Anatomical terms of bone
Many anatomical terms descriptive of bone are defined in anatomical terminology, are derived from Greek and Latin. A long bone is one, cylindrical in shape, being longer than it is wide. However, the term describes the shape of a bone, not its size, relative. Long bones are found in the legs, as well as in the fingers and toes. Long bones function as levers, they are responsible for the body's height. A short bone is one, cube-like in shape, being equal in length and thickness; the only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short bones provide support as well as some limited motion; the term “flat bone” is something of a misnomer because, although a flat bone is thin, it is often curved. Examples include the cranial bones, the scapulae, the sternum, the ribs. Flat bones serve as points of attachment for muscles and protect internal organs. Flat bones do not have a medullary cavity. An irregular bone is one that does not have an classified shape and defies description.
These bones tend to have more complex shapes, like the vertebrae that support the spinal cord and protect it from compressive forces. Many facial bones the ones containing sinuses, are classified as irregular bones. A sesamoid bone is a round bone that, as the name suggests, is shaped like a sesame seed; these bones form in tendons. The sesamoid bones protect tendons by helping them overcome compressive forces. Sesamoid bones vary in number and placement from person to person but are found in tendons associated with the feet and knees; the only type of sesamoid bone, common to everybody is the kneecap, the largest of the sesamoid bones. A condyle is the round prominence at the end of a bone, most part of a joint – an articulation with another bone; the epicondyle refers to a projection near a condyle the medial epicondyle of the humerus. These terms derive from Greek. An eminence refers to a small projection or bump of bone, such as the medial eminence. A process refers to a large projection or prominent bump, as does a promontory such as the sacral promontory.
Both tubercle and tuberosity refer to a projection or bump with a roughened surface, with a "tubercle" smaller than a "tuberosity". These terms are derived from Tuber. A ramus refers to an extension of bone, such as the ramus of the mandible in the jaw or Superior pubic ramus. Ramus may be used to refer to nerves, such as the ramus communicans. A facet refers to a flattened articular surface. A line refers to a long, thin projection with a rough surface. Ridge and crest refer to a narrow line. Unlike many words used to describe anatomical terms, the word ridge is derived from Old English. A spine, as well as referring to the spinal cord, may be used to describe a long, thin projection or bump; these terms are used to describe bony protuberances in specific parts of the body. The Malleolus is the bony prominence on each side of the ankle; these are known as the lateral malleolus. Each leg is supported by two bones, the tibia on the inner side of the leg and the fibula on the outer side of the leg; the medial malleolus is the prominence on the inner side of the ankle, formed by the lower end of the tibia.
The lateral malleolus is the prominence on the outer side of the ankle, formed by the lower end of the fibula. The trochanters are parts of the femur, it may refer to the greater, lesser, or third trochanter The following terms are used to describe cavities that connect to other areas: A foramen is any opening referring to those in bone. Foramina inside the body of humans and other animals allow muscles, arteries, veins, or other structures to connect one part of the body with another. A canal is a long, tunnel-like foramen a passage for notable nerves or blood vessels; the following terms are used to describe cavities that do not connect to other areas: A fossa is a depression or hollow in a bone, such as the hypophyseal fossa, the depression in the sphenoid bone. A meatus is a short canal. A fovea is a small pit on the head of a bone. An example of a fovea is the fovea capitis of the head of the femur; the following terms are used to describe the walls of a cavity: A labyrinth refers to the bony labyrinth and membranous labyrinth, components of the inner ear, due to their fine and complex structure.
A sinus refers to a bony cavity within the skull. A joint, or articulation is the region where adjacent bones contact each other, for example the elbow, shoulder, or costovertebral joint. Terms that refer to joints include: articular process, referring to a projection that contacts an adjacent bone. Suture, referring to an articulation between cranial bones. Bones are described with the terms head, shaft and base The head of a bone refers to the proximal end of the bone; the shaft refers to the elongated sections of long bone, the neck the segment between the head and shaft. The end of the long bone opposite to the head is known as the base; the cortex of a bone is used to refer to its outer layers, medulla used to
The coracoid process is a small hook-like structure on the lateral edge of the superior anterior portion of the scapula. Pointing laterally forward, it, together with the acromion, serves to stabilize the shoulder joint, it is palpable in the deltopectoral groove between the pectoralis major muscles. The coracoid process is a thick curved process attached by a broad base to the upper part of the neck of the scapula; the ascending portion, flattened from before backward, presents in front a smooth concave surface, across which the subscapularis passes. The horizontal portion is flattened from above downward. On the medial part of the root of the coracoid process is a rough impression for the attachment of the conoid ligament, it is the site of attachment for several structures: The pectoralis minor muscle – to 3rd, 4th, 5th and on some rare occasions, 6th rib. The short head of biceps brachii muscle – to Radial tuberosity; the coracobrachialis muscle – to medial humerus. The coracoclavicular ligament – to the clavicle.
