Osteology of the upper extremity

WINDSOR UNIVERSITY SCHOOL OF MEDICINE MD 1

dr kola

Also called Collar bone Elongated S-shaped bone Has no medullary cavity First long bone to ossify

via intramembranous ossification beginning during the 5th and 6th embryonic weeks at the shaft

2nd Ossification ends between 25 and 31 years

clavicle

Has two ends and a shaft

Sternal end also called the medial end is wedge shaped or triangular, articulates with the manubrium of sternum (sternoclavicular joint)

Acromial end is flat and articulates with the acromium of the scapula at the acromioclaviular joint

Shaft Medial two thirds of the shaft is convex

anteriorly The lateral one third is flat and concave

anteriorly

Surfaces Superior surface is smooth and lies just

deep to platysma muscle and skin.

The inferior surface is rough due to attachment of ligaments.

Towards the acromial end, the conoid tubercle gives attachment to the conoid ligament which is a part of the medial side of coracoclavicalucular ligament.

The trapezoid line also at the acromial end gives attachment to the trapezoid ligament from the lateral side of the coracoclavicalucular.

The subclavian groove-Groove for the subclavius muscle in the medial two thirds

Impression for the costoclavicular ligament-

Rough depressed oval area that attaches to the 1st rib and the clavicle

Fracture One of the most fractured bonesAn indirect blow transmitted from an

outstretched hand or a fall directly on the shoulder

Weakest part of the clavicle is the junction of the medial two thirds and the lateral one third.

Applied anatomy

The medial fragment is elevated by the sternocleiodomas-toid muscle

The lateral fragment drops

Greenstick fracture in children

Also called shoulder blade On the posteriolateral aspect of the thorax Overlies 2nd to 7th ribs 2 surfaces 3 angles 3 borders

scapula

Surfaces Posterior surface Spine:divides it into supraspinous fossa and

infraspionous Spine has a deltoild tuberoisty Ends distally in a flat acromion

Costal surface attachment for the subscapularis muscle

Borders Medial border also called vertebral border Lateral or axillary border: runs

superiolaterally towards the apex of the axilla (thickest) and ends superiorly in the lateral angle

Superior borders: thinnest and marked with a suprascapular notch near the junction of the medial two thirds and lateral one third

Arm bone Largest bone in the upper limb Articulates with the scapula and ulna

Long bones with two ends and a shaft

humerus

Proximal end

Head, neck and tubercles Head is rounded for articulataion with the

glenoid cavity of the scapula at the glenohumeral joint

Neck

Anatomical neck and surgical neck Anatomical neck is the neck that

circumscribes the head separating it from the tubercles

Line of attachment of the glenohumeral capsule

Surgical neck: distal to the head and tubercles. Easily fractured

Tubercles Greater tubercle

which is lateral Lesser tubercle

which is anterior Intertubercular

sulcus or bicipital groove which separates the two, allowing for the passage of long head of biceps brachii

Shaft has two prominent features

Deltoild tuberousity Lies laterally for attachment of deltoid

muscle

Radial groove: radial nerve and the deep artery of the arm

Inferior end of the shaft widens as the sharp medial and lateral supracondylar ridges amd med distally in the medial and altera; epicondles

Distal ends Condyle: trochlea, capitulum,

olecranon,coronoid and radial fossae together with the distal end of the humerus make up the condyle

Condyle as two articular surfaces

Radial head and capitulum Proximal end of ulna and

trochleaFossae Anteriorly coronoid fossa

recieves the coronoid process of the ulna on flexion full and radial fossa recieves the head of the radius

Posteriolry the olecranon fossa accomadates olecraon process on full extension

Surgical neck: Axillary nerve and posterior circumflex humeral artery

Midshaft: radial nerve and deep artery of the arm

Supracondylar: Median nerve and brachial artery

Avulsion of medial epicondyle: Ulnar nerve

Fractures of the humerus

Stabilizing bone of the forearm Medial and longer Proximal end for articulation Olecranon and coronoid process Inferior to the coronoid process is the ulnar

tuberosity Lateral side is the radial notch Inferior to the radial notch on the shaft is

the supinator crest and closer to it is the supinator fossa.

