Scapula and back muscle

Angles of the scapula

Lateral, superior, and inferior angles.

Borders of the scapula

Superior, lateral, and medial borders.

Surfaces of the scapula

Costal and posterior surfaces.

Processes of the scapula

Acromion, spine, and coracoid process.

Organization of back muscles

Divided into superficial, intermediate, and deep groups.

Extrinsic muscles of the back

Superficial and intermediate groups called extrinsic because they originate embryologically from locations other than the back.

Innervation of extrinsic back muscles

Superficial and intermediate groups are innervated by anterior rami of spinal nerves.

Function of superficial back muscles

Related to movements of the upper limb.

Function of intermediate back muscles

Attached to ribs; may serve a respiratory function.

Intrinsic muscles of the back

Called intrinsic because they develop in the back.

Innervation of intrinsic back muscles

By posterior rami of spinal nerves.

Related functions of intrinsic back muscles

Movements of the vertebral column and head.

Movements involving extrinsic back muscles

Involved with movements of upper limbs and thoracic wall.

Superficial extrinsic back muscles

Related to upper limbs.

Intermediate extrinsic back muscles

Associated with thoracic wall.

Support and movement by intrinsic back muscles

Support and move the vertebral column and assist in head movement.

Group of intrinsic muscles moving ribs

One group of intrinsic muscles.

Muscles in the superficial group of back muscles

Trapezius, Latissimus dorsi, Rhomboid major, Rhomboid minor, and Levator scapulae.

Superficial shoulder muscles connecting scapula and clavicle to trunk and humerus

Trapezius and deltoid.

Muscle connecting scapula and clavicle to trunk

Trapezius.

Muscle connecting scapula and clavicle to humerus

Deltoid.

Structures connected by trapezius and deltoid

Spine of the scapula, acromion, and clavicle.

Muscles attaching scapula to vertebral column

Levator scapulae, rhomboid minor, and rhomboid major.

Origin of trapezius muscle

Axial skeleton, including sites on the skull and vertebrae from C1 to TXII.

Attachment of trapezius between C1 to CVII

Via ligamentum nuchae.

Insertion of trapezius muscle

Inner margins of a U-shaped line - superior edge of the crest of the spine of the scapula, acromion, posterior border of lateral one-third of clavicle.

Function of trapezius muscle

Powerful shoulder elevator and rotates scapula to extend reach superiorly.

Nerve supply to trapezius muscle

Accessory nerve [XI] and anterior rami of cervical nerves C3 and C4.

Testing trapezius function

Shrug shoulders against resistance.

Shape of deltoid muscle

Large and triangular.

Origin of deltoid muscle

U-shaped line - inferior edge of the crest of the spine of the scapula, lateral margin of acromion, anterior border of lateral one-third of clavicle.

Insertion of deltoid muscle

Deltoid tuberosity on lateral surface of the shaft of the humerus.

Primary function of deltoid muscle

Abducts the arm beyond the initial 15°.

Initial 15° of arm abduction

Accomplished by supraspinatus muscle.

Nerve supply to deltoid muscle

Axillary nerve.

Branch of brachial plexus supplying axillary nerve

Posterior cord.

Artery and vein entering deltoid with axillary nerve

Posterior circumflex humeral artery and vein.

Passage of axillary nerve and vessels into deltoid

Around the surgical neck of the humerus.

Description of latissimus dorsi muscle

Broad, flat muscle occupying the majority of the lower posterior thorax.

Primary function of latissimus dorsi

Upper extremity movement; also a respiratory accessory muscle.

Layer of extrinsic back muscles for latissimus dorsi

Superficial layer.

Shoulder joint movements produced by latissimus dorsi

Internal rotation, adduction, and extension of the arm.

Origin of levator scapulae muscle

Transverse processes of C1 to C4 vertebrae.

Insertion of levator scapulae muscle

Posterior surface of medial border of scapula from superior angle to root of the spine of the scapula.

Nerve supply for levator scapulae

Dorsal scapular nerve and directly from C3 and C4 spinal nerves.

Function of levator scapulae

Elevates the scapula.

Attachments of rhomboid muscles

Medially attach to the vertebral column.

Location of rhomboid muscles

Descend laterally to attach to medial border of the scapula.

Rhomboids' position relative to levator scapulae

Located inferior to levator scapulae on medial border of scapula.

Origin of rhomboid minor

Lower end of ligamentum nuchae and spines of CVII and TI vertebrae.

Insertion of rhomboid minor

Posterior surface of medial border of scapula at root of the spine of the scapula.

Origin of rhomboid major

Spines of TII to TV vertebrae and intervening supraspinous ligaments.

Insertion of rhomboid major

Posterior surface of medial border of scapula from root of spine to inferior angle.

Innervation of rhomboid muscles

Dorsal scapular nerve.

Origin of dorsal scapular nerve

Branch of the brachial plexus.

Function of rhomboid muscles

Retracts and elevates the scapula.

Location of posterior scapular region

Deep to trapezius and deltoid muscles.

Muscles in posterior scapular region passing to the humerus

Supraspinatus, infraspinatus, teres minor, and teres major.

Muscle passing to the forearm in posterior scapular region

Long head of triceps brachii.

Rotator cuff muscles in posterior scapular region

Supraspinatus, infraspinatus, and teres minor.

Function of rotator cuff

Stabilizes the glenohumeral joint.

Origins of supraspinatus and infraspinatus

Supraspinous and infraspinous fossae on posterior surface of scapula.

Insertion of supraspinatus and infraspinatus

On the greater tubercle of the humerus.

Supraspinatus tendon path

Passes under the acromion.

Bursa separating supraspinatus tendon from acromion

Subacromial bursa.

Insertion facet of supraspinatus on greater tubercle

Superior facet.

Infraspinatus tendon path

Passes posteriorly to the glenohumeral joint.

Insertion facet of infraspinatus on greater tubercle

Middle facet.

Function of supraspinatus

Initiates abduction of the arm.

Function of infraspinatus

Laterally rotates the humerus.

Shape of teres minor muscle

Cord-like.

Origin of teres minor

Flattened area of scapula below infraglenoid tubercle.

Insertion of teres minor

Inferior facet of greater tubercle.

Function of teres minor

Laterally rotates the humerus; component of the rotator cuff.

Origin of teres major muscle

Large oval region on posterior surface of inferior angle of scapula.

Insertion of teres major

Medial lip of intertubercular sulcus on anterior surface of humerus.

Function of teres major

Medially rotates and extends the humerus.

Origin of long head of triceps brachii

Infraglenoid tubercle.

Insertion of long head of triceps brachii

With medial and lateral heads.

Insertion of triceps brachii

Olecranon of the ulna.

Primary function of triceps brachii

Extends forearm at elbow joint.

Additional function of long head of triceps brachii

Extends and adducts the humerus.

Spaces for nerves and vessels created by long head of triceps brachii

Between teres minor and teres major.