PELVIC GRIDLE
MINISTRYOF
EDUCATION AND SCIENCE OF KYRGYZ REPUPLIC
OSH STATE UNIVERSITY
PELVIC GRIDLE
TEACHER: Mitalipova A.N.
STUDENT: V.RAJPRIYA
GROUP: 14A
Shoulder girdle
The
shoulder girdle[4] or pectoral girdle,[5] composed of the clavicle and the scapula, connects the upper limb to the axial skeleton through the sternoclavicular
joint (the only
joint in the upper limb that directly articulates with the trunk), a ball and
socket joint supported by the subclavius muscle which acts as a dynamic ligament. While this muscle prevents
dislocation in the joint, strong forces tend to break the clavicle instead.
The acromioclavicular
joint, the joint
between the acromion process on the scapula and the
clavicle, is similarly strengthened by strong ligaments, especially the coracoclavicular ligament which prevents excessive lateral
and medial movements. Between them these two joints allow a wide range of
movements for the shoulder girdle, much because of the lack of a bone-to-bone
contact between the scapula and the axial skeleton. The pelvic girdle is, in contrast, firmly fixed to
the axial skeleton, which increases stability and load-bearing
capabilities. [5]
The
mobility of the shoulder girdle is supported by a large number of muscles. The
most important of these are muscular sheets rather than fusiform or
strap-shaped muscles and they thus never act in isolation but with some fibres acting in coordination with fibres in other
muscles.[5]
Shoulder joint
The glenohumeral joint (colloquially called the
shoulder joint) is the highly mobile ball and socket joint between the glenoid
cavity of the scapula and the head of the humerus. Lacking the passive stabilisation offered by ligaments in other joints,
the glenohumeral joint is actively stabilised by the rotator cuff, a group of short
muscles stretching from the scapula to the humerus. Little inferior support is available
to the joint and dislocation of the shoulder almost exclusively occurs in this
direction. [6]
The large muscles acting at this joint
perform multiple actions and seemingly simple movements are often the result of
composite antagonist and protagonist actions from several muscles. For example,
pectoralis major is the most important arm flexor and latissimus dorsi the most important extensor at the glenohumeral joint, but, acting together, these two
muscles cancel each other's action leaving only their combined medial rotation
component. On the other hand, to achieve pure flexion at the joint the deltoid
and supraspinatus must cancel the adduction component and the teres minor and infraspinatus the medial rotation component of
pectoralis major. Similarly, abduction (moving the arm away from the body) is
performed by different muscles at different stages. The first 10° is performed
entirely by the supraspinatus, but beyond that fibres of the much
stronger deltoid are in position to take over the work until 90°. To achieve
the full 180° range of abduction the arm must be rotated medially and the
scapula most be rotated about itself to direct the glenoid cavity upward.
Forearm
Most of the large number of muscles in
the forearm are divided into the wrist, hand, and finger extensors on the
dorsal side (back of hand) and the ditto flexors in the superficial layers on
the ventral side (side of palm). These muscles are attached to either the
lateral or medial epicondyle of the humerus. They thus act on the elbow, but,
because their origins are located close to the centre of rotation of
the elbow, they mainly act distally at the wrist and hand. Exceptions to this
simple division are brachioradialis — a strong elbow flexor — and palmaris
longus — a weak wrist flexor which mainly acts to tense the palmar aponeurosis.
The deeper flexor muscles are extrinsic hand muscles; strong flexors at the
finger joints used to produce the important power grip of the hand, whilst
forced extension is less useful and the corresponding extensor thus are much
weaker. [8]
Biceps is the major supinator (drive a
screw in with the right arm) and pronator teres and pronator quadratus the major
pronators (unscrewing) — the latter two role the radius around the ulna (hence
the name of the first bone) and the former reverses this action assisted by
supinator. Because biceps is much stronger than its opponents, supination is a
stronger action than pronation (hence the direction of screws)
Neurovascular system
The motor and sensory supply of the
upper limb is provided by the brachial plexus which is formed by the ventral
rami of spinal nerves C5-T1. In the posterior triangle of the neck these rami
form three trunks from which fibers enter the axilla region (armpit) to
innervate the muscles of the anterior and posterior compartments of the limb.
In the axilla, cords are formed to split into branches, including the five
terminal branches listed below. [11] The
muscles of the upper limb are innervated segmentally proximal to distal so that
the proximal muscles are innervated by higher segments (C5–C6) and the distal
muscles are innervated by lower segments (C8–T1). [12]
Motor innervation of upper limb by
the five terminal nerves of the brachial plexus
PELVIC GRIDLE
Neurovascular system
The motor and sensory supply of the
upper limb is provided by the brachial plexus which is formed by the ventral
rami of spinal nerves C5-T1. In the posterior triangle of the neck these rami
form three trunks from which fibers enter the axilla region (armpit) to
innervate the muscles of the anterior and posterior compartments of the limb.
In the axilla, cords are formed to split into branches, including the five
terminal branches listed below. [11] The
muscles of the upper limb are innervated segmentally proximal to distal so that
the proximal muscles are innervated by higher segments (C5–C6) and the distal
muscles are innervated by lower segments (C8–T1). [12]
Motor innervation of upper limb by
the five terminal nerves of the brachial plexus:[
THE END
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