Presentation on theme: "Muscles of back D.Rania Gabr D.Sama. D.Elsherbiny."— Presentation transcript:
Muscles of back D.Rania Gabr D.Sama. D.Elsherbiny
Objectives Identify the superficial and deep muscles of the back in terms of their location, nerve supply and actions. Understand the muscle support of the trunk. Explain the mechanism of body weight transmission.
Vertebral Column Cervical: 7 Thoracic: 12 Lumbar: 5 Sacral: 5 (fused to form 1 sacrum) Coccygeal: 4 (fused to form coccyx) Total= 33 (counted as 26 in the total bones of the body because of fusion.
Movements at the Vertebral Column Flexion: bending forward Extension: bending backwards Lateral flexion: bending side-wards Rotation: Twisting the trunk Circumduction: Combined movements
MUSCLES OF THE BACK They are organized into 3 groups: Deep group: attached to & involved in the movement of vertebral column & head. Intermediate group: attached to ribs & serve respiratory functions. Superficial group: attached to & involved in the movements of upper limb. Intrinsic muscles: Develop in the back Supplied by posterior rami of spinal nerves Extrinsic muscles: Not developed in the back Supplied by anterior rami of spinal nerves.
Extrinsic Muscles of the Back Superficial extrinsic back muscles: 1. Superficial extrinsic back muscles: Trapezius Latissimus dorsi Levator scapulae Rhomboids major & minor They all connect the upper limb to the trunk. Supplied by anterior rami of spinal nerves
Superficial Extrinsic Back Muscles Trapezius Latissimus dorsi Levator scapulae Rhomboids major & minor
LEVATOR SCAPULAE; RHOMBOID MINOR & MAJOR Origin: 1.Levator scapulae: cervical transverse processes 2.Rhomboid minor & major: thoracic spines Insertion: back of medial border of scapula. Nerve supply: dorsal scapular nerve. Actions: 1.Levator scapulae: elevates scapula. 2.Rhomboid minor & major: retract scapula.
LATISSIMUS DORSI Origin: Spinous processes of T7 - L5 vertebrae. Iliac crest of sacrum. Thoracolumbar fascia. Inferior angle of the scapula. Lower three or four ribs. Insertion : floor of bicipital groove of humerus. Nerve supply : thoracodorsal nerve. Actions : extension, adduction & medial rotation of humerus (arm, shoulder joint).
Extrinsic Muscles of the Back Intermediate extrinsic back muscles: 2. Intermediate extrinsic back muscles: Serratus posterior superior Serratus posterior inferior They are superficial respiratory muscles and are supplied by intercostal nerves.
Intermediate Extrinsic Back Muscles It includes: Serratus posterior superior Serratus posterior superior (rib elevator). Serratus posterior inferior Serratus posterior inferior (rib depressor). Nerve supply: Nerve supply: anterior rami of thoracic spinal nerves.
Intrinsic Muscles of the Back Called muscles of the back proper. Deep muscles of the back. All are supplied by the posterior primary rami of spinal nerves. Act to maintain posture and control movement of the vertebral column.
Intrinsic Muscles of the Back Superficial intrinsic back muscles: 1.Superficial intrinsic back muscles: Splenius cervices & splenius capitis N.S: Posterior rami of spinal nerves. Acting alone; Actions: Acting alone; laterally flex neck & rotate head to side of active muscle. Acting together; Acting together; extend head & neck.
Superficial Intrinsic Back Muscles Splenius cervices & splenius capitis
Intermediate intrinsic back muscles: 2.Intermediate intrinsic back muscles: Erector spinae is the chief extensor of the vertebral column & is divided into three columns (also called as the long muscle of the back). Ilio-costalis (forms lateral column) Longissimus (forms intermediate column) Spinalis (forms medial co lumn)
They extend from sacrum to skull. They include extensors and rotators of head & vertebral column. Their tone is responsible for maintenance of normal curvature of vertebral column.
Intrinsic Muscles of the Back Deep intrinsic back muscles: 3.Deep intrinsic back muscles: It can be divided into two groups: Major deep layer Minor deep layer
Deep Intrinsic Muscles of the Back 1-Major deep layer Transversospinal group consist of semispinalis, multifidus & rotators. N.S: N.S: Posterior rami of spinal nerves. Actions: Actions: Extension and stabilization of vertebral column.
Deep Intrinsic Back Muscles Transversospinal group (semispinalis, multifidus & rotators)
Deep Intrinsic Muscles of the Back 2- Minor deep layer Interspinales Intertransversarii Levatores costarum N.S: N.S: Posterior rami of spinal nerves Actions Actions: Extension, rotation, lateral flexion and stabilization of vertebral column.
MUSCULAR TRIANGLES OF BACK Auscultatory Triangle: 2.Boundaries: latissimus dorsi, trapezius, and medial border of scapula. 2. Importance: breath sounds are most easily heard with a stethoscope. Lumbar Triangle: (Triangle of Petit) 1.Boundaries : latissimus dorsi, posterior border of external oblique muscle of the abdomen and iliac crest. 2. Importance: Site of an abdominal hernia
Muscles of the back Extrinsic: Movements of upper limb and respiration. 1 st layer: Trapezius - Latissimus Dorsi 2nd layer:Levator Scapulae- Rhomboids (minor & major) 3rd layer:Serratus posterior (superior & inferior) Intrinsic: Act on vertebral column and neck. 1st layer:Splenius 2nd layer:Erector Spinae:Iliocostalis Longissimus Spinalis 3rd layer:Transversospinal:Multifidus Rotatores Semispinalis