Lecture 3.2 - Muscles of the Back Flashcards
Trapezium
- Proximal attachments: Superior nuchal line, external occipital protuberance, ligamentum nuache. spinous processes from C7 - T12. Distal attachment: lateral one-third of clavicle, acromion, spine of scapula. Innervation: accessory nerve. Main functions: assists in rotating the scapula during abduction of the humerus above horizontal.
- superior fibres - main function: elevate scapula [shrugging]
- middle fibres - main function: adduct scapula [pulls the medial borders of the scapula together]
- inferior fibres - main function: depress scapula
Latissimus Dorsi
Proximal attachments: spinous processes of T7 - L5 and sacrum, iliac crest, ribs (10 - 12). Distal attachments: floor of the intertubercular sulcus of the humerus. Innervation: Thoracodorsal nerve. Main function: extends, adducts and medially rotates the humerus.
Levatore Scapulae
Proximal attachments: transverse processes of C1 - C4. Distal attachments: upper portion medial border of the scapula. Innervation: dorsal and scapular nerve. Main functions: elevates the scapula.
Rhomboid minor
Proximal attachments: lower portion of ligamnentum nuchae, spinous processes of C7 - T1. Distal attachments: medial border of scapula at spine of scapula. Innervation: Dorsal scapular nerve. Main functions: adducts and elevates scapula.
Rhomboid major
Proximal attachments: spinous processes of T2 - T5. Distal attachments: medial border of scapula between spine and inferior angle. Innervation: Dorsal scapular nerve. Main functions: adducts and elevates scapula.
Serratus posterior SUPERIOR
Proximal attachments: lower portion of ligamentum nuchae, spinous process of C7 - T3, supraspinous ligaments. Distal attachments: upper border of ribs 2 - 5 just lateral to their angles. Innervation: Anterior rami of upper thoracic nerves (T2 - T5) [long thoracic nerve]. Main functions: elevates ribs 2 - 5
Serratus posterior INFERIOR
Proximal attachments: spinous processes of T11 - L3, surpaspinous ligaments. Distal attachments: lower border of ribs 9 - 12 just lateral to their angles. Innervation: anterior rami of lower thoracic nerves (T9 - T12) [long thoracic nerve]. Main functions: depresses ribs 9 - 12 and may prevent lower ribs from being elevated when the diaphragm contracts.
Spinotransverales
Main functions: extend the neck [draw head backwards]
- Splenius capitis - Proximal attachments: lower half of ligamentum nuchae, spinous processes of C7 - T4. Distal attachments: Mastoid process, skull below lateral nuchal line. Innervation: posterior rami of middle cervical nerves. Main functions: draw and rotate head to one side [same side to the muscle].
- Splenius cervicis - Proximal attachments: spinous processes of T3- T6. Distal attachments: transverse processes of C1 - C3. Innervation: posterior rami of lower cervical nerves. Main functions: draw and rotate head to one side.
Erector Spinae : Iliocostalis
Most medial. Proximal attachments: thoracolumbar fascia, posterior sacrum, medial part of the iliac crest. Distal attachments: posterior ribs, transverse processes of C4- C7. Innervation: lateral branch of the posterior rami. Main function: extend and ipsilaterally laterally flex the trunk and neck.
- lumborum - Proximal attachments: sacrum, spinous processes of lumber and lower two thoracic vertebrae and their supraspinous ligaments, iliac crest. Distal attachments: angles of the lower 6/7 ribs.
- thoracis - Proximal attachments: angles of the lower 6 ribs. Distal attachments: angles of the upper 6 ribs and the transverse process of C7.
- cervicis - Proximal attachments: angles of ribs 3 - 6. Distal attachments: transverse processes of C4 - C6.
Erector Spinae : Longissimus
Middle. Proximal attachments: posterior sacrum, medial part of the iliac crest, lumbar and thoracic spinous processes, thoracolumbar fascia. Distal attachments: all cervical and thoracic transverse processes, mastoid process in the skull. Innervation: lateral branch of the posterior rami. Main function: extension of the trunk, head and neck.
- capitis - Proximal attachments: transverse processes of upper 4/5 thoracic vertebrae and articular processes of lower 3/4 cervical vertebrae. Distal attachments: posterior margin of the mastoid process
- thoracis - Proximal attachment: blends with ilicostalis in lumbar region and is attached to transverse processes of lumbar vertebrae. Distal attachments: transverse processes of all thoracic vertebrae and just lateral to the tubercles of the lower 9/10 ribs.