ulnar

Shaft is thick and cylindrical proximally but it tapers distally and ends in the ulnar styloid process

The ulna does not participate in the wrist joint

Lateral and shorter bone of forearm Proximally head of radius articulates with

capitulum of the humerus Head also articulates with radial notch of

ulnar head is covered with articular catilage The neck of the radius is a constriction

distal to the head Radial tuberosity: demarcates the head from

shaft

radius

Shaft of radius enlarges distally Distal end on the medial side has an ulnar

notch Lateral side terminates in a radial styloid

process larger then ulnar styloid process and extends farther distally

Dorsal tubercle which allows for passage of tendons

The two bones on the internal aspect have an interroseous border for attachment of the interrouseous membrane of the foream

Usually a transverse fracture at the same level:

Colle’s fracture: most common fracture. The distal fragment is displaced dorsally

Mechanism: forced dorsiflexion of the outstrecthed hand trying to ease a fall

Fracture of the forearm bones

These small bones give flexibility to the wrist.

‘ SHE LOOKS TOO PRETTY TRY TO CHASE HER’ From lateral to medial, the four carpal bones in the

proximal row are the:• Scaphoid (G. skaphé, skiff, boat): a boat-shaped

bonethat articulates proximally with the radius, and has

a prominent scaphoid tubercle; it is the largest bone in the proximal row of carpals.

Carpal bones

• Lunate (L. luna, moon): a moon-shaped bone between the scaphoid and the triquetral bones; it articulates proximally with the radius and is broader anteriorly than posteriorly.

• Triquetrum (L. triquetrus, three-cornered): a pyramidal bone on the medial side of the carpus; it articulates proximally with the articular disc of the distal radio-ulnar joint.

• Pisiform (L. pisum, pea), a small, pea-shaped bone that lies on the palmar surface of the triquetrum.

From lateral to medial, the four carpal bones in the distal row

• Trapezium (G. trapeze, table): a four-sided bone on the lateral side of the carpus; it articulates with the 1st and 2nd metacarpals, scaphoid, and trapezoid bones.

Trapezoid: a wedge-shaped bone that resembles the trapezium; it articulates with the 2nd metacarpal, trapezium, capitate, and scaphoid bones.

• Capitate (L. caput, head): a head-shaped bone with a

rounded extremity is the largest bone in the carpus; itarticulates primarily with the 3rd metacarpal distally,

and with the trapezoid, scaphoid, lunate, and hamate.

• Hamate (L. hamulus, a little hook): a wedge-shaped bone on the medial side of the hand; it articulates with the 4th and 5th metacarpal, capitate, and triquetral bones; it has a distinctive hooked process, the hook of the hamate, that extends anteriorly.

Fracture of ScaphoidMost frequently

fractured carpal bone

Pain experienced on the lateral side of the wrist mostly during dorsiflexion and abduction

Avascular necrosis can occur due to loss of blood supply to the proximal part of the scaphoid

Fracture of Hamate This may cause

injury to the ulnar nerve sometimes the ulnar artery also

It is composed of five metacarpal bones (metacarpals).

Each metacarpal consists of a base, shaft, and head.

The proximal bases of the meta carpals articulate with the carpal bones, and the distal heads of the metacarpals articulate with the proximal phalanges,

and form the knuckles of the hand. The 1st metacarpal (of the thumb)

is the thickest and shortest of these bones.

Metacarpal bones

Fracture of fifth metarcarpal

Common with unskilled boxers who punch with a closed fist

Boxers fracture

Each digit (finger) has three phalanges except for the first (the thumb), which has only two.

Each phalanx has a base proximally, a shaft (body), and a head distally.

The proximal phalanges are the largest, the middle ones are intermediate in size, and then distal ones are the smallest. The shafts of the phalanges taper distally.

The terminal phalanges are flattened and expanded at their distal ends, which underlie the nail beds.

phalanges