Superficial Muscles of the Thorax

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Questions and Answers

What is the primary action of the pronator teres muscle?

Extends the wrist

Flexes the wrist

Pronates the forearm (correct)

Abducts the hand

Which muscle is responsible for flexing the wrist and abducting the hand?

Extensor carpi ulnaris

Palmaris longus

Flexor carpi ulnaris

Flexor carpi radialis (correct)

Which of the following muscles originates at the lateral epicondyle of the humerus?

Pronator teres

Flexor carpi ulnaris

Flexor carpi radialis

Extensor carpi ulnaris (correct)

What is the specific action of the extensor digitorum muscle?

Extends digits 2-5 and wrist Signup and view all the answers

Which muscle is considered a weak flexor of the wrist?

Palmaris longus Signup and view all the answers

The abductor pollicis longus is primarily responsible for which action?

Abducting the thumb Signup and view all the answers

Which muscle acts to extend the 5th digit and the wrist?

Extensor digiti minimi Signup and view all the answers

What is the action of the extensor carpi radialis muscles?

Extends and abducts the wrist Signup and view all the answers

What is the primary action of the Psoas major muscle?

Prime mover in thigh flexion Signup and view all the answers

Which muscle is responsible for flexing and laterally rotating the thigh?

Sartorius Signup and view all the answers

Where does the Adductor magnus originate?

Ischium and pubis Signup and view all the answers

Which of the following muscles is part of the quadriceps femoris group?

Vastus lateralis Signup and view all the answers

What is the insertion point for the Rectus femoris muscle?

Patella and tibial tuberosity Signup and view all the answers

What action is primarily performed by the Gluteus maximus?

Major extensor of thigh Signup and view all the answers

Where does the Iliacus muscle originate?

Iliac fossa Signup and view all the answers

Which of these muscles adducts, flexes, and medially rotates the thigh?

Adductor longus Signup and view all the answers

What is the primary action of the superior oblique muscle?

Rotates eyeball inferiorly and laterally Signup and view all the answers

Which muscle is responsible for flexing the vertebral column and is located in the abdominal wall?

Rectus abdominis Signup and view all the answers

What is the main action of the masseter muscle?

Prime mover of jaw closure Signup and view all the answers

What is the role of the orbicularis oris muscle?

Compresses and purses the lips Signup and view all the answers

Which of the following muscles assists with lateral flexion of the vertebral column?

Transversus abdominis Signup and view all the answers

Which muscle is primarily involved in raising the upper lip?

Zygomaticus minor Signup and view all the answers

What is the action performed by the inferior rectus muscle?

Depresses and adducts the eyeball Signup and view all the answers

Which muscle is primarily responsible for elevating and retracting the scapula?

Rhomboids Signup and view all the answers

Which muscle primarily retracts the scalp?

Occipital belly of the epicranius Signup and view all the answers

What is the main action of the sternothyroid muscle?

Depresses the thyroid cartilage Signup and view all the answers

What action is performed by the internal intercostals?

Depresses ribs for forced expiration Signup and view all the answers

Which muscle is known for compressing the cheek, facilitating whistling and sucking?

Buccinator Signup and view all the answers

Which of the following muscles originates from the spinous processes of T7-T12?

Latissimus dorsi Signup and view all the answers

The action of abducting the humerus is primarily associated with which muscle?

Supraspinatus Signup and view all the answers

Which muscle acts as a synergist to the latissimus dorsi?

Teres major Signup and view all the answers

Which muscle is identified as the prime mover for inspiration?

Diaphragm Signup and view all the answers

What is the action of the biceps brachii?

Flexes the arm and forearm Signup and view all the answers

What is the main action of the external intercostals?

Elevate ribs Signup and view all the answers

Which muscle is responsible for extending and adducting the arm?

Triceps brachii Signup and view all the answers

The muscle that protracts and rotates the scapula superiorly is known as?

Serratus anterior Signup and view all the answers

Which muscle is responsible for medially rotating the thigh?

Semitendinosus Signup and view all the answers

What is the common insertion point of the gastrocnemius and soleus muscles?

Calcaneus Signup and view all the answers

Which muscle primarily acts as a mover of dorsiflexion?

Tibialis anterior Signup and view all the answers

Which muscle has lateral rotation as part of its action?

Biceps femoris Signup and view all the answers

What is the origin of the semimembranosus muscle?

