Thoracic limb anatomy.Part1.SVF120 - StudentCopy.pdf

Anatomy of the Thoracic Limb Chapter 6 Part 1 (p 6.1 – 6.8) Dr Christine Steyn Dep. Anatomy & Physiology Faculty Vet Science, UP  6.1 Extrinsic muscles of the thoracic limb Attach the front limb to the body Muscles attach lateral and medial to the scapula Funct...

Anatomy of the Thoracic Limb Chapter 6 Part 1 (p 6.1 – 6.8) Dr Christine Steyn Dep. Anatomy & Physiology Faculty Vet Science, UP  6.1 Extrinsic muscles of the thoracic limb Attach the front limb to the body Muscles attach lateral and medial to the scapula Functional note (page 6-6): – No bony attachment between front limb and body – Muscles caudal to the scapula – retract the limb (pull limb back) – Muscles cranial to the scapula – protract the limb (bring limb forward)  6.1 Extrinsic muscles of the thoracic limb M. latissimus dorsi – Origin: spinous processes of thoracic & lumbar vertebrae – Insertion: Medial aspect of the brachium (arm) – Innervation: N. thoracodorsalis  Extrinsic muscles of the thoracic limb M. trapezius – Consists of cervical and thoracic parts – Origin: Spinous processes of cervical & thoracic vertebrae – Insertion: Spine of the scapula  Extrinsic muscles of the thoracic limb M. omotransversarius – Origin: Distal part of scapular spine – Insertion: Wing of the atlas *Note: M. omotransversarius and M. trapezius diverge as they pass cranially – triangular area free of muscle - Ln. cervicalis superficialis  Extrinsic muscles of the thoracic limb M. brachiocephalicus – Origin: Median raphe of the neck & mastoid process of the temporal bone – Insertion: Distal part of the humerus (brachium) *Note: Fibrous intersection in the muscle just cranial to the shoulder joint – Clavicular intersection (remnant of the clavicle) - M. cleidobrachialis; - M. cleidocervicalis; - M. cleidomastoideus  Extrinsic muscles of the thoracic limb M. rhomboideus (lies deep to the M. trapezius) – Capital, cervical and thoracic parts – Origin: Spinous processes of cervical 7 thoracic vertebrae & back of head – Insertion: Medial surface of proximal scapula  Extrinsic muscles of the thoracic limb M. pectoralis superficialis (descendens) – Origin: Manubrium of sternum – Insertion: Humerus M. pectoralis profundus (ascendens) – Origin: Caudal aspect of the sternum – Insertion: Major & minor tubercles of the humerus Innervation: Nn. pectorales  Extrinsic muscles of the thoracic limb M. serratus ventralis – Cervical & thoracic parts. Two muscles form a sling that suspends the trunk between the thoracic limbs – Origin: Medial aspect of scapula – Insertion: Ribs & transverse processes of cervical vertebrae – Innervation: N. thoracis longus Nerves of the thoracic limb www.sweethaven.com  Nerves of the thoracic limb Brachial plexus – ventral rami of C6-T2 - Nn. pectorales – innervate M. pectorales - N. thoracicus longus – M. serratus ventralis - N. axillaris – True flexors of the shoulder joint - N. thoracicus dorsalis – M. latissimus dorsi - N. thoracicus lateralis – Cutaneous muscles of the trunk - N. subscapularis – M. subscapularis - N. suprascapularis – M. supraspinatus & M. infraspinatus  Nerves of the thoracic limb Brachial plexus (cont) – N. radialis – extensor muscles of the elbow, carpus and toes/digits. Sensory supply to cranial aspect of antebrachium and dorsal aspect of manus – N. ulnaris - flexor muscles of the elbow, carpus and toes/digits. Sensory supply to caudal aspect of antebrachium and palmar aspect of manus  Brachial plexus (cont.) – N. medianus – same function as N. ulnaris. Connection between median nerve and musculocutaneous nerve. – N. musculocutaneous – flexor muscles of the elbow and sensory supply to medial aspect of antebrachium Brachial plexus Blood supply to Thoracic Limb Subclavian artery – Axillary artery – Brachial artery – Median artery – Main supply to manus Cephalic vein  6.2 Muscles of the shoulder joint Flexion and extension of the shoulder joint Muscles arranged medially and laterally around the joint Origin: Scapula Insert: Humerus  Muscles of the shoulder joint M. subscapularis – Fills the subscapular fossa. – Origin: Subscapular fossa – Insertion: Minor tubercle of humerus. – Serves as medial collateral ligament of shoulder joint – N. subscapularis  Muscles of the shoulder joint M. teres major – Origin: Caudal angle of scapula – Insertion: Medial, proximal end of humerus – Flexion of the shoulder joint – N. axillaris  Muscles of the shoulder joint M. supraspinatus – Origin: Supraspinous fossa of scapula – Insertion: Major tubercle of humerus – Extension of shoulder joint – N. suprascapularis  Muscles of the shoulder joint M. infraspinatus – Origin: Infraspinous fossa of scapula – Insertion: Major tubercle of humerus – Flexion of the shoulder joint – Deltoid muscle covers distal part – N. suprascapularis  Muscles of the shoulder joint M. deltoideus – Acromial – Origin: Acromion of scapula – Scapular – Origin: M. infraspinatus and spine of scapula – Inserts: Deltoid tuberosity of humerus – Flexion of the shoulder joint – N. axillaris  6.3 Muscles of the elbow joint Typical hinge joint Muscles arranged around the brachium – Origin: Scapula or Humerus – Insertion: Proximal radius and ulna Extension and flexion of the elbow joint Fixation of shoulder and elbow – Well developed  Muscles of the elbow joint M. biceps brachii – Lies on cranial aspect of arm (Humerus) – Origin: Supraglenoid tubercle – Insertion: Radial tuberosity – Flexion of the elbow joint – N. musculocutaneous  Muscles of the elbow joint M. brachialis – Origin: Caudal aspect of humerus (proximal) – Insertion: Radial tuberosity – Flexion of the elbow joint – N. musculocutaneous  Muscles of the elbow joint M. triceps brachii – Lies in angle between shoulder and humerus – Large muscle – 4 heads (long, lateral, medial, accessory) – Origin: Caudal border of scapula and caudal aspect of humerus – Insertion: Olecranon – Extension of elbow joint – N. radialis