sign in sign up
<<
Home , Pectoralis major, Pectoralis minor, Serratus anterior muscle, Subclavius muscle, Trapezius

Back and muscles General division

Extrinsic back muscles of the back muscles Superficial extrinsic back muscles (posterior thoracoappendicular muscles)

Intermediate extrinsic back muscles (spinocostal muscles)

Intrinsic back muscles

Superficial layer (Splenius muscles)

Intermediate layer (Erector spinae)

Deep layer (Transverospinal muscles)

Minor deep layer (Short back muscles) Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic muscles)

 Superficial posterior  Deep posterior thoracoappendicular thoracoappendicular muscles muscles  Levator scapulae   Latissimus dorsi  Rhomboid minor  Rhomboid major Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles) Trapezius Attachments  Origin (proximal attachment) • , and spinous processes of C7 to T12 vertebrae  Insertion (distal attachment) • , and spine of Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles)

Trapezius Innervation  Spinal roots of accessory (CN XI)  Cervical plexus Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles) Trapezius  Function- movements of scapula:  Superior part- elevation  Middle part- retraction  Inferior part- depression  Common action of superior and inferior parts results in rotation of scapula which enables elevation of the above the level of the shoulder.

Trapezius cooperates then with Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles) Latissimus dorsi Attachments  Origin • Spinous processes of T6- T12 vertebrae, thoracolumbar , iliac crest, inferior 3 or 4  Insertion • Floor of the intertubercular groove of Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles)

Latissimus dorsi  Innervation  Thoracodorsal nerve- branch of the

 Thoracodorsal nerve is situated on the posterior wall of the and may be injured during surgery in this region Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles)

Functions of latissimus dorsi  Action on the glenohumeral joint:  Extension, adduction and medial rotation (folding behind the back)

 Together with  Depresses elevated upper limb (for example during chopping wood)  Raises body towards arms during climbing Raising the body

Latissimus dorsi Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles)

Levator scapulae Attachments Origin • Transverse processes of C1 to C4 vertebrae Insertion • Superior part of medial border of scapula Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles) Rhomboid minor  Attachments  Proximal • Nuchal ligament and spinous processes of C7 and T1 vertebrae

Rhomboid major  Attachments  Proximal • Spinous processes of T2 to T4 vertebrae

 Distal attachments of both rhomboids  Medial border of scapula Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles)

Levator scapulae and rhomboids Function- movements of scapula:  Elevation of scapula and tilting the glenoid cavity inferiorly by rotating the scapula  Retraction of scapula (rhomboids)  Fixing scapula to the Superficial extrinsic back muscles (posterior thoracoappendicular or extrinsic shoulder muscles) Levator scapulae and rhomboids  Innervation  Dorsal scapular nerve- branch of the brachial plexus (its supraclavicular part- root C4- C5)

 Testing the rhomboids or dorsal scapular nerve or C4- C5 roots  Patient has its hands on the hips and pushes elbows posteriorly against the resistence provided by examiner Intermediate extrinsic back muscles (spinocostal muscles) Serratus posterior superior  Attachments  Superior- nuchal ligament, spinous processes of C7 to T3 vertebrae  Inferior- 2nd to 4th ribs Serratus posterior inferior  Attachments  Superior- spinous processes of T11 to L2 vertebrae  Inferior- 8th to 12th ribs  Function of serratus posterior muscles  accessory muscles of inspiration  Innervation of serratus posterior muscles  intercostal Intrinsic (deep) back muscles

Back muscles Innervation- dorsal rami of the Extrinsic back muscles spinal nerves

Superficial extrinsic back muscles (posterior thoracoappendicular muscles)

Intermediate extrinsic back muscles (spinocostal muscles)

Intrinsic back muscles

Superficial layer (Splenius muscles)

Intermediate layer (Erector spinae)

Deep layer (Transverospinal muscles)

Minor deep layer (Short back muscles) Intrinsic (deep) back muscles Action •Acting bilaterally (together)- extend trunk and head

