Humerus Bone Anatomy
Humerus: The humerus is the long bone in the upper arm. It is located between the elbow joint and the shoulder. At the elbow, it connects primarily to the ulna, as the forearm’s radial bone connects to the wrist. At the shoulder, the humerus connects to the frame of the body via the glenoid fossa of the scapula. The humerus is the foundation to which many muscles insert, such as the deltoid, the pectoralis major, and others. The brachial artery travels most of the bone’s length, before it subdivides into the ulnar and radial arteries at the elbow.
In the upper arm, the brachial artery branches into several arteries, distributing oxygenated blood from the lungs and heart. The radial nerve runs a similar course over the bone and into the forearm. Because it connects at the shoulder with a rotational joint, the humerus is instrumental in supporting many of the arm’s functions. For example, the humerus supports all lifting and physical activities. The humerus is one of the longest bones in the body. This means it is also one of the most commonly broken or fractured.
The proximal humerus is marked by a head, anatomical neck, surgical neck, greater and lesser tubercles 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 tubercles by the anatomical neck.
The greater tubercle 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 tubercle.
The lesser tubercle is much smaller, and more medially located on the bone. It only has an anterior surface. It provides attachment for the last rotator cuff muscle – the subscapularis.
Separating the two tubercles 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. This can be remembered with the mnemonic “a lady between two majors”, with latissimus dorsi attaching between teres major on the medial lip and pectoralis major laterally.
The surgical neck runs from just distal to the tubercles to the shaft of the humerus. The axillary nerve and circumflex humeral vessels lie against the bone here.
Humerus, long bone of the upper limb or forelimb of land vertebrates that forms the shoulder joint above, where it articulates with a lateral depression of the shoulder blade (glenoid cavity of scapula), and the elbow joint below, where it articulates with projections of the ulna and the radius.
In humans the articular surface of the head of the humerus is hemispherical; two rounded projections below and to one side receive, from the scapula, muscles that rotate the arm. The shaft is triangular in cross section and roughened where muscles attach. The lower end of the humerus includes two smooth articular surfaces (capitulum and trochlea), two depressions (fossae) that form part of the elbow joint, and two projections (epicondyles). The capitulum laterally articulates with the radius; the trochlea, a spool-shaped surface, articulates with the ulna. The two depressions—the olecranon fossa, behind and above the trochlea, and the coronoid fossa, in front and above—receive projections of the ulna as the elbow is alternately straightened and flexed. The epicondyles, one on either side of the bone, provide attachment for muscles concerned with movements of the forearm and fingers.
The humerus is the largest bone of the upper extremity and defines the human brachium (arm). It articulates proximally with the glenoid via the glenohumeral (GH) joint, and distally with the radius and ulna at the elbow joint. The most proximal portion of the humerus is the head of the humerus, which forms a ball and socket joint with the glenoid cavity on the scapula. Just inferior to the head of the humerus is the anatomical neck of the humerus, which divides the head of the humerus from the greater and lesser tubercles. The anatomical neck of the humerus is the residual epiphyseal plate. An intertubercular groove is located proximally, which demarcates the two tubercles vertically. Following the tubercles is the surgical neck of the humerus, a site commonly susceptible to fractures.
Continuing distally is the cylindrical-shaped shaft of the humerus, which contains a deltoid tubercle on its lateral aspect and a radial groove on its posterior aspect (also referred to as the spiral groove). At the distal portion of the humerus, there exists a widening of the bone that forms the medial and lateral epicondyles. The distal portion of the humerus ends with an area referred to as the condyle which is composed of the trochlea, capitulum, olecranon, coronoid and radial fossae. On the anterior lateral surface of the condyle is the lateral capitulum which articulates with the head of the radius bone, and on the anterior medial surface of the condyle is the trochlea which articulates the trochlear notch of the ulna bone. The coronoid fossa is located superior to the trochlea and accommodates the coronoid process of the ulna and superior to the capitulum on the anterior surface of the condyle, is the radial fossa which receives with the head of the radius, both upon flexion of the elbow joint. On the posterior surface of the condyle is the olecranon fossa which articulates with the olecranon of the ulnar bone upon flexion of the elbow joint.
Structure and Function
Mouse humeri are dissected and transversely sectioned along the mid-diaphysis into two halves (Fig. 19.6) using a diamond saw under constant irrigation with water. The proximal half of the humerus is used, and the head of the humerus is secured in dental cement using a specially made ABS mold system in order to mount the bone sample in the bending tester. The securing process involves applying a dental adhesive to the humeral head and placing it upright into the dental cement within an ABS mold, where the cement was set with a couple of minutes. If UV-curable cements are used, the set period is a few seconds, but a lead shield needs to be placed over the middle region of the sample during curing to avoid changing the material properties of the tissue during UV radiation. Using a diamond wire saw, the bone is further sectioned along the long axis (from the mid-diaphysis to the dental block surface) of the humerus. This procedure generates an elongated cantilever bending strut of ~ 5 mm length (L), ~ 200 μm thickness (b), and ~ 500 μm in width (d) from the anterior quadrant of the humerus. Samples are wrapped in phosphate-buffered solution-soaked tissue paper and stored at − 200 °C until required (approximately 1 week) for mechanical testing.
The humeral head articulates with the glenoid fossa of the scapula and forms the glenohumeral joint, a synovial ball and socket joint. This joint allows movement along multiple planes, including internal and external rotation, abduction and adduction, flexion and extension, and is principally determined by activation of the rotator cuff muscles (teres minor, subscapularis, supraspinatus, infraspinatus) pectoralis major and deltoid. The glenohumeral joint contains multiple synovial bursae that allow frictionless mobility, including the subacromial, subdeltoid, subcoracoid and coracobrachial bursae. The coracoacromial and acromioclavicular ligaments stabilize the GH joint; these prevent proximal migration of the humerus.
Why is it called the humerus bone?
Where did the humerus bone get it’s name? HUMERUS: The bone of the upper arm, extending from the shoulder-joint to the elbow-joint; the homogenetic bone in other vertebrates. From Latin (more correctly umerus) = shoulder, (rarely) upper arm.]
What is the humerus also known as?
The humerus — also known as the upper arm bone — is a long bone that runs from the shoulder and scapula (shoulder blade) to the elbow.