Ischial tuberosity Signup and view all the answers

Study Notes

Superficial Muscles of the Anterior and Posterior thorax

Trapezius: Elevates, rotates, retracts, and depresses scapula. Originates from the occipital bone, spines of C7 and all Thoracic vertebrae. Inserts into the spine and acromion of scapula, lateral clavicle.
Latissimus dorsi: Extends, adducts, and medially rotates arm. It's often called the "swimmer's muscle." Originates via thoracolumbar fascia, the spinous processes of T7-T12, ribs 8-12, and iliac crest. Inserts into the intertubercular groove of humerus.
Serratus anterior: Protracts and rotates scapula superiorly. It's known as the "boxer's muscle." Originates from ribs 1-8. Inserts into the anterior aspect of the medial (vertebral) border of scapula.
Pectoralis minor: Protracts and depresses scapula. Originates from ribs 3, 4, and 5. Inserts into the coracoid process of scapula.
Rhomboids (major and minor): Elevates and retracts scapula; inferior rotation of scapula. Originates from the spinous process of C7-T5. Inserts into the medial border of scapula.

Deep Muscles of the Thorax: Breathing

External intercostals: Elevates ribs for inspiration.
Internal intercostals: Depresses ribs for forced expiration.
Diaphragm: Prime muscle of inspiration. Flattens on contraction. Originates from the cartilages of the lowest ribs and lumbar vertebrae. Inserts into the central tendon. It's innervated by the phrenic nerve: "C3, C4, C5 - keeps the diaphragm alive."

Muscles crossing the shoulder joint: movements of the humerus

Supraspinatus: Abducts humerus. Originates from the supraspinous fossa of scapula. Inserts into the greater tubercle of the humerus.
Infraspinatus: Adducts and lateral rotation of humerus. Originates from the infraspinous fossa. Inserts into the greater tubercle of the humerus.
Subscapularis: Medial rotation of humerus. Originates from the subscapular fossa of scapula. Inserts into the lesser tubercle of humerus.
Teres Major: Extends, adducts and medially rotates arm. It's a synergist to the latissimus dorsi. Originates from the posterior surface of the inferior angle of scapula. Inserts into the lesser tubercle of humerus.
Teres Minor: Adducts and lateral rotation of humerus. It's a synergist to the infraspinatus. Originates from the lateral border of scapula. Inserts into the greater tubercle of the humerus.
Pectoralis major: Flexes, adducts and medially rotates arm. Originates from the clavicle, sternum, and costal cartilages of ribs 2-6. Inserts into the intertubercular groove of humerus.
Deltoid: Flexes & medially rotates; Abducts; extends and laterally rotates humerus. Originates from the clavicle, acromion, and scapular spine. Inserts into the deltoid tuberosity of humerus.

Muscles Crossing elbow joint--flexion and extension of forearm

Biceps brachii: Flexes arm and flexes forearm. Originates from the supraglenoid tubercle and coracoid process. Inserts into the radial tuberosity.
Brachialis: Flexes forearm. Originates from the distal anterior humerus. Inserts into the coronoid process of ulna.
Triceps brachii: Extends forearm; extends and adducts arm. Originates from the infraglenoid tubercle of scapula and posterior humerus. Inserts into the olecranon process of the ulna.
Brachioradialis: Flexes forearm. Originates from the lateral supracondylar ridge of humerus. Inserts into the styloid process of radius.

Muscles of the Forearm: Movements of the Wrist, Hand, and Fingers

Flexor and extensor retinaculum: These are connective tissue straps around the wrist, not muscles. They function as "wrist bands" to keep tendons from bulging outward during muscular contraction.
Anterior compartment:
- Pronator teres: Pronates forearm. Originates from the medial epicondyle of the humerus and coronoid process of ulna. Inserts into lateral radius.
- Flexor carpi radialis: Flexes wrist; abducts hand. Originates from the medial epicondyle of humerus. Inserts into the base of 2nd and 3rd metacarpals. Its tendon is easily seen when you take the pulse of the radial artery.
- Palmaris longus: Weak flexor of wrist. Originates from the medial epicondyle of the humerus. Inserts into the Flexor retinaculum and palmar aponeurosis.
- Flexor carpi ulnaris: Flexes wrist; adducts hand. Originates from the medial epicondyle of the humerus. Inserts into the Pisiform and hamate and fith metacarpal.
Posterior compartment:
- Brachioradialis: This muscle originates high in the arm and travels posteriorly, but can be readily seen on the anterior-lateral surface.
- Extensor carpi radialis (longus & brevis): Extends and abducts wrist. Originates from the Supracondylar ridge and Lateral epicondyle of humerus. Inserts into the base of 2nd and 3rd metacarpal.
- Extensor digitorum: Extends digits 2-5 and wrist. Originates from the lateral epicondyle of the humerus. Inserts into the distal and middle phalanges of digits 2-5.
- Extensor digiti minimi (“lateralis” in cat): Extends 5th digit and wrist.
- Extensor carpi ulnaris: Extends and adducts wrist. Originates from the lateral epicondyle of the humerus. Inserts into the 5th metacarpal.