•Acting unilaterally (alone)- flex laterally and rotate trunk and head Superficial layer of the intrinsic back muscles Splenius capitis Splenius cervicis  Location  Lateral and posterior side of  Extended between midline and (transverse processes- splenius cervicis) and skull (mastoid process of temporal bone- splenius capitis)  Main action  Acting alone- bend and rotate head to side of active muscle  Acting together- extend head and neck ErectorErector spinaespinae

Intermediate layer of the intrinsic back muscles (erector spinae) Erector spinae (sacrospinalis) muscle  Origin  Posterior part of iliac crest and sacrum Parts:  Lateral column • (lumborum, thoracis and cervicis)- attached to the angles of ribs and cervical transverse processes  Intermediate column • (thoracis, cervicis and capitis)- attached to ribs between angles and tubercules, cervical transverse processes and mastoid process of skull  Medial column • (thoracis, cervicis and capitis)- attached to spinous processes of and skull Deep layer of the intrinsic back muscles (transversospinal muscles)

Transversospinal muscles  Attachments  Extended between transverse and spinous processes of vertebrae  Parts (have different length):  Semispinalis (thoracis, cervicis and capitis)- spanns 4-6 segments  Multifidi- spann 2- 4 segments  Rotatores muscles- spann 1-2 segments Minor deep layer of the intrinsic back muscles

 Interspinales muscles  muscles  Attachments • Extended between spinous or transverse processes of adjacent vertebrae  Levatores costarum muscles  Extended between transverse processes of thoracic vertebrae and situated inferolaterally Suboccipital region

 Situated in the upper part of the posterior surface of the neck, below the occipital bone, at the level of C1 and C2 vertebrae

 Covered by the trapezius, splenius capitis and semispinalis capitis muscles Suboccipital muscles (deep neck muscles)  Rectus capitis posterior minor  Rectus capitis posterior major  Rectus capitis lateralis  Superior oblique of the head  Inferior oblique of the head

 Suboccipital muscles are extended between C1 or C2 vertebrae and occipital bone.

The only exception is the inferior oblique of the head extended between C1 and C2 vertebrae Suboccipital muscles (deep neck muscles)  Rectus capitis posterior minor  Rectus capitis posterior major  Rectus capitis lateral  Superior oblique of the head  Inferior oblique of the head

 Suboccipital muscles are innervated by the suboccipital nerve (motor nerve being the posterior ramus of C1 ) Boundaries  Superomedial- rectus capitis posterior major  Superolateral- superior oblique of head  Inferolateral- inferior oblique of head

 Floor- posterior atlanto- occipital membrane, arch of C1  Roof- semispinalis capitis muscle

Contents:  Suboccipital nerve  Vertebral Innervation of the skin in the occipital region

In the innervation of the skin in the occipital region participate:  Greater occipital nerve- posterior branch of the 2nd cervical spinal nerve (C2)

 Lesser occipital nerve- branch of the cervical plexus (contains the anterior branch of the 3rd cervical spinal nerve C3)

 1st cervical spinal nerve C1 (and suboccipital nerve) has no sensory fibers and it results in lack of the C1 dermatome of the skin Greater occipital nerve  Exits the vertebral canal between the vertebrae C1 i C2  Runs superiorly under the trapezius and splenius capitis muscles  Pierces lateral border of the of the trapezius, just under the inferior nuchal line of the occipital bone  In the occipital region runs together with Lesser occipital nerve

Is a branch of the cervical plexus Arises in the midpoint of the posterior edge of the sternocleidomastoid muscle Blocks of the lesser and greater occipital nerves Block of the sensory branches of the cervical plexus Superficial muscles of the (anterior thoracoappendicular muscles) Pectoralis major  Extended between clavicle, and ribs and lateral lip of the intertubercular groove of humerus  Main action- adduction, medial rotation and flexion of humerus, muscle of climbing  Innervation- medial and lateral pectoral nerves  Extended between ribs and of scapula  Main action- protraction and depression of scapula  Innervation- Boxer’s muscle

Serratus anterior

Superficial muscles of the thorax (anterior thoracoappendicular muscles) Serratus anterior  Extended between ribs and medial border of scapula  Innervation-  Main action- protraction and rotation of scapula, participation in elevation of arm above the level of shoulder Pushing a wall

