Spring 2026 Muscle Packet

Rectus Capitis Posterior Major - Origin

SP C2

Rectus Capitis Posterior Major - Insertion

Lateral aspect of the inferior nuchal line

Rectus Capitis Posterior Major - Innervation

PR C1 (Suboccipital n.)

Rectus Capitis Posterior Major - Action

Extends head, ipsilateral rotation

Rectus Capitis Posterior Minor - Origin

Posterior tubercle of C1

Rectus Capitis Posterior Minor - Insertion

Medial aspect of inferior nuchal line

Rectus Capitis Posterior Minor - Innervation

PR C1 (Suboccipital n.)

Rectus Capitis Posterior Minor - Action

Extends head

Obliquus Capitis Superior - Origin

TP C1

Obliquus Capitis Superior - Insertion

Between superior and inferior nuchal lines

Obliquus Capitis Superior - Innervation

PR C1 (Suboccipital n.)

Obliquus Capitis Superior - Action

Extends head

Obliquus Capitis Inferior - Origin

SP C2

Obliquus Capitis Inferior - Insertion

TP C1

Obliquus Capitis Inferior - Innervation

PR C1 (Suboccipital n.)

Obliquus Capitis Inferior - Action

Rotates atlas, turning head ipsilaterally

Platysma - Superior Attachment

Inferior border of mandible, skin, and subcutaneous tissue of lower face

Platysma - Inferior Attachment

Fascia covering superior parts of pectoralis major and deltoid muscles

Platysma - Innervation

Cervical branch of facial nerve (CN VII)

Platysma - Action

Draws corners of mouth inferiorly and widens it, draws skin of neck superiorly

Scalenus Anterior/Anterior scalene - Superior Attachment

TP C3-C6

Scalenus Anterior/Anterior scalene - Inferior Attachment

Scalene tubercle of 1^st rib

Scalenus Anterior/Anterior scalene - Innervation

AR C4-C6

Scalenus Anterior/Anterior scalene - Action

neck flexion, elevates 1^st rib during forced inspiration

Scalenus Medius/Middle scalene - Superior Attachment

TP C2-C7

Scalenus Medius/Middle scalene - Inferior Attachment

superior surface of 1^st rib, posterior to groove for subclavian artery

Scalenus Medius/Middle scalene - Inervation

AR of cervical spinal nerves

Scalenus Medius/Middle scalene - Action

Laterally flexes neck; elevates 1^st rib during forced inspiration

Scalenus Posterior/Posterior scalene - Superior Attachment

TP C5-C7

Scalenus Posterior/Posterior scalene - Inferior Attachment

2^nd rib

Scalenus Posterior/Posterior scalene - Innervation

AR C7-C8

Scalenus Posterior/Posterior scalene - Action

Laterally flexes neck; elevates 2^nd rib during forced inspiration

What muscle is this?

Longus Colli

Longus Colli - Action

AR C2-C6

Longus Colli - Innervation

Bilaterally: Flexes neck. Unilaterally: Flexes neck, laterally flexes neck, contralateral rotation

What muscle is this?

Longus Capitis

Longus Capitis - Action

Flexes head

Longus Capitis - Innervation

AR C1-C3

What muscle is this?

Rectus Capitis Anterior

Rectus Capitis Anterior - Action

Flexes head

Rectus Capitis Anterior - Innervation

Branches from loop between C1 and C2

What muscle is this?

Rectus Capitis Lateralis

Rectus Capitis Lateralis - Action

Flexes and stabilizes head

Rectus Capitis Lateralis - Innervation

Branches from loop between C1 and C2

Subclavius - Innervation

Nerve to subclavius (C5, C6)

Subclavius - Action

Anchors and depresses clavicle

Subclavius - Proximal Attachment

Junction of 1st rib and its costal cartilage

Subclavius - Distal Attachment

Inferior surface of middle third of clavicle

Levator Scapulae - Proximal Attachment

TPs C1-4

Levator Scapulae - Distal Attachment

Medial border of scapula superior to root of scapular spine

Levator Scapulae - Innervation

Dorsal scapular n. (C5) and C3, C4

Levator Scapulae - Action

Elevates and downwardly rotates scapula

Masseter - Proximal Attachment

Inferior border and medial surface of maxillary process of zygomatic bone and the zygomatic arch

Masseter - Distal Attachment

angle and lateral surface of ramus of mandible

Masseter - Innervation

CN V3 via masseteric nerve

Masseter - Action

Elevates mandible closing jaws; superficial fibers may make limited contribution to protrusion of mandible

