Humerus Anatomy PDF

HUMERUS DR. MADHURIMA RUDRA The humerus is a long bone of the upper limb, which extends from the shoulder to the elbow. The proximal aspect of the humerus articulates with the glenoid fossa of the scapula, forming the glenohumeral joint. Distally, at the elbow joint, the humerus articulates with th...

HUMERUS DR. MADHURIMA RUDRA The humerus is a long bone of the upper limb, which extends from the shoulder to the elbow. The proximal aspect of the humerus articulates with the glenoid fossa of the scapula, forming the glenohumeral joint. Distally, at the elbow joint, the humerus articulates with the head of the radius and trochlear notch of the ulna. The proximal humerus is marked by a head, anatomical neck, surgical neck, greater and lesser tuberosity and intertubercular sulcus. The upper end of the humerus consists of the head. This faces medially, upwards and backwards and is separated from the greater and lesser tuberosities by the anatomical neck. The greater tuberosity is located laterally on the humerus and has anterior and posterior surfaces. It serves as an attachment site for three of the rotator cuff muscles – supraspinatus, infraspinatus and teres minor – they attach to superior, middle and inferior facets (respectively) on the greater tuberosity. The lesser tuberosity is much smaller, and more medially AND anteriorly located on the bone. It only has an anterior surface. It provides attachment for the last rotator cuff muscle – the subscapularis. Separating the two tuberosities is a deep groove, known as the intertubercular sulcus. The tendon of the long head of the biceps brachii emerges from the shoulder joint and runs through this groove. The edges of the intertubercular sulcus are known as lips. Pectoralis major, teres major and latissimus dorsi insert on the lips of the intertubercular sulcus. The surgical neck extends from just below to the tuberosities to the shaft of the humerus. The axillary nerve and circumflex humeral vessels lie against the bone here. The shaft of the humerus is the site of attachment for various muscles. On the lateral side of the humeral shaft is a roughened surface where the deltoid muscle attaches. This is known is as the deltoid tuberosity. The radial (or spiral) groove is a shallow depression that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity. The radial nerve and profunda brachii artery lie in this groove. The following muscles attach to the humerus along its shaft: Anteriorly – coracobrachialis, deltoid, brachialis, brachioradialis. Posteriorly – medial and lateral heads of the triceps (the spiral groove demarcates their respective origins).  Distal Region Articular part,- The capitulum is a rounded projection which articulates with the head of radius. The trochlea articulates with the trochlear notch of ulna. Non articulating part The lateral border at the lower end forms lateral supracondylar ridge. The medial border at the lower end forms medial supracondylar ridge. The medial epicondyle is a prominent bony projection on the medial side of lower end. The lateral epicondyle is smaller than the medial one and present on the lateral side of lower end. The coronoid fossa is a depression just above the anterior aspect of trochlea. The radial fossa is a depression just above the anterior aspect of capitulum. The olecranon fossa lies just above the posterior aspect of trochlea.  Anterior Posterior view view Articulations The proximal region of the humerus articulates with the glenoid fossa of the scapula to form the glenohumeral joint (shoulder joint).it is ball and socket joint. Distally, at the elbow joint, the capitulum of the humerus articulates with the head of the radius and the trochlea of the humerus articulates with the trochlear notch of the ulna. It is a hinge joint.