The coracoacromial ligament – to the acromion The coracohumeral ligament – to the humerus The superior transverse scapular ligament – from the base of the coracoid to the medial portion of the suprascapular notch The coracoid process is palpable just below the lateral end of the clavicle. It is otherwise known as the "Surgeon's Lighthouse" because it serves as a landmark to avoid neurovascular damage. Major neurovascular structures enter the upper limb medial to the coracoid process, so that surgical approaches to the shoulder region should always take place laterally to the coracoid process. In monotremes, the coracoid is a separate bone. Reptiles and frogs possess a bone by this name, but is not homologous with the coracoid process of mammals. Analyses of the size and shape of the coracoid process in Australopithecus africanus have shown that in this species it displayed a prominent dorsolateral tubercle placed more laterally than in modern humans; this reflect, according to one interpretation, a scapula positioned high on a funnel-shaped thorax and a clavicle positioned obliquely as in extant great apes.
Anatomy image: skel/scapula2 at Human Anatomy Lecture, Pennsylvania State University Coracoid Process - BlueLink Anatomy, University of Michigan Medical School
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 transmits a branch of the anterior humeral circumflex artery to the shoulder joint. The insertion of the latissimus dorsi is found along the floor of the bicipital groove; the teres major inserts on the medial lip of the groove. It runs obliquely downward, ends near the junction of the upper with the middle third of the bone, it is the lateral wall of the axilla. Radial groove Medial bicipital groove This article incorporates text in the public domain from page 209 of the 20th edition of Gray's Anatomy Anatomy photo:03:st-0204 at the SUNY Downstate Medical Center
Radial collateral ligament of elbow joint
The radial collateral ligament, lateral collateral ligament, or external lateral ligament is a ligament in the elbow on the side of the radius. The composition of the triangular ligamentous structure on the lateral side of the elbow varies between individuals and can be considered either a single ligament, in which case multiple distal attachments are mentioned and the annular ligament is described separately, or as several separate ligaments, in which case parts of those ligaments are described as indistinguishable from each other. In the latter case, the ligaments are collectively referred to as the lateral collateral ligament complex, consisting of four ligaments: the radial collateral ligament, from the lateral epicondyle to the annular ligament deep to the common extensor tendon the lateral ulnar collateral ligament, from the lateral epicondyle to the supinator crest on the ulna. Near the attachment on the humerus this ligament is indistinguishable from the RCL and can be considered the posterior portion of it.
Martin 1958 described the distal part of the LUCL as "a definite bundle which crosses the annular band and gains attachment to the supinator crest to a special tubercle on that crest" but didn't name it. The annular ligament, from the posterior to the anterior margins of radial notch on the ulna, encircles the head of radius and holds it against the radial notch of ulna. the accessory lateral collateral ligament. From the inferior margin of the annular ligament to the supinator crest
The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans it consists of the scapula; some mammalian species have only the scapula. The pectoral girdles are to the upper limbs. In humans, the only true anatomical joints between the shoulder girdle and the axial skeleton are the sternoclavicular joints on each side. No anatomical joint exists between the rib cage. In those species having only the scapula, no joint exists between the forelimb and the thorax, the only attachment being muscular; the shoulder girdle is the anatomical mechanism that allows for all upper arm and shoulder movement in humans. The shoulder girdle consists of five muscles that attach to the clavicle and scapula and allow for the motion of the sternoclavicular joint and acromioclavicular joint; the five muscles that comprise the function of the shoulder girdle are the trapezius muscle, levator scapulae muscle, rhomboid muscles, serratus anterior muscle, pectoralis minor muscle.
The shoulder girdle is a complex of five joints. Three of these joints are true anatomical joints. Within each group, the joints are mechanically linked so that both groups contribute to the different movements of the shoulder to variable degrees. In the first group, the scapulohumeral or glenohumeral joint is the anatomical joint mechanically linked to the physiological subdeltoid or suprahumeral joint so that movements in the suprahumeral joint results in movements in the glenohumeral joint. In the second group, the scapulocostal or scapulothoracic joint is the important physiological joint that can not function without the two anatomical joints in the group, the acromioclavicular and sternoclavicular joints, i.e. they join both ends of the clavicle. The glenohumeral joint is the articulation between the head of the humerus and the glenoid cavity of the scapula, it is a ball and socket type of synovial joint with three rotatory and three translatory degree of freedom. The glenohumeral joint allows for adduction, abduction and lateral rotation and extension of the arm.
