Lecture 3 & 4 - Pectoral Girdle and Scapular Control Flashcards
what is the shoulder/pectoral girdle?
the attachment point of the upper limb to the axial skeleton
- > it has high mobility and therefore lower stability
parts of the sternum
Upper Portion
- > manubrium
Mid Portion
- > body
Lower portion
- > xiphoid process
Joints/Articulations of the pectoral girdle
- Sternocostal
- Sternoclavicular
- Acromioclavicular
- Glenohumeral (Shoulder joint)
- Costovertebral
- (Scapulothorasic) articulation
- (interclavicular) articulation
movement of sternoclavicular joint
- > synovial saddle joint
- > Movement
* full elevation is around 60 deg
*ant/post, protraction/retraction and small amounts of rotational movement
ligaments of the sternoclavicular joint and how they each limit motion
- Interclavicular ligament
- > limits sup and lateral displacement of clavicle - Sternoclavicular ligament
- > limits ant and post gliding of clavicle - Costoclavicular ligament
- > main support limits all ROM except depression
Parts of the clavicle
movements of the acromioclavicular joint and what’s its main function
synovial plane joint, gliding motions
- > serves as a restriction too over-head arm movements; scapular movements with respect to the clavicle
- > up/downward in/external rotation
- > ant/posterior tilting or tipping
ligaments of the acromioclavicular joint and how they limit motion
Coracoclavicular ligament
- > conoid and trapezoid
- > primary retraint to vertical displacement
Acromioclavicular lig
- > prevents separation of clavicle and scapula, and posterior displacement
Coracoacromial lig
- > forms roof over glenohumeral joint
- > provides limit to superior humeral head movement
- > protects bursa and supraspinatus tendons
scapulothoracic joint movements
- > physiological joint
movm’t in three directions
- pro/retraction (also known as add/abduction)
- sup/inf rotation (also known as up/downwards rot)
- elevation/depression
function of scapulothoracic joint and explain scapulo-humeral rhythm
allows arm to abduct beyond the 120deg allowed by the glenohumeral joint alone
Scapulo-humeral rhythm
- > 1deg of scapular rotation for ever 2deg of humeral abduction
layout of the structures of the pectoral girdle in anatomical position
- > clavicle is 20deg posterior to frontal plane
- > scapula is oriented 35 degrees anterior to the frontal plane
primary muscles involved with protraction and retraction of the scapula
Protraction
- > serratus anterior (also holds scapula against thoracic wall)
- > pectoralis major and minor
Retraction
- > trapezius (middle part)
- > rhomboids
origin and insertion points of the serratus anterior
Origin
- > external surfaces of the lateral parts of ribs 1-8 (ser(8)tus)
Insertion
- > anterior surface of the medial border of the scapula
actions of the serratus anterior and what innervates this muscle
- > it protracts the scapula and hold it against the thoracic wall
- > rotates the scapula in an upwards direction
- > it is innervated by the long thoracic nerve
origin and insertion of pectoralis major
Origin
- > clavicular head: anterior surface of the medial half of the clavicle
- > sternocostal head: anterior surface of the sternum
Insertion
- > lateral lip of the intertubuercular/bicepital groove of the humerus
actions of pectoralis major and how its innervated
- > adducts and medially rotates the humerus
- > draws the scapula anteriorly and inferiorly
- > innervated by the lateral and medial pectoral nerves
origin and insertion, actions of pectoralis minor and how its innervated
Origin
- > anterior surface of ribs 3,4,5
Insertion
- > coracoid process of the scapula
Action
- > anchors and depresses the scapula
Innervated by medial pectoral nerve
insertion and origin, action, and innervation of middle trapezius
origin
- > spinous processes of T1-5
insertion
- > medial margin of the acromion and superior lip of the spine of the scapula
action
- > retracts the scapula
innervation
- > spinal accessory nerves (Cranial Nerve 11)
insertion and origin, action, and innervation of upper fibres of trapezius
Origin
- > external occipital protuberance, medial ⅓ of the superior nuchal line, ligamentum nuchae and spinous process C7
insertion
- > lateral ⅓ of the clavicle and acromion process of the scapula
action
- > elevates the scapula
Innervation
- > spinal accessory nerves
Origin and insertion, action, and innervation of lower fibres of trapezius
origin
- > spinous process of T6-12
insertion
- > tubercle at the apex of spine of the scapula
action
- > depresses the scapula and retracts scapula
innervation
- > spinal accessory nerves
rhomboids
origin
- > ligamentus nuchae, spinous process of C7 and T1 (minor)
- > spinous processes of T2-5 (major)
insertion
- > medial border of the scapula between the pine and inferior angle (major)
- > medial border of the scapula, at the root of the spine of scapula (minor)
action
- > adducts and elevates the scapula
innervated
- > dorsal scapular nerve
what actions are possible with the pectoral girdle
which muscles would elevate the scapula
- > levator scapulae
- > trapezius
- > rhomboids
origin/insertion, action and innervation of levator scapulae
origin
- > transverse processes of C1-4
insertion
- > medial border of scapula, between sup angle and root of spine
action
- > elevates scapula and assists with downward rotation
innervation
cervical nerves 3 and 4, dorsal scapular nerve
