE(SA)
Intramuscular injections are often given into the deltoid. They should be given in the middle of the muscle to avoid injury to the axillary nerve.
∙Paralysis of deltoid: produced by any damage to the axillary nerve Resulting in loss of power of abduction upto 90˚ at the shoulder.
Paralysis of Deltoid muscle ( inability to abduct the shoulder)
Sensory loss over the lower half of deltoid ( regimental badge anaesthesia)
AXILLARY NERVE (SE)
Axillary Nerve is a branch of posterior cord of Brachial plexus.
Root Value: C5,C6
Distribution ( Branches):
Trunk- articular twig to shoulder joint Anterior division –
Supplies deltoid muscle and skin over lower part of deltoid.
Posterior division- Supplies Teres minor and
gives upper lateral cutaneous nerve of arm
Applied anatomy-
Axillary nerve may be injured by Dislocation of shoulderjoint Fracture of surgical neck of humerus
Effects of injury to Axillary nerve- Rounded contour of shoulder is lost
Paralysis of Deltoid muscle ( inability to abduct the shoulder)
Sensory loss over the lower half of deltoid ( regimental badge anaesthesia).
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