Podcast
Questions and Answers
Which muscle extends the shoulders and draws the head and neck to the side?
Which muscle extends the shoulders and draws the head and neck to the side?
Which muscle attaches to the nuchal crest of the occipital bone?
Which muscle attaches to the nuchal crest of the occipital bone?
Which muscle extends from the spinous processes of the 1st to 7th thoracic vertebrae to the thoracolumbar fascia?
Which muscle extends from the spinous processes of the 1st to 7th thoracic vertebrae to the thoracolumbar fascia?
Which muscle originates from the clavicular intersection and extends to the humerus?
Which muscle originates from the clavicular intersection and extends to the humerus?
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Which muscle is associated with the median raphe cervicis of the neck and the supraspinous ligament?
Which muscle is associated with the median raphe cervicis of the neck and the supraspinous ligament?
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Study Notes
Extrinsic Muscles of the Thoracic Limb
- Extrinsic muscles connect the thoracic limb to the axial skeleton, often referred to as girdle muscles.
- These muscles play a crucial role in limb movement and stability.
Superficial Pectoral Muscles
- Comprises two parts:
- Descending Pectoral: Originates from the 1st sternebra (manubrium).
- Transverse Pectoral: Originates from the first 2 or 3 sternebrae.
Deep Pectoral Muscle
- Originates from the ventral part of the sternum and the fibrous raphe between adjoining muscles; extends to the deep abdominal fascia near the xiphoid cartilage.
- Insertion includes:
- Major portion on the greater tubercle of the humerus.
- Lesser tubercle of the humerus is partially muscular, partially tendinous.
- Aponeurosis connects to the greater tubercle and its crest, while the caudal part attaches to the medial brachial fascia.
Actions and Innervation
- Key actions include:
- Adducting the limb when weight-bearing.
- Drawing the limb cranially and caudally.
- Lateral trunk movement and cranial trunk pull.
- Extending the shoulder joint and flexing the shoulder joint when drawing the limb caudally.
- The cranial and caudal pectoral nerves (C7, C8 for cranial; C8, T1 for caudal) provide innervation for these actions.
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Description
Test your knowledge of the extrinsic muscles of the thoracic limb, also known as girdle muscles, including the superficial pectoral, descending pectoral, transverse pectoral, and brachiocephalic. Identify their origins and attachment points on the axial skeleton.