Deep muscles of the forearm:

Abductor pollicis longus: Abducts thumb.
Extensor pollicis brevis: Extends thumb.
Extensor pollicis longus: Extends thumb.

Eye- 6 extrinsic eye muscles (move eyeball)

Superior rectus: Rotates eyeball superiorly and medially (elevates and adducts). Originates from the "annular ring" deep in the orbit.
Inferior rectus: Rotates eyeball inferiorly and medially (depresses and adducts). Originates from the "annular ring" deep in the orbit.
Medial rectus: Rotates eyeball medially (adducts). Originates from the "annular ring" deep in the orbit.
Lateral rectus: Rotates eyeball laterally (abducts). Originates from the "annular ring" deep in the orbit.
Superior oblique: Rotates eyeball inferiorly and laterally (depresses and abducts). Originates from the "annular ring" deep in the orbit.
Inferior oblique: Rotates eyeball superiorly and laterally (elevates and abducts). Originates from the "annular ring" deep in the orbit.

Muscles of the abdominal wall: trunk movements and compression of abdominal viscera

Linea alba: Not a muscle, but a connective tissue line running vertically. Often called the "white line."
Rectus abdominis: Flexes vertebral column. Originates from the superior surface of pubis near symphysis. Inserts into the Costal cartilages of ribs 5-7 and xiphoid process.
External oblique: Flexion and rotation; lateral flexion of the vertebral column. Originates from the inferior 8 ribs. Inserts into the linea alba and iliac crest.
Internal oblique: Flexion and rotation; lateral flexion of the vertebral column. Originates from lumbar fascia, the inguinal ligament and iliac crest. Inserts into the inferior 4 ribs, the linea alba, and the pubic crest.
Transversus abdominis: Flexion; lateral flexion of the vertebral column. Originates from the iliac crest and cartilages of inferior 6 ribs. Inserts into the linea alba and pubic crest.

Muscles of the Head: Facial Expression

Epicranius : A bipartite muscle consisting of a frontal belly and occipital belly. They're attached by the galea aponeurotica, which is an aponeurosis (a sheet of connective tissue; a flat tendon).
- Frontal belly: Raises eyebrows.
- Occipital belly: Retracts scalp.

Muscles of Mastication

Masseter: Prime mover of jaw closure. Elevates and protracts mandible. Originates from the zygomatic arch. Inserts into the coronoid process and ramus of the mandible.
Temporalis: Elevates and retracts mandible.

Facial Muscles of Expression

Zygomaticus (major and minor): Elevates corners of the mouth. Often referred to as the "smiling muscle."
Levator labii superioris: Raises upper lip.
Risorius: Draws corner of lip laterally. Acts as a synergist with the zygomaticus.
Orbicularis oculi: Closes eye.
Orbicularis oris: Compresses and purses lips. Essential for kissing and whistling.
Buccinator: Compresses cheek. Used for whistling and sucking.

Muscles of the anterior neck and throat: Swallowing

Sternothyroid: Depresses thyroid cartilage (of larynx). Originates from the manubrium. Inserts into the thyroid cartilage.
Sternohyoid: Depresses hyoid. Originates from the manubrium and clavicle. Inserts into the hyoid bone.
Thyrohyoid: Depresses hyoid and elevates larynx. Originates from the thyroid cartilage. Inserts into the hyoid bone.
**Digastric “two bellies”: Depresses mandible; elevates hyoid bone. Originates from the mandible and mastoid process. Inserts into the hyoid bone by a connective tissue loop.
Mylohyoid: Elevates hyoid. Originates from the mandible. Inserts into the hyoid.

