SCAPULA

The scapula also known as the shoulder bone, shoulder blade, wing bone or blade bone, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side of the body being roughly a mirror image of the other. The name derives from the Classical Latin word for trowel or small shovel, which it was thought to resemble.

The scapula forms the back of the shoulder girdle. In humans, it is a flat and thin bone, roughly triangular in shape, placed on a posterolateral aspect of the thoracic cage.

GENERAL FEATURES

SURFACES: There are two surfaces costal and dorsal.

1. Costal surface or subscapular fossa is concave and directed medially and forwards. It is marked by 3 longitudinal ridges and one more thick ridge joins the lateral border which is almost rod - like. At the upper part of the fossa is a transverse depression, where the bone appears to be bent on itself along a line at right angles to and passing through the center of the glenoid cavity, forming a considerable angle, called the subscapular angle; this gives greater strength to the body of the bone by its arched form, while the summit of the arch serves to support the spine and acromion.

COSTAL SURFACE

2. Dorsal surface gives attachment to the spine of scapula which divides the surface into smaller supraspinatous fossa and a larger infraspinatous fossa. These two are connected by spinoglenoid notch which lateral to the root of the spine.

DORSAL SURFACE

BORDERS:

1. Superior border is the shortest and thinnest; it is concave and extends from the superior angle to the base of the coracoid process. It is referred to as the cranial border in animals. At its lateral part is a deep, semicircular notch, the scapular notch, formed partly by the base of the coracoid process. This notch is converted into a foramen by the superior transverse scapular ligament and serves for the passage of the suprascapular nerve; sometimes the ligament is ossified. The adjacent part of the superior border affords attachment to the omohyoideus.

Red line is Superior Border

2. Axillary border (or "lateral border") is the thickest of the three. It begins above at the lower margin of the glenoid cavity, and inclines obliquely downward and backward to the inferior angle. At the upper end it presents the infragleniod tubercle. It is referred to as the caudal border in animals.

Lateral Border

3. Medial border (also called the vertebral border or medial margin) is the thinnest and is the longest of the three borders and extends from the superior angle to the inferior angle. In animals it is referred to as the dorsal border.

Medial Border

ANGLES

1. Superior angle of the scapula or Medial angle is covered by the trapezius muscle. This angle is formed by the junction of the superior and medial borders of the scapula. The superior angle is located at the approximate level of the second thoracic vertebra. The superior angle of the scapula is thin, smooth, rounded, and inclined somewhat lateralward, and gives attachment to a few fibers of the levator scapulae muscle.

Superior angle of Scapula

2. Inferior angle of the scapula is the lowest part of the scapula and is covered by the latissimus dorsi muscle. It moves forwards round the chest when the arm is abducted. The inferior angle is formed by the union of the medial and lateral borders of the scapula. It is thick and rough, and its posterior or back surface affords attachment to the teres major and often to a few fibers of the latissimus dorsi. The anatomical plane that passes vertically through the inferior angle is named the scapular line.

Inferior angle of Scapula

3. Lateral angle of the scapula or glenoid angle also known as the head of the scapula is the thickest part of the scapula. It is broad and bears the glenoid cavity on its articular surface which is directed forward, laterally and slightly upwards, and articulates with the head of the humerus. The inferior angle is broader below than above and its vertical diameter is the longest. The surface is covered with cartilage in the fresh state; and its margins, slightly raised, give attachment to a fibrocartilaginous structure, the glenoidal labrum, which deepens the cavity. At its apex is a slight elevation, the supraglenoid tuberosity, to which the long head of the biceps brachii is attached.

Lateral angle of Scapula

PROCESSES

1. Spine or spinous process is a triangular plate of bone with 3 borders and 2 surfaces.   It divides the dorsal surface of the scapula into the supraspinatus and infraspinatus   fossae. Its posterior border is called the crest of the spine. The crest has upper and   lower lips.

