University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2022
Views:

78

Pages:

31
Author:

Neeleworvorhx4

Muscles of the Back Superficial muscles (extrinsic) are associated with movements of the shoulder. Intermediate muscles (extrinsic) are associated with movements of the thoracic cage. Deep muscles (intrinsic) are associated with movements of the vertebral column. The extrinsic muscles are superficial to the intrinsic muscles. Trapezius Latissimus dorsi Superficial Levator scapulae Rhomboids major Extrinsic Muscles of the Back Rhomboids minor Serratus posterior superior Intermediate Serratus posterior inferior Splenius cervices Superficial Splenius capitis Intermediate Erector spinae Ilio-costalis Longissimus Spinalis Intrinsic Semispinalis Multifidus Transversospinalinalis Deep Interspinales Intertransversarii Levatores costarum Rotatores brevis Rotatores longus Extrinsic MusclesSuperficial Group Trapezius ..1/2 Origin: Occipital bone(external occipital protuberance), superior nuchal line, ligamentum nuchae, spine of seventh cervical vertebra, spines of all thoracic vertebrae and their supraspinous ligament Insertion: • Upper fibers into posterior border of lateral third of clavicle • middle fibres- medial border of acromion and upper lip of crest of spine • lower fibers pass upward and laterally and insert on medial end of spine of scapula Trapezius ..2/2 Nerve Supply: • Spinal part of accessory nerve (motor) and ventral rami of C3 and 4 (sensoryproprioceptive) Action: • Upper fibers along with levator scapulae elevate the scapula; • middle fibers with rhomboids pull scapula medially (retracts); • lower fibers pull medial border of scapula downward , so upper and lower fibres acting together rotate scapula-glenoid cavity face upward assisted by lower 5 digitations of serratus anterior Latissimus dorsi Origin • Iliac crest, lumbar fascia, spines of lower six thoracic vertebrae(T7T12), lower three or four ribs, and inferior angle of scapula Insertion • Floor of bicipital groove of humerus Nerve Supply • Thoracodorsal nerve (C6, 7, 8) Action • Extends, adducts, and medially rotates the arm • Its called the climbing muscle • Raising of the trunk above the arm Levator scapulae Origin • Transverse processes of first fourth cervical vertebrae Insertion • Medial border of scapula Nerve supply • C3 and 4 and dorsal scapular nerve • C3, 4, 5 Action • Raises medial border of scapula ligamentum nuchae The ligamentum nuchae is a large median ligament composed of tendons and fascia located between the posterior muscles of the neck. It covers the spines of C1 to C6 vertebrae. It is a superior and posterior extension of the supraspinous ligament Rhomboid minor Origin • Ligamentum nuchae and spines of C7and T1-T3 Insertion • Medial border of scapula Nerve supply • Dorsal scapular nerve C4, 5 Rhomboid major Origin • Second to fifth thoracic spines Insertion • Medial border of scapula Nerve supply • Dorsal scapular nerve C4, 5 Action • Retract scapula • The rhomboids work collectively with the levator scapulae muscles to elevate the medial border of the scapula, downwardly rotating the scapula with respect to the glenohumeral joint. Superficial extrinsic back muscles connect the upper limb to the trunk. Intermediate extrinsic back muscles are superficial respiratory muscles and are supplied by intercostal nerves. Intrinsic Muscles of the Back are called muscles of the back proper. All are supplied by the posterior primary rami of spinal nerves. Act to maintain posture and control movement of the vertebral column. Superficial MusclesIntermediate Group Serratus Posterior Superior Origin: from the lower part of the ligamentum nuchae, and the cervical and thoracic spines (usually C7 – T3). Insertion: The fibres pass in an inferolateral direction, attaching to ribs 2-5. Nerve Supply: Intercostal nerves. Action: Elevates ribs 2-5. Serratus Posterior Inferior Origin: from the thoracic and lumbar spines (usually T11 – L3). Insertion: The fibres pass in a superolateral direction, attaching to ribs 9-12. Nerve Supply: Intercostal nerves. Action: Depresses ribs 9-12 Trapezius Latissimus dorsi Superficial Levator scapulae Rhomboids major Extrinsic Rhomboids minor Intermediate Muscles of the Back Serratus posterior superior Serratus posterior inferior Splenius cervices Superficial Splenius capitis Intermediate Erector spinae Intrinsic Ilio-costalis Longissimus Spinalis Semispinalis Transversospinalinali s Deep Interspinales Intertransversarii Levatores costarum Multifidus Rotatores brevis Rotatores longus Intrinsic MusclesSuperficial Group Splenius Capitis Origin: from the lower aspect of the ligamentum nuchae, and the spinous processes of C7 – T3/4 vertebrae. Insertion: The fibres ascend, attaching to the mastoid process and the occipital bone of the skull. Nerve Supply: Posterior rami of spinal nerves C3 and C4. Action: • Rotate head to the same side. • Acting together, muscles on both sides extend the head and neck. Splenius Cervices Origin: from the spinous processes of T3-T6 vertebrae. Insertion: The fibres ascend, attaching to the transverse processes of C1-3/4. Nerve Supply: Posterior rami of the lower cervical spinal nerves. Action: • Rotate head to the same side. • Acting together, muscles on both sides extend the head and neck. Iliocostalis Origin: Arises from the common tendinous origin, Insertion: to the costal angle of the ribs and the cervical transverse processes. Nerve Supply: Posterior rami of the spinal nerves. Action: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head. Longissimus Origin: Arises from the common tendinous origin, Insertion: to the lower ribs, the transverse processes of C2 – T12, and the mastoid process of the skull. Nerve Supply: Posterior rami of the spinal nerves. Action: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head. Spinalis Origin: Arises from the common tendinous origin, Insertion: to the spinous processes of C2, T1-T8 and the occipital bone of the skull. Nerve Supply: Posterior rami of the spinal nerves. Action: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.

Muscles of the Back

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