Upper extremity of humerus

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Upper extremity of humerus
Humeral-head-anterior-posterior.png
Left humerus. Anterior and posterior views.
Details
Identifiers
Latin Extremitas proximalis humeri
FMA 23362
Anatomical terms of bone

The upper or proximal extremity of the humerus consists of the bone's large rounded head joined to the body by a constricted portion called the neck, and two eminences, the greater and lesser tubercles.

Contents

Humeral head

The head (caput humeri), is nearly hemispherical in form. It is directed upward, medialward, and a little backward, and articulates with the glenoid cavity of the scapula to form the glenohumeral joint (shoulder joint). The circumference of its articular surface is slightly constricted and is termed the anatomical neck, in contradistinction to a constriction below the tubercles called the surgical neck which is frequently the seat of fracture. Fracture of the anatomical neck rarely occurs. [1] The diameter of the humeral head is generally larger in men than in women.

Anatomical neck

The anatomical neck (collum anatomicum) is obliquely directed, forming an obtuse angle with the body. It is best marked in the lower half of its circumference; in the upper half it is represented by a narrow groove separating the head from the tubercles. It affords attachment to the articular capsule of the shoulder-joint, and is perforated by numerous vascular foramina. Fracture of the anatomical neck rarely occurs. [1]

The anatomical neck of the humerus is an indentation distal to the head of the humerus on which the articular capsule attaches.

Tubercles

The greater tubercle (tuberculum majus; greater tuberosity) is situated lateral to the head and lesser tubercle, and just lateral to the anatomical neck. Its upper surface is rounded and marked by three flat impressions: the highest of these gives insertion to the supraspinatus muscle; the middle to the infraspinatus muscle; the lowest one, and the body of the bone for about 2.5 cm. below it, to the teres minor muscle. The lateral surface of the greater tubercle is convex, rough, and continuous with the lateral surface of the body. [1]

The lesser tuberosity or lesser tubercle (tuberculum minus; lesser tuberosity), although smaller, is more prominent than the greater: it is situated in front, and is directed medialward and forward. Above and in front it presents an impression for the insertion of the tendon of the subscapularis muscle. [1]

Bicipital groove

The tubercles are separated from each other by a deep groove, the bicipital groove (intertubercular groove), which lodges the long tendon of the biceps brachii muscle and transmits a branch of the anterior humeral circumflex artery to the shoulder-joint. It runs obliquely downward, and ends near the junction of the upper with the middle third of the bone. In the fresh state its upper part is covered with a thin layer of cartilage, lined by a prolongation of the synovial membrane of the shoulder-joint; its lower portion gives insertion to the tendon of the latissimus dorsi muscle. It is deep and narrow above, and becomes shallow and a little broader as it descends. Its lips are called, respectively, the crests of the greater and lesser tubercles (bicipital ridges), and form the upper parts of the anterior and medial borders of the body of the bone. [1]

Surgical neck

The surgical neck is a narrow area distal to the tubercles that is a common site of fracture. It makes contact with the axillary nerve and the posterior humeral circumflex artery.

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Related Research Articles

Femur

The femur, or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and kneecap, forming the knee joint. By most measures the two femurs are the strongest bones of the body, and in humans, the longest.

Ulna

The ulna is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. It runs parallel to the radius, the other long bone in the forearm. The ulna is usually slightly longer than the radius, but the radius is thicker. Therefore the radius is considered to be the larger of the two.

Humerus Long bone of the upper arm

The humerus is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes. The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes, and 3 fossae. As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.

Biceps

The biceps is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. Both heads of the muscle arise on the scapula and join to form a single muscle belly which is attached to the upper forearm. While the biceps crosses both the shoulder and elbow joints, its main function is at the elbow where it flexes the forearm and supinates the forearm. Both these movements are used when opening a bottle with a corkscrew: first biceps screws in the cork (supination), then it pulls the cork out (flexion).

Axillary nerve

The axillary nerve or the circumflex nerve is a nerve of the human body, that originates from the brachial plexus at the level of the axilla (armpit) and carries nerve fibers from C5 and C6. The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein to innervate the deltoid and teres minor.

