Class notes USMLE Bd Chaurasia's Handbook of General Anatomy
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Bd Chaurasia\'s Handbook of General Anatomy
This document will help you build the concepts of scapula and clavicle from the chapter upper limb. it will clear all the queries regarding attachments of muscle
Class notes Muskan 20 Bd Chaurasia's Handbook of General Anatomy
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1
Introduction
One pronates while giving, and supinates while getting
—Anonymous
The fore- and hindlimbs were evolved basically for PARTS OF THE UPPER LIMB
bearing the weight of the body and for locomotion as It has been seen that the upper limb is made up
is seen in quadrupeds, e.g. cows or dogs. The two pairs four parts: (1) Shoulder region; (2) arm or brachi
of limbs are, therefore, built on the same basic principle. (3) forearm or antebrachium; and (4) hand or ma
Each limb is made up of a basal segment or girdle, Further subdivisions of these parts are given in T
and a free part divided into proximal, middle and distal 1.2 and Fig. 1.1.
segments. The girdle attaches the limb to the axial
skeleton. The distal segment carries five digits.
Table 1.1 shows homologous parts of upper and lower
limbs.
However, with the evolution of the erect posture in
man, the function of weight-bearing was taken over by
the lower limbs. Thus the upper limbs, especially the
hands, became free and gradually evolved into organs
having great manipulative skills.
This has become possible because of a wide range of
mobility at the shoulder. The whole upper limb works
as a jointed lever. The human hand is a grasping tool.
It is exquisitely adaptable to perform various complex
functions under the control of a large area of the brain.
The unique position of man as a master mechanic of
the animal world is because of the skilled movements
of his hands.
Table 1.1: Homologous parts of the limbs
Upper limb Lower limb
1. Shoulder girdle Hip girdle
2. Shoulder joint Hip joint
3. Arm with humerus Thigh with femur
4. Elbow joint Knee joint
5. Forearm with radius and ulna Leg with tibia and fibula
6. Wrist joint Ankle joint
7. Hand with Foot with
a. Carpus a. Tarsus
b. Metacarpus b. Metatarsus
c. 5 digits c. 5 digits
Fig. 1.1: Parts and 32 bones of the upper limb
3
, UPPER LIMB
4
Table 1.2: Parts of the upper limb
Parts Subdivisions Bones Joints
1. Shoulder region a. Pectoral region on the Bones of the shoulder girdle • Sternoclavicular join
front of the chest a. Clavicle • Acromioclavicular jo
b. Axilla or armpit b. Scapula
c. Scapular region on the
back
2. Upper arm (arm or brachium) — Humerus Shoulder joint
from shoulder to the elbow (scapulohumeral joint)
3. Forearm (antebrachium) — a. Radius • Elbow joint
from elbow to the wrist b. Ulna • Radioulnar joints
4. Hand a. Wrist • Carpus, made up of • Wrist joint
8 carpal bones (radiocarpal joint)
• Intercarpal joints
b. Hand proper • Metacarpus, made up of • Carpometacarpal joi
5 metacarpal bones
c. Five digits, numbered • 14 phalanges—two for • Intermetacarpal join
from lateral to medial side the thumb, and three for
First = Thumb or pollex each of the four fingers • Metacarpophalange
Second = Index or forefinger joints
Third = Middle finger • Proximal and distal
Fourth = Ring finger interphalangeal join
Fifth = Little finger
1 The shoulder region includes: 4 The hand (manus) includes:
a. The pectoral or breast region on the front of the chest; a. The wrist or carpus, supported by 8 carpal bo
b. The axilla or armpit; and arranged in two rows.
c. The scapular region on the back comprising parts b. The hand proper or metacarpus, supported b
around the scapula. metacarpal bones.
The bones of the shoulder girdle are the clavicle and c. Five digits (thumb and four fingers). Each fin
the scapula. is supported by three phalanges, but the thu
Of these, only the clavicle articulates with the axial has only 2 phalanges (there being 14 phalan
skeleton at the sternoclavicular joint. The scapula is in all).
mobile and is held in position by muscles. The The carpal bones form the wrist joint with the rad
clavicle and scapula articulate with each other at the intercarpal joints with one another, and carpom
acromioclavicular joint. carpal joints with the metacarpals.
2 The arm (upper arm or brachium) extends from the The phalanges form metacarpophalangeal joints w
shoulder to the elbow (cubitus). The bone of the arm the metacarpals and interphalangeal joints with
is the humerus. Its upper end meets the scapula and another.
forms the shoulder joint. The shoulder joint permits Movements of the hand are permitted chiefly at
wrist joint. The thumb moves at the first carpom
Upper Limb
movements of the arm.
3 The forearm (antebrachium) extends from the elbow carpal joint; where an exclusive movemen
to the wrist. The bones of the forearm are the radius opposition besides the other usual movement
and the ulna. At their upper ends, they meet the permitted. Each of the second to fifth digits move
lower end of the humerus to form the elbow joint. metacarpophalangeal, proximal and distal in
Their lower ends meet the carpal bones to form the phalangeal joints. Figure 1.2 and Flowchart 1.1 sh
wrist joint. The radius and ulna meet each other at the lines of force transmission.
the radioulnar joints.
The elbow joint permits movements of the forearm, EVOLUTION OF UPPER LIMBS
1
namely flexion and extension. The radioulnar joints The forelimbs have evolved from the pectoral fin
Section
permit rotatory movements of the forearm called fishes. In tetrapods (terrestrial/land vertebrates), al
pronation and supination. In a mid-flexed elbow, the four limbs are used for supporting body weight, and
palm faces upwards in supination and downwards locomotion. In arboreal (tree-dwelling) human an
in pronation. During the movement of pronation, the tors, the forelimbs have been set free from their wei
radius rotates around the ulna (see Fig. 10.23). bearing function. The forelimbs, thus ‘emancipat
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