- cervicis - Proximal attachments: transverse processes of upper 4/5 thoracic vertebrae. Distal attachments: transverse processes of C2 - C6
Erector Spinae : Spinalis
Most lateral. Proximal attachments: ligaments nuchae, all cervical and thoracic spinous processes. Distal attachments: all cervical and thoracic spinous processes. Innervation: medial branches of the posterior rami. Main function: concentrically extend the trunk.
- capitis - proximal attachments: usually blends with semispinalis capitis. Distal attachments: with semispinalis capitis
- thoracis - Proximal attachments: spinous processes of T10/T11 - L2. Distal attachments: spinous processes of T1 - T8 (variable).
- cervicis - Proximal attachment: lower part of ligamentum nuchae and spinous process of C7 (sometimes T1/T2). Distal attachments: spinous process of C2 [axis].
Transversospinalis : Semispinalis capitis
Proximal attachments: All cervical and thoracic transverse processes. Distal attachments: In between the superior and inferior nuchal lines of occipital bone. Innervation: Medial branch of the posterior rami. Main function: extension of the neck and head. Assists in lateral flexion and rotation of the head and neck.
Transversospinalis : Semispinalis cervicis
Proximal attachments: all cervical and thoracic transverse processes. Distal attachments: all thoracic and cervical spinous processes. Innervation: Medial branches of posterior rami. Main function: bilaterally extends the cervical spine and laterally flexes and rotates it.
Transversospinalis : semispinalis thoracis
Proximal attachments: transverse processes of T6 - T10. Distal attachments: spinous processes of upper 4 thoracic and lower 2 cervical vertebrae. Innervation: Medial branches of posterior rami. Main functions: extension of the head and neck. Lateral flexion of the head, cervical and thoracic spine on the same side and rotation of head, cervical and thoracic spine on the opposite side; unilateral contraction.
Transversospinalis : Multifidus
Proximal attachments: upper sacrum, posterior superior iliac spine, all lumbar and thoracic transverse processes. Distal attachments: spinous processes from L5 - C2. Innervation: Medial branch of posterior rami. Main functions: extends, contralaterally rotates and ipsilaterally laterally flexes trunk and neck. Major stabiliser if the lumber vertebral column
Transversospinalis : Rotatores
Proximal attachments: transverse processes of T2 - T12. Distal attachments: spinous processes of T1 - T11. Innervation: Medial branch of posterior rami. Main functions: stabiliser group.
Uni-segmental group : Interspinales
Proximal attachments: all lumbar spinous processes. Distal attachments: spinous processes at the next level below. Innervation: Medial branch of the posterior rami. Main functions: dynamic ligament [fixator action → a fixator is a short muscle locates close to a joint. It stabilises by acting as a dynamic (muscular) ligament - providing stability]
Uni-segmental group : Medial intertransversarii
Proximal attachments: accessory process. Distal attachments: mammillary processes at the next level below. Innervation: Medial branches of the posterior rami. Main functions: dynamic ligament.
Uni-segmental group : Lateral intertransversarii
Proximal attachments: transverse processes. Distal attachments: transverse processes at the next level below. Innervation: anterior rami [functionally muscles of the back but developed from the ventral body wall]. Main functions: dynamic ligament
Uni-segmental group : Levatores costrarum
Proximal attachments: transverse processes at C7 - T11. Distal attachments: upper border of rib immediately below. Innervation: lateral branches of posterior rami [functionally muscles of the thoracic wall, but developed from the back]. Main functions: elevates ribs during breathing.
Rectus capitis posterior MAJOR
Proximal attachments: spinous process of axis (C2). Distal attachments: lateral portion of occipital bone below inferior nuchal line. Innervation: posterior ramus of C1. Main function: extension of the head, rotation of face to same side as muscle.
Rectus capitis posterior MINOR
Proximal attachments: posterior tubercle of atlas (C1). Distal attachments: medial portion of occipital bone below inferior nuchal line. Innervation: posterior ramus of C1. Main functions: extension of the head.
Obliquus capitis INFERIOR
Proximal attachments: spinous process of axis (C2). Distal attachments: transverse process of atlas (C1). Innervation: posterior ramus of C1. Main functions: rotation of face to same side.
Obliquus capitis SUPERIOR
Proximal attachments: transverse process of the atlas (C1). Distal attachments: occipital bone between superior and inferior nuchal lines. Innervation: posterior ramus of C1. Main functions: extension of the head and bends it to same side
