Feb 5 & 11 - Axial Muscles

Bilateral action

Contract together.

Unilateral action

Only one side contracts.

Axial Muscle Categories

Includes head and neck, vertebral column, respiration, abdominal wall, pelvis and perineum.

Sternocleidomastoid muscle

Bilaterally: flexion of head at the neck; Unilaterally: lateral flexion and contralateral rotation of the head.

Scalene group

Origins on C-spine TPs and insert into rib 1 & 2; Accessory breathing muscles.

Extrinsic muscles of the back

Produce and control limb & respiratory movements.

Intrinsic muscles of the back

Act specifically on vertebral column to move the vertebrae & maintain posture.

Spinotransversales muscles

Thick & flat 'bandage' muscles that wrap vertical muscles and hold them in position.

Splenius cervicis

Part of the spinotransversales muscles; bilaterally extends head/neck, unilaterally causes lateral flexion and ipsilateral rotation.

Splenius capitus

Part of the spinotransversales muscles; bilaterally extends head/neck, unilaterally causes lateral flexion and ipsilateral rotation.

Erector spinae muscles

Important postural muscles with fibres that extend from sacrum to skull.

Iliocostalis

1st column of the erector spinae muscles.

Longissimus

2nd column of the erector spinae muscles.

Spinalis

3rd column of the erector spinae muscles.

Thoracolumbar fascia

Part of the intrinsic muscles of the back; binds muscles from pelvis to cranium.

Superficial layer of back muscles

Includes spinotransversales muscles.

Intermediate layer of back muscles

Massive muscle group laid in three columns between SPs centrally and rib angles laterally.

Accessory breathing muscles

Muscles that assist in breathing, such as the scalene group.

Muscles of respiration

Muscles involved in the process of breathing.

Anterior neck muscles

Muscles involved in facial expression, extrinsic eye movement, mastication, tongue movement, pharynx, and larynx.

Supra & Infrahyoid muscles

Muscles located in the anterior neck region.

Bilaterally

Extend vertebral column and maintain upright posture.

Unilaterally

Lateral flexion.

Erector Spinae

A muscle group that extends the vertebral column.

Transversospinalis Muscle Group

A group of muscles with shorter fibers than the erector spinae that extend the vertebral column and head bilaterally and cause contralateral rotation unilaterally.

Suboccipital Triangle

An anatomical region where the suboccipital nerve and vertebral artery are found, formed by muscles that attach C1 & C2 to the base of the skull.

Diaphragm Muscle

Muscle contraction during inspiration causes it to flatten, increasing the size of the thoracic cavity and drawing breath in.

External Intercostal Muscle

Muscle that elevates the ribs during respiration.

Scalene Muscle Group

Muscles that assist in elevating the ribs.

Serratus Posterior Superior

Muscle that elevates the ribs.

Levator Costarum

Muscle that elevates the ribs.

Internal Intercostal Muscle

Muscle that depresses the ribs.

Transversus Thoracic Muscle

Muscle that depresses the ribs.

Serratus Posterior Inferior

Muscle that depresses the ribs.

Rectus Abdominis

Muscle that compresses the abdominal wall and flexes the vertebral column bilaterally.

External Oblique

Muscle that compresses the abdominal wall, depresses ribs, and causes lateral flexion and contralateral rotation unilaterally.

Internal Oblique

Muscle that compresses the abdominal wall, depresses ribs, and causes lateral flexion and ipsilateral rotation unilaterally.

Transversus Abdominis

Deepest of the anterior abdominal muscles that compresses the abdominal wall and supports abdominal organs.

Psoas Major

Muscle primarily responsible for hip flexion and contributes to flexion of the vertebral column when femurs are fixed.

Iliacus

Muscle that works with the psoas major for hip flexion.

Quadratus Lumborum

Muscle that causes lateral flexion of the vertebral column (weak!).

Aponeurosis

Dense regular connective tissue that forms from abdominal muscles.

Rectus Sheath

Formed by the aponeuroses and encloses the rectus abdominis muscle.

Linea Alba

Vertical landmark where the aponeuroses meet.

Tendinous Inscriptions

Fibrous horizontal lines of connective tissue in the rectus abdominis muscle.