SerratusErectoranteriorspinae Scapulohumeral (intrinsic shoulder) muscles  muscles  Supraspinatus  Infraspinatus  Teres minor  Subscapularis  Teres major muscle Scapulohumeral (intrinsic shoulder) muscles

Deltoid muscle  Attachments  Proximal • Posterior part: • Middle part- acromion • Anterior part- clavicle  Distal  Deltoid tuberosity of humerus  Innervation  Axillary nerve (branch of the posterior cord of brachial plexus) Scapulohumeral (intrinsic shoulder) muscles

Deltoid muscle  Main action  Posterior part: extension and lateral rotation of arm  Middle part- abduction of arm (cooperates with supraspinatus)  Anterior part- flexion and medial rotation of arm Scapulohumeral (intrinsic shoulder) muscles Muscles of rotator cuff

 Rotator cuff muscles form a musculotendinous cuff around the glenohumeral joint  Rotator cuff muscles reinforce and stabilize the glenohumeral joint blending with its articular capsule

 Supraspinatus muscle   Teres minor  Scapulohumeral (intrinsic shoulder) muscles Muscles of rotator cuff Supraspinatus muscle  Attachments  Proximal • Supraspinous fossa of scapula  Distal • Superior facet on greater tubercle of humerus  Innervation  (branch of the superior trunk of brachial plexus)  Action  Abduction of arm Between the acromion and the tendon of supraspinatus is located the subacromial bursa. Subacromial bursa, filled with synovial fluid, diminish friction of supraspinatus during its contraction. Scapulohumeral (intrinsic shoulder) muscles Muscles of rotator cuff Infraspinatus muscle  Attachments  Proximal • Infraspinous fossa of scapula  Distal • Middle facet on greater tubercle of humerus

 Innervation  Suprascapular nerve (branch of the superior trunk of brachial plexus) Scapulohumeral (intrinsic shoulder) muscles Muscles of rotator cuff Teres minor  Attachments  Proximal • Lateral border of scapula  Distal • Inferior facet on greater tubercle of humerus  Innervation  Axillary nerve (branch of the posterior cord of brachial plexus)

Action of infraspinatus and teres minor  Lateral rotation of arm Scapulohumeral (intrinsic shoulder) muscles Muscles of rotator cuff Subscapularis muscle  Attachments  Proximal • Subscapular fossa of scapula  Distal • Lesser tubercle of humerus  Innervation  Subscapular nerves (branches of the posterior cord of brachial plexus)  Action  Medial rotation of arm Tearing of the rotator cuff tendons Scapulohumeral (intrinsic shoulder) muscles

Teres major  Attachments  Proximal • Inferior angle of scapula  Distal • Medial lip of intertubercular groove of humerus  Innervation  Subscapular nerves (branches of the posterior cord of brachial plexus)  Action  Adduction and medial rotation of arm Axilla (armpit) Axilla (armpit)

 Pyramidal space between thorax and upper limb

 Axilla provides a passageway from neck for vessels and nerves supplying upper limb Boundaries of axilla Apex- entrance from neck  Situated between 1st rib, clavicle and subscapularis Base of axilla  Skin, subcutaneous tissue and axillary fascia Boundaries of axilla

 Anterior wall- formed by pectoralis major and pectoralis minor muscles

 Posterior wall- formed by scapula and subscapularis muscle and latissimus dorsi and teres major muscles

 Medial wall- formed by wall of thorax and covering it serratus anterior

 Lateral wall (or narrow lateral border)- formed by intertubercular groove of humerus Contents of axilla

Brachial plexus (its cords and branches) Axillary blood vessels  and its branches  Axillary vein and its tributaries  Openings in the posterior wall of axilla Quadrangular space  Boundaries  Superior- teres minor  Inferior- teres major  Medial- long head of triceps brachii muscle  Lateral- surgical neck of humerus  Contents  Axillary nerve  Posterior circumflex humeral artery Openings in the posterior wall of axilla Triangular space  Boundaries  Superior- teres minor  Inferior- teres major  Lateral- long head of triceps brachii muscle  Contents  Circumflex scapular artery Brachial plexus

