# muscular triangle

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Related to muscular triangle: Occipital triangle, carotid triangle, subclavian triangle, submandibular triangle, supraclavicular triangle, omoclavicular triangle, muscular triangle of neck

## mus·cu·lar tri·an·gle

(mŭs'kyū-lăr trī'ang-gĕl)The triangle bounded by the sternocleidomastoid muscle, the superior belly of the omohyoid muscle, and the anterior midline of the neck; the infrahyoid muscles occupy most of it.

Synonym(s): trigonum musculare [TA] .

Synonym(s): trigonum musculare [TA] .

## triangle

(tri'ang-gel) [L.**triangulum**]

A figure or area formed by three angles and three sides.

### anal triangle

The dorsal triangular region of the perineum from the point at the tip of the coccyx to a line between the two ischial tuberosities. The anal triangle contains the anus.

### anterior triangle of neck

The space bounded by the middle line of the neck, the anterior border of the sternocleidomastoid muscle, and a line running along the lower border of the mandible and continued to the mastoid process of the temporal bone.

### cephalic triangle

The triangle on the anteroposterior plane of the skull formed by lines joining the occiput and forehead and chin, and a line uniting the occiput and the chin.

### digastric triangle

The triangular region of the neck. Its borders are the mandible, stylohyoid muscle, and the anterior belly of the digastric muscle.

### triangle of elbow

The area in front of the elbow bounded by the brachioradialis and the pronator teres muscles on the sides, and with the base toward the humerus.

### facial triangle

The triangle bounded by the lines uniting the basion and the alveolar and nasal points, and one uniting the nasal and basion.

### femoral triangle

A triangular space located at the top of the thigh beneath the skin and the fascia lata. The base of the triangle is the inguinal ligament. The medial side is the adductor longus muscle, which meets the lateral side (the sartorius muscle) at the apex of the triangle approx. 4 cm down the thigh. The inside (deep) wall of the femoral triangle is formed by the iliopsoas and pectineus muscles. Running through the femoral triangle are the femoral nerve and the femoral sheath. See: femoral sheath

### frontal triangle

The triangle bounded by the maximum frontal diameter and the lines joining its extremities and the glabella.

### Hesselbach triangle

See: Hesselbach triangle.### inferior carotid triangle

The triangular space bounded by the middle line of the neck, the sternomastoid muscle, and the anterior belly of the omohyoid muscle. Synonym:

*muscular triangle*### inferior occipital triangle

The area having the bimastoid diameter for its base and the inion for its apex.

### Lesser's triangle

The triangle bounded below by the anterior and posterior bellies of the digastric muscle and above by the hypogastric nerve.

### lumbocostoabdominal triangle

The triangle bounded in front by the obliquus abdominis externus, above by the lower border of the serratus posterior inferior and the point of the 12th rib, behind by the outer edge of the erector spinae, and below by the obliquus abdominis internus.

### muscular triangle

Inferior carotid triangle.### mylohyoid triangle

The triangular space formed by the mylohyoid muscle and the two bellies of the digastric muscle.

### triangle of necessity

Inferior carotid triangle.### occipital triangle of the neck

The triangle bounded by the sternocleidomastoid, the trapezius, and the omohyoid muscles.

### omoclavicular triangle

Subclavian triangle.### omohyoid triangle

Superior carotid triangle.### triangle of Petit

The space above the hip bone between the exterior oblique muscle, the latissimus dorsi, and the interior oblique muscle.

### posterior cervical triangle

The triangular region wrapping around the side of the neck bounded by the upper border of the clavicle, the posterior border of the sternocleidomastoid muscle, and the anterior border of the trapezius muscle.

### pubourethral triangle

A triangular space in the perineum bounded laterally by the ischiocavernous muscle, medially by the bulbocavernous muscle, and posteriorly by the superficial transverse perineus muscle.

### Scarpa's triangle

See: Scarpa's triangle### subclavian triangle

A triangular space bounded by the posterior belly of the omohyoid, the upper border of the clavicle, and the posterior margin of the sternocleidomastoid. Synonym:

*omoclavicular triangle*;*supraclavicular triangle*### submandibular triangle

The triangular region of the neck, bounded by the inferior border of the mandible, the stylohyoid muscle and the posterior belly of the digastric muscle, and the anterior belly of the digastric muscle; it is one of three triangles included in the anterior triangle of the neck. This was formerly called the submaxillary triangle.

### submental triangle

A superficial region under the chin with its base being the hyoid bone and its right and left walls being the right and left anterior bellies of the digastric muscle. The front wall of the triangle is skin; the back wall is the outer surface of the mylohyoid muscle.

### suboccipital triangle

The triangle bounded by the obliquus inferior and superior muscles on two sides and the rectus capitis posterior major muscle on the third side. The floor contains the posterior arch of the atlas bone and the vertebral artery. It is covered by the semispinalis capitis muscle.

### superior carotid triangle

The space bounded by the anterior belly of the omohyoid muscle, the posterior belly of the digastricus muscle, and the sternomastoid muscle.

### supraclavicular triangle

Subclavian triangle.### suprameatal triangle

The triangle slightly above and behind the exterior auditory meatus. It is bounded above by the root of the zygoma and anteriorly by the posterior wall of the exterior auditory meatus.

### urogenital triangle

The triangle with its base formed by a line between the two ischial tuberosities and its apex just below the symphysis pubis.

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