Scapular region
Scapular region or shoulder region occupied by many muscles Deltoid, Supraspinatus, Infraspinatus, Teres minor and Tere major.
Scapular region or shoulder region occupied by many muscles Deltoid, Supraspinatus, Infraspinatus, Teres minor and Tere major.
Deltoid muscle
Origin: It shows extensive origin of different fibres anterior fibres shows origin on anterior border and upper surface of lateral 1/3 of clavicle, lateral fibres shows origin on lateral margin of acromion process and posterior fibres from lower lip of crest of spine of scapula.
Insertion: Anterior, Lateral and Posterior fibres goes downwards and shows insertion on deltoid tuberosity of humerus bone.
Deltoid is a multi pennate muscle because 4 small tubercles present on lateral margin of acromion process gives attachment to 3 fibrous septa which are present in muscle from the three septa multiple muscle fibres arises.
Nerve supply: Axillary nerve C5 C6
Action: Anterior fibres produce flexion, adduction and medial rotation of arm at shoulder joint. Posterior fibres produce extension, adduction and lateral rotation of arm at shoulder joint. Acromial fibres are mainly for abduction of shoulder joint.
Origin: It shows extensive origin of different fibres anterior fibres shows origin on anterior border and upper surface of lateral 1/3 of clavicle, lateral fibres shows origin on lateral margin of acromion process and posterior fibres from lower lip of crest of spine of scapula.
Insertion: Anterior, Lateral and Posterior fibres goes downwards and shows insertion on deltoid tuberosity of humerus bone.
Deltoid is a multi pennate muscle because 4 small tubercles present on lateral margin of acromion process gives attachment to 3 fibrous septa which are present in muscle from the three septa multiple muscle fibres arises.
Nerve supply: Axillary nerve C5 C6
Action: Anterior fibres produce flexion, adduction and medial rotation of arm at shoulder joint. Posterior fibres produce extension, adduction and lateral rotation of arm at shoulder joint. Acromial fibres are mainly for abduction of shoulder joint.
Supraspinatus
Origin: Shows origin from medial 2/3 part of supraspinous fossa of scapula.
Insertion: It shows insertion on upper part of greater tubercle of humerus.
Nerve supply: From suprascapular nerve C5 C6
Action: It is initiator of abduction up to 15 degree at shoulder joint also maintain stability of shoulder joint.
Infraspinatus
Origin: It shows origin from medial 2/3 part of infraspinous fossa of scapula.
Insertion: Muscle goes laterally, upward and shows insertion on area just below insertion of supraspinatus on greater tubercle of humerus.
Nerve supply: From suprascapular nerve.
Action: It is the lateral rotator of shoulder joint also helps in abduction at shoulder joint by fixing head of humerus during abduction at shoulder joint.
Teres minor
Origin: Shows origin from lateral border of dorsal surface of scapula from its upper two-thirds part.
Insertion: It goes laterally and shows insertion on greater tubercle of humerus just below insertion of the infraspinatus muscle.
Nerve supply: From a branch of axillary nerve C5 C6 this branch shows a small pseudo ganglion.
Action: It is the lateral rotator of humerus also help in abduction at shoulder joint by fixing head of humerus.
Teres major
Origin: From dorsal surface of lateral border lower 1/3 part and inferior angle of scapula.
Insertion: It shows insertion on medial lip of intertubercular sulcus.
Nerve supply: Lower subscapular nerve.
Action: It is the medial rotator and helps in adduction of shoulder joint.
Subscapularis
Origin: From medial 2/3 part of subscapular fossa.
Insertion: It shows insertion on lesser tubercle of humerus.
Nervr supply: Upper and lower subscapular nerves.
Action : It is a helps in medial rotation and adduction of arm at shoulder joint.
Origin: Shows origin from medial 2/3 part of supraspinous fossa of scapula.
Insertion: It shows insertion on upper part of greater tubercle of humerus.
Nerve supply: From suprascapular nerve C5 C6
Action: It is initiator of abduction up to 15 degree at shoulder joint also maintain stability of shoulder joint.
Infraspinatus
Origin: It shows origin from medial 2/3 part of infraspinous fossa of scapula.
Insertion: Muscle goes laterally, upward and shows insertion on area just below insertion of supraspinatus on greater tubercle of humerus.
Nerve supply: From suprascapular nerve.
Action: It is the lateral rotator of shoulder joint also helps in abduction at shoulder joint by fixing head of humerus during abduction at shoulder joint.
Teres minor
Origin: Shows origin from lateral border of dorsal surface of scapula from its upper two-thirds part.
