This is the region that lies at the posterior thoracic wall. This region presents one bone known as the scapular which gives attachment to the following muscles:
It arises from the following areas:
· Medial 1/3rd of the superior nuchal line
· The external occipital protuberance
· -The ligamentum nuchea which extends from the 1st cervical vertebra to the spine of 7th cervical vertebra
· The spinous process of T1 – T12 and the supraspinous ligament.
Upper fibers are inserted into the lateral 1/3rd of the posterior surface of the clavicle.
Intermediate fibers into the medial and superior surface of the acromin, the upper lip of the crest of the spine it is also attached to the deltoid tubercle.
The inferior fibers ascend laterally to be inserted into the medial end of the spine of the scapular.
It is supplied by the spinal accessory nerve and branches from C3 and C4, (sensory supply).
Action: It stabilizes the shoulder with other muscles.
· With the levator scapulae muscle the upper fibers elevate the scapular.
· The intermediate fibers retract the scapular thereby squaring up the shoulder. With the Rhomboid muscles and pectoralis minor muscle it helps to rotate the scapular.
· With the serratus anterior muscle the inferior fibers helps to depress the scapular.
From the transverse process of C1 – C4
Insertion: Medial border of the scapular between the superior angle and the upper base of the spine of the scapular.
Action: Elevation of the scapular
Nerve supply: Branch of the dorsal scapular nerve.
From the spinous process of the 7th cervical and the 1st thoracic vertebrae.
It is attached to the medial border of the scapular at an angular area at the base of the spine.
It arises from the spinous process of the second to the fifth thoracic vertebrae
It is attached to the medial border of scapular below the base of the spine of the scapular up to the inferior angle.
Never supply: It is supplied by nerve to Rhomoboidus a branch of the dorsal scapular nerve.
Action: Both muscles retract the scapular.
It is a triangular muscle or fan shaped muscle.
It takes its origin from:
· The posterior 1/3rd of the outer lip of the iliac crest.
· The posterior layer of a though fascia known as the lumbar fascia which is attached to the spinous processes of the sacrum and lumbar vertebrae
· The spinous processes and supraspinous ligament of the lower five thoracic vertebra. Here it covers the lower fiber origin of trapezius (T7-T12).
· From the inferior angle of the scapular.
· From the lower 3-4 ribs.
It ascends to form the posterior axillary fold with the teres major. It is initially posterior to the teres major, twisting over the teres major muscles towards its point of insertion.
It is inserted into the floor of intertubercular sulcus.
NEVER SUPPLY: Thoracodorsal nerve
· It adducts the arm
· Extension at the shoulder joint
· It functions in media rotation of the arm. All these actions are put into play in swimming, climbing, pushing, in pulling and in pushing.
Medial 2/3rd of the supraspinous fossa and from the fascia enclosing it.
It is inserted at the supra facet of the greater lubercle of the humonis.
NEVER SUPPLY: Suprascapular nerve which is a branch arising from the upper trunk of the brachial plexus.
ACTION: It is said to be the initiator of Addiction, when acting alone it can adduct the arm up to 15O.
From the medial 2/3rd of the infraspinous fossa and it’s enclosing fascia.
Intermediate facet at the greater tubercle of the humerus.
NERVE SUPPLY: Suprascapular Nerve.
ACTION: Lateral rotation of the humerus.
Origin: Lateral border of scapular close to the infraglenoid tubercle.
Insertion: Inferior facet of the greater tubercle
Nerve supply: Axillary nerve a branch from the lower trunk of the brachial plexus
Action: Lateral rotation of the humerus.
Origin: Inferior angle of the scapular.
Insertion: Medial lip of intertubercular sulcus
Nerve Supply: Lower subscapular nerve a branch from the lower trunk of the brachial plexus.
Action: Adduction of the humerus medial rotation of the humerus
Origin: The long head of tricep originates from the infraglenoid tubercle. It is discuss under muscles of the arm.
Origin: Medial 4/5th of the subscapular fossa.Insertion: lesser tubercle of the humerus.
Nerve supply: Upper and lower subscapular nerve.
Action: Medial rotation of the humerus
It is a four sided space lying within the scapular region. It bounded
laterally by the surgical neck of the humerus, medially by the long head of the tricep, superiorly by the teres minor and subscapularis, inferiorly by the teres major muscle
content: Axillary nerve and posterior circumflex humeral artery and vein. UPPER TRIANGULAR SPACE
It is bounded superiorly by the teres minor, inferiorly by the teres major and latissmus dorsi while laterally is the long head of tricep.
Circumftex scapular artery and vein
LOWER TRIANGULUR SPACE
It is bounded superiorly by the teres major, medially by the long head of tricep. Laterally by the shaft of the humerus
It transmits the radial nerve and the profund brachii artery and vein.
DELTOID MUSCLE:it is a triangular muscle both in origin and insertion.
ORIGIN: It takes origin from:
· The anterior fibers arises from the anterior surface of the lateral 1/3rd of the clavicle
· Intermediate fibers arise from the lateral border and surface of the acromion
· Posterior fibers arise from the lower lip of the crest of the spine of the scapular.
It is attached to the deltoid tuberosity at the middle aspect of the lateral surface of the shaft of the humerus.
· Anterior fiber causes flexion
· Posterior fiber causes extension
· Intermediate fiber causes abduction of the humerus. It abducts the humerus as the supraspinatus initiates abduction up to 90O after which it is assisted by the anterior and posterior fibers.
Nerve supply: Axillary nerve
Upper 8th ribs and membrane of the corresponding intercostal spaces it may extend to the 9th or 10th rib.
It is inserted medial part of the costal surface of the scapular from the superior angle to the inferior angle where it is concentrated most.
Action: Protraction of the scapular.
Nerve supply: Long thoracic nerve of bell.