Shoulder Flashcards
Pectoral Gridle/ shoulder complex
title
Lever systems
Levers
Levers
use
mechanical advantage
to make lifting or applying pressure easier. All levers are made of a bar and a
pivot
, called a
fulcrum
. Levers have three main parts:
effort
- the amount of force applied by the user, also referred to as the
input
fulcrum - where the lever pivots
load
- the weight that needs to be moved, also referred to as the output
Pectoral girdle joints
3 true joints-
sternoclavicular joint (SCJ)
Acromioclavicular joint (ACJ)
Glenohumeral joint (GJ)
2 other-
Scapulthoracic articulation
Subascromial articulation
Sternoclavicular joint
synovial sellar (or saddle) joint and is the only articulation between the axial skeleton and the upper limb
acromioclavicular joint
is a synovial joint formed between the acromion of the scapula and the acromial end of the clavicle
Glenohumeral joint
is a synovial joint formed between the scapula, particularly the glenoid process, and the head of the humerus
1st Class joint lever
The first class lever is one of three classes of levers and is one possible arrangement of muscles, bones, and joints found in the human body. While less common in the body than second and third class levers, the first class lever system is found in the neck at the atlanto-occipital joint and in the elbow joint.
2nd class joint lever
the load is in the middle between the fulcrum and the effort. This type of lever is found in the ankle area. When standing on tiptoe, the ball of the foot acts as the fulcrum, the weight of the body acts as the load and the effort comes from the contraction of the gastrocnemius muscle.
3rd class joint lever
the effort is in the middle between the fulcrum and the load. Third class lever During a biceps curl, the fulcrum is the elbow joint, the effort comes from the biceps contracting and the resistance is the weight of the forearm and any weight that it may be holding.
Scapula- movement
trapezius,
levator scapulae,
rhomboids,
latissimus dori, subclavicus,
pectoralis minor,
serratus anterior,
pectoralis major
trapezius
Origin: External occipital protuberance and superior nuchal line of occipital bone, nuchal ligament, spinous processes of C7 to T12 vertebrae.
Insertion: Posterior aspect of lateral one third of clavicle, acromion, and spine of scapula.
Action: Elevates, depresses, retracts, and upwardly rotates the pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints; extends and laterally flexes head and neck.
Innervation: Accessory nerve, anterior rami of third and fourth cervical nerves.
levator scapulae
Origin: Transverse processes of C1-C2 vertebrae, posterior tubercles of transverse processes of C3-C4 vertebrae.
Insertion: Superior angle of scapula, medial border of scapula superior to spine of scapula.
Action: Elevates and downwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints; extends and laterally flexes neck at cervical vertebral joints.
Innervation: Anterior rami of third and fourth cervical nerves, dorsal scapular nerve (C5).
rhomboids
Origin: Spinous processes of T2-T5 vertebrae.
Insertion: Medial border of scapula inferior to spine of scapula.
Action: Retracts and downwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints.
Innervation: Dorsal scapular nerve (C4-C5).
latissiumus dorsi
Origin: Spinous processes of T7-T12 vertebrae, spinous processes of L1-L5 vertebrae via thoracolumbar fascia, ninth to twelfth ribs, iliac crest.
Insertion: Floor of intertubercular sulcus of humerus.
Action: Adducts, medially rotates, and extends arm at glenohumeral (shoulder) joint.
Innervation: Thoracodorsal nerve (C6-C8).
subclavius
Origin: Superior surface of costal end of first rib and adjacent first costal cartilage.
Insertion: Inferior surface of the middle one third of clavicle.
Action: Stabilizes clavicle.
Innervation: Nerve to subclavius muscle (C5-C6)
pectoralis minor
Origin: Anterior ends of third to fifth ribs.
Insertion: Coracoid process of scapula.
Action: Protracts and downwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints.
Innervation: Medial and lateral pectoral nerves (C5-T1)
serratus anterior
Origin: External surfaces of first to ninth ribs.
Insertion: Medial border of scapula.
Action: Protracts and upwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints.
Innervation: Long thoracic nerve (C5-C7).
pectoralis major
Origin: Clavicular head: anterior aspects of medial half of clavicle; Sternocostal head: manubrium, sternal body, the true ribs and their costal cartilages; Abdominal part: external abdominal oblique aponeurosis.
Insertion: Crest of greater tubercle of humerus.
Action: Adducts, medially rotates, and transversely adducts arm at glenohumeral (shoulder) joint; depresses pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints.
Innervation: Medial and lateral pectoral nerves (C5-T1).
Muscles around the glenohumeral joint
deltoid
pectoralis major
long head bicep brachii
rotator cuff muscles-
supraspinatus
infraspinatus
teres minor
subscapularis
Deltoid
Origin: Lateral one third of clavicle, acromion and spine of scapula.
Insertion: Deltoid tuberosity of humerus.
Action: Abducts, flexes, extends, and medially and laterally rotates arm at glenohumeral (shoulder) joint.
Innervation: Axillary nerve (C5-C6).
pectoralis major
Origin: Clavicular head: anterior aspects of medial half of clavicle; Sternocostal head: manubrium, sternal body, the true ribs and their costal cartilages; Abdominal part: external abdominal oblique aponeurosis.
Insertion: Crest of greater tubercle of humerus.
Action: Adducts, medially rotates, and transversely adducts arm at glenohumeral (shoulder) joint; depresses pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints.
Innervation: Medial and lateral pectoral nerves (C5-T1).
long head bicep brachii
Origin: Supraglenoid tubercle of scapula.
Insertion: Radial tuberosity and antebrachial fascia.
Action: Supinates forearm; flexes forearm at elbow joint, most effectively when the forearm is supinated.
Innervation: Musculocutaneous nerve (C5-C6).
