Download L05 and L06 - Superficial Back Muscles and Posterior Shoulder with

L05 and L06 - Superficial Back Muscles and Posterior
Shoulder with Deep Back Muscles and Suboccipital
Triangle
Thursday, October 30, 2014
11:00 AM
Types of back muscles:
– Superficial muscles: extrinsic and move the appendicular muscles
 Hypaxial differentiation
 Innervated by ventral motor roots which split into ventral rami
– Deep muscles: intrinsic and move the head and the trunk, acting on the spine as principle extensors in lateral
flexion and rotation spanning from the pelvis to the skull base
 Epaxial differentiation
 Innervated by dorsal sensory root which split into dorsal rami
– Movements rarely involve a single muscle, acting in coordinated and synergistic movements
Superficial back muscles and associated structures:
– Trapezius
 Scapular movements:
► Elevation and depression
► Superior and inferior rotation
► Protraction and retraction
– Latissimus Dorsi: possesses fibers that attach to the scapula as it crosses the inferior angle of the scapula
 Innervation: thoracodosal nerve -- a branch of the posterior cord of the brachial plexus made of
cranial nerve VI, VII, and VIII
– Triangle of Auscultation -- created by the superior latissimus dorsi, medial border of the scapula, lateral
trapezius
– Levator Scapulae
– Rhomboid Major
– Rhomboid Minor
Intermediate back muscles and associated structures:
– Serratus Posterior Superior
– Serratus Posterior Inferior
Posterior shoulder muscles and associated structures:
– Teres Major
– Deltoid
– Bursae -- flat sac of synovial membrane that lubricates the joint
 Shoulder: Subacromial Head and Subdeltoid Head
Anatomy Page 1
 Clinical causes of bursitis:
► Calcifying tendinitis -- calcification of the tendon and related degenerative change
► Supraspinatous tendon avulsion -- rotator cuff tear
□ Rotator Cuff -- musculotendinous cuff of 4 muscles that adhere to the
fibrous capsule of the glenohumerol joint, stabilizing the joint (as the only
muscle that inserts on the greater and lesser tubercles of the humerus)
 Supraspinatus
 Infraspinatus
 Teres Minor
 Subscapularis
– Serratus Anterior
 Innervation: long thoracic nerve that runs along the surface of the muscle
– Anatomical spaces formed by muscles near the proximal arm containing neurovasculature:
 Quadrangular space -- bound by the teres minor, teres major, surgical neck of the humerus, and long
head of the triceps
► Contains: posterior circumflex humeral artery, axillary nerve
 Triangular space -- bound by the teres minor, teres major, and long head of the triceps
► Contains: circumflex scapular artery
Other associations:
– Cutaneous nerve supply:
 Posterior cutaneous nerves as medial branches of the dorsal rami and lateral branches
of the dorsal rami
 Lateral cutaneous nerves as posterior branches of the ventral rami
– Blood supply:
 Subclavian artery of the thyrocervical trunk
► Superficial transverse cervical artery
► Deep dorsal scapular artery
► Suprascapular artery
 Rib 1
 Axillary artery
Anatomy Page 2
► Deep dorsal scapular artery
► Suprascapular artery
 Rib 1
 Axillary artery
► Subscapular artery
□ Thoracodorsal nerve
□ Circumflex scapular artery
► Posterior humeral circumflex artery
 Scapular anastomosis -- a system connecting certain subclavian artery and their corresponding axillary
artery, forming a circulatory anastomosis around the scapular (that allows blood to flow past the joint
in the event of occlusion, damage, or pinching of the transverse cervical artery, dorsal scapular artery,
suprascapular artery, branches of the subscapular artery, and branches of the thoracic aorta)
Deep back muscles:
– Thoracolumbar fascia -- dense, tough connective tissue layers, extending from the iliac crest and dorsal
sacrum upwards to the thoracic region and neck
 Tri-laminar (as posterior, middle, and anterior portions) in the lumbar region
 Functions: invests the intrinsic back muscles in a fascial compartment, serves as attachment points for
several muscles (e.g., latissimus dorsi, internal oblique, transversus abdominis), continues into the
neck as nuchal fascia
– Superficial:
 Splenius
– Intermediate: organized into groups based on attachment and function that are deep to the extrinsic
Anatomy Page 3
– Intermediate: organized into groups based on attachment and function that are deep to the extrinsic
muscles, innervating from the dorsal (posterior) rami of the spinal nerves with vasculature supply from the
posterior branches of the aorta
 Erector Spinae ("I like spaghetti"):
► Lateral: Iliocostalis
► Less lateral/more medial: longissimus
► Medial: Spinalis
□ Spinalis cervicis
□ Spinalis thoracis
– Deep: Transversospinales -- relatively short muscles that attach to the transverse processes inferiorly and
the spinous processes superiorly (in the groove), innervating with the dorsal (posterior) rami with
vasculature supply from the posterior branches of the aorta
 Superficial: Semispinalis
► Semispinalis capitis
 Less superficial/more deep: Multifidus (prominent in the lumbar region)
 Deep: Rotatores (prominent in the thoracic region) -- densely loaded with sensory organs, acting as
proprioceptive organs
 Minor muscles:
► Levator costarum
□ Innervation: dorsal (posterior) rami
► Intertransversarii
□ Innervation: dorsal (posterior) rami (except the anterior cervical intertransversarii)
► Interspinales
□ Innervation: dorsal (posterior) rami
Suboccipital triangle -- located at the posterior base of the skull (deep to the trapezius, sternocleidomastoid,
splenius, and semispinalis muscles), acting principally as postural muscles that assist in stabilizing the upper cervical
spine and skull
– Includes: C1-C2, 2 small muscle pairs, multiple nerves, and the vertebral artery
 Rectus Capitis Posterior on the superiomedial
border of the triangle
► Major
► Minor
 Obliquus Capitis on the superlateral and inferior
borders of the triangle
► Superior
► Inferior
– Landmarks:
 External occipital protuberance
Anatomy Page 4
► Superior
► Inferior
– Landmarks:
 External occipital protuberance
 C2 spinous process
 Inerfior nuchal line
 Foramen magnum
 Transverse foramina of C1-C2
– Innervation:
 Suboccipital nerve -- dorsal rami of C1 spinal nerve that acts primarily in motion to the muscles of the
triangle
 Greater occipital nerve -- dorsal rami of C2 spinal nerve that acts primarily in sensory to the
suboccipital region and posterior scalp, emerging inferior to the obliquus capitis inferior
 Vasculature: vertebral artery -- arises from the subclavian artery in the root of the neck, passing
through the transverse foramina of all the cervical vertebra (except C 7) before coming together to
form the basilar artery at the foramen magnum
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