Trapezoid

The trapezoid bone  or lesser multangular bone is smallest bone in the distal row. [See fig].

It is s wedge-shaped and has having four articular facets touching each other, and separated by sharp edges.

Surfaces and Articulations

The superior surface, quadrilateral, smooth, and slightly concave, articulates with the scaphoid.

The inferior surface articulates with the proximal end of the second metacarpal bone.

The dorsal and palmar surfaces are rough for the attachment of ligaments, the former being the larger of the two.

The lateral surface articulates with the trapezium.

The medial surface is concave and smooth in front, for articulation with the capitate rough behind, for the attachment of an interosseous ligament.

Capitate

Capitatetate bone is the largest of the carpal bones, and occupies  the distal row in the center of the wrist.

It has

• A rounded portion or head, which is received into the concavity formed by the scaphoid and lunate bones
• A constricted portion or neck
• The body. The bone is also found in many other mammals, and is homologous with the “third distal carpal” of reptiles and amphibians.

Capitatus in Latin means having a head.

Surfaces & Articulations

The superior surface is round, smooth, and articulates with the lunate bone.

The inferior surface is divided by two ridges into three facets, for articulation with the second, third, and fourth metacarpal bones, that for the third being the largest.

The dorsal surface is broad and rough.

The volar surface is narrow, rounded, and rough, for the attachment of ligaments and a part of the Adductor pollicis muscle.

The lateral surface articulates with the trapezoid by a small facet at its anterior inferior angle.

The medial surface articulates with the hamate nt.

The capitate articulates with seven bones

• Scaphoid and lunate proximally
• Second, third and fourth metacarpal distally
• Trapezoid on the radial side, and hamate on the ulnar side.

Hamate

The hamate bone (unciform bone) is a  wedge-shaped bone and has a hook-like process which projects from its volar surface. It is situated at the medial most side of distal row of carpal bones. It has a downward base that rests on the 4thand 5th metacarpal bones, and apex is  directed upward and lateralward.

In Latin hamatus  means hooked.

The superior surface, the apex of the wedge, is narrow, convex, smooth, and articulates with the lunate.

The inferior surface articulates with the fourth and fifth metacarpal bones, by concave facets which are separated by a ridge.

The dorsal surface is triangular and rough for ligamentous attachment.

The volar surface presents, at its lower and ulnar side, a curved, hook-like process, the hamulus, directed forward and lateralward.

The medial surface articulates with the triquetral bone by an oblong facet, cut obliquely from above, downward and medialward.

The lateral surface articulates with the capitate by its upper and posterior part, the remaining portion being rough, for the attachment of ligaments

Hamate bone fracture is a common injury in baseball players. Radiological identification of hamate is used to do estimation of age.

Diffuse Idiopathic Skeletal Hyperostosis

Diffuse idiopathic skeletal hyperostosis, also called Forestier’s disease is characterized by unique, flowing (wave like in shape) calcification along the sides of the vertebrae of the spine. It is also commonly associated with inflammation and calcification of tendons at their attachments points to bone, a condition called enthesitis. Enthesitis can frequently lead to bone spurs such as heel spurs.

Usually the disease occurs after fifth decade of life. [Read more]

Scaphoid

The scaphoid bone is the largest bone of the proximal row of wrist bones and is situated at the radial (radius bone) side of the carpus [See fig below].

It is approximately the size and shape of a medium sized cashew and its long axis is directed  from above downward, lateralward, and forward.

Skaphe means “a boat,” and  eidos means “form” in Greek. The name scaphoid is derived by combining two words signifying its shape.

Surfaces & Articulations

The superior surface is convex, smooth, of triangular shape, and articulates with the lower end of the radius.

The inferior surface, directed downward, lateralward, and backward, is also smooth, convex, and triangular, and is divided by a slight ridge into two parts, the lateral articulating with the trapezium, the medial with the trapezoid.

On the dorsal surface is a narrow, rough groove, which runs the entire length of the bone, and serves for the attachment of ligaments.

The volar surface is concave above, and  has a tubercle, which is directed forward and gives attachment to the transverse carpal ligament and sometimes origin to a few fibers of the abductor pollicis brevis.