Tibia

The tibia, also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates, and it connects the knee with the ankle bones. The tibia is found on the medial side of the leg next to the fibula and closer to the median plane or centre-line. The tibia is connected to the fibula by the interosseous membrane of the leg, forming a type of fibrous joint called a syndesmosis with very little movement. The tibia is named for the flute tibia. It is the second largest bone in the human body next to the femur. The leg bones are the strongest long bones as they support the rest of the body.

Shoulder Part of the body

The human shoulder is made up of three bones: the clavicle (collarbone), the scapula, and the humerus as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints. The shoulder joint, also known as the glenohumeral joint, is the major joint of the shoulder, but can more broadly include the acromioclavicular joint. In human anatomy, the shoulder joint comprises the part of the body where the humerus attaches to the scapula, and the head sits in the glenoid cavity. The shoulder is the group of structures in the region of the joint.

Deltoid muscle

The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, it appears to be made up of three distinct sets of fibers, namely 1. anterior or clavicular part 2. posterior or scapular part 3. intermediate or acromial part. However, electromyography suggests that it consists of at least seven groups that can be independently coordinated by the nervous system.

Radius (bone)

The radius or bot bone is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is usually slightly longer than the radius, but the radius is thicker. Therefore the radius is considered to be the larger of the two. It is a long bone, prism-shaped and slightly curved longitudinally.

Teres minor muscle

The teres minor is a narrow, elongated muscle of the rotator cuff. The muscle originates from the lateral border and adjacent posterior surface of the corresponding right or left scapula and inserts at both the greater tubercle of the humerus and the posterior surface of the joint capsule.

Talus bone

The talus, talus bone, astragalus, or ankle bone is one of the group of foot bones known as the tarsus. The tarsus forms the lower part of the ankle joint. It transmits the entire weight of the body from the lower legs to the foot.

Shoulder joint Synovial ball and socket joint in the shoulder

The shoulder joint is structurally classified as a synovial ball and socket joint and functionally as a diarthrosis and multiaxial joint. It involves articulation between the glenoid cavity of the scapula and the head of the humerus.

Subscapularis muscle Large triangle muscle of the shoulder

The subscapularis is a large triangular muscle which fills the subscapular fossa and inserts into the lesser tubercle of the humerus and the front of the capsule of the shoulder-joint.

Bicipital groove Groove in the humerus bone

The bicipital groove is a deep groove on the humerus that separates the greater tubercle from the lesser tubercle. The bicipital groove lodges the long tendon of the biceps brachii between the tendon of the pectoralis major on the lateral lip and the tendon of the teres major on the medial lip. It also transmits a branch of the anterior humeral circumflex artery to the shoulder joint.

Body of humerus Structure of long bone in the arm that runs from the shoulder to the elbow

The body or shaft of the humerus is almost cylindrical in the upper half of its extent, prismatic and flattened below, and has three borders and three surfaces.

Greater tubercle Bony projection on the proximal end of the humerus

The greater tubercle of the humerus is situated lateral to the head of the humerus and posterolateral to the lesser tubercle.

Glenohumeral ligaments

In human anatomy, the glenohumeral ligaments (GHL) are three ligaments on the anterior side of the glenohumeral joint. Reinforcing the anterior glenohumeral joint capsule, the superior, middle, and inferior glenohumeral ligaments play different roles in the stability of the head of the humerus depending on arm position and degree of rotation.

Surgical neck of the humerus Constriction below the tubercles of the greater tubercle and lesser tubercle, and above the deltoid tuberosity

The surgical neck of the humerus is a constriction below the tubercles of the greater tubercle and lesser tubercle, and above the deltoid tuberosity.

Outline of human anatomy Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

In the human skeleton and that of at least other mammals, a tubercle, tuberosity or apophysis is a protrusion or eminence that serves as an attachment for skeletal muscles. The muscles attach by tendons, where the enthesis is the connective tissue between the tendon and bone. A tuberosity is generally a larger tubercle.

References

This article incorporates text in the public domain from page 209 of the 20th edition of Gray's Anatomy (1918)