Muscles of the Back

Gross Anatomy


Superficial Muscles of the Back, Intermediate Muscles of the Back, Deep muscles of the Back


Anatomy Tables for Today's Topic

Bones of the Back
Muscles of the Back - Superficial Group
Muscles of the Back - Intermediate Group
Muscles of the Back - Deep Group
Topographic Anatomy of the Back

Bones of the Back

Bone Structure Description Notes
scapula   the bone of the shoulder the scapula floats in a sea of muscles, so it is difficult to fracture; it articulates with the clavicle at the coracoclavicular and acromioclavicular joints
superior border the superior edge of the scapula the superior border of the scapula is marked by the scapular notch laterally
medial border the border of the scapula that runs from the superior angle to the inferior angle it is an important site of muscle attachments for the intermediate layer of back muscles
superior angle the angle of the scapula formed at the union of the superior and medial borders it is the attachment site for the levator scapulae m.
lateral border the portion of the scapula that runs inferomedially from the infraglenoid tubercle to the inferior angle it is an important site of muscle attachments for the teres major and teres minor mm.; it has a groove for passage of the circumflex scapular vessels
inferior angle the angle of the scapula formed by the union of the medial and lateral borders the inferior angle of the scapula often has a slip of origin of the latissimus dorsi attached to it
glenoid fossa the articular surface located at the junction of the superior and lateral borders of the scapula it articulates with the head of the humerus; it is deepened by a fibrocartilaginous rim called the glenoid labrum
supraglenoid tubercle a projection of bone located superior to the glenoid cavity it is the attachment site for the tendon of the long head of the biceps brachii m.
infraglenoid tubercle a projection of bone located inferior to the glenoid cavity it is the attachment site of the tendon of the long head of the triceps brachii m.
spine a heavy ridge that runs from the medial border of the scapula to the acromion process it supports the acromion process; it divides the posterior surface of the scapula into a supraspinatous fossa and an infraspinatous fossa
scapular notch a notch on the superior border of the scapula located medial to the attachment of the coracoid process it is bridged by the superior transverse scapular ligament; the suprascapular a. passes superior to the superior transverse scapular ligament and the suprascapular n. passes inferior to it (Army goes over the bridge, Navy goes under the bridge)
coracoid process a beak-like process that projects anteriorly from the lateral end of the superior border of the scapula it is the attachment site for the short head of the biceps brachii m., the coracobrachialis m., the pectoralis minor m. and the coracoacromial and coracoclavicular ligaments
acromion a broad, flat process located at the lateral end of the scapular spine it articulates with the clavicle through a synovial joint (acromioclavicular joint)
supraspinatous fossa a broad depression located superior to the spine of the scapula it is the site of origin of the supraspinatus m.
infraspinatous fossa a broad depression located inferior to the spine of the scapula it is the site of origin of the infraspinatus m.
vertebra one of a series of irregular bones that form the spine a vertebra has two parts: the vertebral body and the vertebral arch; there are 33 vertebrae total: 7 cervical, 12 thoracic, 5 lumbar, 5 fused to form the sacrum, 4 coccygeal; features of a typical vertebra include: body, pedicles, transverse processes, laminae, articular processes, spinous process
vertebral body the largest part of the vertebra it is shaped like a short cylinder; adjacent vertebral bodies articulate through a symphysis
vertebral arch the ring of bone formed by the paired pedicles and paired laminae of the vertebra the transverse processes and spinous process are attached to the neural arch; the neural arch protects the spinal cord
pedicle short strong process that extends posteriorly from the posterolateral surface of the vertebral body paired; it connects the body with the transverse process; it is marked by superior & inferior vertebral notches;
transverse process a lateral process the extends from the junction of the pedicle and the lamina of the vertebra a site for muscle attachment and rib articulation
lamina a broad flat plate of bone located between the transverse process and the spinous process of the vertebra paired; it is flattened markedly in the anteroposterior direction; ligamenta flava span the interval between the laminae of adjacent vertebrae
articular processes processes that project inferiorly and superiorly from the junction of the lamina and pedicle of the vertebra two pair on each vertebra (superior and inferior); the superior articular processes of one vertebra articulate with the inferior processes of the adjacent vertebra through synovial joints
vertebral notch a notch on the superior and inferior surface of the vertebral pedicle the superior vertebral notch of one vertebra combined with the inferior vertebral notch of the adjacent vertebra forms the intervertebral foramen
intervertebral foramen an opening between the pedicles of adjacent vertebrae adjacent vertebral notches form the intervertebral foramen; an opening for passage of the spinal nerve
vertebral canal a canal formed by the combination of the vertebral foramina of all vertebrae it contains the spinal cord, meninges, epidural fat and the internal vertebral plexus of veins
vertebral foramen the opening formed by the body and the vertebral arch when all vertebrae are articulated, the combined vertebral foramina form the vertebral canal
spinous process a posterior midline process arising from the junction of the two laminae of the vertebra an important site of muscle attachment
cervical vertebrae   the seven vertebrae of the neck cervical vertebrae have the features of the typical vertebra plus all have transverse foramina (for passage of the vertebral artery); C2-C6 have bifid spinous processes; cervical vertebrae have relatively small bodies; several cervical vertebra are named: atlas, axis, vertebra prominens
atlas (C1) the first cervical vertebra atlas has no vertebral body, only anterior and posterior arches; it articulates with the occipital bone and the odontoid process of the axis
axis (C2) the second cervical vertebra the odontoid process (dens) projects superiorly from its body; it articulates with the anterior arch of the atlas
vertebra prominens the seventh cervical vertebra it has a long, non-bifid spinous process which is prominent at the nape of the neck, hence its name
thoracic vertebrae   the 12 vertebrae associated with the thoracic region thoracic vertebrae have the features of a typical vertebra plus they are characterized by long slender spines that project inferiorly; they have facets for articulation with ribs; thoracic vertebrae have bodies of intermediate size
costal articular facet on the body small smooth areas at the junction of the body and the vertebral arch most thoracic vertebrae have 2 costal facets on each side (one superior and one inferior); the superior costal facet of one vertebra and the inferior costal facet of the adjacent vertebra both articulate with the head of the same rib; also known as demifacets
costal articular facet on the transverse process a small smooth area on the transverse process of the thoracic vertebra it articulates with the articular facet on the tubercle of the rib
lumbar vertebrae   the 5 vertebrae located in the lumbar region lumbar vertebrae have the features of a typical vertebra plus they are characterized by short, blunt spines that project posteriorly; lumbar spines do not overlap making the lumbar level a good one for spinal tap; lumbar vertebrae are built strong and have the largest bodies of all vertebrae
sacrum   a triangular bone that is the posterior skeletal element forming the pelvis it is formed by 5 fused vertebrae; the sacrum and two os coxae bones form the pelvis
anterior sacral foramina openings on the anterior surface of the sacrum there are four pairs; each transmits the ventral primary ramus of the respective sacral spinal nerve; branches of the lateral sacral aa. and vv. reach the sacral canal by passing through these openings
posterior sacral foramina openings on the posterior surface of the sacrum there are four pairs; each transmits the dorsal primary ramus of the respective sacral spinal nerve
promontory the anterior aspect of the body of the first sacral vertebra the body of the fifth lumbar vertebra sits on the body of the first sacral vertebra; the anterior longitudinal ligament attaches to the promontory
sacral canal the opening in the center of the sacrum it is the continuation of the vertebral canal at sacral vertebral levels
articular surface the roughened area located on the lateral surface of the sacrum this surface articulates with the ilium in the sacroiliac articulation
body the central portion of the sacrum the body is equivalent to the bodies of the other vertebra
base the superior surface of the sacrum the base of the sacrum articulates with the fifth lumbar vertebra through an intervertebral disk
sacral hiatus an opening on the posterior surface of the sacrum in the midline it is a normal feature that results from the failure of fusion of the laminae of the fifth sacral segment (and sometimes the fourth) during development
ala the lateral portion of the sacrum paired; it projects laterally from the body of the sacrum; it represents the fused costal and transverse processes of the first sacral vertebra
coccyx   the most inferior portion of the vertebral column the coccyx results from the fusion of the four coccygeal vertebrae; it may be a single bone or the first coccygeal vertebra may be separated from the other three; it articulates with the fifth sacral segment; coccygeal vertebrae are reduced in complexity, having no pedicles, laminae or spines

