Upper Limb Anatomy - Part 1 PDF | Clavicle & Scapula

UPPER LIMB Part 1 By Dr. Afsheen Irfan Usmani  Introduction to Pectoral Definition: Girdle The pectoral girdle (shoulder girdle) consists of the clavicle (collarbone) and scapula (shoulder blade). It connects the upper limbs to the axial skeleton. Functions: Provides attac...

UPPER LIMB Part 1 By Dr. Afsheen Irfan Usmani  Introduction to Pectoral Definition: Girdle The pectoral girdle (shoulder girdle) consists of the clavicle (collarbone) and scapula (shoulder blade). It connects the upper limbs to the axial skeleton. Functions: Provides attachment sites for muscles that move the upper limbs. Enhances upper limb mobility due to the scapula's free movement across the thorax. Key Feature: The scapula is not directly attached to the axial skeleton, allowing for greater range of motion.  Clavicle (Collar bone) The clavicle(Latin a small key) is a long bone and has a cylindrical part called the shaft, and two ends, lateral and medial. Its supports the shoulder so that the arm can swing clearly away from the trunk. It transmits the weight of the limb to the sternum. Only long bone that lies horizontally. It is subcutaneous throughout.  Side Determination The lateral end is flat, and the medial end is large and quadrilateral. The shaft is slightly curved, so that it is convex forwards in its medial two-thirds, and concave forwards in its lateral one-third. The inferior surface is grooved longitudinally in its middle one-third.  Features SHAFT The shaft is divisible into the lateral one-third and the medial two- thirds. The lateral one-third of the shaft is flattened from above downwards. It has two borders, anterior and posterior. The anterior border is concave forwards. The posterior border is convex backwards. This part of the bone has two surfaces, superior and inferior. The superior surface is subcutaneous and the inferior surface presents an elevation called the conoid (Greek cone) tubercle and a ridge called the trapezoid ridge. The medial two-thirds of the shaft is rounded and is said to have four surfaces. The anterior surface is convex forwards. The posterior surface is smooth. The superior surface is rough in its medial part. The inferior surface has a rough oval impression (costal tuberosity) at the medial end. The lateral half of this surface has a longitudinal subclavian groove. The nutrient foramen lies at the lateral end of the groove.  Ends of the Clavicle Lateral (Acromial) End: Flattened from above downwards. Bears a facet for articulation with the acromion process of the scapula (Acromioclavicular joint). Medial (Sternal) End: Quadrangular in shape. Articulates with the clavicular notch of the manubrium sterni (Sternoclavicular joint).  Muscular Attachments Muscle Origin Insertion Half of the superior Mastoid process of Sternocleidomastoid surface of medial two temporal bone, superior thirds of clavicle, nuchal line of occipital manubrium of sternum bone Most of the anterior surface of the medial Lateral lip of Pectoralis Major two thirds of clavicle, intertubercular groove of sternum, upper costal humerus cartilages Anterior border of the lateral third of clavicle, Deltoid tuberosity of Deltoid acromion, spine of humerus scapula  Muscle Origin Insertion Occipital bone, Posterior border of nuchal ligament, the lateral third of Trapezius spinous processes clavicle, acromion, of C7-T12 spine of scapula vertebrae Subclavian groove Subclavius First rib and its on inferior surface costal cartilage of middle third of clavicle  Ligament Attachments Costoclavicular Ligament: Oval impression on the inferior surface at th medial end gives attachment to costoclavicular ligament. It attaches the clavicle to the first rib, preventing excessive elevation. Coracoclavicular Ligament: The conoid tubercle and trapezoid ridge give attachment to the conoid and trapezoid parts of coracoclavicular ligaments. Attach the clavicle to the coracoid process of the scapula, preventing dislocation.  Joints Sternoclavicular Joint: Saddle synovial joint. Articulates with manubrium of sternum & first costal cartilage. Movements:Elevation, depression, protraction, retraction, rotation. Acromioclavicular Joint: Plane synovial joint. Articulates with acromion process of scapula. Movements: Slight gliding during shoulder motion.  Movements Elevation & Depression: Shrugging shoulders. Protraction & Retraction: Moving shoulders forward and backward. Axial Rotation: During shoulder abduction.  Clinical Conditions 1. Fracture of Clavicle: The clavicle is commonly fractured by falling on the outstretched hand (indirect violence). The most common site of fracture is the junction between the two curvatures of the bone, which is the weakest point. The lateral fragment is displaced downwards by the weight of the limb as trapezius muscle alone is unable to support the weight of upper limb.  Scapula (Shoulder Blade) The scapula is a large, flat, triangular bone located on the posteriolateral aspect of the thoracic cage. It has two surfaces, 3 borders, 3 angles, and 3 processes.  Side determination 1. The lateral or glenoid (Greek shallow form) side is large and bears the glenoid cavity. 2. The dorsal surface is convex and is divided by the triangular spine into the supraspinous and infraspinous fossae. The costal surface is occupied by the concave subscapular fossa to fit on the convex chest wall. 3. The thickest lateral border runs from the glenoid cavity above to the inferior angle below.  