Location of the brachial plexus

Supraclavicular part Supraclavicular region of the neck between the anterior and middle Infraclavicular part Axilla

Brachial plexus (supraclavicular part)

Roots of the brachial plexus

 Ventral rami of last four cervical spinal nerves and first thoracic nerve (C5 to T1 nerves)

 Situated in the neck (posterior triangle) between anterior and middle scalene muscles Brachial plexus (supraclavicular part) Trunks of the brachial plexus

 In the inferior part of the neck (posterior triangle), between the anterior and middle scalene muscles, roots of the brachial plexus unite to form the trunks of the brachial plexus

 Superior trunk (union of C5 and C6 roots)  Middle trunk (continuation of C7 root)  Inferior trunk (union of C8 and T1 roots) Brachial plexus (infraclavicular part) Cords of the brachial plexus

 In the place of passage between clavicle and 1st rib (cervicoaxillary canal) each trunk of the brachial plexus divides into anterior and posterior divisions

 Divisions of the brachial plexus form three cords located in axilla  Posterior cord (posterior divisions of all three trunks)  Lateral cord (anterior divisions of superior and middle trunks)  Medial cord (anterior division of inferior trunk)

Interscalene block of the brachial plexus Supraclavicular block of the brachial plexus Infraclavicular block of the brachial plexus Axillary block of the brachial plexus of brachial plexus

Dorsal scapular nerve

 Arises from C4 and C5 roots  Runs along medial border of scapula  Innervates  Levator scapulae  Rhomboid minor  Rhomboid major Supraclavicular nerves of brachial plexus

Long thoracic nerve  Arises from C5, C6 and C7 roots  Runs on the lateral wall of thorax, on the surface of serratus anterior muscle  Innervates  Serratus anterior muscle  Symptoms of injury  Supraclavicular nerves of brachial plexus

Suprascapular nerve

 Arises from superior trunk of the brachial plexus

 Passes across the posterior triangle of the neck, and via the scapular notch reaches the supraspinous fossa of scapula

 Innervates  Supraspinatus muscle  Infraspinatus muscle

 Symptoms of injury  Difficulties with abduction of arm Supraclavicular nerves of brachial plexus Nerve to subclavius  Arises from superior trunk of the brachial plexus  Runs posteriorly to clavicle  Innervates  Short (side) nerves of the infraclavicular part of brachial plexus

Lateral (from lateral cord) and medial (from medial cord) pectoral nerves

 Pierce the and reach deep surfaces of the pectoralis major and minor muscles Short (side) nerves of the infraclavicular part of brachial plexus

Subscapular nerves (upper and lower) from posterior cord of the brachial plexus

 Pass posteriorly and inferolaterally  Innervate  Subscapularis muscle  Teres major muscle Short (side) nerves of the infraclavicular part of brachial plexus

Thoracodorsal nerve from posterior cord of the brachial plexus  Runs inferolaterally along the posterior axillary wall to latissimus dorsi  Innervate  Short nerves of the infraclavicular part of brachial plexus

Axillary nerve from posterior cord of the brachial plexus  Leaves the axilla via the quadrangular space, winds around the surgical neck of humerus, reaches deltoid and teres minor, gives rise to lateral brachial cutaneous nerve  Innervate  Deltoid muscle  Teres minor muscle   Skin over inferior part of deltoid  Injury  May be caused by fracture of the surgical neck of humerus or dislocation of the head of humerus from the shoulder joint  Symptoms  Difficulties with abduction of shoulder joint  Area of anesthesia on the lateral surface of the shoulder Palsy of axillary nerve

Atrophy of deltoid muscle Long nerves of the infraclavicular part of brachial plexus  Posterior cord   Lateral cord   Lateral root of the median nerve  Medial cord  Ulnar nerve  Medial root of the median nerve  Medial brachial cutaneous nerve  Medial antebrachial cutaneous nerve