Upper Extremity Anatomy for Athletic Trainers

• These notes relate to upper extremity gross anatomy for athletic trainers

Cervical Spine

• The typical cervical vertebrae and the bony features, joints, and movements of C1 and C2 should be discussed. Also consider the muscles associated with the cervical spine (origin, insertion, action, and nerve innervation)
• Trapezius originates at the medial 1/3 of the superior nuchal line, external occipital protuberance, nuchal ligament, and spinous processes of C7-T12 and inserts at the lateral 1/3 of the clavicle, acromion process, and scapular spine
  • Trapezius enables scapular elevation, retraction, rotation, and depression
  • Trapezius is innervated by the spinal accessory nerve (CNXI)
• Levator Scapula originates at the posterior tubercles of transverse processes C1-C4 and inserts at the superior medial border of the scapula
  • Levator Scapula elevates and rotates the scapula
    • Levator Scapula is innervated by the dorsal scapular nerve (C4-C5)
• Rhomboid Minor originates at the inferior nuchal ligament and spinous processes of C7-T1 and inserts at the medial border of the scapula
  • Rhomboid Minor retracts and rotates the scapula, fixing it to the thoracic cavity
  • Rhomboid Minor is innervated by the dorsal scapular nerve (C4-C5)
• Splenius Capitis originates at the nuchal ligament and spinous processes of C7-T3/4 and inserts at the mastoid process and the lateral 1/3 of the superior nuchal line
  • Splenius Capitis unilaterally rotates and laterally flexes the head to the same side; bilaterally, it extends the head
  • Splenius Capitis is innervated by dorsal rami (C1-C3)
• Splenius Cervicus originates at the spinous processes of T3-6 and inserts at the transverse processes of C1-C3
  • Splenius Cervicus unilaterally rotates and laterally flexes the head to the same side; bilaterally, it extends the head
  • Splenius Cervicus is innervated by dorsal rami (C5-C7)
• C1, also known as the atlas, possesses several distinctive features that facilitate its unique role in the cervical spine. The posterior tubercle serves as an attachment site for ligaments and muscles, while the superior articular processes articulate with the occipital condyles, allowing for nodding motions of the head. The transverse process provides structural support and stability, and the anterior facet for the dens articulates with C2, enabling rotational movement. The posterior arch contributes to the overall structure of the vertebra, ensuring protection for the spinal cord.
• C2, also known as the axis, is characterized by the presence of the dens, a prominent bony projection that serves as a pivot point for rotation of the atlas (C1). The foramen transversarium allows passage for the vertebral artery and veins. Facets for the alar ligaments provide attachment points, contributing to the stability of the cervical spine. Additionally, the posterior tubercle serves as an important landmark for muscle attachment.

ACJ-Girdle

• The acromioclavicular joint and associated supporting structures should be discussed. Also cover the axio-scapular muscles that assist with shoulder girdle movements, and the scapular anastomosis
• The trapezius allows for scapular elevation, retraction, rotation, and depression, transverse cervical and dorsal scapular (lower) and is innervated by the spinal accessory nerve (XI). Supplied by the transverse cervical and dorsal scapular arteries.
• Levator Scapulae enables elevation and rotates scapula from the dorsal scapular and is innervated by the dorsal scapular nerve (C4-C5). Supplied by dorsal scapular artery.
• Rhomboid Major retracts and Rotates Scapula, fixing scapula to thoracic Cavity and is innervated by the dorsal scapular nerve (C4-C5). Supplied by dorsal scapular artery.
• Rhomboid Minor retracts and Rotates Scapula, fixes scapula to thoracic Cavity and is innervated by the dorsal scapular nerve (C4-C5). Supplied by dorsal scapular artery.
• Ligaments include the superior and inferior AC ligaments, coraco-acromial ligament, and coracoclavicular ligament
• Scapular Anastamosis:
• The suprascapular and dorsal scapular arteries originate from the thyrocervical trunk, which is a key branch of the subclavian artery. This anatomical relationship is crucial for understanding blood supply to the upper extremity and shoulder region.
• The suprascapular artery specifically traverses the posterolateral aspect of the scapula, providing vital blood flow to various muscles such as the supraspinatus and infraspinatus, which play significant roles in shoulder stability and movement.
• Conversely, the dorsal scapular artery follows a path along the medial border of the scapula. It intersects with the intercostal arteries, emphasizing its importance in supplying the rhomboid and levator scapulae muscles, thus contributing to proper scapular function and movement.
• The axillary artery, which arises from the subclavian artery, subsequently branches into the subscapular artery, the circumflex humeral arteries, and the thoracodorsal artery, collectively ensuring comprehensive vascularization of the shoulder joint and upper arm.