Muscles of the Back - Superficial Group

Muscle Origin Insertion Action Innervation Artery Notes
trapezius medial third of the superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of vertebrae C7-T12 lateral third of the clavicle; acromion and spine of the scapula elevates and depresses the scapula (depending on which part of the muscle contracts); rotates the scapula superiorly; retracts scapula motor: spinal accessory (XI), proprioception: C3-C4 transverse cervical a. named for its shape; trapezius is an example of a muscle that migrates during development from its level of origin (cervical) to its final position, pulling its nerve and artery along behind
latissimus dorsi vertebral spines from T7 to the sacrum, posterior third of the iliac crest, lower 3 or 4 ribs, sometimes from the inferior angle of the scapula floor of the intertubercular groove extends the arm and rotates the arm medially thoracodorsal nerve (C7,8) from the posterior cord of the brachial plexus thoracodorsal a. latissimus dorsi tendon passes in close relationship to the teres major tendon at their insertions
levator scapulae transverse processes of C1-C4 vertebrae medial border of the scapula from the superior angle to the spine elevates the scapula dorsal scapular nerve (C5); the upper part of the muscle receives branches of C3 & C4 dorsal scapular a. levator scapulae is named for its action
rhomboideus major spines of vertebrae T2-T5 medial border of the scapula inferior to the spine of the scapula retracts, elevates and rotates the scapula which depresses the glenoid fossa dorsal scapular nerve (C5) dorsal scapular a. named for its shape
rhomboideus minor inferior end of the ligamentum nuchae, spines of vertebrae C7 and T1 medial border of the scapula at the root of the spine of the scapula retracts, elevates and rotates the scapula which depresses the glenoid fossa dorsal scapular nerve (C5) dorsal scapular a named for its shape

