Objectives:
1. to identify the major skeletal muscles of the human body
2. to know the origin and insertion of number of skeletal muscles
3. to know the function of some of the skeletal muscles
4. to correlate between the different bones and the related skeletal muscles.
The skeletal muscles are named according to the following categories:
· the origin and insertion( the connected bones by a certain muscle)
· the function of the muscle
· the shape of the muscle
· the direction of the muscle fibers
· the region that the muscle is found in
In addition to the previous categories, the size of the muscle may be used in the name of the muscle especially if there were more than one muscle with the same shape or region of the muscles, also the depth of the muscle may be used in naming muscles.
The muscles of the head:
1. OCCIPITALIS muscle: a superficial thin muscle located at the posterior side of the skull (covering the occipital bone)
2. FRONTALIS muscle: a superficial thin muscle located at the anterior side of the skull (covering the frontal bone)
3. TEMPORALIS muscle: a superficial thin muscle located at the lateral side of the skull (covering the temporal bone)
The muscles of the face:
1. ORBICCULARIS OCCULI muscle: a superficial thin muscle surrounding the orbit.
2. ORBICCULARIS ORIS muscle: a superficial thin muscle surrounding the mouth.
3. NASALIS muscle: a superficial thin muscle covering the nasal bone.
4. MASSETER muscle: a superficial muscle connects between the zygomatic bone and the mandible.
5. BUCCINATOR muscle:
6. RISORIOUS muscle: a fibrous muscle extends from the mouth angle posteriorly to cover the parotid gland.
7. LEVATOR LABII SUPERIORIS muscle: extends from infraorbital foramen down to the moth.
8. MENTALIS muscle: a small muscle that is located at the medial region over the mandible.
9. DEPRESSOR LABII INFERIORIS muscle: lies at the lateral side of the mentalis muscle, depresses the lower lip.
10. DEPRESSOR ANGULI ORIS muscle: the most lateral muscle covering the mandible, lowering the angles of mouth.
The muscles of the neck:
1. PLATYSMA muscle: the most superficial muscle of the neck region. It is a very thin sheet of muscle, starting from the level of mouth angle, descending covering the neck with widening of its fibers till reaching the upper region of the chest.
2. STERNOCLIEDOMASTOID muscle: afibrous muscle attachés the sternum and clavicle, extending superiorly to inserts its fibers at the mastoid process of the temporal bone.
3. LEVATOR SCAPULAE muscle: attaches the scapula, directs its fibers superiorly to reach the transverse processes of the first five cervical vertebrae, acting in elevation of the scapula.
4. STERNOHYOID muscle: a thin muscle connecting between the sternum and hyoid bone.
5. STERNOTHYROID muscle: a connecting muscle between the sternum and thyroid cartilage.
6. THYROHYOID muscle: a connecting muscle between the hyoid and the thyroid cartilage.
7. OMOHYOID muscle: this thin fibrous muscle extends from hyoid bone down to the scapula obliquely.
The muscles of the chest wall:
1. PECTORALIS MAJOR muscle: the most superficial muscle of the chest, attaches the lateral sides of the sternum medially and the humerous laterally.
2. PECTORALIS MINOR muscle: lies deeper the pectoralis major muscle, connecting between the 3rd, 4th and 5th ribs medially and the coronoid process of the scapula laterally.
3. SERRATUS ANTERIOR muscle: a wide muscle that connects between the lateral border of the scapula and the first eight ribs anteriorly.
4. EXTERNAL INTERCOSTAL muscles: the deepest muscle connecting between the ribs obliquely directed from lateral to medial in the intercostal space, acting in inhalation.
5. INTERNAL INTERCOSTAL muscles: the innermost layer connecting between ribs obliquely from medial to lateral side in intercostal space, acting in exhalation.
6. SUBCLAVIUS muscle: very small one lies inferior to the scapula.
The muscles of the abdominal wall:
1. RECTUS ABDOMINIS muscle: the most superficial one, extends from the pubic bone superiorly to reach the costal cartilage of the 5th, 6th and 7th ribs.