Muscles of the Neck and Vertebral Column: Head Movements and Trunk Extension

Sternocleidomastoid: Singly, rotates head to opposite shoulder. Together, flexes head. Originates from the manubrium of the sternum and clavicle. Inserts into the mastoid process.
Erector Spinae: Prime mover of back extension. Maintains posture. Consists of three muscles: iliocostalis, longissimus, and spinalis.

Muscles Crossing the Hip and Knee Joints: Movements of the thigh and leg

Iliopsoas: Part of the Iliopsoas complex (Illiacus and Psoas Major). It's visible inside the abdominal cavity. On beef, it's the filet mignon!
- Psoas major: Prime mover in thigh flexion. Originates from the lumbar vertebrae. Inserts into the lesser trochanter of the femur.
- Iliacus: Prime mover in thigh flexion. Originates from the iliac fossa. Inserts into the lesser trochanter of the femur.
Sartorius: Flexes and laterally rotates thigh; flexes knee. Originates from the anterior superior iliac spine. Inserts into the tibia.

The Thigh Adductors

Adductor longus: Adducts, flexes thigh. Originates from the pubis near the pubic symphysis. Inserts into the linea aspera.
Adductor magnus (= "adductor femoris" in cats): Adducts, flexes and medially rotates thigh. Originates from the ischium and pubis. Inserts into the linea aspera of the femur.
Pectineus: Adducts, flexes thigh. Originates from the pubis. Inserts into the posterior femur.
Gracilis: Flexes knee; adducts and flexes thigh. Originates from the pubis. Inserts into the medial tibia.

Anterior Muscles of Thigh - Quadriceps femoris = Group name (composed of 4 muscles)

Rectus femoris: Extends knee and flexes thigh. Originates from the anterior inferior iliac spine. Inserts into the patella and tibial tuberosity.
Vastus lateralis: Extends knee. Originates from the Greater trochanter and linea aspera. Inserts into the patella and tibial tuberosity.
Vastus medialis: Extends knee. Originates from the linea aspera. Inserts into the patella and tibial tuberosity.
Vastus intermedius: Extends knee. Originates from the anterolateral femur. Inserts into the patella and tibial tuberosity.
Tensor fasciae latae: Steadies trunk on thigh. Originates from the iliac crest and anterior superior iliac spine. Inserts into the iliotibial tract (The fascia lata that ensheathes all the muscles of the thigh).

Posterior Muscles of Thigh

Gluteus maximus: Major extensor of thigh; laterally rotates thigh. Originates from the ilium, sacrum, and coccyx. Inserts into the gluteal tuberosity of the femur.
Gluteus medius: Abduction and medial thigh rotation. Originates from the ilium. Inserts into the greater trochanter of the femur.

Lower Leg Movements- 3 muscles called Hamstrings. These are located on the posterior thigh and have the same actions.

Semimembranosus: Extends thigh, flexes knee; medially rotates thigh. Originates from the ischial tuberosity. Inserts into the medial condyle of the tibia.
Semitendinosus: Extends thigh, flexes knee; medially rotates thigh. Originates from the ischial tuberosity. Inserts into the proximal medial surface of the tibia.
Biceps femoris: Extends thigh, flexes knee; laterally rotates thigh. Originates from the ischial tuberosity and the femur. Inserts into the fibula.

Muscles of the Leg: Movements of the ankle and Toe:

Triceps Surae- Large superficial muscle with two parts; Common insertion: via Achilles tendon onto calcaneous (gastrocnemius and soleus).
- Gastrocnemius: Plantarflexes foot; flexes lower leg. Originates from the medial and lateral condyles of the femur. Inserts into the calcaneal (achilles) tendon onto calcaneus.
- Soleus: Plantarflexes foot. Originates from the head of the fibula and tibia. Inserts into the calcaneal tendon onto calcaneus.
Tibialis anterior: Prime mover of dorsiflexion; inverts foot. Originates from the lateral condyle and tibial shaft. Inserts into the medial cuneiform and first metatarsals.
Fibularis longus: Plantarflexion and foot eversion. Originates from the head of the fibula. Inserts into the First metatarsal and medial cuneiform.

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This quiz covers the superficial muscles located in the anterior and posterior thorax, including the trapezius, latissimus dorsi, serratus anterior, pectoralis minor, and rhomboids. Test your knowledge on their functions, origins, and insertions. Ideal for anatomy students and healthcare professionals.