2. Acromion has 2 borders, 2 surfaces and a facet.

3. Coracoid process is directed forwards and slightly laterally.

ATTACHMENTS

MUSCLES

• Subscapularis arises from the medial 2/3rds of the subscapular fossa.
• Supraspinatus arises from medial 2/3rds of supraspinous fossa including upper surface of the spine
• Infraspinatus arises from medial 2/3rds of infraspinous fossa, including lower surface of spine.
• Deltoid arises from lower border of the crest of spine and from lateral border acromion.
• Latissimus Dorsi lower fibres originate from inferior angle of scapula.
• Trapezius is inserted into the upper border of the crest of the spine and into medial border of the acromion.
• Serratus anterior is inserted along the medial border of costal surface; 1 digitation from the superior angle to the root of the spine, 2 digitations to the medial border, 5 digitations to the inferior angle.
• The long head of biceps brachii arises from supraglenoid tubercle and the short head from the lateral part of the tip of the coracoid process.
• Coracobrachialis arises from medial part of tip of the coracoids process
• Pectoralis minor is inserted into the medial border and superior surface of coracoid process.
• The long head of triceps arises from infraglenoid tubercle
• Teres minor arises from upper 2/3rds of rough strip on the dorsal surface along the lateral border.
• Teres major arises from lower 1/3rd of rough strip on the dorsal aspect of lateral border
• Levator scapulae is inserted along the dorsal aspect of the medial border, from superior angle up to root of spine
• Rhomboideus minor is inserted into medial border (dorsal aspect) opposite to root of spine
• Rhomboideus major is inserted into the medial border (dorsal aspect) between the root of spine and inferior angle
• Inferior belly of omohyoid arises from upper border near suprascapular notch.
  

LIGAMENTS

• The margin of glenoid cavity gives attachment to the capsule of shoulder joint and to the glenoid labrum
• The margin of the facet on the medial aspect of the acromion gives attachment to the capsule of the acromioclavicular joint
• The coracoacromial ligament is attached to the lateral border of the coracoids process and to the medial side of the tip of the acromion process
• The coracohumeral ligament is attached to the root of the coracoids 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 coracoclavicular ligament is made up of 2 bands: the conoid and the trapezoid, both of which provide vertical stability. The coracoacromial ligament connects the coracoid process to the acromion.
• The suprascapular ligament bridges across the suprascapular notch and converts it into a foramen which transmits the suprascapular nerve. The suprascapular ligament lies above the ligament.
• The spinoglenoid ligament bridges the spinoglenoid notch. The suprascapular vessels and nerve pass to it.
• The acromioclavicular ligament connects the distal end of the clavicle to the acromion and provides horizontal stability
  

BURSAE

1. Scapulothoracic Bursa, between the serratus and the thorax, and
2. Subscapularis Bursa, between the subscapularis and the serratus.

OSSIFICATION

The scapula is ossified from 7 or more centers: one for the body, two for the coracoid process, two for the acromion, one for the vertebral border, and one for the inferior angle. Ossification of the body begins about the second month of fetal life, by an irregular quadrilateral plate of bone forming, immediately behind the glenoid cavity. This plate extends to form the chief part of the bone, the scapular spine growing up from its dorsal surface about the third month. Ossification starts as membranous ossification before birth. After birth, the cartilaginous components would undergo endochondral ossification. The larger part of the scapula undergoes membranous ossification. Some of the outer parts of the scapula are cartilaginous at birth and would therefore undergo endochondral ossification.

At birth, a large part of the scapula is osseous, but the glenoid cavity, the coracoid process, the acromion, the vertebral border and the inferior angle are cartilaginous. From the 15th to the 18th month after birth, ossification takes place in the middle of the coracoid process, which as a rule becomes joined with the rest of the bone about the 15th year.

Between the 14th and 20th years, the remaining parts ossify in quick succession, and usually in the following order: first, in the root of the coracoid process, in the form of a broad scale; secondly, near the base of the acromion; thirdly, in the inferior angle and contiguous part of the vertebral border; fourthly, near the outer end of the acromion; fifthly, in the vertebral border. The base of the acromion is formed by an extension from the spine; the two nuclei of the acromion unite and then join with the extension from the spine. The upper third of the glenoid cavity is ossified from a separate center (sub coracoid), which appears between the 10th and 11th years and joins between the 16th and the 18th years. Further, an epiphysial plate appears for the lower part of the glenoid cavity, and the tip of the coracoid process frequently has a separate nucleus. These various epiphyses are joined to the bone by the 25th year.

Failure of bony union between the acromion and spine sometimes occurs (see os acromiale), the junction being affected by fibrous tissue, or by an imperfect articulation; in some cases of supposed fracture of the acromion with ligamentous union, it is probable that the detached segment was never united to the rest of the bone.

