Anterior Axioappendicular Muscles – Origin, Function

Anterior Axioappendicular Muscles /The Axioappendicular muscles are the muscles that extend between the axial and (superior or inferior) appendicular skeletons. There are two groups, the anterior axioappendicular muscles, and the posterior axioappendicular muscles.

Anterior Axioappendicular Muscles (Thoracoappendicular Muscles)

Pectoralis major

  • Function: flexion, adduction, medial rotation of the humerus.
  • Origin: clavicular head: medial clavicle anteriorly, sternocostal head: anterior sternum and costal cartilages of ribs 1 to 6 as well as external oblique aponeurosis
  • Insertion: the lateral edge of an intertrabecular groove of the humerus
  • Innervation: medial pectoral nerve (C8, T1) lateral pectoral nerve (C5, C6, C7) of brachial plexus

Pectoralis minor

  • Function: Depression of the shoulder, protraction of the scapula
  • Origin: Third, fourth, fifth ribs close to their respective costal cartilages
  • Insertion: Coracoid process
  • Innervation: Medial pectoral nerve (C8, T1)

Subclavius

  • Function: Depression and stabilization of the clavicle
  • Origin: First rib medially
  • Insertion: Middle of the clavicle, inferiorly
  • Innervation: Nerve to subclavius (C5, C6)

Serratus anterior  

  • Function: Protraction of scapula, rotation of the scapula
  • Origin: Lateral first to the eighth rib
  • Insertion: anterior scapula, medially
  • Innervation: long thoracic nerve (C5, C6, C7)

Posterior Axioappendicular Muscles

Superficial Layer

Latissimus dorsi 

  • Function: Adduction, medial rotation, extension of humerus
  • Origin: Spinous processes of seventh to 12th thoracic vertebrae, iliac crest, thoracolumbar fascia, and inferior third and fourth rib
  • Insertion: Intertubercular groove of humerus
  • Innervation: Thoracodorsal nerve (C5,C6,C7)

Trapezius 

  • Function: Elevation, depression, and retraction of the scapula, rotation of glenoid cavity
  • Origin: Superior nuchal line, nuchal ligament, occipital protuberance, spinous processes of C7- T12
  • Insertion: Spine of scapula, acromion, and lateral clavicle
  • Innervation: CN XI

Deep Layer

Levator scapulae

  • Function: Adduction, medial rotation, an extension of humerus
  • Origin: Transverse processes of C1 through C4 vertebrae
  • Insertion: Scapula at its medial border
  • Innervation: Thoracodorsal nerve (C5, C6, C7)

Rhomboid major

  • Function: Retraction of scapula and depression of glenoid cavity
  • Origin: Spinous processes of T2 through T5 vertebrae
  • Insertion: Inferior aspect of medial scapula
  • Innervation: Dorsal scapular nerve (C4, C5)

Rhomboid minor

  • Function: Retraction of scapula and depression of glenoid cavity
  • Origin: Nuchal ligament as well as spines of C7 and T1 vertebrae
  • Insertion: Superior aspect of medial scapula
  • Innervation: Dorsal scapular nerve (C4, C5)

References

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