IFS Exam 1

Stylohyoid (intermediate - suprahyoid)

O: Styloid process of temporal bone

I: Body of hyoid

N: Stylohyoid (preparotid) branch of facial nerve (CN VII)

A: Elevates and retracts hyoid, thus elongating floor of mouth

Mylohyoid (intermediate - suprahyoid)

O: Mylohyoid line of mandible

I: Mylohyoid raphe and body of hyoid

N: Nerve to mylohyoid, a branch of inferior alveolar nerve, from mandibular nerve, CN V3

A: Elevates hyoid, floor of mouth, and tongue during swallowing and speaking

Geniohyoid (intemediate - suprahyoid)

O: Inferior mental spine of mandible

I: Body of hyoid

N: C1 via hypoglossal nerve (CN XII) and nerve to geniohyoid

A: Pulls hyoid anterosuperiorly; shortens floor of mouth; widens pharynx

Digastric (suprahyoid)

O:

• Anterior belly: digastric fossa of mandible

• Posterior belly: mastoid notch of temporal bone

I: Intermediate tendon to body and greater horn of hyoid

N:

• Anterior belly: Nerve to mylohyoid, a branch of inferior alveolar nerve

• Posterior belly: digastric branch of facial nerve (CN VII)

A: Digastric: Working with infrahyoid muscles, depresses mandible against resistance; elevates and steadies hyoid during swallowing and speaking

Omohyoid (intermediate - infrahyoid)

O: superior border of scapula near suprascapular notch

I: Inferior border of hyoid

N: C1-C3 by branch of ansa cervicalis

A: Depreses, retracts, and steadies hyoid

sternohyoid (intermediate - infrahyoid)

O: manubrium of sternum and medial end of clavicle

I: Body of hyoid

N: C1-C3 by a branch of ansa cervicalis

A: Depresses hyoid after elevation during swallowing

thyrohyoid (intermediate)

O: Oblique line of thyroid cartilage

I: Inferior border of body and greater horn of hyoid

N: C1 via hypoglossal nerve (CN XII) and nerve to thyrohyoid

A: Depresses hyoid and elevates larynx

sternothyroid (intermediate - infrahyoid)

O: Posteiror surface of manubrium of sternum

I: Oblique line of thyroid cartilage

N: C2 and C3 by a branch of ansa cervicalis

A: Depresses hyoid and larynx

Longus Capitis (prevertebral - deep)

Superior Attachment (I): Basilar part of occipital bone

Inferior Attachment (O): Anterior tubercles of C3-C6 transverse process

Nerve: Anterior rami of C1-C3 spinal nerves

Action: Flex head

Longus colli (prevertebral - deep)

Superior Attachment (I): Anterior tubercle of C1 vertebra (atlas); bodies of C1–C3 and transverse processes of C3–C6 vertebrae

Inferior Attachment (O): Bodies of C5–T3 vertebrae; transverse processes of C3–C5 vertebrae

Nerve: Anterior rami of C2–C6 spinal nerves

Action: Flexes neck with rotation (torsion) to opposite side if acting unilaterally

rectus capitis anterior (prevertebral - deep)

Superior Attachment (I): Base of cranium, just anterior to occipital condyle

Inferior Attachment (O): Anterior surface of lateral mass of atlas (C1 vertebra)

Nerve: Branches from loop between C1 and C2 spinal nerves

Action: Flex head

rectus capitis lateralis (prevertebral - deep)

Superior Attachment (I): Jugular process of occipital bone

Inferior Attachment (O): Transverse process of atlas (C1)

Nerve: Branches from loop between C1 and C2 spinal nerves

Action: Flex head and helps stabilize it

Anterior scalene (deep)

Superior Attachment (O): TP of C3-C6

Inferior Attachment (I): 1st rib

Nerve: Cervical spinal nerves C4-C6

Action: Flexes neck laterally; elevates 1st rib during forced inspiration - laterally flexes ipsilaterally (contraction bends the neck to the same side)

Middle scalene (deep)

