Anatomy Exam 5 - Muscles: Origin, Insertion, Fxn Flashcards
Name the origin, insertion, innervation, and function of each muscle listed.
Trapezius
*Extrinsic back muscle (hypaxial/ventral rami)
Superficial layer
Origin: Nuchal ligament; Vertebrae
Insertion: Scapula; Acromion of scapula
Function: Elevates, depresses, rotates, and retracts the scapula
Innervation:
Motor: CNXI (Accessory nerve)
Sensory: Ventral rami of cervical plexus
Latissimus dorsi
*Extrinsic back muscle (hypaxial/ventral rami)
Superficial layer
Origin: Vertebrae; Thoracolumbar fascia; Ribs; Inferior angle of scapular
Insertion: Intertubercular sulcus of the humerus
Function: Extends, adducts, medially rotates humerus; elevates torso when humerus is fixed
Innervation:
Motor: Thoracodorsal n.
Sensory: Ventral rami of cervical plexus
Levator scapulae
*Extrinsic back muscle (hypaxial/ventral rami)
Middle layer
Origin: Transverse processes of C1-C4
Insertion: Medial border of scapula
Function: Elevates scapulae
Innervation:
Motor: Dorsal scapular n. and ventral rami of cervical plexus.
Sensory: Ventral rami of cervical plexus
Rhomboid minor
*Extrinsic back muscle (hypaxial/ventral rami)
Middle layer
Origin: Nuchal ligament, spinous processes of C7-T1
Insertion: Medial border of scapula
Function: Elevates scapulae; retracts scapulae
Innervation:
Motor: Dorsal scapular nerve
Sensory: Ventral rami of cervical plexus
Rhomboid major
*Extrinsic back muscle (hypaxial/ventral rami)
Middle layer
Origin: Spinous process of T2-T5
Insertion: Medial border of scapula
Function: Elevates scapulae; retracts scapulae
Innervation:
Motor: Dorsal scapular nerve
Sensory: Ventral rami of cervical plexus
Serratus posterior superior
*Extrinsic back muscle (hypaxial/ventral rami)
Deep layer
Origin: Nuchal ligament, spinous processes of C7-T3
Insertion: Ribs 2-5
Function: Elevates ribs
Innervation:
Motor: Intercostal nerve branches
Sensory: none
Serratus posterior inferior
*Extrinsic back muscle (hypaxial/ventral rami)
Deep layer
Origin: Spinous processes of T11-L2
Insertion: Ribs 9-12
Function: Depress ribs
Innervation:
Motor: Intercostal nerve branches
Sensory: none
Iliocostalis
*Intrinsic back muscle (epaxial/dorsal rami)
Erector spinae group
Origin: Ribs 3-12; lateral crest of sacrum; thoracolumbar fascia
Insertion: Superior vertebrae and ribs (positioned most laterally)
Function: Extension of spine (bilateral use); lateral flexion (unilateral use- ipsilateral)
Innervation: Dorsal rami of spinal nerves
Longissimus
*Intrinsic back muscle (epaxial/dorsal rami)
Erector spinae group
Origin: Vertebrae
Insertion: Superior vertebrae and ribs (positioned between iliocostalis and spinalis)
Function: Extension of spine (bilateral use); lateral flexion (unilateral use- ipsilateral)
Innervation: Dorsal rami of spinal nerves
Spinalis
*Intrinsic back muscle (epaxial/dorsal rami)
Erector spinae group
Origin: Ribs 3-12; lateral crest of sacrum; thoracolumbar fascia
Insertion: Superior vertebrae (positioned most medially)
Function: Extension of spine (bilateral use); lateral flexion (unilateral use- ipsilateral)
Innervation: Dorsal rami of spinal nerves
Semispinalis
*Intrinsic back muscle (epaxial/dorsal rami)
Transversospinalis group
Origin: Transverse processes of vertebrae
Primarily found in the thoracic region
Insertion: Spinous processes of vertebrae
Function: Assist in extension of spine (bilateral use); rotation (unilateral use- contralateral)
Innervation: Dorsal rami of spinal nerves
Multifidus
*Intrinsic back muscle (epaxial/dorsal rami)
Transversospinalis group
Origin: Vertebrae - found in all spinal regions
