Extrinsic Muscles of the Forelimb

Origin: (descending) 1st sternebra, (transverse)1st 2 or 3 sternebraInsertion: Crest of the greater tubercle of the humerus Action: To adduct the limbwhen it is not bearing weight or to prevent the limb from being abducted when bearing weightInnervation: Ventral branch of spinal nerves C7 and C8

Origin: Ventral part of the sternum, the fibrous raphe between fellow muscles and the deep abdominal fascia in the region of the xiphoid cartilageInsertion: Lesser tubercle of the humerus Action: To adduct the limbInnervation: Caudal pectoral nerves C8 and T1

Origin: Clavicular tendonInsertion: (Cleidobrachialis) Distal cranial border of the humerus (Cleidomastoideus) matoid part of the temporal bone (Cleidocervicalis) mid-dorsal fibrous raphe or nuchal crest of the occipital bone)Action: To advance the limb; to extend the shoulder joint and draw the head and neck to the sideInnervation: Accessory nerve and ventral branches of the cervical spinal nerves

Origin: Transverse wing of the atlasInsertion: Distal spine of the scapulaAction: To advance the limb or flex the neck laterallyInnervation: Accessory nerve

Origin: Median raphe of the neck and supraspinous ligamentInsertion: Spine of the scapulaAction: To elevate and abduct the limbInnervation: Accessory nerve

Origin: Nuchal crest of the occipital bone, median fibrous raphe of the neck and the spinous processes of the first 7 thoracic vertebraeInsertion: Drsal border and adjacent surfaces of the scapulaAction: To elevate the forelimb and draw the scapula to the trunkInnervation: Accessory nerve

Origin: Thoracolumbar fascia from the spinous processes of the lumbar and the last 7 or 8 thoracic vertebrae, a muscular attachment to the last 2 or 3 ribs Insertion: Teres major tuberosity of the humerus and the teres major tendonAction: To draw the free limb caudally as in digging, to flex the shoulder jointInnervation: Accessory nerve

Origin: Transverse processes of the last 5 cervical vertebrae and the first 7 or 8 ribs ventral to their midlineInsertion: Serrated face of the scapulaAction: To support the trunk and depress the scapulaInnervation: Ventral branches of the cervical spinal nerves and the long thoracic nerve (C7)

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