The acromioclavicular joint is the articulation between the acromion process of the scapula and the lateral end of the clavicle. It is a plane type of synovial joint; the acromion of the scapula rotates on the acromial end of the clavicle. The sternoclavicular joint is the articulation of the manubrium of the sternum and the first costal cartilage with the medial end of the clavicle, it is functions as a plane joint. The sternoclavicular joint accommodates a wide range of scapula movements and can be raised to a 60° angle; the scapulocostal joint is a physiological joint formed by an articulation of the anterior scapula and the posterior thoracic rib cage. It is musculotendinous in nature and is formed predominantly by the trapezius and serratus anterior muscles; the pectoralis minor plays a role in its movements. The gliding movements at the scapulocostal joint are elevation, retraction and superior and inferior rotation of the scapula. Disorders of the scapulocostal joint are not common and restricted to snapping scapula.
The suprahumeral joint is a physiological joint formed by an articulation of the coracoacromial ligament and the head of the humerus. It is formed by the acromion process of the scapula; this space is filled by the subacromial bursa and the tendon of supraspinatus. This joint plays a role during complex movements while the arm is flexed at the glenohumeral joint, such as changing a lightbulb, or painting a ceiling. From its neutral position, the shoulder girdle can be rotated about an imaginary vertical axis at the medial end of the clavicle. Throughout this movement the scapula is rotated around the chest wall so that it moves 15 centimetres laterally and the glenoid cavity is rotated 40–45° in the horizontal plane; when the scapula is moved medially it lies in a frontal plane with the glenoid cavity facing directly laterally. At this position, the lateral end of the clavicle is rotated posteriorly so that the angle at the acromioclavicular joint opens up slightly; when the scapula is moved laterally it lies in a sagittal plane with the glenoid cavity facing anteriorly.
At this position, the lateral end of the clavicle is rotated anteriorly so that the clavicle lies in a frontal plane. While this closes the angle between the clavicle and the scapula, it widens the shoulder; the scapula can be elevated and depressed from the neutral position to a total range of 10 to 12 centimetres. During this tilting, the scapula rotates to a maximum angle of 60° about an axis passing perpendicularly through the bone below the spin
The infraspinatous fossa of the scapula is much larger than the supraspinatous fossa. The medial two-thirds of the fossa give origin to the Infraspinatus; this article incorporates text in the public domain from page 203 of the 20th edition of Gray's Anatomy Anatomy figure: 03:01-10 at Human Anatomy Online, SUNY Downstate Medical Center
The glenoid cavity or glenoid fossa of scapula is a part of the shoulder. It is a shallow, pyriform articular surface, located on the lateral angle of the scapula, it articulates with the head of the humerus. This cavity forms the glenohumeral joint along with the humerus; this type of joint is classified as a synovial and socket joint. The humerus is held in place within the glenoid cavity by means of the long head of the biceps tendon; this tendon originates on the superior margin of the glenoid cavity and loops over the shoulder, bracing humerus against the cavity. The rotator cuff reinforces this joint more with the supraspinatus tendon to hold the head of the humerus in the glenoid cavity; the cavity surface is covered with cartilage in the fresh state, its margins raised, give attachment to a fibrocartilaginous structure, the glenoid labrum, which deepens the cavity. This cartilage is susceptible to tearing; when torn, it is most known as a SLAP lesion, caused by repetitive shoulder movements.
Compared to the acetabulum the glenoid cavity is shallow. This makes the shoulder joint prone to dislocation. Strong glenohumeral ligaments and muscles prevents dislocation in most cases. By being so shallow the glenoid cavity allows the shoulder joint to have the greatest mobility of all joints in the body, allowing 120 degrees of unassisted flexion. Additional range of motion in shoulder flexion is accomplished by the great mobility of the scapula through a process known as scapulohumeral rhythm. Interpretations of the fossil remains of Australopithecus africanas and A. afarensis suggest that the glenoid fossa was oriented more cranially in these species than in modern humans. This reflects the importance of overhead limb postures and suggests a retention of arboreal adaptations in these hominoid primates, whereas the lateral orientation of the glenoid in modern humans reflects the typical lowered position of the arm. In dinosaurs the main bones of the pectoral girdle were the scapula and the coracoid, both of which directly articulated with the clavicle.
The place on the scapula where it articulated with the humerus is called the glenoid. The glenoid is important. Glenopolar angle This article incorporates text in the public domain from page 207 of the 20th edition of Gray's Anatomy Larson, Susan G.. "Evolution of the Hominin Shoulder: Early Homo". In Grine, Frederick E.. The First Humans – Origin and Early Evolution of the Genus Homo. Springer. Doi:10.1007/978-1-4020-9980-9. ISBN 978-1-4020-9979-3. ANATOMY & PHYSIOLOGY: THE UNITY OF FORM AND FUNCTION, SIXTH EDITION Published by McGraw-Hill Written by Kenneth Saladin http://www.ucsfhealth.org/conditions/glenoid_labrum_tear/index.html Diagram at cerrocoso.edu Anatomy figure: 03:02-07 at Human Anatomy Online, SUNY Downstate Medical Center Mechanics of Glenohumeral Instability at University of Washington Department of Orthopaedics