2. EXTERNAL OBLIQUE muscle: directs from the inferior eight ribs inferiorly to reach the iliac crest.
3. INTERNAL OBLIQUE muscle: connects between the iliac crest and the costal cartilage of the last 3-4 ribs.
4. TRANSVERSUS ABDOMINIS muscle: the deepest muscle of the abdominal wall, orients its fiber transversely.
The muscles of the back:
1. TRAPIZIOUS muscle: the most superficial muscle of the back originates from the occipital bone, the spinous processes of the cervical vertebrae and the spinous processes of the thoracic vertebrae then inserts its fibers at the spine of the scapula and the clavicle.
2. LATISSEMUS DORSII muscle: in the lower half of the back, originates from the spinous processes of the lower six thoracic vertebrae, the lumber vertebrae, the iliac crest and sacrum then inserts at the humerous.
3. SUBSCAPULARIS muscle: fills the subscapular fossa.
4. INFRASPINATUS muscle: fills the infraspinous fossa.
5. SUPRASPINATUS muscle: fills the supraspinous fossa.
6. RHOMBOIDEUS MAJOR muscle: intermediate muscle connecting between the medial border of the scapula and the spinous processes of 2nd, 3rd, 4th and 5th of thoracic vertebrae.
7. RHOMBOIDEUS MINOR muscle: intermediate muscle connecting between the medial border of the scapula and the spinous processes of the 7th cervical and the 1st thoracic vertebrae.
The muscles of the gluteal region:
1. GLUTEAS MAXIMUS muscle: the most superficial one, extends from the posterior superior iliac spine and the lateral sides of the sacrum and coccyx to the proximal end of the femur.
2. GLUTEAS MEDIUS muscle: intermediate muscle extends from the iliac crest as a wide origin and inserts at the femur as narrow one.
3. GLUTEAS MINIMUS muscle: filling the iliac fossa of the ilium.
The muscles of the upper limb:
1. DELTOID muscle: the muscle of the shoulder connecting between the spine of the scapula and the clavicle superiorly and the humerous at the deltoid tuberosity inferiorly.
2. BICEPS muscle: the superficial muscle of the arm anteriorly.
3. TRICEPS muscle: the superficial muscle of the arm posteriorly.
4. BRACHIORADIALIS muscle: superficial muscle of the forearm laterally.
5. FLEXOR CARPI RADIALIS muscle: superficial muscle of the forearm located intermedially and obliquely inserted at the metacarpal bones causing the flexing of the wrist joint.
6. FLEXOR CARPI ULNARIS muscle: superficial muscle of the forearm located medially, inserted at the metacarpals, causing the flexing of the wrist joint.
The muscles of the lower limb:
1. QUADRICEPS muscle: the largest and most superficial muscle of the thigh, located at the anterior aspect, composed of four portions: RECTUS FEMORIS
VASTUS MEDIALIS muscle
VASTUS LATERALIS muscle
VASTUS INTERMEDIALIS muscle
2. SARTORIUS muscle: the tallest fibrous muscle, located at the medial aspects of the thigh obliquely.
3. GASTROCNEMIOUS muscle: the largest muscle of the leg, located posteriorly at the most top region of the leg.
4. SOLIOUS muscle: intermediate muscle, lies beneath the gastrocnemious muscle.
The types of muscle tissue:
1. STRIATED MUSCLE: each skeletal muscle contains many fibers, while each fiber is composed of large number of fibrils. The muscle fibril contains large number of nuclei, each fibril is divided into many zones separated by T tubes which gives the muscle the appearance of striation.
2. SMOOTH MUSCLE: the smooth muscle fibers are found individually, each one fiber has a spindle shaped cell, contains its own nucleus having the purple color.
3. CARDIAC MUSCLE: each cardiac cell may contain more than one nucleus, connected with intercalated discs formed from gap junction.
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