Anatomy of Clavicle and Scapula

Clavicle (Collarbone)

• Long bone connecting the sternum (breastbone) to the scapula (shoulder blade)
• Helps transfer weight and facilitate movement
• Triangular shape, with anterior convexity allowing structures to pass from neck to upper limb.
• Articulates with the acromion of the scapula laterally and the sternum medially, forming the acromioclavicular and sternoclavicular joints.
• Key features include: conoid tubercle for ligament attachment, and anterior and posterior areas for ligament attachments.

Scapula (Shoulder Blade)

• Large, flat, triangular bone in the upper back.
• Key features include: superior, medial, and lateral borders.
• Key features include: superior, inferior, and lateral angles.
• Surfaces include the subscapular fossa, offering muscle attachment sites, and a posterior surface with the supraspinous and infraspinous fossae, for muscle attachment.
• Processes include the acromion, contributing to the shoulder joint, and the coracoid process, providing attachment for muscles and ligaments.
• Glenoid cavity located at the lateral angle articulates with the head of the humerus forming the shoulder joint.

Humerus (Upper Arm Bone)

• Long bone, the largest bone in the upper limb.
• Major bony prominences include greater and lesser tubercles, serving as muscle attachments for rotator cuff muscles.
• Deltoid tuberosity supports the deltoid muscle.
• Anatomical neck distinguishes the head from the shaft, while the surgical neck is a more fragile portion prone to fractures.
• Intertubercular sulcus (bicipital groove) provides space for the tendon of the biceps brachii muscle.

Deltoid Muscle

• Large, triangular shoulder muscle.
• Originates from the clavicle, acromion, and spine of the scapula.
• Insertions are on the deltoid tuberosity.
• Innervated by the axillary nerve.
• Functions include arm abduction, flexion, and extension, and external and internal rotation.

Rotator Cuff Muscles

• Group of four muscles crucial for shoulder stability and movement.
• Include supraspinatus, infraspinatus, teres minor, and subscapularis.
• Each has specific origins, insertions, innervations, and functions related to shoulder joint movement.

Trapezius Muscle

• Large, superficial muscle of the upper back and neck resembling a trapezoid.
• Originates from the occipital bone, nuchal ligament, and the spinous processes of the thoracic vertebrae.
• Inserts into the clavicle, acromion, and spine of the scapula.
• Innervated by the accessory nerve.
• Three parts function in elevating, retracting, and depressing/rotating the scapulae.

Levator Scapulae

• Elongated muscle situated on the side of the neck.
• Originates from the transverse processes of C1-C4 vertebrae.
• Inserts into the medial border of the scapula, specifically from the superior angle to the root of the scapular spine.
• Innervated by the dorsal scapular nerve, and cervical spinal nerves C3 and C4.
• Functions include elevating the scapula, laterally tilting the neck, and fixing the cervical vertebrae.

Rhomboid Muscles (Minor and Major)

• Located deep to the trapezius muscle, assisting with scapular movement.
• Originate from the spinous processes of the thoracic vertebrae (major) or cervical vertebrae (minor).
• Insert into the medial border of the scapula.
• Innervated by the dorsal scapular nerve.
• Functions in retracting and downwardly rotating the scapulae.

Latissimus Dorsi

• Large, flat, broad muscle on the lower back.
• Originates from the spinous processes of inferior thoracic vertebrae, lower ribs, lumbar spine, iliac crest, and thoracolumbar fascia.
• Inserts into the intertubercular groove of the humerus.
• Innervated by the thoracodorsal nerve (C6, C7, C8).
• Functions in extending, adducting, and medially rotating the arm.

Pectoralis Minor

• Located beneath the pectoralis major, a smaller triangular muscle.
• Originates from the ribs 3-5.
• Inserts into the coracoid process of the scapula.
• Innervated by the medial and lateral pectoral nerves.
• Functions in stabilizing the scapula, assisting with shoulder flexion and medial rotation and preventing excessive upward movement of the arm.

Subclavius

• Small muscle situated beneath the clavicle.
• Originates from the first rib.
• Inserts into the inferior surface of the clavicle.
• Innervated by the subclavian nerve.
• Functions to depress and stabilize the sternoclavicular joint and prevent the excessive upward movement of the shoulder.