Complied & Written by Dr. Palak Shah

Evolution of Human Anatomy

The human anatomy studies to explore it began from B.C. and it still continues to explore and discover more and more...

Over the years many inventions, discoveries where seen and studied but when all these started no proper tools, machines where there but yet we humans still did!

Let us being with whom and when the exploration begin...:

1. Greek Period (B.C.)

    a. Hippocrates of Cos (circa 400 B.C.), the 'Father of Medicine', is regarded as one of the founders of anatomy. 

He had two theories in his ancient school of Greek Medicine, first was Knidian which was also known as School of Medicine which mainly focused on diagnosis. The other was Koan that mainly applied general diagnosis and passive treatment, also it focused on patient care, prognosis and not on the diagnosis. 

    b. Herophilus of Chalcedon (circa 300 B.C.), is called 'Father of Anatomy'. He was a Greek physician and was one of the first to dissect the Human Body. He distinguished cerebrum from cerebellum, nerves from tendons, arteries from veins, motor from sensory nerves, described various parts of eye, meninges, torcular Herophili, fourth ventricle with calamus scriptorius, hyoid bone, duodenum, prostrate gland, etc. He was a successful teacher and wrote a book on anatomy, A special treatise of the eyes. 

2. Roman Period (A.D.)

Galen of Pergamum (Circa 130-200 A.D.) was also known as 'The Prince of Physicians', practised medicine at Rome. He wrote on many medical subjects like anatomy, physiology, pathology, symptomalogy and treatment. He wrote on anatomy "De anatomicis-administrationibus", his teachings were followed nearly 15 centuries 

3. Fourteenth Century:

Mundinus or Mondino d'Luzzi (1276-1326) alao known as the "restorer of anatomy", was an Italian anatomistand professor at University of Bologna. He wrote a book named as Anathomia, after his death, Mondino was regarded as a "divine master" to such an extent that anything differing from the descriptions in his book was regarded as anomalous or even monstrous.

4. Fifteenth Century:

Leonardo di Vinci of Italy (1452-1519) had originated the cross sectional anatomy, also was one of the greatest geniuses the world has ever known. He made the observations that humours were not located in cerebral spaces or ventricles. He documented that the humours were not contained in the heart or the liver, and that it was the heart that defined the circulatory system. He was the first to define atherosclerosis and liver cirrhosis. He created models of the cerebral ventricles with the use of melted wax and constructed a glass aorta to observe the circulation of blood through the aortic valve by using water and grass seed to watch flow patterns. The drawing of his where created by his observation on dissection named as Treatise on painting.

5. Sixteenth Century:

Vesalius (1514-1564), also known as 'Reformer of Anatomy', was a professor at Padua. He challenged traditional anatomy by applying empirical methods of cadaveric dissection to the study of the human body by Galen thus reviving anatomy after a deadlock of about 15 centuries. His anatomical treatise De Febricia Humani Corporis, written in 7 volumes, revolutionized the anatomy which remained for 2 centuries. 

6. Seventeenth Century:
William Harvey (1578-1657) was an English physician who discovered the blood circulation. His has wrote and published it as Anatomical Exercise on the Motion of the Heart and Blood in Animals, The Works of William Harvey & The Circulation of the Blood and other writings. 

7. Eighteenth Century: 

William Hunter (1718-1783) was a London anatomist and obstetrician. His greatest work was Anatomia uteri umani gravidi. He and his brother founded Hunterian Museum. 

8. Nineteenth Century:

Dissection was mandatory for medical students. Formalin was used as a fixative in 1890s.

Roentgen discovered X-rays in 1895.

Various types of Endoscopes were devised between 1819 and 1899.

Few remarkable anatomists during this century were Ashley Cooper (British Surgeon), Cuvier (French Naturalist), Meckel (German Anatomist) and Henry Gray (wrote Gray's Anatomy).

9. Twentieth Century:

Electron Microscope was invented and also its various modificationsof itswere also devised like transmission EM & SEM, etc.

Ultrasonography & echocardiography were discovered. 

CT - Scan and MRI were devised.

Tissue culture was developed. 

Infertility was discovered, which gave hopes to families Gamete Intrafallopian Transfer (GIFT) was started. 

10. Twenty First Century:

Foetal medicine and 'in-utero' treatments are emerging.

Many vaccines are researched for various diseases including COVID 19.

by Dr. Palak Shah