Superior Attachment: Posterior tubercles of TP of C5-C7

Inferior Attachment: Superior surface of 1st rib; posterior to groove for subclavian artery

Nerve: Anterior rami of cervical spinal nerves

Action: Flexes neck laterally; elevates 1st rib during forced inspirationa

Posterior scalene (deep)

Superior Attachment: Posterior tubercles of TP of C5-C7

Inferior Attachment: External border of 2nd rib

Nerve: Anterior rami of cervical spinal nerves C7 and C8

Action: Flexes neck laterally; elevates 2nd rib during forced inspirtaion

Platysma - Superficial

Superior/Medial Attachment: Inferior border of mandible, skin, and subcutaneous tissues of lower face

Inferior/Lateral Attachment: Fascia covering superior parts of pectoralis major and deltoid muscles

Nerve: Cervical branch of facial nerve (CN VII)

Action: Draws corners of mouth inferiorly and widens it as in expressions of sadness and fright; draws skin of neck superiorly when teeth are clenched

Sternocleidomastoid - Superficial

Superior/Medial Attachment (I): Lateral surface of mastoid process of temporal bone and lateral half of superior nuchal line

Inferior/Lateral Attachment (O):

• Sternal head: anterior surface of manubrium of sternum

• Clavicular head: superior surface of medial third of clavicle

Nerve: Spinal accessory nerve (CN XI, motor); C3 and C4 nerves (pain and proprioception)

Action: Unilateral contraction: tilts head to same side (i.e., laterally flexes neck) and rotates it so face is turned superiorly toward opposite side

Bilateral contraction: (1) extends neck at atlanto-occipital joints, (2) flexes cervical vertebrae so that chin approaches manubrium, or (3) extends superior cervical vertebrae while flexing inferior vertebrae, so chin is thrust forward with head kept level

With cervical vertebrae fixed, may elevate manubrium and medial ends of clavicles, assisting pump-handle action of deep respiration

• Action Unilaterally:

  • Laterally flex the neck to same side

  • Rotate the neck to opposite side

• Action Together Bilaterally:

  • Flex the neck

  • Assists in elevation of rib cage during inhalation

Trapezius - Superficial

Proximal Attachment (O): Medial third of superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes of C7–T12 vertebrae

Distal Attachment (I): Lateral third of clavicle; acromion and spine of scapula

Nerve: Spinal accessory nerve (CN XI) (motor fibers) and C3, C4 spinal nerves (pain and proprioceptive fibers)

Action: Descending part elevates; descending and ascending parts act together to rotate glenoid cavity superiorly

Action: middle part (or all parts together) retracts scapula

Action: ascending part depresses; descending and ascending parts act together to rotate glenoid cavity superiorly

**Cervical Extension - upper

Upper trapezius — unilateral contraction

• Ipsilateral lateral flexion → bends the neck toward the contracting side

• Contralateral rotation → turns the head away from the contracting side

Example: Right upper trapezius contracts
→ right lateral flexion
→ left rotation

Latissimus Dorsi

(Superficial Layer - Extrinsic Back Muscles - axio-appendicular)

Proximal Attachment (O): Spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs

Distal Attachment (I): Floor of intertubercular sulcus of humerus

Nerve: Thoracodorsal Nerve (C6. C7. C8)

Action: Extends, adducts, and medially rotates humerus; raises body toward arms during climbing

Same-side shoulder extension, adduction, medial rotaiton - Right lat contracts —> right arm ext, add, IR

Rhomboid Major

(Superficial Layer - Extrinsic Back Muscles - axio-appendicular)

Proximal Attachment (O): SP of T2-T5 vertebrae

Distal Attachment (I): medial border of scapula from level of spine to inferior angle

Nerve: Dorsal scapular nerve (C4, C5)

Action: Retract scapula and rotate its glenoid cavity inferiorly; fix scapula to thoracic wall

Right rhomboids act on the right scapula

Rhomboid Minor

(Superficial Layer - Extrinsic Back Muscles - axio-appendicular)

