Anatomy of the Back Muscles

Comprehensive vocabulary list of back muscles including their attachments, physiological actions, and nerve innervations as described in the lecture transcript.

Trapezius

A muscle with attachments at Ligamentum Nuchae, Spinus processes of $C7-T12$, Superior nuchal line, External occipital protuberance, spine of the scapula, clavicle (posterior aspect of lateral $1/3$), and acromion process. It performs scapular depression, retraction, elevation, and upwards rotation. Innervation: motor Accessory nerve ($XI$), sensory $C3-4$.

Latissimus Dori

A muscle attached to thoracolumbar fascia $L1-5$, Iliac crest, spinous processes of $T7-12$, $9-12$ ribs, and the floor of the intertubercular sulcus of humerus. Its actions include humoral adduction, extension, and medial rotation. Innervation: motor thoracodorsal nerve, sensory $C6-8$.

Levator Scapulae

A muscle attached to transverse processes $C1-5$, superior angle of the scapulae, and superomedial border of the scapulae. It performs scapular elevation, lateral flexion, and scapular downward rotation. Innervation: motor dorsal scapular nerve $C4-5$, sensory $C3-4$.

Rhomboids

Muscles attached to the medial border of the scapula and spinous process $C7-T3$. Actions include scapular retraction, elevation, and downward rotation. Innervation: motor Dorsoscapular nerve $C4-5$, sensory $C3-4$.

Serratus Posterior Superior

A muscle attached to spinous processes $C7-T3$ and inferior borders of ribs $2-5$. It assists with proprioception and respiration. Innervation is the Intercostal nerve $T2-4$.

Serratus Posterior Inferior

A muscle attached to spinous processes $T11-L2$ and inferior border of ribs $9-12$. It assists with proprioception and respiration. Innervation is the Intercostal nerve $T9-12$.

Erector Spinae

A muscle group attached to the thoracolumbar fascia (attached to sacrum), Iliac crest, spinous processes $L5-T11$, and Supraspinous ligament. Subcomponents include iliocostalis (angles of ribs), longissimus (ribs and transverse processes), and spinalis (spinous processes). Actions: extension and lateral flexion of vertebrae. Innervation: Dorsal rami of the spinal nerves.

Splenius Cervicis

A muscle attached to spinous processes $T3-6$ and transverse process of $C1-3$. It performs extension, lateral flexion, and ipsilateral rotation of the neck. Innervation: Dorsal Rami of spinal nerves.

Splenius Capitis

A muscle attached to spinous processes $T4-C7$, mastoid process, and ligamentum nuchae. Actions: extension, lateral flexion, and ipsilateral rotation. Innervation: Dorsal Rami of spinal nerves.

Semispinalis (transversospinales group)

Muscles passing from transverse processes to distant superior spinous process. Actions: extension and contralateral rotation of the vertebral column. Innervation: greater occipital nerve (capitis) and medial branches of dorsal rami (cervicis and thoracis).

Multifidus (transversospinales group)

Muscles attached from the sacrum, posterior SI ligament, posterior iliac spine, and transverse processes to more superior spinous processes. Actions: extension and contralateral rotation of the vertebral column. Innervation: medial branches of posterior rami.

Rotatores longus and brevis (transversospinales group)

Muscles attached from transverse processes to the spinous process of the vertebra. Actions: extension and contralateral rotation of the vertebral column. Innervation: medial branches of posterior rami.

Interspinales

Muscles located between spinous processes of adjacent vertebrae, specifically recorded at $C6$, $T2-3$, and $L4$. Action: extension of spine. Innervation: posterior rami.

Intertransversarii

Muscles located between the transverse process of adjacent vertebrae. Action: extension of spine. Innervation: posterior rami.