Insertion: Vertebrae
Function: Assist in extension of spine (bilateral use); rotation (unilateral use- contralateral)
Innervation: Dorsal rami of spinal nerves
Rotatores
*Intrinsic back muscle (epaxial/dorsal rami)
Transversospinalis group
Origin: Transverse processes of vertebrae
Primarily found in the thoracic region, smaller than semispinalis
Insertion: Spinous processes of vertebrae
Function: Proprioception and stabilization
Innervation: Dorsal rami of spinal nerves
Pectoralis major
Origin: Clavicular head = clavicle
Sternocostal head = anterior sternum
Abdominal head = rectus sheath
Insertion: Greater tubercle of humerus
Function: Adduction, internal rotation; moves scapula anteriorly if humerus is fixed
Innervation: Medial and lateral pectoral nerves from brachial plexus
Pectoralis minor
Origin: Ribs 3-5
Insertion: Medial border and the coracoid process of the scapula
Function: Pulls scapula anteriorly; stabilizes it on posterior thorax
Innervation: Medial pectoral nerve
Serratus anterior
Origin: Ribs
Insertion: Scapula, from the superior angle, medial border, and inferior angle
Function: Protraction, superior rotation
Innervation: Long thoracic nerve
Subclavius
Origin: Sternal end of rib 1
Insertion: Clavicle
Function: Anchors, depresses clavicle
Innervation: Nerve to subclavius
Deltoid
**NOT a rotator cuff muscle!
Origin: Clavicle; Acromion; Spine of scapula
Insertion: Deltoid tuberosity of humerus
Function: Flex, extend, medially and laterally rotate, and abduct the humerus
Innervation: Axillary nerve
Teres major
**NOT a rotator cuff muscle!
Origin: Inf. angle of scapula
Insertion: Lesser tubercle of humerus
Function: Adduct, medially rotate humerus
Innervation: Lower subscapular nerve
Supraspinatus
Rotator cuff muscle!
Origin: Supraspinatus fossa of scapula
Insertion: Greater tubercle of humerus
Function: Abduction of humerus; stabilization of shoulder joint
Innervation: Lower subscapular nerve
Teres minor
Rotator cuff muscle!
Origin: Lateral border of scapula
Insertion: Greater tubercle of humerus
Function: Lateral rotation of humerus, stabilization
Innervation: Axillary nerve
Subscapularis
Rotator cuff muscle!
Origin: Subscapular fossa of scapula
Insertion: Greater tubercle of humerus
Function: Medial rotation of humerus
Innervation: Upper and lower subscapular nerves
Infraspinatus
Rotator cuff muscle!
Origin: Infraspinous fossa of scapula
Insertion: Greater tubercle of humerus
Function: Lateral rotation of humerus, stabilization
Innervation: Suprascapular nerve (which is confusing)
Biceps brachii
Anterior compartment
Origin:
Long head: Supraglenoid tubercle of the scapula
Short head: Coracoid process of the scapula
Insertion: Radial tuberosity of the radius
Function: Forearm flexion, pronation
Innervation: Musculocutaneous nerve
Coracobrachialis
Anterior compartment
Origin: Coracoid process of scapula
Insertion: Shaft of humerus
Function: Arm flexion, arm adduction
Innervation: Musculocutaneous nerve
Brachialis
Anterior compartment
Origin: Distal humerus
Insertion: Coranoid process of ulna
Function: Strong flexion of forearm
Innervation: Musculocutaneous nerve and radial nerve
Triceps brachii
Posterior compartment
Origin:
Long head: Supraglenoid tubercle of scapula
Short head: Coracoid process of scapula
Insertion: Radial tuberosity of radius
Function: Extension of forearm
Innervation: Radial nerve
Anconeous
Posterior compartment
Origin: Lateral epicondyle of humerus
Insertion: Olecranon
Function: Abducts ulna during pronation; Stablizes elbow; Assists extension
Innervation: Radial nerve