Proximal Attachment (O): nuchal ligament; spinous processes of C7 and T1 vertebrae

Distal Attachment (I): smooth triangular area at medial end of scapular spine

Nerve: Dorsal scapular nerve (C4, C5)

Action: Retract scapula and rotate its glenoid cavity inferiorly; fix scapula to thoracic wall

Levator Scapulae

(Extrinsic back muscle - superficial layer)

Proximal Attachment (O): Posterior tubercles of transverse processes of C1–C4 vertebrae

Distal Attachment (I): Medial border of scapula superior to root of scapular spine

Nerve: Dorsal scapular (C4, C5) and cervical (C3, C4) nerves

Action: Elevates scapula and rotates its glenoid cavity inferiorly by rotating scapula (**scapula downward rotation)

• Extends neck (with trapezius)

• Laterally flexes neck to the same side

Right lateral flexion of neck —> ipsilateral; right scapular elevation —> ipsilateral

Serratus Posterior Superior

(Intermediate Layer - Extrinsic Back Muscles - thoracic wal)

Superior Attachment (O): Nuchal ligament, SP of C7-T3 vertebrae

Inferior Attachment (I): Superior borders of 2nd-4th ribs

Nerve: 2nd-5th intercostal nerves

Action: Proprioception (elevate ribs)

Serratus Posterior Inferior

(Intermediate Layer - Extrinsic Back Muscles - thoracic wal)

Superior Attachment (O): SP of T11-L2 vertebrae

Inferior Attachment (I): Inferior borders of 8th-12th ribs near their angles

Nerve: Anterior rami to T9–T12 thoracic spinal nerves

Action: Proprioception (depress ribs)

Splenius Cervicis

(Superficial Layer of Intrinsic Back Muscles)

Proximal Attach (O): Nuchal ligament and SP of C7-T6

Distal Attach (I): Tubercles of transverse processes of C1-C3 or C4 vertebrae

Nerve: Posterior rami of spinal nerves

Action:

• Unilaterally: laterally flexes the neck and rotates the head to side of active musces

• Bilaterally: extend the head and neck

Right splenius cervicis contracts —> right lateral flexion + right rotation

Splenius Capitis

(Superficial Layer of Intrinsic Back Muscles)

Proximal Attach (O): Nuchal ligament and SP of C7-T6

Distal Attach (I): Fibers run superolaterally to mastoid process of temporal bone and lateral 1/3rd of superior nuchal line of occipital bone

Nerve: Posterior rami of spinal nerves

Action:

• Unilaterally: laterally flexes the neck and rotates the head to side of active musces

• Bilaterally: extend the head and neck

Iliocostalis

(Intermediate Layer of Intrinsic Back Muscles)

Proximal Attachment (O): Arises by a broad tendon from the posterior part of the iliac crest, posterior surface of the sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament

Distal Attachment (I): lumborum, thoracis, cervicis; fibers run superiorly to angles of lower ribs and cervical transverse processes.

Nerve: Posterior rami of spinal nerves

Action:

• Bilaterally: Extend vertebral column and head; as back is flexed, control movement via eccentric contraction

• Unilaterally: Laterally felxes vertebral column

**rotation

Laterally flexes ipsilaterally (not really a rotator, but ipsilateral)

Longissimus

(Intermediate Layer of Intrinsic Back Muscles)

Proximal Attachment (O): Arises by a broad tendon from the posterior part of the iliac crest, posterior surface of the sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament

Distal Attachment: thoracis, cervicis, capitis; fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone

Nerve: Posterior rami of spinal nerves

Action:

• Bilaterally: Extend vertebral column and head; as back is flexed, control movement via eccentric contraction

• Unilaterally: Laterally felxes vertebral column

**Rotation

Spinalis

(Intermediate Layer of Intrinsic Back Muscles)

Proximal Attachment (O): Arises by a broad tendon from the posterior part of the iliac crest, posterior surface of the sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament

Distal Attachment (I): thoracis, cervicis, capitis; fibers run superiorly to spinous processes in the upper thoracic region and to cranium.

