sign in sign up
<<
Home , Erector spinae muscles

MUSCLES OF THE BACK The

Back

Boundaries Landmarks Regions • Regio colli • Regio vertebralis • Regio scapularis • Regio infrascapularis • Regio lumbalis

Muscles of the back

Three groups (in layers) with distinct functions: A. Superficial layer – move the upper limb (arm). B. Intermediate layer – (attach to the ribs). C. Deep layer – move body and back.

Superficial muscles

Connect the upper limb to the body: • •Latissimus dorsi (the widest muscle of the back) •Levator scapulae (deep to trapezius) •Rhomboidei

SUPERFICIAL MUSCLES

Attach to: 1) Clavicula 2) Scapula 3) Humerus Functions – specialized for freedom of movement

TRAPEZIUS

Origin: 1) - Protuberantia occipitalis externa 2) - Ligamentum nuchae 3) Vertebrae - C7, T1-T12 Insertion: 1) Clavicula - lateral 1/3; 2) Scapula - acromion & spina scapulae Function: 1) Elevation (upper fibers) and depression (lower fibers) of the shoulder 2) Retarction of the scapula 3) Extension of the head Innervation: N. accessorius (CN XI)

Latissimus dorsi Origin: Proc. spinosi T6-T12 Fascia thoracolumbalis Crista iliaca Insertion: Humerus-sulcus intertubercularis Function: Adduction, extension and medial rotation of the arm Innervation: N. thoracodorsalis FASCIA THORACOLUMBALIS

Covers the deep muscles Attached: - medially to proc. spinosi - downwards to ilium Serves as attachment of muscles

LEVATOR SCAPULAE Origin: Proc. transversi C1-C4 Insertion: Scapula (superior angle and medial border)

RHOMBOIDEUS MINOR Origin: Proc. spinosi C7, T1 Insertion: Scapula (medial border)

RHOMBOIDEUS MAJOR Origin: Proc. spinosi T2-T5; Insertion: Scapula (medial border, to the inferior angle)

Function: Elevation, adduction and downward rotation (rhomboids) of the scapula * Reversed action: contralateral rotation of the trunk Innervation: N. dorsalis scapulae

Auscultation triangle

Medial to the scapula Borders Inferiorly - Lat. dorsi Superiorly - Trapezius Laterally – Rhomboideus major Overlies VІ intercostal space; No large muscles on the floor, which alleviates auscultation of lungs.

Intermediate group

• Auxiliary muscles of respiration • All originate from the vertebrae • All insert to the ribs

SERRATUS POSTERIOR SUPERIOR Origin: Pr. spinosi (cervical and upper thoracic) Insertion: Ribs Function: Elevate ribs in inspiration Inervation: Nn. Intercostales 2-5

SERRATUS POSTERIOR INFERIOR Origin: Pr. spinosi (lumber and lower thoracic) Insertion: Ribs Function: Depress ribs in expiration Inervation: Nn. intercostales 9-11, n. sucostalis

Deep group (epaxial muscles)

Derivatives of somaties Segmental organization Located dorsally to the vertebral collummn Divides into three subgroups: - Splenius - Erector spinae - Transversospinalis Erect the body and neck when act bilaterally Inervation: rr. dorsales на nn. spinales

Splenius capitis & splenius cervicis

Deep to trapezius Both muscles have common origin but different insertions Origin: Proc. spinosi T1- T4 Insertion: Splenius Capitis – Occipital, temporal bone Splenius Cervicis- Proc. Transversi C2, C3 Function: Extension of head and neck; Rotation in unilateral contraction

Erector spinae

Three parallel collumns • - medial • - intermediate • - lateral

SPINALIS LONGISSIMUS ILIOCOSTALIS O: Pr. spinosi O: Pr. transversi O: Ilium & ribs I: Pr. transversi I: Ribs or I: Pr. spinosi pr. transversi above

Spinalis Longissimus Iliocostalis

According to attachment divides into: • Iliocostalis Cervicis • Iliocostalis Thoracis • Iliocostalis Lumborum

Transversospinalis

Origin: Proc. transversi Insertion: Proc. spinosi of the vertebrae above Different parts according to the overlied vertebrae a. Semispinalis- 5 - 6 b. Multifidus- 3 - 4 c. Rotatores- 1 – 2 d. Interspinales – between pr. spinosi e. – between pr. transversi Function: Extension of the body in bilateral or rotation in unilateral contraction Note: Orientation of the fibers: transversospinalis run oblique and upward to pr. spinosi; erector spinae are parallel to the vertebral collumn.

Levatores costarum Origin: Pr. transversi C7,T1-11 Insertion: Ribs (below the origin) Function: Elevate ribs on inspiration Inervation: Rr. dorsales nn. spinales

Movements of the back

Flexion: • Rectus abdominis • Psoas major Extension: • Erector spinae – muscles act as one (spinalis, iliocostalis, longissimus)

Movements of the back

Lateral flexion: • Unilateral function of muscles (e.g., m. quadratus lumborum) Rotation: • Obliquus abdominis externus & internus • Transversospinalis (semispinalis, multifidus, rotatores)