Surfaces of Scapula Costal Surface (Anterior): Faces the ribs and has a concave subscapular fossa, where the subscapularis muscle attaches. Dorsal Surface (Posterior):This surface gives attachment to the spine of the scapula which divides the surface into a smaller supraspinous fossa and a larger infraspinous fossa.  Borders of Scapula The superior border is thin and shorter. Near the root of the coracoid process it presents the suprascapular notch. The lateral border is thick. At the upper end it presents the infra-glenoid tubercle. The medial border is thin. It extends from the superior angle to the inferior angle.  Angles Superior Angle: Located at the junction of the superior and medial borders. Inferior Angle: Formed by the convergence of the medial and lateral borders; moves during scapular motion. Lateral Angle: Contains the glenoid cavity, which articulates with the humerus to form the shoulder joint.  Processes Spine or the spinous process: It is a triangular plate of bone. It divides the dorsal surface of the scapula into supra-spinous and infraspinous fossae. Acromion Process: A lateral extension of the spine; it has a facet that articulates with the clavicle at the acromioclavicular joint. Coracoid Process: A beak-like projection that serves as an attachment for muscles, including the pectoralis minor, coracobrachialis, and short head of the biceps brachii.  Muscular Attachment Muscles Attached to the Anterior (Costal) Surface Muscle Origin Insertion Lesser Subscapu Subscapu tubercle laris lar fossa of humerus Serratus Ribs 1-8 Medial Anterior (lateral border of surface) scapula  Muscles Attached to the Posterior (Dorsal) Surface Insertio Muscle Origin n Greater Supraspi Supraspi tubercle nous natus of fossa humerus Greater Infraspi Infraspi tubercle nous natus of fossa humerus  Muscles Attached to the Borders of the Scapula Border Muscle Origin Insertion Superior Border Omohyoid (Inferior Near the Suprascapular Hyoid bone Belly) notch Dorsal aspect of the Medial Border Levator Scapulae Transverse processes of medial border, from the C1-C4 superior angle up to the root of the spine Spinous processes of C7- Medial border (dorsal Medial Border Rhomboid Minor T1 aspect opposite the root of the spine) of scapula Medial border (dorsal Medial Border Rhomboid Major Spinous processes of T2- aspect between the root T5 of the spine and inferior angle) of scapula Lateral Border Teres Minor Upper lateral border of Greater tubercle of scapula (dorsal aspect) humerus Lower lateral border of Lateral Border Teres Major scapula (dorsal aspect Intertubercular sulcus of and inferior angle) humerus  Muscles Attached to the Angles of the Scapula Angle Muscle Origin Insertion Transverse Superior Angle Levator processes of Superior angle Scapulae C1-C4 of scapula Teres Major Lower lateral Intertubercular Frequently few border of sulcus of Inferior Angle fibers of scapula (dorsal humerus latissimus aspect and dorsi inferior angle) Muscles Attached to the tubercles of the Scapula Tubercal Muscle Origin Insertion Supraglenoid Long Head of Supraglenoid Radial Biceps Brachii Tubercal Tuberosity Infraglenoid Long Head of Infraglenoid Olecranon Triceps Brichii Tubercal process  Muscles Attached to the Processes of the Scapula Process Muscle Origin Insertion Occipital bone, spinous Spine of Spine Trapezius processes of scapula C7-T12 Deltoid Spine of Spine Deltoid tuberosity of scapula humerus Occipital bone, spinous Acromion of Acromion Trapezius processes of scapula C7-T12 Deltoid Acromion of Acromion Deltoid tuberosity of scapula humerus Medial border Coracoid Pectoralis of Coracoid Ribs 3-5 Process Minor process of scapula Tip of the  Ligaments The coracoacromial ligament is attached (a) to the lateral border of the coracoid process, and (b) to the medial side of the tip of the acromion process. The coracohumeral ligament is attached to the root of the coracoid process. The coracoclavicular ligament is attached to the coracoid process: The trapezoid part on the superior aspect, and the conoid part near the root). The transverse ligament bridges across the suprascapular notch and converts it into a foramen which transmits the suprascapular nerve. The suprascapular vessels lie above the ligament. The spinoglenoid ligament may bridge the spinoglenoid notch. The suprascapular vessels and nerve pass deep to it.  Joint Articulation Glenohumeral Joint(Shoulder joint): Articulation: Humeral head with the glenoid cavity of the scapula. ​Type: Ball-and-socket synovial joint. Acromioclavicular Joint: plane synovial joint Articulates with lateral (acromial) end of clavicle Movement: Slight gliding movement during shoulder motion  Movement s Elevation: The scapula moves upward, like when you shrug your shoulders. Depression: The scapula moves downward, as seen when you lower your shoulders after shrugging. Protraction (Abduction): The scapula moves away from the spine, often seen when you reach forward. Retraction (Adduction): The scapula moves toward the spine, like when you squeeze your shoulder blades together. Upward Rotation: The scapula rotates such that the glenoid (socket part of the shoulder) moves upward. This is essential for raising the arm overhead. Downward Rotation: The scapula rotates in the opposite direction, bringing the glenoid downward, as when the arm is lowered from an overhead position.  Clinical Condition 'Winging' of the scapula: Caused due to paralysis of the serratus anterior. The medial border of the bone becomes unduly prominent, and the arm cannot be abducted beyond 90 degrees.