GHI + RC

• The glenohumeral joint and associated structures should be discussed. Also cover the rotator cuff muscles (O, I, A, Inn)
• The glenohumeral joint is classified as a ball-and-socket joint, which allows for a wide range of motion in multiple directions. The head of the humerus articulates with the glenoid cavity of the scapula, creating a dynamic relationship crucial for shoulder mobility. Additionally, the glenoid labrum, a fibrocartilaginous rim, deepens the glenoid cavity, enhancing joint stability and preventing dislocations. SITS
• Supporting Structures:
  • Coracohumeral ligament
  • Transverse humeral ligament
  • Superior, middle, and inferior glenohumeral ligaments
• Supraspinatus:
  • Originates at the supraspinatus fossa and inserts at the greater tubercle
  • Assists deltoid in abduction and GH stability
  • Supplied by suprascapular artery
  • Innervated by the suprascapular nerve
• Infraspinatus:
  • Originates at the infraspinatus fossa and inserts at the greater tubercle
  • Enables external rotation, abduction, and horizontal abduction, GH stability
  • Supplied by suprascapular and circumflex scapular arteries
  • Innervated by the suprascapular nerve (C5-6)
• Teres Minor:
  • Originates at the lateral border of the scapula and inserts at the greater tubercle
  • Enables external rotation and horizontal abduction and GH Stability
  • Supplied by circumflex scapular artery
  • Innervated by the axillary nerve (C5-6)
• Subscapularis:
  • Originates at the subscapular fossa and inserts at the lesser tubercle
  • Enables internal rotation and prevents anterior displacement
  • Supplied by subscapular artery
  • Innervated by the upper and lower subscapular nerves (C5-6)

GHJ (not RC)

• Glenohumeral joint and the scapulohumeral muscles that are NOT part of the rotator cuff should be discussed. Also cover the GH anastomosis
• Teres Major:
  • Originates at the inferior angle of the scapula and inserts at the bicipital groove
  • Enables extension, adduction, internal rotation, and horizontal abduction
  • Supplied by circumflex scapular artery
  • Innervated by the lower subscapular nerve (C5-6)
• Deltoid (Anterior Head):
  • Originates at the lateral 1/3 of the clavicle and inserts at the deltoid tuberosity
  • Enables flexion, horizontal abduction, and external rotation
  • Supplied by posterior circumflex humeral artery
  • Innervated by the axillary nerve (C5-C6)
• Deltoid (Posterior head):
  • Originates at the scapular spine and inserts at the deltoid tuberosity
  • Enables extension, horizontal abduction, and external rotation
  • Supplied by posterior circumflex humeral artery
  • Innervated by the axillary nerve (C5-C6)
• Deltoid (middle Head):
  • Originates at the acromion process and inserts at the deltoid tuberosity
  • Enables abduction
  • Posterior circumflex humeral artery
  • Innervated by the axillary nerve (C5-C6)
• Coracobrachialis:
  • Originates at the coracoid process and inserts at the Medial surface border of the body humerus
  • Enables flexion, adduction, and horizontal adduction and retains humeral head in glenoid cavity)
  • Supplied by brachial artery
  • Innervated by the musculocutaneous nerve (C5-7)
• Glenohumeral Anastomosis:
• The glenohumeral anastomosis is crucial for maintaining blood supply to the shoulder region. The transverse cervical artery supplies blood to the trapezius and neck muscles, while the suprascapular artery provides blood to the posterior shoulder. The axillary artery, along with its circumflex branches, facilitates circulation around the humerus. The profunda brachii artery, a major branch of the brachial artery, serves the posterior compartment of the arm, whereas the subscapular artery supports the scapular muscles. Each of these vessels plays a significant role in the vascular network supporting shoulder function and stability.

Brachial Plexus

• The brachial plexus in detail should be discussed including what each branch is responsible for innervating
• Roots: C5-T1
  • Dorsal Scapular (C5) - innervates the levator scapulae and rhomboid major and minor
  • Long Thoracic (C5-C7) - innervates the serratus anterior
• Trunks: upper — middle — lower
  • Suprascapular (upper) (C5-C6) - supraspinatus and infraspinatus
  • Nerve to Subclavius (upper) (C5-C6) - subclavius
• Divisions: anterior and posterior
  • Upper Subscapular (C5-C6) - subscapularis
  • Middle Subscapular (C7) - latissimus dorsi
  • Lower Subscapular (C8-T1) - Subscapularis and teres major
• Cords: lateral — posterior — medial
  • Lateral Pectoral (lateral) (C5-C6) - pec major
  • Medial Pectoral (medial) (C8-T1) - pec major and pec minor
  • Medial Cutaneous (medial) (C8-T1) - sensory of the lateral shoulder
• Branches:
  • Musculocutaneous (lateral)(C5-C6) - biceps, coracobrachialis, and brachialis
  • Ulnar (medial) (C8-T1) - flexor carpi ulnaris and medial half of flexor digitorum profundus
  • Median (medial and lateral) (C5,C6,C8,T1) - anterior forearm muscles not innervated by ulnar
  • Radial (posterior) (C7) - triceps and aconeus
  • Axillary (posterior) (C7) - deltoid and teres minor