Insertion: It goes laterally and shows insertion on greater tubercle of humerus just below insertion of the infraspinatus muscle.
Nerve supply: From a branch of axillary nerve C5 C6 this branch shows a small pseudo ganglion.
Action: It is the lateral rotator of humerus also help in abduction at shoulder joint by fixing head of humerus.
Teres major
Origin: From dorsal surface of lateral border lower 1/3 part and inferior angle of scapula.
Insertion: It shows insertion on medial lip of intertubercular sulcus.
Nerve supply: Lower subscapular nerve.
Action: It is the medial rotator and helps in adduction of shoulder joint.
Subscapularis
Origin: From medial 2/3 part of subscapular fossa.
Insertion: It shows insertion on lesser tubercle of humerus.
Nervr supply: Upper and lower subscapular nerves.
Action : It is a helps in medial rotation and adduction of arm at shoulder joint.
Quadrangular and triangular muscular spaces
There are three intermuscular spaces visible in the scapular region 1. Quadrangular space 2. Upper triangular space 3. Lower triangular space
1. Quadrangular space
Boundaries:
Upper subscapularis muscle, lower part of capsule of shoulder joint and teres minor muscle, lower boundary by teres major muscle, medial long head of triceps muscle and lateral boundary by surgical neck of humerus.
Contents: Axillary nerve and posterior circumplex humeral vessels.
2. Upper triangular space
Boundaries:
Upper boundary by teres minor, lower boundary by teres major and lateral boundary by long head of triceps.
Contents: circumflex scapular vessels.
3. Lower triangular space
Boundaries:
Upper boundary by teres major, medial boundary by long head of triceps and lateral boundary by shaft of humerus.
Contents: radial nerve and profunda brachii vessels.
There are three intermuscular spaces visible in the scapular region 1. Quadrangular space 2. Upper triangular space 3. Lower triangular space
1. Quadrangular space
Boundaries:
Upper subscapularis muscle, lower part of capsule of shoulder joint and teres minor muscle, lower boundary by teres major muscle, medial long head of triceps muscle and lateral boundary by surgical neck of humerus.
Contents: Axillary nerve and posterior circumplex humeral vessels.
2. Upper triangular space
Boundaries:
Upper boundary by teres minor, lower boundary by teres major and lateral boundary by long head of triceps.
Contents: circumflex scapular vessels.
3. Lower triangular space
Boundaries:
Upper boundary by teres major, medial boundary by long head of triceps and lateral boundary by shaft of humerus.
Contents: radial nerve and profunda brachii vessels.
Scapular anastomosis
Anastomosis visible in relation with scapula in subscapular, supraspinous and infraspinous fossa. It is an anastomosis between first part of subclavian artery and third part of axillary artery.
Branches forming anastomosis are suprascapular artery branch of first part of subclavian artery, deep branch of transverse cervical artery i.e. branch of thyrocervical trunk from first part of subclavian artery anastomoses with circumflex scapular artery which is branch of third part of axillary artery.
Anastomosis around acromion process this anastomosis formed by acromial branches of thoraco acromial artery and suprascapular artery these are branches of subclavian artery and posterior circumflex humeral artery branch of axillary artery.
Subacromial bursa
It is a bursa situated below coracoacromial arch and supraspinatus muscle it may extend deep to deltoid muscle. This bursa reduces friction during abduction at shoulder joint. So it reduces friction of supraspinatus tendon with a acromion process.
Applied importance
Subacromial bursitis inflammation of bursa causes pain when there is pressure over deltoid muscle in relation to subacromial bursa.
Anastomosis visible in relation with scapula in subscapular, supraspinous and infraspinous fossa. It is an anastomosis between first part of subclavian artery and third part of axillary artery.
Branches forming anastomosis are suprascapular artery branch of first part of subclavian artery, deep branch of transverse cervical artery i.e. branch of thyrocervical trunk from first part of subclavian artery anastomoses with circumflex scapular artery which is branch of third part of axillary artery.
Anastomosis around acromion process this anastomosis formed by acromial branches of thoraco acromial artery and suprascapular artery these are branches of subclavian artery and posterior circumflex humeral artery branch of axillary artery.
Subacromial bursa
It is a bursa situated below coracoacromial arch and supraspinatus muscle it may extend deep to deltoid muscle. This bursa reduces friction during abduction at shoulder joint. So it reduces friction of supraspinatus tendon with a acromion process.
Applied importance
Subacromial bursitis inflammation of bursa causes pain when there is pressure over deltoid muscle in relation to subacromial bursa.