Muscles of the Back - Intermediate Group

Muscle Origin Insertion Action Innervation Artery Notes
serratus posterior superior ligamentum nuchae, spines of vertebrae C7 and T1-T3 ribs 2-5, lateral to the angles elevates the upper ribs branches of the ventral primary rami of spinal nerves T1-T4 posterior intercostal aa. 1-4 a respiratory muscle, it receives ventral ramus innervation; embryonically related to the intercostal muscles, not the deep back mm.
serratus posterior inferior thoracolumbar fascia, spines of vertebrae T11-T12 and L1-L2 ribs 9-12, lateral to the angles pulls down lower ribs branches of the ventral primary rami of spinal nerves T9-T12 lowest posterior intercostal a., subcostal a., first two lumbar aa. a respiratory muscle, it receives ventral ramus innervation; embryonically related to the intercostal muscles, not the deep back mm.

Muscles of the Back - Deep Group

Muscle Origin Insertion Action Innervation Artery Notes
splenius capitis ligamentum nuchae and spines of C7-T6 vertebrae mastoid process and lateral end of the superior nuchal line extends and laterally bends the neck and head, rotates head to the same side dorsal primary rami of spinal nerves C2-C6 supplied segmentally by: deep cervical a., posterior intercostal aa. named for its shape: splenius means bandage and capitis refers to the insertion of this portion of the muscle
splenius cervicis ligamentum nuchae and spines of C7-T6 vertebrae posterior tubercles of the transverse processes of C1-C3 vertebrae extends and laterally bends neck and head, rotates head to the same side dorsal primary rami of spinal nerves C2-C6 supplied segmentally by: deep cervical a., posterior intercostal aa. named for its shape: splenius means bandage and cervicis refers to the insertion of this portion of the muscle
iliocostalis iliac crest and sacrum angles of the ribs extends and laterally bends the trunk and neck dorsal primary rami of spinal nerves C4-S5 supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa. the most lateral part of the erector spinae; it may be subdivided into lumborum, thoracis and cervicis portions
longissimus transverse process at inferior vertebral levels transverse process at superior vertebral levels and mastoid process extends and laterally bends the trunk, neck and head dorsal primary rami of spinal nerves C1-S1 supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa. the intermediate part of the erector spinae;it may be subdivided into thoracis, cervicis and capitis portions
spinalis spinous processes at inferior vertebral levels spinous processes at superior vertebral levels and base of the skull extends and laterally bends trunk and neck dorsal primary rami of spinal nerves C2-L3 supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa. most medial part of the erector spinae; may be subdivided into thoracis, cervicis and capitis portions
semispinalis transverse processes of C7-T12 capitis: back of skull between nuchal lines; cervicis & thoracis: spines 4-6 vertebrae above origin extends the trunk and laterally bends the trunk, rotates the trunk to the opposite side dorsal primary rami of spinal nerves C1-T12 supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa. three parts are named based on their insertions: capitis, cervicis and thoracis; semispinalis, multifidus and rotatores make up the transversospinal muscle group
semispinalis, multifidus, and rotatores this group of muscles provides rotational, extension and lateral bending movements between adjacent vertabrae; they extend the head and neck these muscles make up the transversospinal muscle group

Topographic Anatomy of the Back

Structure/Space Boundaries/Description Significance
triangle of auscultation a triangle located medial to the inferior angle of the scapula; it is bounded by the trapezius m. medially, rhomboideus major m. superiorly and the latissimus dorsi m. inferiorly; its floor is the posterior thoracic wall triangle of auscultation is used to listen to (auscultate) the lungs because the stethoscope can be placed close to the thoracic wall at this location
lumbar triangle a triangle defined by the border of the latissimus dorsi m. medially, the external abdominal oblique m. laterally and the iliac crest inferiorly; its floor is the internal abdominal oblique m. lumbar triangle may be the site of an abdominal hernia; also known as: triangle of Petit


Other Tables of Interest:


Back Region


Upper Limb

All Anatomy Tables

Tables Organized by System Tables Organized by Region


Some of the material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest and Jaye Schlesinger
Published by ILOC, Inc., New York. Copyright 1995.

Content of tables edited for use in this course by Patrick W. Tank, Ph.D.
Copyright 2005, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences.

Unauthorized use is prohibited.