Axilla

• The axilla should be discussed defining the borders and key contents. The muscles, nerves, and arteries associated with the axilla should be discussed
• Pec Major (anterior wall):
  • Originates at the medial 1/2 of the clavicle, sternum, costal cartilage 2-6, and external oblique fascia
  • Inserts at the lateral lip of the bicipital groove
  • Enables numerous movements including flexion, adduction, horizontal adduction, internal rotation, scapular downward rotation
  • Supplied by the pectoral branch of thoracodorsal artery
  • Innervated by the medial and lateral pectoral branch (C5-T1)
• Pec Minor (anterior wall):
  • Originates at ribs 3-5
  • Inserts at the coracoid process
  • Allows for scapula depression, downward rotation, abduction, and rib elevation
  • Supplied by the pectoral branch of thoracodorsal artery
  • Innervated by medial pectoral branch (C8-T1)
• Intercostals (medial wall):
  • Originates at the lower border of ribs 1-11
  • Inserts at the upper border of ribs 2-12
  • Elevates ribs
  • Supplied by intercostal arteries
  • Innervated by intercostal nerve
• Serratus Anterior (medial wall):
  • Originates at ribs 1-8/9
  • Inserts at the anterior surface of the medial border of the scapula
  • Enables abduction, upward rotation, and stabilization of the scapula
  • Supplied by lateral thoracic (upper) and thoracodorsal (lower) arteries
  • Innervated by the long thoracic nerve (C5-7)
• Subscapularis (posterior wall):
  • Originates at the subscapular fossa
  • Inserts at the lesser tubercle
  • Enables internal rotation and prevents anterior displacement
  • Supplied by subscapular artery
  • Innervated by the upper and lower subscapular nerves (C5-C6)
• Latissimus Dorsi (posterior wall):
  • Originates at the spinous process of T7-12, thoracolumbar fascia, iliac crest, inferior 3-4 ribs, and inferior angle of the scapula
  • Inserts at the bicipital groove
  • Enables extension, adduction, and internal rotation and elevates body when climbing
  • Supplied by thoracodorsal artery
  • Innervated by the thoracodorsal nerve (C6-8)
• Teres Major (posterior wall):
  • Originates at the inferior angle of the scapula
  • Inserts at the bicipital groove
  • Enables extension, adduction, internal rotation, and horizontal abduction
  • Supplied by circumflex scapular artery
  • Innervated by the lower subscapular nerve (C5-6)
• The lateral wall (no muscles) consists of the intertubercular groove of the humerus (bicipital groove)

Anterior Brachium

• Anterior brachium muscles, nerves, and arteries should be discussed
• Bicep (long head):
  • Originates at the supraglenoid tubercle of the scapula
  • Inserts at radial tuberosity (bicipital aponeurosis)
  • Shoulder flexion and forearm flexion/supination
  • Supplied by brachial artery
  • Innervated by the musculocutaneous nerve (C5-7)
• Bicep (short head):
  • Originates at the tip of the coracoid process
  • Inserts at radial tuberosity (bicipital aponeurosis)
  • Shoulder flexion and forearm flexion/supination
  • Supplied by brachial artery
  • Innervated by the musculocutaneous nerve (C5-7)
• Coracobrachialis:
  • Originates at the coracoid process
  • Inserts at the medial surface border of the body of the humerus
  • Enables flexion, adduction, and horizontal adduction and retains the numeral head in the glenoid cavity
  • Supplied by brachial artery
  • Innervated by the Musculocutaneous nerve (C5-7)
• Brachialis:
  • Originates at the distal 2/3 of the anterior surface of the humerus
  • Inserts at coranoid process and ulnar tuberosity
  • Enables forearm flexion
  • Supplied by radial recurrent artery
  • Innervated by the musculocutaneous (C5-6) and radial (C5/7) nerves

Posterior Brachium

• Posterior brachium muscles, nerves, and arteries should be discussed
• Tricep (lateral head):
  • Originates at the posterior surface of the humerus, superior to the radial groove
  • Inserts at the proximal end of the olecranon
  • Extension of forearm
  • Supplied by profounda brachii artery
  • Innervated by the radial nerve (C6-C8)
• Tricep (long head):
  • Originates at the infraglenoid tubercle of the scapula
  • Inserts at the proximal end of the olecranon
  • Extension of forearm
  • Supplied by profounda brachii artery
  • Innervated by the radial nerve (C6-C8)
• Tricep (short head):
  • Originates at the posterior surface of the humerus, inferior to the radial groove
  • Inserts at the proximal end of the olecranon
  • Extension of the forearm
  • Supplied by profounda brachii artery
  • Innervated by the radial nerve (C6-C8)