SUBJECT:-RACHANA SHARIR
Topic:-Rotator Cuff
Name - RaHuL KuMaR
Roll no - 40
Batch - 2022-2023
Guided By - Dr. Amit Kumar Singh [H.O.D]
-Dr. Varsha gupta
JEEVAK AYURVEDIC MEDICAL COLLEGE AND HOSPITAL RESEARCH CENTRE
INTRO
In the human body, the rotator cuff is a functional anatomical unit located in the upper extremity.
Its function is related to the glenohumeral joint, where the muscles of the cuff function both as the executors of the movements of the joint and the stabilization of the joint as well.
Injuries of the rotator cuff interfere with the function of the glenohumeral joint and correspond with inability to perform the movements associated with this joint.
The shoulder Girdle consist of two bones
The clavicle
The scapula
Rotator cuff SITS on the shoulder
* Supraspinatus
* Infraspinatus
* Teres minor
* Subscapularis
The following article describes the anatomy, including the origins and insertions, together with the function and pathologies of the rotator cuff.
Supraspinatus muscle
Origin: supraspinatous fossa of scapula
Insertion: greater tubercle of humerus
Innervation: suprascapular nerve (C4, C6)
Function: initiation of abduction of arm to 15° at glenohumeral
joint; stabilization of humeral head in glenoid cavity.
The supraspinatus muscle has its origin in the supraspinatous fossa and inserts on the greater tubercle of the humerus – similar to the teres minor muscle.
Supraspinatus muscle
Infraspinatus muscle
Origin: infraspinatous fossa of scapula
Insertion: greater tubercle of humerus
Innervation: suprascapular nerve (C5, C6)
Function: external rotation of arm at glenohumeral joint;
stabilization of the humeral head in glenoid
cavity.
The fourth muscle of the rotator cuff is the infraspinatus muscle. It originates in the infraspinatous fossa of the scapula and inserts on the greater tubercle as well.
Infraspinatus muscle
Teres minor muscle
Origin: lateral border of scapula
Insertion: greater tubercle of humerus
Innervation: axillary nerve (C5, C6)
Function: external rotation and adduction of arm at
Glenohumeral joint; stabilization of the humeral
head in glenoid cavity.
The teres minor muscle originates from the lateral border of the scapula and inserts on the greater tubercle of the humerus.
Teres minor muscle
Subscapularis muscle
Origin: medial two-third of the subscapular fossa
Insertion: lesser tubercle of the humerus
Innervation: upper and lower subscapular nerves (C5, C7)
Function: internal rotation of arm; stabilization of humeral
head in glenoid cavity.
The subscapularis muscle is very important for the internal rotation of the humerus. It arises from the subscapular fossa and inserts on the lesser tubercle of the humerus.
Subscapularis muscle
Functions
The main function of the rotator cuff is to stabilize and center the humeral head in the joint socket, the glenoid cavity. In addition, the muscles tighten the joint capsule preventing a pinch during shoulder movements.
Certainly the rotator cuff – as the name suggests – plays a major role in the internal and external rotation of the arm in the shoulder joint. All the muscles mentioned above fulfill different functions.
The subscapularis muscle is a powerful internal rotator which also supports the arm during abduction and adduction. Conversely, the teres minor muscle’s function consists primarily of external rotation and adduction of the arm.
The supraspinatus muscle initiates the abduction of the of the arm. Finally, the infraspinatus muscle is a strong external rotator and additionally assists in both abduction and adduction.
Muscle | Origin | Insertion |
Supraspinatus | Medial two-thirds of the supraspinous Fossa of the scapula. The muscle passes as a tendon of the humerus laterally beneath coracoacromial arch to blend with the capsule of shoulder joint. The tendon is separated from the arch by the subacromial bursa | Upper impression on the greater tubercle of the humerus |
Infraspinatus | Medial two-thirds of the infraspinous fossa of the scapula | Middle impression on the greater tubercle of the humerus |
Teres minor | Upper two-thirds of the dorsal surface of thelateral border of the scapula as 2 slips | Lowest impression on the greater tubercle of the humerus |
Subscapularis | Medial two-thirds of the subscapular fossa | Lesser tubercle of the humerus |
Teres major | . Lower one-third of the dorsal surface of lateral border and inferior angle of the scapula | Medial lip of the bicipital groove of the humerus |
Muscle | Nerve supply | Actions |
Supraspinatus | Suprascapular nerve (C5, C6) | Along with other short scapular muscles, it steadies the head of the humerus during movements of the arm. Its action as abductor of shoulder joint from 0°–15° is controversial. Both supraspinatus and deltoid are involved in initiation of abduction and continuation of abduction. |
Infraspinatus | Suprascapular nerve (C5, C6) | • Lateral rotator of arm (at shoulder joint |
Teres minor | Axillary nerve (C5, C6) | Same as infraspinatus |
Subscapularis | Upper and lower subscapular nerves (C5, C6) | Medial rotator and adductor of arm |
Teres major | Lower subscapular nerve (C5, C6) | Medial rotator, adductor and extensor of arm |
MR Imaging of Rotator Cuff Injury: What the Clinician Needs to Know
The rotator cuff muscles generate torque forces to move the humerus while acting in concord to produce balanced compressive forces to stabilize the glenohumeral joint. Thus, rotator cuff tears are often associated with loss of shoulder strength and stability, which are crucial for optimal shoulder function.Thus, rotator cuff tears are often associated with loss of shoulder strength and stability, which are crucial for optimal shoulder function.
The dimensions and extent of rotator cuff tears, the condition of the involved tendon, tear morphologic features, involvement of the subscapularis and infraspinatus tendons or of contiguous structures (eg, rotator interval, long head of the biceps brachii tendon, specific cuff tendons), and evidence of muscle atrophy may all have implications for rotator cuff treatment and prognosis. Magnetic resonance imaging can demonstrate the extent and configuration of rotator cuff abnormalities, suggest mechanical imbalance within the cuff, and document abnormalities of the cuff muscles and adjacent structures. A thorough understanding of the anatomy and function of the rotator cuff and of the consequences of rotator cuff disorders is essential for optimal treatment planning and prognostic accuracy. Identifying the disorder, understanding the potential clinical consequences, and reporting all relevant findings at rotator cuff imaging are also essential.
Citation
Morag, Yoav, Jon A. Jacobson, Bruce Miller, Michel De Maeseneer, Gandikota Girish, and David Jamadar. "MR imaging of rotator cuff injury: what the clinician needs to know." Radiographics 26, no. 4 (2006): 1045-1065.
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