Nerve: Posterior rami of spinal nerves

Action:

• Bilaterally: Extend vertebral column and head; as back is flexed, control movement via eccentric contraction

• Unilaterally: Laterally felxes vertebral column

Semispinalis

(Major Deep Layer of Intrinsic Back Muscles)

Inferior Attachment (O): Arises from TP of C4-T12 vertebrae

Superior Attachment (I): thoracis, cervicis, capitis; fibers run superomedially to occipital bone and spinous processes in thoracic and cervical regions, spanning 4–6 segments.

Nerve: Posterior rami of spinal nerves

Actions: Extends head and thoracic and cervical regions of vertebral column and rotates them contralaterally

Contralateral rotation

Rotatores

(Major Deep Layer of Intrinsic Back Muscles)

Inferior Attachment (O): Arises from TP of vertebrae; best developed in thorcic region

Superior Attachment (I): Fibers pass superomedially to attach to junciton of lamina and TP or SP of vertebra immediately (brevis) or 2 segments (longus) superior to vertebra of attachment.

Nerve: Posterior rami of spinal nerves

Action: Stabilizes vertebrae and assist with local extension and rotatory movements of vertebral column; may function as organs of proprioception

Contralateral rotation

Multifidus

(Deep layers of intrinsic back muscles)

Inferior Attachment (O): arises from posterior sacrum, posterior superior iliac spine of the ilium, aponeurosis of erector spinae, sacro-iliac ligaments, mammillary processes of lumbar vertebrae, transverse processes of T1–T3, articular processes of C4–C7

Superior Attachment (I): thickest in lumbar region; fibers pass obliquely superomedially to entire length of spinous processes, located 2–4 segments superior to proximal attachment.

Nerve: Posterior Rami of spinal nerves

Action: stabilizes vertebrae during local movements of vertebral column

**Rotation and lateral bending

(Extension for all transversospinalis)

Contralateral rotation, ipsilateral lateral flexion

Transversospinalis group (semispinalis, multifidus, rotatores)

(Major Deep Layer of Intrinsic Back Muscles)

Inferior Attachment (O): Transverse process

Superior Attachment (I): SP of more superior vertebrae

Nerve: Posterior rami of spinal nerves

Action: Extension

Interspinales

(Minor Deep Layer of Intrinsic Back Muscles)

Inferior Attachment (O): Superior surfaces of spinous processes of cervical and lumbar vertebrae

Superior Attachment (I): Inferior surfaces of spinous processes of vertebra superior to vertebra of proximal attachment

Nerves: Posterior rami of spinal nerves

Action: Aid in extension and rotation of vertebral column

Intertransversarii

(Minor Deep Layer of Intrinsic Back Muscles)

Inferior Attachment (O): TP of cervical and lumbar vertebrae

Superior Attachment (I): TP of adjacent vertebrae

Nerve: Posterior and anterior rami of spinal nerves

Action: Aid in lateral flexion of vertebral column; acting bilaterally, stabilize vertebral column

Right lateral flexion - ipsilateral

Levator costarum

(Minor Deep Layer of Intrinsic Back Muscles)

Superior Attachment (O): Tips of transverse processes of C7 and T1–T11 vertebrae

Inferior Attachment (I): Pass inferolaterally and insert on rib between tubercle and angle

Nerve: Posterior rami of C8-T11 spinal nerves

Action: Elevate ribs, assisting respiration; assist with lateral flexion of vertebral column

lateral felxion —> ipsilateral

Quadratus Lumborum

(Muscle of Posteiror Abdominal Wall)

Inferior Attachment (O): Iliolumbar ligament and internal lip of iliac crest

Superior Attachment (I): Medial half of inferior border of 12th ribs and tips of lumbar transverse processes

Nerve: Anterior branches of T12 and L1–L4 nerves

Action: Extends and laterally flexes vertebral column; fixes 12th rib during inspiration

Lateral flexion —> ipsilateral