15B - Pectoral Girdle Muscles Flashcards
How do you injure the AC joint?
Tackling
What is the conceptual joint?
Is a functional not true joint between the medial scapula and thorax. Braces the scapula onto the thorax for stability. Has lots of fluid of lubrication
What are the muscles that go from axial skeleton to pectoral girdle?
Pectoralis MINOR, subclavius, serratus anterior, trapezius, rhomboid major and minor, levator scapulae
Muscles from axial skeleton to humerus?
Pectoralis Major, Latissimus Dorsi
Muscles from pectoral girdle to humerus?
Supraspinatus, Infraspinatus, Teres Minor and Major, Subscapularis, Deltoid, Coracobrachialis, Biceps and Triceps Brachii
What do I need to know about these muscles?
NERVE. Primary actions. General origins and insertions
What is Trapezius O and I?
O: broad from skull to T12 spinous processes
I: anatomical horseshoe (clavicle, acromion, spine)
> superior: clavicle
> middle: acromion
> inferior: spine of scapula
Action of trapezius?
All fibres together: retract
Superior: Elevates
Middle: Retracts
Inferior: Depresses
Superior and Inferior Fibres: STRONG superior rotation
Nerve to trapezius
Accessory Nerve (CN 11)
Levator Scauplae?
O: TRANSVERSE processes of upper cervical vertebrae
I: Superior angle of scaupla
> Dorsal Scapula Nerve
Elevates
O and I can swap to laterally flex head
Rhomboid Major and Minor
O: Spinous processes of lower cervical and upper thoracic vertebra
I: Medial Border of Scapula
> Dorsal Scapula Nerve
Retracts scapula
Latissimus Dorsi?
O: T7 - S5, iliac crest, lower ribs
I: FLOOR of intertubercular groove of anterior humerus
> adducts and internally rotates arm. Depress scapula
Thoracodorsal Nerve
Significance of lat dorsi origin including iliac crest?
- is of lower limb. This doesn’t move so is a stable base to anchor the upper limb to (mechanical advantage)
What does lat dorsi form?
The posterior fold of the armpit/axilla.
Pectoralis Major?
O: Sternocostal head and clavicular head
I: Lateral Lip of intertubercular groove
> internally rotates arm and adducts (and protract)
Lateral and Medial Pectoral Nerves
When do you use pectoralis major?
Climbing trees, using crutches.
Pectoralis Minor?
O: Ribs 3,4,5
I: Coracoid
> Depresses scapula and is a weak stabiliser i.e. during heavy breathing it locks the scapula and pulls the ribs up
Medial Pectoral Nerve
Subclavius
O: Costal cartilage of first rib
I: Subclavian groove of clavicle
> Braces clavicle and is a weak depressor
C5 nerve
Where does the NM bundle of the upper limb run? Why is this significant?
Below pectoralis minor - if you sleep woth your arm abducted then you can stretch the BP under the coracoid with pec minor in front resulting in a numb arm
Where does the Medial Pectoral Nerve run?
Through pectoralis minor to major
What is serratus anterior known as?
Boxers muscle
Serratus Anterior?
O: Anterior Lateral Thorax
I: Medial border of scapula
> protracts scapula
LOWER fibres help superiorly rotate the scapula
Long Thoracic Nerve
Where does serratus anterior insert?
Below the rhomboids at the medial scapula
What results after damage to the Long Thoracic Nerve?
Winged scapula.
What muscles elevate the scapula?
Elevator Scapulae, Superior Fibres of Trapezius
What muscles depress the scapula?
Inferior Trapezius, Subclavius (weak), Pec Minor, Lower Fibres of Lat Dorsi
What muscles protract scapula?
Serratus anterior and pec major
What muscles retract scapula?
Rhomboids, trapezius total and middle fibres,
What muscles superiorly rotate the scapula?
Inferior and superior fibres of trapezius, lower fibres of serratus anterior
