PARTS AND BONES OF UPPER LIMB

The fore and hind limbs were evolved basically for bearing the weight of the body and for locomotion as is seen in quadrupeds for example cows or dogs.

Upper limb is made up of 4 parts

1. The shoulder region

a. The pectoral or breast region on the Front of the chest.

b. The axilla or armpit

c. The scapular region on the back comprising parts around the scapula.

2. The Arm or brachium :-

The arm extends from the shoulder to the elbow. The bone of the arm is the humerus. It upper end meets the scapula and forms the shoulder joint. The shoulder joint permits movements of the arm.

3. The forearm or antebrachium :-

The forearm extends from elbow to the wrist. The bones of the forearm are the radius and ulna. At their upper ends they meet the lower end of the humerus to form the elbow joint. Their lower ends meet the carpal bones to form the wrist joint. The radius and ulna meet each other at the radioulnar joints.

4. The hand

A. The wrist or carpus supportedby 8 carpal bones arranged in 2 rows.

B. The hand proper or metacarpus supported by 5 metacarpal bones.

C. 5 digits each finger is supported by 3 phalanges.

Image

BONES OF UPPER LIMB

Out of 206 total bones in man
The upper limb 64 bones. Each side consists of 32 bones

CLAVICLE

The clavicle is a long bone. It supports the shulder so that the arm can swing cleralu qway from the trunk. The clavicle transmits the weight of the limb to the sternum. The bone has a cylindrical part called the shaft and 2 ends lateral and medial.

SEX DETERMINATION

1. In the females the calvicle is shorter

2. lighter thinner smoother and less curved than in males.

2. The midshaff circumference and the weight of the clavicle are reliable criteria for sex determination of the clavicle.

3. In females the lateral end of the clavicle is the little below the medial end in males the lateral end is either at the same level or slightly higher than tha medial end.

FEATURES

1. AT THE LATERAL END the margin of the articular surface for its acromioclavicular joint gives attachment to the joint capsule.

2. AT THE MEDIAL END the margin of the articular surface for the sternum

3. LATERAL ONE THIRD OF SHAFT

A. The anterior border gives origin to the deltoid

B. The posterior border provides insertion to the trapezius.

C. The conoid tubercle and trapezoid ridge give attachment to the conoid and trapezoid parts of the coracoclavicular ligament .

Image 2.3 a b 2.4 2.5

4. Medial two third of the shaft

A. Most of the anterior surface give origin to the pactoralis major.

B. Half of the rough superior surface gives origin to the clavicular head of the sternocleidomastoid.

C. The oval impressions on the inferior surface at the medial end gives attachement to the costoclavicular ligament.

D. The subclavian groove gives insertion to the subclavius muscle.

E. The posterior surface close to medial end gives origin to sternohyoid muscle.

Others

1. It is the only long bone that lie horizontally.

2. It is subcutaneous throughout.

3. It is the first bone to start ossifying.

4. It is the only long bone which ossifies in membrane.

5. It is the only long bone which has 2 primary centres of ossification.

6. It is generally said to have no medullary cavity but this is not always true.

7. It is occasionally by the middle supra clavicular nerve.

SCAPULA

The scapula is a thin bone placed on the postero lateral aspect of the thoracic cage. The scapula has 2 surface 3 border 3 angles 3 processes.

SIDE DETRMINATION

1. The lateral or glenoid angle is large and bears the glenoid cavity.

2. The dorsal surfave is convex and is divided by the triangular spine into the supraspinous and infraspinous fossae.

3. The thickest lateral border runs from the glenoid cavity above to the inferior angle below.

FEATURES

MUSCLES

1. The multipennate subcapularis arises from the medial two- thirds of the subscapular fossa.

2. The supraspinatus arise from the medial two thirds of the supraspinous fossa including the upper surface of the spine.

3. The infraspinatus arise from the medial two thirds of the infraspinous fossa. Including the lower surface of the spine

4. The deltoid arise from the lower border of the crest of the spine and from the lateral border of the acromion .

5. The trapezius is inserted into the upper border of the crest of the spine and into the medial border of the acromion.

6. The serratus anterior is inserted along the medial border of the costal surface.

7. The long head of the triceps brachii arises from the infraglenoid tubercle.

8. Long head of the biceps brachii arises from the supraglenoid tubercle

9. The teres minor arises from lateral border

10. Thecoracobrachialis arises from the medial part of the tip of the coracoid process.

11. The inferior belly of the omohyoid arises from the upper border near the suprascapular notch

12. The pectoralis minor is inserted into the medial border

13. The teres major arises from the lateral border

14. The levator scapulae is inserted root of spine.

15. The rhomboideus minor is inserted into the root of spine

HUMERUS

The humerus is the bone of the arm. It is the longest bone of the upper limb. It has anupperend a lower end and a shaft.

SIDE DETERMINATION

1. The upper end is rounded to form the head. The lower end is expanded from side to side and flattend from before backwards.

2. The head is directed medially upwards and backwards.

3. The lesser tubercle projects from the front of the upper end and is limited laterally by the intertubercular sulcus or bicipital groove.

RADIUS

The radius is lateral bone of the forearm and is homologous with the tibia of the lower limb. It has an upper end a lower end and a shaft.

UPPER END

BORDERS

1. The Anterior

2. The Posterior

3. The medial

SURFACES

1. The Anterior

2. The posterior

3. The lateral

LOWER END 5 surface

1. The Anterior surface

2. The posterior surface

3. The medial surface

4. The lateral surface

5. The inferior surface

SIDE DETERMINATION

1. The smaller circular upper end is concave followed by constricted neck. Just below the medial aspect of neck is the radial tuberosity.
2. The wider lower end is thick with a pointed styloid process on its lateral aspect and a prominent dorsal tubercle on its posterior surface.

ULNA

The ulna is the medial bone of the forearm and is homologous with the fibula of the lower limb. It has upper end shaft and lower end.

CARPAL BONES

The carpus is made up of 8 carpal bones which are arranged in 2 rows.

1. The proximal row

2. The scaphoid

3. The lunate

4. The triquetral

5. The pisiform

6. The distal row

7. The trapezium

8. The trapezoid

9. The capitate

10. The hamate

IDENTIFICATION

1. The scaphoid is boat shaped and has a tubercle on its lateral side.

2. The lunate is half moon shaped

3. The triquetral is pyramidal in shape

4. The pisiform is pea shaped

5. The trapezoid is quadrangular in shape

6. The trapezoid resembles the shoe of a baby

7. The carpitate is the largest carpal bone with a rounded head.

8. The hamate is wedge shaped with a hook near its base.

Milan Tomic

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