Temporalis - Proximal Attachment

Temporal fossa and temporal fascia

Temporalis - Distal Attachment

Coronoid process and anterior border of ramus of mandible

Temporalis - Innervation

CN V3 via deep temporal branches

Temporalis - Action

Elevates mandible closing jaws. Posterior fibers are primary retractors of the mandible

Medial Pterygoid - Proximal Attachment

Medial surface of lateral pterygoid plate and pyramidal process of palatine bone and tuberosity of the maxilla

Medial Pterygoid - Distal Attachment

Medial surface of ramus of mandible

Medial Pterygoid - Innervation

CN V3 via medial pterygoid nerve

Medial Pterygoid - Action

Elevates mandible, contributes to protrusion; alternate unilateral activity produces smaller grinding movements

Lateral Pterygoid - Proximal Attachment

Infratemporal surface and crest of the greater wing of the sphenoid and lateral surface of the lateral pterygoid plate

Lateral Pterygoid (Superior) - Distal Attachment

articular capsule and disk

Lateral Pterygoid (Inferior) - Distal Attachment

pterygoid fovea on neck of condyloid process of mandible

Lateral Pterygoid - Innervation

CN V3 via lateral pterygoid nerve

Lateral Pterygoid - Action

Bilaterally: protracts mandible and depresses chin. Unilaterally: lateral deviation to the contralateral side. Alternate unilateral contraction produces larger lateral chewing movements

Intercostals (Internal/External/Innermost) - Superior Attachment

Inferior border of ribs

Intercostals (Internal/External/Innermost) - Inferior Attachment

Superior border of ribs below

Intercostals (Internal/External/Innermost) - Innervation

AR T1-T12 (intercostal nerves)

Intercostals (Internal/External/Innermost) - Action

Approximate Ribs

Levator Costarum - Superior Attachment

TP C7-T11

Levator Costarum - Inferior Attachment

Subjacent ribs between tubercle and angle

Levator Costarum - Innervation

PR C8-T11

Levator Costarum - Action

Elevate Ribs

Diaphragm - Proximal Attachment

L1-L3, medial and lateral arcuate ligaments, lower 6 ribs and costal cartilages, xiphoid process

Diaphragm - Distal Attachment

Central tendon of diaphragm

Diaphragm - Innervation

Phrenic n. (C3, C4, C5)

Diaphragm - Action

Flattens central tendon, increasing vertical diameter of thoracic cavity in inspiration

Rectus Abdominis - Origin

Pubic symphysis and pubic crest

Rectus Abdominis - Insertion

Xiphoid process and costal cartilages of 5th-7th ribs

Rectus Abdominis - Innervation

Thoracoabdominal nerves (AR T6-T12)

Rectus Abdominis - Action

Flexes trunk (lumbar vertebrae) and compresses/supports abdominal viscera. Stabilizes pelvis

External Oblique - Origin

External surfaces of 5th-12th ribs

External Oblique - Insertion

Linea alba, pubic tubercle, and anterior half of iliac crest

External Oblique - Innervation

Thoracoabdominal nerves (AR T6-T12)

External Oblique - Action

Flex trunk, laterally flex trunk to ipsilateral side, rotate trunk to contralateral side (with opposite internal oblique). Compresses/supports abdominal viscera

Internal Oblique - Origin

Thoracolumbar fascia, anterior two thirds of iliac crest and connective tissue deep to the lateral third of inguinal ligament

Internal Oblique - Insertion

Inferior borders of 10th-12th ribs, linea alba, and pecten pubis (pectineal line of pubis) via conjoint tendon

Internal Oblique - Innervation

Thoracoabdominal nerves (AR T6-T12) and L1

Internal Oblique - Action

Flex trunk, laterally flex trunk to ipsilateral side, and rotate trunk to ipsilateral side. Compresses/supports abdominal viscera

Transversus Abdominis - Origin

Internal surfaces 7th-12th costal cartilages, thoracolumbar fascia, iliac crest, and connective tissue deep to lateral third of inguinal ligament

Transversus Abdominis - Insertion

Linea alba with the aponeurosis of the internal oblique, pubic crest, and pecten pubis (pectineal line of pubis) via the conjoint tendon

Transversus Abdominis - Innervation

Thoracoabdominal nerves (AR T6-T12) and L1

Transversus Abdominis - Action

Compresses/supports abdominal viscera

Pyramidalis - Proximal Attachment

Linea alba

Pyramidalis - Distal Attachment

pubic crest

Pyramidalis - Innervation

AR T12-L1