The lateral surface is rough and narrow, and gives attachment to the radial collateral ligament of the wrist.

The medial surface presents two articular facets; of these, the superior  articulates with the lunate bone the inferior for the head of the capitate bone.

The distal convex surface articulates with trapezium and trapezoid.

Scaphoid receives its blood supply primarily from radial artery and is the most commonly fracture.

What Is Halo Vest?

A halo is a ring that is encircles the head and is fixed to it by means of pins that are inserted in the head. It is also known as “halo ring” or “halo crown,”.
This device is used in management of cervical spine diseases where spine needs external stabilization. Halo ring can be used to put traction on the cervical spine or to provide external support and immobilization. In the latter case the ring is attached to a brace that encircles patient’s torso and the whole assembly is termed as halo vest. [Read more]

Scapholunate ligament

The scapholunate ligament is an intraarticular ligament binding the scaphoid and lunate bones of the wrist together.

It is the main stabilizer of the scaphoid. In contrast to the scapholunate ligament,  Complete rupture of this ligament may occur following injury due to fall on outstretched hand and leads to wrist instability.

Untreated, over time, collapse and cause premature wear of the joint cartilage and arthritis may occur due to instability and abnormal motion.

Triquetral

The triquetral bone (also called triquetrum bone, pyramidal bone, three-cornered bone, and triangular bone) is located in the wrist on the medial side of the proximal row of the carpus between the lunate and pisiform bones. [See below]

It is on the ulnar side of the hand and articulates connects with the pisiform, hamate, and lunate bones. It is the 3rd most commonly fractured carpal bone.</p>

The triangular bone may be distinguished by its pyramidal shape, and by an oval isolated facet for articulation with the pisiform bone.

In  Latin triquetrus which means “three-cornered.”

The superior surface presents a medial, rough, non-articular portion, and a lateral convex articular portion which articulates with the triangular articular disk of the wrist.

The inferior surface, directed lateralward, is concave, sinuously curved, and smooth for articulation with the hamate. The dorsal surface is rough for the attachment of ligaments.

The volar surface presents, on its medial part, an oval facet, for articulation with the pisiform; its lateral part is rough for ligamentous attachment.

The lateral surface, the base of the pyramid, is marked by a flat, quadrilateral facet, for articulation with the lunate.

The medial surface, the summit of the pyramid, is pointed and roughened, for the attachment of the ulnar collateral ligament of the wrist.

Surgery In Upper Cervical Spine Injury

Surgery in cervical spine injuries consist of following procedurtes either alone or in combination.

• Decompression
• Osteosynthesis of a fracture and arthrodesis of vertebral motion segments.

The choice of procedure is dependent on the nature of injury and the profile of the patient.

Decompression

Decompression of neural elements in upper cervical spine fractures is rarely necessary. Decompression should be performed only if indirect fracture reduction maneuvers fail and if compression of neural elements from bony elements remains.

The approach to dempression  can be anterior or posterior depending upon the offending structure.

Osteosynthesis

Repair of the fracture fragments using internal fixation is indicated in very few cases in upper cervical spine. These injuries are type II odontoid fractures and type II  traumatic spondylolisthesis of the axis.

Arthrodesis

Arthrodesis is fusion of the vertebrae and along with instrumentation, it is most common surgery employed in cervical spine injuries.

The most common upper cervical fusion procedure involves an atlantoaxial  fusion followed by an occipitocervical fusion. Very rarely is a C1–3 fusion indicated.

Lunate

The lunate bone  or semilunar bone is a carpal bone situated in the center of the proximal row of the carpus (wrist).  {See diagram below}

Lunate is situated between the lateral scaphoid bone and medial triquetral bone. .

The name derives from the Latin luna which means “moon”, the lunate bone looks semi-similar to a crescent moon.

The superior surface, convex and smooth, articulates with the radius.

The inferior surface is deeply concave and  articulates with the head of the capitate, and, by a long, narrow facet with the hamate.

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The dorsal and palmar surfaces are rough, for the attachment of ligaments.

The lateral surface articulates with the scaphoid.

The medial surface is marked by a smooth, quadrilateral facet, for articulation with the triangular bone (triquetral).

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