L3: Clavicle, Scapula and Arm Flashcards
Muscle Originating on Clavicle:
2
Clavicular Head of Pectoralis Major:
Sternocleidomastoid
(This muscle originates from the sternum and clavicle)
Deltoid (front)
Muscles Attaching on Clavicle
Subclavius
Trapezius
originates
Pectoralis Major
Origin:
Clavicular head: anterior Medial half of the clavicle.
Sternocostal head: anterior surface of sternum, superior six costal cartilages
Insertion: Lateral lip of the intertubercular sulcus of the humerus.(bicipital groove)
Function: Flexion, adduction, and medial rotation of the arm at the shoulder joint.
Nerve Supply: Medial pectoral nerve (C8, T1).
originates
Sternocleidomastoid
Sternocleidomastoid:
Origin:
Sternal head - Manubrium of the sternum,
Clavicular head - Medial third of the clavicle.
Insertion:
Mastoid process of the temporal bone, superior nuchal line of the occipital bone.
Function:
Bilateral contraction - Neck flexion, Unilateral contraction - Lateral flexion to the same side and rotation to the opposite side.
Nerve Supply:
Accessory nerve (CN XI) for motor functions, and branches of the cervical plexus (C2, C3) for sensory functions.
attaches
Subclavius
Subclavius:
- Origin: First rib at its junction with its costal cartilage.
- Insertion: Inferior surface of the clavicle.
- Function: Stabilizes and depresses the lateral clavicle.
- Nerve Supply: subclaviun
attaches
Trapezius
kinda
Trapezius:
-
Origin:
- Upper fibers: External occipital protuberance, medial third of the superior nuchal line of the occipital bone.
- Middle fibers: Nuchal ligament, spinous processes of C7-T4.
- Lower fibers: Spinous processes of T5-T12.
-
Insertion:
- Upper fibers: Lateral third of the clavicle.
- Middle fibers: Acromion and spine of the scapula.
- Lower fibers: Base of the spine of the scapula.
-
Function:
- Upper fibers: Elevate and upwardly rotate the scapula.
- Middle fibers: Retract the scapula.
- Lower fibers: Depress and upwardly rotate the scapula.
- Nerve Supply: Accessory nerve (cranial nerve XI) for motor innervation (mainly), and branches of the cervical nerves (C3-C4) for proprioception.
What Muscle have Origins or Attachments on the Humerus?
Deltoid
Pectoralis Major
Latissimus Dorsi
Rotator Cuff Muscles
Biceps Brachii
Triceps Brachii
Deltoid
Origin: Anterior border and upper surface of the lateral third of the clavicle, acromion, and spine of the scapula.
Insertion: Deltoid tuberosity of the humerus.
Function: Abduction, flexion, and extension of the shoulder.
Nerve Supply: Axillary nerve (C5, C6).
Pectoralis Major
Origin: Clavicular head - Medial half of the clavicle; Sternocostal head - Sternum, upper six costal cartilages, aponeurosis of the external oblique muscle.
Insertion: Lateral lip of the bicipital groove of the humerus.
Function: Adduction, flexion, and medial rotation of the shoulder.
Nerve Supply: Medial and lateral pectoral nerves (C5–C8, T1).
Latissimus Dorsi:
Origin: Spinous processes of the lower six thoracic vertebrae, iliac crest, and thoracolumbar fascia.
Insertion: Floor of the intertubercular sulcus of the humerus.
Function: Extension, adduction, and medial rotation of the shoulder.
Nerve Supply: Thoracodorsal nerve (C6, C7, C8)
Biceps Brachii:
Origin: Long head - Supraglenoid tubercle of the scapula;
Short head - Coracoid process of the scapula.
Insertion: Radial tuberosity and bicipital aponeurosis of the forearm.
Function: Flexion of the elbow and shoulder, supination of the forearm.
Nerve Supply: Musculocutaneous nerve (C5, C6, C7).
Triceps Brachii:
Origin: Long head - Infraglenoid tubercle of the scapula;
Lateral head - Lateral and posterior surface of the humerus;
Medial head - Posterior surface of the humerus.
Insertion: Olecranon process of the ulna.
Function: Extension of the elbow.
long head extends shoulder
Nerve Supply: Radial nerve (C7, C8, T1).
What are the Rotator Cuff Muscles?
4 SITS
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
Supraspinatus
Origin: Supraspinous fossa of the scapula.
Insertion: Superior facet of the greater tubercle of the humerus.
Function: Initiates abduction of the arm and stabilizes the shoulder joint.
Nerve Supply: Suprascapular nerve (C5, C6).
Infraspinatus
Origin: Infraspinous fossa of the scapula.
Insertion: Middle facet of the greater tubercle of the humerus.
Function: Lateral rotation of the arm at the shoulder joint, stabilizes the shoulder joint.
Nerve Supply: Suprascapular nerve (C5, C6).
Teres Minor
Origin: Upper two-thirds of the lateral border of the scapula.
Insertion: Inferior facet of the greater tubercle of the humerus.
Function: Lateral rotation of the arm at the shoulder joint, helps in adduction and extension of the arm.
Nerve Supply: Axillary nerve (C5, C6).
Subscapularis
Origin: Subscapular fossa of the scapula.
Insertion: Lesser tubercle of the humerus.
Function: Medial rotation of the arm at the shoulder joint, stabilizes the shoulder joint.
Nerve Supply: Upper and lower subscapular nerves (C5, C6)
Teres Major
Origin: Posterior surface of the inferior angle of the scapula.
Insertion: Medial lip of the intertubercular sulcus of the humerus. (Bicipital groove)
Function: Medial rotation, adduction, and extension of the arm.
Nerve Supply: Lower subscapular nerve
Teres Minor
Origin: Lateral border of the scapula, near the upper end.
Insertion: Greater tubercle of the humerus.
Function: Lateral rotation of the arm.
Nerve Supply: Axillary nerve.
Rhomboid Major
Origin: Spinous processes of T2-T5.
Insertion: Medial border of the scapula, from the level of the spine to the inferior angle.
Function: Retracts and elevates the scapula.
Nerve Supply: Dorsal scapular nerve.
Coracobrachialis
O: Tip of coracoid process of scapula
I: Middle third of medial surface of humerus
F: Helps flex and adduct shoulder joint; resists dislocation of shoulder
N: Musculocutaneous nerve (C5, C6, C7)
Anconeus
O: Lateral epicondyle of humerus
I: Lateral surface of olecranon and superior part of posterior surface of ulna
F: Assists triceps in extending elbow joint; stabilizes elbow joint; abducts ulna during pronation
N: Radial nerve (C7, C8, T1)
